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Chpt. 12 (Nervous System Overview)
Why is it important to study the nervous system?
Overview
Basic Functions of the Nervous System
Sensory Input
Stimulus – a change (e.g., temperature changes) in something outside or inside the body.
Sensory Receptors – monitor changes (e.g., falling temperature).
Integration – processing and interpreting stimuli to decide “what to do…” (e.g., shiver).
Motor Output – response, “what is done” (e.g., shivering)
Effectors – effector organs (e.g., muscles and glands) that carry out response (skeletal muscle
contraction and relaxation during shivering).
Basic Structural Divisions of the Nervous System
Central Nervous System/CNS
Brain & Spinal Cord
Peripheral Nervous System/PNS
Cranial Nerves
Spinal Nerves
Ganglia
Discussion Question
Explain to your neighbor how the brain and spinal cord form. Be sure to specify developmental stage of brain
and spinal cord formation, the primary germ layer(s) involved, and the role of the notochord.
Basic Terms Associated with the Functional Divisions of Nervous System
Sensory/Afferent – carrying signals toward the CNS.
Motor/Efferent – carrying signals away from the CNS.
Somatic – structures external to the ventral body cavity; “outer tube” structures.
Visceral – structures within the ventral body cavity; “inner tube” structures.
1
Functional Subdivisions of the Nervous System
Somatic Sensory – “outer tube” senses.
General/Widespread – touch, pain, pressure, vibration, temperature.
Proprioception – “body sense” (e.g., circumduct your finger with your eyes closed).
Special/Localized – hearing, equilibrium/balance, and vision.
Visceral Sensory – “inner tube” senses.
General/Widespread – stretch, pain, temperature.
Special/Localized – taste and smell.
Somatic Motor – voluntary nervous system (e.g., contraction of skeletal muscles).
Visceral Motor – involuntary nervous system [e.g., contraction of small intestine smooth muscle
(peristalsis)].
Nervous Tissue – two main types of cells.
Neurons – excitable cells.
Function, Special Characteristics, Structure, Synapses, Classification (Structural & Functional Classifications)
Supporting Cells – largely non-excitable cells.
CNS vs. PNS
Myelin Sheaths
CNS vs. PNS
Questions
Provide example of a scenario involving sensory input, integration, and motor output.
a hot our face figure out it's not da removes hand
fingerWhat
touching
are the two primary structural
components of the CNS?
,
,
from surface
.
Brain da spinal cord
What are the three primary structural components of the PNS?
cranial spinal , 4
Provide a synonym for ganglia
“sensory” and define the term.
,
Afferent conducting
-
inward
or
toward something
Provide a synonym for “motor” and define the term.
Efferent conducting outward or away from romething
Provide an example
of an “outer tube” structure.
-
ear
Provide an example of an “inner tube” structure.
Provide tongue
an example of a general somatic “feeling”.
touch
Provide an example of a specific visceral “feeling”.
shivering
Briefly differentiate between somatic motor and visceral motor subdivisions of the PNS.
VO Matic
-
voluntary
visceral
-
involuntary
2
Neurons/Nerve Cells
Function of Neurons - transmission of electrical signals and release of neurotransmitters.
Nerve Impulses & Action Potentials – reversals of electrical charge (e.g., action potentials) travel
along the plasma membrane of a neuron; depolarization [interior membrane potential becomes less
negative (> -70 mV)] followed by repolarization [interior membrane potential returns to resting
potential (-70 mV)]. Most neurons also release chemical messengers/neurotransmitters.
Special Characteristics of Neurons
Extreme Longevity – neurons last a lifetime (100+ years).
Do Not Divide – in general, neurons do not undergo cell division; however, some exceptions.
High Metabolic Rate – neurons require lots of O2 and glucose; neurons can only live for a few minutes
without molecular oxygen.
Structure of Neurons
Cell Body/Soma/Perikaryon – houses the nucleus with nucleoli surrounded by cytoplasm.
Processes – two types of cellular processes; differ structurally and functionally.
Dendrites – most numerous, more than one per neuron; serve as receptive sites for signals from other
neurons; conduct signals toward the cell body/soma.
Axons – one per neuron; serve as impulse generators and conductors; conduct signals away from cell
body/soma.
Nerve Fibers – name given to long axons.
Synapses – sites of neuron communication; specialized cell junction.
Neurotransmitters – chemical messengers; most neurons communicate using neurotransmitters.
Presynaptic Neurons – carry electrical signals toward a synapse.
Postsynaptic Neurons – carry electrical signals away from a synapse.
Types of Synapses
Common Synapses
Axodendritic – most common type of synapse; axon to dendrite.
Axosomatic – common; axon to cell body/soma.
Uncommon Synapses
Axoaxonic – not very common; axon to axon.
Dendrodendritic – not very common; dendrite to dendrite.
Dendrosomatic – not very common; dendrite to cell body/soma.
Electrical Signals – remember that the direction the signal travels is important.
3
Classification of Neurons
Structural – classes based on structural differences.
Multipolar Neurons – more than two processes; most neurons (~99%).
Bipolar Neurons – two processes; rare, occur in special sensory organs (e.g., inner ear and eye).
Unipolar Neurons – short, single process that branches; actually fused processes of bipolar neurons; so, in
fact, should be called pseudounipolar; these are typical sensory neurons.
Functional – classes based on functional differences.
Sensory/Afferent Neurons – carry signals toward the CNS; almost all are unipolar.
Motor/Efferent Neurons – carry signals away from the CNS; multipolar.
Interneurons/Association Neurons – located between sensory and motor neurons; confined to CNS; ~99%
of all neurons; mostly multipolar.
Questions
Briefly describe the 3 “special characteristics” of neurons.
lait a lifetime Do Not divide
longevity
Differentiate
between axons and dendrites.
extreme
axon r
-
one
-
"
per neuron , conducts
What are nerve fibers?
"
signals away
from cell
-
no
cell division
bodytoo ma
High
Metabolic Rate alot of 02h
glucose
-
five only
dendrite o
-
more
a
few minute i
than
r
longareaxon
What
the chemicals called that are released at axon terminals?
one
's
conduct
w
Io
signal rate
,
neurotransmitter
Briefly differentiate between presynaptic and postsynaptic neurons.
toward synapse
electrical
presynaptic
pastry haptic electrical signal away
Briefly describe signals
a dendrosomatic synapse.
-
-
dendwromatio
-
from
synapse
dendrite to all body) roma
Which structural class of neurons is most common?
Multipolar
Which functionalNeurons
class of neurons is most common?
Association
neuron
Draw a typical multipolar neuron labeling the following: nucleus, nucleolus, cell body/soma, axon, Schwann cells,
axon terminals, and dendrites.
ifeng.g.ba
day,roy
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.
4
Supporting Cells – largely non-excitable cells that surround and may even wrap around neurons; six types (four
CNS, two PNS).
CNS
Neuroglia/Glial Cells – “nerve glue”; are capable of cell division; comprise about ½ mass of brain.
Astrocytes – star-shaped glial cells; most numerous; take up and release ions; recycle neurotransmitters.
Microglial Cells – smallest glial cells; least numerous; they are phagocytoic cells, generalist defense cells.
Ependymal Cells – form a simple ciliated epithelium that is very permeable; this epithelium lines the
central cavity of the brain and spinal cord; recall that the brain and spinal cord are derived from the
embryonic dorsal hollow nerve cord.
Cerebrospinal Fluid vs. Tissue Fluid – cerebrospinal fluid fills the central cavity of the brain and
spinal cord and tissue fluid bathes/surrounds the cells of the CNS.
Oligodendrocytes – glial cells that send out processes to wrap around several thick axons of the CNS; form
myelin sheaths.
PNS
Satellite Cells – surround cell bodies within the ganglia.
Schwann Cells/Neurolemmocytes – surround axons in the PNS; form myelin sheaths.
Myelin Sheaths – help to speed impulse conduction along axons; electrical impulse jumps between Nodes of
Ranvier.
PNS
Schwann Cells – surround axons of the PNS.
Nodes of Ranvier/Neurofibral Nodes – gaps in myelin sheath between Schwann cells.
Unmyelinated Axons – relatively, thin and slowly conducting axons; Schwann cells are still present but do
not wrap around axons.
CNS
Oligodendrocytes – cellular processes coil around several axons at the same time within the CNS.
Nodes of Ranvier – gaps in myelin sheath between cellular extensions.
Discussion Question
Explain to your neighbor the differences and similarities between Schwann cells and oligodentrocytes. Be sure
to describe the functional role of myelin sheaths and Nodes of Ranvier.
5
Nerves & Associated Connective Tissues
Nerve – a collection of nerve fibers; the cable-like organs of the PNS; each nerve consists of many axons both
myelinated and unmyelinated.
Axons – the one per neuron; serve as impulse generators and conductors; conduct signals away from cell
body/soma.
Schwann Cells – surround axons of the PNS.
Endoneurium – loose connective tissue that surrounds the Schwann cells.
Nerve Fascicles – groups of axons bundled together.
Perineurium – connective tissue that surrounds nerve fascicles.
Nerve – a collection of nerve fascicles bundled together along with blood vessels, which provide
nourishment to axons and Schwann cells.
Epineurium – fibrous connective tissue that surrounds a nerve.
Caution
Neurons = nerve cells.
Nerve Fiber = long axon.
Nerve = a collection of nerve fibers/long axons.
Reflex Arc – simple chain of neurons involved in simple reflex behaviors (i.e., rapid, automatic motor responses)
Stimulus → Receptor → Sensory/Afferent Neuron → Integration in CNS (Interneurons) → Motor/Efferent
Neuron → Effector Organ → Response
Neuronal Circuits
Diverging Circuit to Multiple Pathways
Converging Circuits to a Single Pathway
Questions
Differentiate among axons, nerve fascicles, and nerves.
axons da newer collection of nerve farcider
axon ii
away ;Never farcider group
gnaw
Differentiate among endoneurium,
perineurium,, and epineurium.
endometrium loose connective time , rumoured Schwann cells , perineurium , connective surround nerve fascicler 4 Epineurium fibrour connective
surrounds nerve
Differentiate among neurons, nerve fibers, and nerves.
-
of
-
-
,
-
neuronV
-
nerve cellr nerve fiber
-
-
long axon 4
,
Nerve=
-
collection of nervefibersI
long axon
6
Chpt. 13 (Central Nervous System)
Why is it important to study the central nervous system?
CNS
Brain & Spinal Cord
DHNC derived from ectoderm
Overview
Gray Matter – sites where neuron cell bodies are clustered; surrounds hollow central cavity; also, external gray
matter present in the brain.
White Matter – external to internal gray matter; no cell bodies, but millions of axons present; color is from
myelin sheaths.
Directional Terms – a new directional term associated with the head.
Rostral – toward the snout/nose; you may also use anterior in humans.
Caudal – toward the tail.
Brain Development – initially the brain is a simple neural tube and then it swells in some areas and the primary
vesicles (forebrain, midbrain, and hindbrain) develop; secondary vesicles then form; followed by adult brain
structures; the neural/central canal will also expand within the developing brain, forming ventricles, which are
filled with cerebrospinal fluid.
Basic Structural Components of the Brain
Cerebral Hemispheres, Diencephalon, Brain Stem, Cerebellum, and Ventricles
Functional Systems of the Brain
Limbic and Reticular Systems
Protection of the Brain
Spinal Cord – neural tube caudal to the brain.
Anatomy
Sensor and Motor Pathways
Questions
During which embryonic stage do the brain and spinal cord form?
Neuralation
The brain and spinal cord are derived from which primary germ layer?
ectoderm
Briefly differentiate between gray matter and white matter.
matter neuron cell bodies clustered ;surrounding central cavity ; White millions of axon ;
da color from mykin r heath
gray
What is unique about the brain with respect to distribution of gray matter as compared to the
spinal cord?
-
-
Differentiate among anterior, cranial, and rostral.
they
all mean toward the
novel rnout
7
Prosencephalon, Mesencephalon, & Rhombencephalon
Prosencephalon – forebrain
Telencephalon → Cerebral Hemispheres/Cerebrum
Lateral Ventricles
Diencephalon → Thalamus, Hypothalamus, & Epithalamus
Third Ventricle
Mesencephalon – midbrain
Mesenecephalon → Midbrain Portion of Brain Stem
Cerebral Aqueduct
Rhombencephalon – hindbrain
Metencephalon → Pons Portion of Brain Stem + Cerebellum
Fourth Ventricle
Myelencephalon => Medulla Oblongata Portion of Brain Stem
Fourth Ventricle
Questions
Differentiate between vesicles and ventricles with respect to the brain.
Ventricle is the
hollow cavity
j vesicle
is the filled
cavity
What are the three primary vesicles of the brain?
Pros encephalon
,
Metencephalon da
,
Rhombencephalon
The telencephalon will differentiate into the __________.
cerebrum
Thalamus __________, and Epithalamia
The diencephalon will differentiate into __________,
__________.
Hypothalamus
What is the cerebral aqueduct?
Midbrain
What are the three parts of the brain stem?
midbrain , pond da medulla oblongata
,
Differentiate between cerebrum and cerebellum.
(ftp.brumir
the
lateral vent tribal
da cerebellum ir
the
fourth ventricle
Sketch the primary brain vesicles (prosencephalon, mesencephalon, rhombencephalon) and spinal cord. List the
secondary brain vesicle derivatives of the primary brain vesicles.
mmmm
.÷¥ix
t.enam.vn
Metencephalon
Nylencephalon
8
Basic Parts of the Brain
Cerebral Hemispheres/Cerebrum
Diencephalon
Brain Stem
Midbrain
Pons
Medulla Oblongata
Cerebellum
Ventricles & Central Canal
Ventricles – expansions of the brain’s central cavity/canal filled with cerebrospinal fluid.
Lateral Ventricles – are the paired (i.e., left and right) 1st and 2nd ventricles located within the cerebral
hemispheres.
Third Ventricle – located within the diencephalon.
Cerebral Aqueduct – located within the midbrain; connects 3rd and 4th ventricles.
Fourth Ventricle – located within the hindbrain (i.e., pons, cerebellum, & medulla oblongata).
Central Canal – spinal cord; not a ventricle.
Cerebral Hemispheres/Cerebrum
Gross Anatomy
Grooves and Ridges
Fissures – deepest grooves; separate major portions of the brain.
Sulci – smaller grooves on the surface of cerebral hemispheres.
Gyri – folds/ridges on the surface of the cerebral hemispheres located between the sulci.
Lobes – are separated by deep sulci and are named for the overlying cranial bones.
Frontal, Parietal, Occipital, & Temporal
Internal Structure – look at a frontal section through the brain.
Cerebral Cortex – external/superficial gray matter.
Cerebral White Matter – located in between the cerebral cortex and deep gray matter; composed of
axons.
Deep Gray Matter – internal/deep surrounding ventricles.
Basal Ganglia & Basal Forebrain Nuclei
Questions
List the four primary structural divisions of the brain.
dice hp halo n , brainstem, da cerebellum
Why is the third ventricle not called
the second ventricle and what is the function of the cerebral aqueduct?
made up of three parter ; cerebral
aqueduct connect the 4th da 3rd ventricle
Differentiate among fissures, sulci and gyri.
folder fridge
Fivvurev deepest grower , sulci smaller-1 groover , 4 gyri
List the four lobes of the cerebral cortex and point to them as you list them.
Frontal , parietal , occipital da temporal
cerebrum
,
-
-
-
-
9
Cerebral Cortex – “conscious mind”; superficial gray matter.
Motor Areas – control motor functions, mostly movements.
Primary Motor Cortex – controls skilled voluntary movements (e.g., fingers, facial muscles).
Premotor Cortex – controls complex movements (e.g., hand-eye coordination).
Frontal Eye Field – controls voluntary eye movements.
Broca’s Area – controls speech production.
Sensory Areas – conscious awareness of sensation.
Primary Somatosensory Cortex – processes general somatic sensory information (e.g., touch, pain, pressure,
temperature, proprioception).
Primary Visual Cortex – processes sensory information from the eye (i.e., retina).
Primary Auditory Cortex – processes sensory information from the inner ear (i.e., cochlea).
Gustatory Cortex – processes sensory information from tastebuds.
Vestibular Cortex – processes sensory information on equilibrium/balance from inner ear [i.e, vestibule, semicircular
canals (ducts)].
Olfactory Cortex – processes sensory information on smell from the olfactory epithelia.
Association Areas – integrate senses and memories; make sense of sensory information; “higher order processing areas”.
Somatosensory Association Cortex – integrates sensory information from primary somatosensory cortex to
understand sensations (e.g., someone standing very close to you and you feel pressure on your foot → maybe
someone standing very close to you is standing on your foot).
Visual Association Area – processes visual information by analyzing color, form, movement (e.g., zebra).
Auditory Association Area – identifies sound and memories of past sounds (In the jungle, the mighty jungle…)
Prefrontal Cortex – performs cognitive functions (i.e., “thinking”) and helps to control emotions.
General Interpretation Area – integrates information from all other sensory association areas (e.g., looks like a duck,
quacks like a duck…).
Language Area
Wernicke’s Area – recognizing and understanding speech.
Insula – sometimes referred to as the 5th lobe; it perceives visceral sensations such as nausea.
Lateralization – 90-95% of individuals exhibit these generalizations.
Left Hemisphere – Details
Language, Math, Logic
Right Hemisphere – Big Picture
Visual-Spatial, Social, Art, Music, Emotion
Body Map – illustrates the relative amount of cortical tissue devoted to a function as indicated by the relative size of the
body region/part; note the size of the hands and size of the lips.
Primary Motor Cortex – controls skilled voluntary movements.
Primary Somatosensory Cortex – touch, pain, pressure, temperature, proprioception.
Brodmann’s Areas – 52 structurally different areas of the cerebral cortex; motor areas – movement; sensory areas –
awareness; association areas – integration of senses and memories; note prefrontal cortex – “thinking” and medial
occipital lobe – vision.
10
Questions
Which part of your cerebral cortex are you using when you successfully swat a fly?
premotor
Which part
of your cerebral cortex are you using when you write your name with a pen?
primary
Motor
Which part of your cerebral cortex are you using when you watch a bird fly across the sky?
virtual
primary
Which part
of your cerebral cortex are you using when you say “dorsoepitrochlearis”?
Broca 's area
Which part of your cerebral cortex are you using when you see a humerus?
primary
Which
part of your cerebral cortex are you using when you hear a dog bark?
somatosensory
auditory
primary
Which part of
your cerebral cortex
are you using when you taste chocolate?
gustatory
Which part of your
cerebral cortex are you using when you smell a burning candle?
olfactory
Which part of your
cerebral cortex are you using when you “feel cold”?
romatouenrory
Which primary
part of your cerebral
cortex are you using when you lean to the left?
Which part of yourvestibular
cerebral cortex are you using when you recognize photos of your parents?
visual aooociati on
Which part of your cerebral cortex are you using when you recognize your friend’s voice?
avvociati on
Which part ofauditory
your cerebral cortex are you using when you think about blood flow through the heart?
Vomatosenrory arrow
ion
Which part of your cerebral cortex are you using whenat
you understand the word “ethmoid”?
Wernicke 's area
Which part of your cerebral cortex may you be using when you ride a roller coaster?
Brodmann 's
area
Discussion Question
While looking at the body map, discuss with your neighbor the relative size relationships among hands, feet, and
lips. Why are they represented in this way?
Cerebral White Matter – allows for communication via long axons/nerve fibers, which bundle together to form
tracts.
Commissural Fibers
Corpus Callosum – connects right and left cerebral hemispheres.
Association Fibers – connect different parts of the same cerebral hemisphere.
Projection Fibers – connect the cerebral cortex to more caudal parts of the CNS (e.g., medulla oblongata, spinal
cord).
Deep Gray Matter
Basal Ganglia – involved in motor control; coordinates with cerebral cortex; also non-motor function-act like an
hourglass, tracking the passage of time.
Basal Forebrain Nuclei – associated with memory; degeneration is associated with Alzheimer’s.
11
Diencephalon – forms the central core of the forebrain/prosencephalon and is composed of the thalamus,
hypothalamus, and epithalamus.
Thalamus
Structure – egg-shaped, paired structure, makes up ~80% of the diencephalon, forms superolateral wall
of the 3rd ventricle.
Intermediate Mass/Interthalamic Adhesion – connects right and left halves of thalamus.
Function – processes and relays information to the cerebral cortex.
Hypothalamus – main visceral control center; located below the thalamus.
Structure
Third Ventricle – forms inferolateral walls.
Pituitary/Hypophysis – projects inferiorly from hypothalamus; sits in hypophyseal fossa of the sella
turcica of the sphenoid.
Functions
Controls Autonomic Nervous System
Controls Emotional Response
Regulation of Body Temperature
Regulation of Hunger and Thirst Sensations
Controls Behavior
Regulation of Sleep-Wake Cycles
Control of Endocrine System (Pituitary Gland)
Formation of Memory (Mammillary Body)
Epithalamus
Pineal Gland – located superior to thalamus.
Third Ventricle Roof
Melatonin – a hormone secreted by the pineal gland that signals the body to prepare for nighttime sleep.
Questions
What are the three components of the diencephalon?
hypothalamus epithalamium
pituitary gland
Melatonin is secreted by which part of the diencephalon?
pineal gland
thalamus
,
,
Which part of the diencephalon is sometimes called the “master gland”?
12
Brain Stem – composed of three regions: midbrain, pons, & medulla oblongata.
Midbrain – mesencephalon.
Structure
Cerebral Aqueduct – ventricle; connects third and fourth ventricles.
Tectum – roof of the midbrain.
Cerebral Peduncles – floor of midbrain.
CN III-IV Nuclei
Corpora Quadrigemina
Superior Colliculus – associated with visual reflexes.
Inferior Colliculus – associated with auditory reflexes.
Function – associated with “fight or flight” response/integration.
Pons
Structure – forms a bridge supporting right and left cerebellar hemispheres.
CN V-VII Nuclei
Function – a relay center.
Medulla Oblongata
Structure – continuous with the spinal cord.
CN VIII-XII
Functions
Cardiac Center – adjusts force and rate of heartbeat.
Vasomotor Center –helps to regulate blood pressure.
Medullary Respiratory Center – sets basic rhythm and rate of breathing.
Hiccupping, Swallowing, Coughing, Sneezing
Questions
What does the acronym CN mean?
cranial
nerve
What is the function of the cerebral aqueduct?
to connect 3rd da 4th ventri cat
What are the components of the corpora quadrigemina and how many components are there?
inferior colliculus
Vuperiordg
What does the midbrain do?
4
component
fight or flight reaction
Which cranial nerve is capable of lowering heart rate?
CNX
What part of the brain controls sneezing reflex?
Medullary Respiratory center
What part of the brain helps regulate blood pressure?
Volvo motor Center
"
"
13
Cerebellum – often described as a “cauliflower-like” organ; constitutes 11% of brain’s mass.
Structure
Cerebellar Hemispheres – right and left halves.
Vermis – median “worm-like” structure.
Folia – ridges.
Fissures – grooves.
Arbor Vitae – internal white matter; “tree of life”.
Function – smoothes and coordinates body movements; helps maintain posture and balance (i.e., coordination).
Functional Brain Systems – networks of neurons that work together despite the locations.
Limbic System – sometimes referred to as the “emotional brain”; it is spread widely throughout the forebrain.
Structures and Functions
Fornix – a fiber tract that links the limbic system together, in part.
Amygdaloid Body/Amygdala – processes fear and stimulates sympathetic response.
Cingulate Gyrus – allows one to shift between thoughts and express emotions through gestures.
Hippocampus – encodes, consolidates, and retrieves memories of facts and events.
Reticular Formation – spans the brainstem.
Structure – runs through the central core of the midbrain, pons, and medulla oblongata.
Function – maintains cerebral cortex alertness and consciousness.
Questions
How would you briefly describe the function of the cerebellum?
hand eye coordination
Which part of the limbic system would be active while you are smiling?
Gurus
cingulate
Which part
of the limbic system allowed you to learn the concept of the “humerus”?
Which functionalHippocampus
part of your brain must work very hard during “mindnumbing” lectures?
Reticular Formation
What structure links the limbic system together?
Fornix
If an individual has difficulty remembering the muscle “omotransversarius”, what part of the brain may not be
functioning optimally? Hippocampus
14
Protection of the Brain – the brain is protected by the skull, surrounding membranes, cerebrospinal fluid, and the
blood-brain barrier.
Bone – cranial bones (e.g., frontal, parietal, temporal).
Meninges – connective tissue membranes that lie external to the brain and spinal cord.
Dura Mater – the most external membrane, tough two-layered membrane.
Periosteal – portion associated with the periosteum of the overlying cranial bones.
Meningeal – true external covering of the brain.
Subdural Space – the space between the dura mater and the arachnoid mater.
Arachnoid Mater – middle membrane; “spider-like” membrane.
Subarachnoid Space – the space between the arachnoid mater and the pia mater; contains large blood
vessels that supply the brain.
Pia Mater – the most internal membrane; clings to the brain’s surface; composed of delicate connective
tissue that is richly vascularized.
Cerebrospinal Fluid – watery substance that helps to nourish the brain.
Blood-Brain Barrier – some blood-borne molecules cannot cross continuous brain capillaries (e.g., urea, food
and bacterial toxins).
Questions
Briefly describe how the brain is protected?
fluid
Bones
, cerebrospinal
Name the Meininger
three types of meninges?
dltr a maters Arachnoid Mater ,
What type(s) of capillaries are found within the brain?
continuous brain ca pillar ie r
Name a cranial bone.
Barrier
Blood brain
-
,
du pi
a
Mater
occipital
15
Spinal Cord – runs through the vertebral canal.
Functions
Sensory and Motor Innervations Inferior to Head
31 Pairs of Spinal Nerves of PNS (Dorsal/Ventral Roots)
Cervical, Thoracic, Lumbar, Sacral, Coccygeal – divisions of the spinal nerves.
Two-Way Conduction Pathway Between Body and Head
Major Center for Reflexes – reflex arcs.
Structure
Protection
Vertebrae, Meninges, and Spinal Dural Sheath
Epidural Space – cushioning fat and a network of veins, anesthetics are injected into the epidural space.
Anterior Median Fissure and Posterior Median Sulcus – deep grooves that roughly divide the spinal cord
into right and left halves.
Lateral vs. Anteroposterior – spinal cord is wider laterally.
Gray Matter – inner region only; composed of neuron cell bodies.
H “Shaped”
Gray Commissure – forms “crossbar” between the right and left halves.
Central Canal – filled with cerebrospinal fluid.
Posterior Horns – interneurons.
Anterior Horns – mostly motor neurons.
Lateral Horns – present in thoracic and superior lumbar regions.
Dorsal Root & Doral Root Ganglia vs. Ventral Root (PNS) – dorsal root–sensory; ventral root–motor.
Divisions – correspond to basic divisions of the nervous system.
Somatic Sensory
Visceral Sensory
Visceral Motor
Somatic Motor
White Matter – composed of myelinated and unmyelinated axons; allows communication between different
parts of the spinal cord and between the spinal cord and the brain.
Nerve Fibers/Long Axons
Ascending Fibers – carry sensory information to the brain from sensory neurons.
Descending Fibers – carry motor instructions from the brain and spinal cord to effector organs.
Commissural Fibers – cross from one side of the spinal cord to the other side within the spinal cord.
16
Questions
What bony structures protect the spinal cord?
Vetebrae
31
How many pairs of cranial nerves?
How many pairs of spinal nerves?
12
Describe the epidural space.
✓
LUV hi on in
; network of nerve
Faf
Where is the spinalgcord
gray matter located?
inner region only
What types of neurons
are found throughout the spinal cord?
durrah Root da Dorval Root Gan alia , Ventral
Differentiate between dorsal and ventral roots.
dorsal sensory ventral
What makes up spinal cord white matter?
myelinated du unmyelinated axon
Define nerve fibers.
-
-
motor
long among ascending descending, and commissural nerve fibers.
Differentiate
ascending reno or y info to brain ;
Root
atour
descending
-
Comin is Surat
-
cross
from
one
-
sensory
info away
.
fbhfamin
ride to the other
17
Chpt. 14 (Peripheral Nervous System)
Why is it important to study the peripheral nervous system?
Peripheral Nervous System/PNS
Cranial Nerves & Spinal Nerves
Functional Organization
Sensory/Afferent Division – carries signals toward the CNS.
Somatic Sensory – “outer tube” senses.
General/Widespread – touch, pain, pressure, vibration, temperature.
Special/Localized – hearing and balance.
Visceral Sensory – “inner tube” senses.
General/Widespread – stretch, pain, temperature.
Special/Localized – taste and smell
Motor/Efferent Division – carries signals away from the CNS.
Somatic/Voluntary Motor/Voluntary Nervous System – voluntary nervous system (e.g., contraction
of skeletal muscles).
Visceral/Involuntary Motor/Autonomic Nervous System – involuntary nervous system [e.g.,
contraction of small intestine smooth muscle (peristalsis)].
Parasympathetic – “rest & digest”; “housekeeping”.
Sympathetic – “fight, flight, or fright”.
Questions
What are the two main subdivisions of the nervous system?
Peripheral da cranial
What are the components of the CNS?
rehrory a motor
What are the components of the PNS?
cranial Grp in at newer
Briefly differentiate between afferent
and efferent divisions of the PNS.
toward brain
efferent
from brain
Briefly differentiate between somatic senses and visceral senses.away
romantic hearing h balance visceral tarted vmeu
Briefly differentiate between somatic motor and visceral motor.
Vomatic skeletal muncher visceral smooth musher
What is the ANS and what are its two primary components?
Autonomic Nervous syvtem parasympathetic
afferent
-
-
-
-
-
-
-
sympathetic
18
Structural Components of PNS
Sensory Receptors – pick up stimuli (changes inside and outside of the body); sensory/afferent neurons
carry signals toward the CNS.
Classification by Location, Stimulus Detected, & Structure
Motor Endings – axon terminals of motor/efferent neurons that innervate effectors (i.e., muscles & glands);
carry signals away from the CNS.
Innervation of Somatic (i.e., Skeletal) Muscles – largely under voluntary control.
Innervation of Visceral (i.e., Smooth & Cardiac) Muscle & Glands (ANS) – largely under involuntary
control.
Nerves and Ganglia
Nerve – a collection of nerve fibers/long axons wrapped in connective tissue and containing vessels.
Sensory, Motor, & Mixed Nerves – most nerves contain both sensory and motor axons (i.e., they are
mixed nerves).
Cranial Nerves – 12 pairs associated with the brain.
Spinal Nerves – 31 pairs associated with the spinal cord.
Ganglia – areas of concentrated cell bodies wrapped in connective tissue.
Questions
Differentiate between sensory receptors and motor endings with respect to the CNS.
✓ env ory pick up stimuli motor innervate effectorV
Differentiate between motor innervation of skeletal muscle, smooth muscle, and cardiac muscle.
V ke let al voluntary smooth h cardiac
involuntary
Differentiate between nerve, nerve fiber, and neuron.
nerve collection of nerve fiber , nerve fiber u long axonr , neuron
Differentiate between cranial and spinal nerves.
cranial 12 Pairs spinal 31 pair r
What are ganglia?
concentrated cell bodie r
Name a common type of ganglion associated with spinal nerves?
-
-
-
-
-
-
-
-
-
spinal cord
19
Peripheral Sensory Receptors – classified up to three different ways: location, stimulus detected, and structure.
Classification by Location
Exteroceptors – located near the body surface; sense touch, pressure, pain, temperature, special senses.
Interoceptors – internal; gut tube, bladder, lungs; sense visceral pain, nausea, hunger, fullness.
Proprioceptors – associated with musculoskeltal organs; “body sense” (e.g., close your eyes and move
your arm about – you still have some sense of where your arm is even though you no longer see it).
Classification by Stimulus Detected
Mechanoreceptors – sense mechanical forces; touch, pressure, stretch, vibrations, itch.
Thermoreceptors – sense temperature changes.
Chemoreceptors – sense chemicals in solution; taste, smell.
Photoreceptors – sense light.
Nociceptors – sense harmful stimuli that result in the feeling of pain.
Classification of General Sensory Receptors by Structure
Free/Unencapsulated – not enclosed in a connective tissue capsule; found within epithelial tissues and
underlying connective tissues; respond to pain and temperature.
Encapsulated – enclosed within a connective tissue capsule; vary widely in shape, size, and distribution;
all are mechanoreceptors.
Proprioceptors – encapsulated nerve endings that monitor stretch in locomotory organs (e.g., skeletal
muscles and tendons).
Questions
Would your retina be considered an exteroceptor, an interoceptor, or a proprioceptor?
proprioceptorr
Would your retina be considered a mechanoreceptor, thermoreceptor, chemoreceptor, photoreceptor, or
nociceptor?
Pho torecepterr
If you circumduct your digit II with your eyes closed, you still know it location in space because of the actions
of which peripheral sensory receptor based on location? What about based on structure?
proprioceptor v
Differentiate between the special senses of taste and smell.
chemoreceptor r
20
Peripheral Motor Endings – activate effectors (i.e., muscles and glands)
Innervation of Somatic Muscles
Skeletal Muscles
Neuromuscular Junctions/Motor End Plates – place where motor axons and skeletal muscle fibers
meet; very similar to synapses between neurons.
Motor Units
Single Neuron + All Skeletal Muscle Cells/Fibers – that the neuron innervates; so that all skeletal
muscle cells/fibers of the motor unit contract together.
Neurotransmitters – acetylcholine signals contraction.
Innervation of Visceral (Smooth & Cardiac) Muscle & Glands (ANS)
Varicosities – swellings of visceral motor axons forming a row of “knobs” near the smooth muscle or gland
cells; sites where neurotransmitters are released; a relatively wide synaptic cleft is present, resulting in
comparatively slower responses than skeletal muscle motor units; no varicosities are associated with cardiac
muscle cells.
Questions
Name two general types of glands.
G pineal
pituitary
Name a specific exocrine gland.
pituitary
Name
a specific endocrine gland.
pineal
Name a specific skeletal muscle organ.
From what organ were the histological sections of smooth muscle in lab taken?
Name two excitable tissues.
Define synapse.
Differentiate between Acetyl-CoA and acetylcholine.
What is a neurotransmitter?
acetylcholine vignalv
contraction
21
Cranial Nerves
Forebrain/Prosencephalon
CN I/Olfactory Nerve – sense of smell.
CN II/Optic Nerve – vision; not a “true” nerve because it is an outgrowth of the brain.
Brain Stem
Midbrain
CN III/Oculomotor Nerve – “eye mover”; innervates four of the six extrinsic eye muscles.
CN IV/Trochlear Nerve – “pulley”; innervates one of the six extrinsic eye muscles.
Pons
CN V/Trigeminal Nerve – sensory innervation of the face; motor innervation of chewing muscles.
CN VI/Abducens Nerve – innervates one of the six extrinsic eye muscles.
CN VII/Facial Nerve – innervates muscles of facial expression.
Medulla Oblongata
CN VIII/Vestibulocochlear Nerve – hearing and equilibrium.
CN IX/Glossopharyngeal Nerve – innervates tongue and pharynx.
CN X/Vagus Nerve – “vagabond”; innervates thorax and abdomen.
CN XI/Accessory Nerve – innervates head and neck muscles.
CN XII/Hypoglossal Nerve – innervates tongue muscles.
Cranial Nerves
Purely Sensory – CNs I, II, VIII
Primarily or Exclusively Motor – CNs III, IV, VI, XI, XII
Mixed – CNs V, VII, IX, X
Questions
The passage of olfactory nerve fibers occurs through which bone?
frontal bone
What do CNs III, IV, & VI have in common?
six extrinsic eye murder
Name two “chewing” muscles.
(NV da CN VII
What does the Greek word “glossa” mean?
opening
What do the
names of CNs IX and XII have in common?
they have
lava inthem
g
Which cranial nerve innervates
the heart?
CN X
CN VII
Which cranial nerve allows you to smile?
Which cranial nerve allows you to feel the wind on your face?
( NV
Which cervical vertebra allows you to rotate your head?
axis
Which cranial nerve allows you to rotate your head?
CN xi
22
Spinal Nerves
31 Pairs
General Structure (Roots vs. Rami)
Dorsal Root – connects spinal nerves to spinal cord; sensory fibers (somatic and visceral).
Rootlets – branches that attach directly to the spinal cord.
Dorsal Root Ganglion – contains sensory nerve cell bodies.
Ventral Root – connects spinal nerves to spinal cord; motor fibers (somatic and visceral).
Rootlets – branches that attach directly to the spinal cord.
Dorsal Ramus – contain both sensory & motor fibers/axons; signals travel to & from body & CNS.
Ventral Ramus – contain both sensory & motor fibers/axons; signals travel to & from body & CNS.
Rami Communicantes – connects to the base of the ventral ramus and leads to sympathetic
trunk ganglion.
Sympathetic Trunk Ganglia – 22-24 pairs containing motor neuron cell bodies.
Regions
Cervical, Thoracic, Lumbar, Sacral & Coccygeal
Questions
What do dorsal and ventral roots do?
dorval renoory ventral
motor
How are dorsal and ventral roots connected to the spinal cord?
rootlet v
-
-
Briefly differentiate between dorsal and ventral roots in terms of function.
dorval venvory ventral motor
What is the function of rami communicantes?
-
-
trunk ganglion
sympathetic
Differentiate between dorsal root ganglia and sympathetic trunk ganglia.
connect v
dorval
ventral
ram ur
leader
to
nerve cell bodierjvympathetic
renvoryis capable
ganglia
What type
of extrinsic innervation
of increasing the base heart rate and rhythm?motoneuron
-
Sympathetic
To which skeletal structures do the regions of spinal nerves correspond?
cervical , Thoracic, Lumbar , sacral 4
-
body
Coccygeal
23
Chpt. 15 (Autonomic Nervous System)
Why is it important to study the autonomic nervous system?
Autonomic Nervous System – “self-governing” nervous system; visceral motor/efferent division.
ANS/Visceral/Involuntary Motor
Two Motor Unit Neurons
Preganglionic Neuron – cell body/soma lies within the CNS.
Preganglionic Axon – synapses with ganglionic neuron.
Ganglionic Neuron
Autonomic Ganglion – location where synapse occurs and it contains the ganglionic neuron cell
body/soma; this is a motor ganglion, not sensory as in dorsal root ganglion.
Postganglionic Axon – extends to visceral organs.
Divisions (Stimulation vs. Inhibition) – sympathetic and parasympathetic divisions often have
antagonistic/opposite effects on the same visceral organs.
Sympathetic Division of ANS
“Fight, Flight, or Fright”
Thoracolumbar Division
Preganglionic Neurotransmitter Acetylcholine
Long Postganglionic Fibers and Profuse Branching
Postganglionic Axon Neurotransmitter Norepinephrine is Adrenergic
Innervates Adrenal Gland & Skin/Integument
Parasympathetic Division of ANS
“Housekeeping”/ “Rest & Digest”
Craniosacral Division
Preganglionic Neurotransmitter Acetylcholine
Short Postganglionic Fibers and No Profuse Branching
Postganglionic Axon Neurotransmitter Acetylcholine is Cholinergic
Questions
What does the term autonomic mean?
governing
Is the autonomic
nervous system sensory?
self
-
NO
How many motor neurons are present in each pathway?
What are thetwo
two subdivisions of the ANS and how are they related?
4 parasympathetic ; the opposite of each
Sympathetic
What do parasympathetic
and sympathetic divisions have in common?
pre ganglionic
-
Acetylcholine
other in the same
organ
24
Parasympathetic Division/Craniosacral Division – “Housekeeping” “Rest & Digest”
Basic Organization
Cranial Outflow – from brain stem gray matter to organs of the head, neck, thorax, and most of the
abdomen.
Preganglionic Fibers –run alongside cranial nerves (CN III, CN VII, CN IX, CN X)
Sacral Outflow – from sacral region of spinal cord gray matter and supplies the rest of the abdomen and
pelvic organs.
Preganglionic Fibers
Ventral Roots and Rami – axons of preganglionic neurons run within ventral roots and rami.
Pelvic Splanchnic Nerves – branch from ventral rami.
Sympathetic Division/Thoracolumbar Division – “Fight, Flight, or Fright”
Basic Organization
More Complex than Parasympathetic – innervates more organs (i.e., skin/integument and adrenal gland).
Sweat Glands, Errector Pili Muscles, Smooth Muscles of Arteries & Veins – when frightened → sweat, hair
stands up, blood pressure increases.
Ganglia
Sympathetic Trunk Ganglia – 22-24 pairs containing motor neuron cell bodies; neck to pelvis; often
described as “a string of beads”.
Prevertebral/Collateral Ganglia – not paired; located near abdomen and pelvis.
Sympathetic Pathways – can be complex.
Adrenal Medulla – internal portion/region of the adrenal gland; essentially the largest and most specialized
sympathetic ganglion; it is composed of a collection of modified ganglionic neurons that lack neuronal
processes (i.e, axons and dendrites).
Sympathetic Division
Adrenal Gland
Kidney – adrenal glands are located on the superior aspect of the kidneys in humans.
Adrenal Medulla – internal region/portion of the adrenal gland.
Sympathetic Ganglion – largest, most specialized.
Secretes Hormones
Norepinephrine – secreted by postganglionic sympathetic fibers.
Epinephrine/Adrenaline – excitatory molecule.
25
Questions
What are the two major regulatory systems of the body?
ok in
a adrenal gland v
Why is the parasympathetic division of the ANS also referred to as the craniosacral division?
dealer w/ the cranial da racial regions division?
Why is the sympathetic division of the ANS also referred to as the thoracolumbar
dealer WI the thoracic lumbar regions
How would you describe the adrenal medulla anatomically with respect
to the nervous system?
of
the
adrenal
gland
portion
What are inner
the two secretions
of the adrenal medulla?
4 Adrenaline
norepinephrine
How would
you classify the secretions of the adrenal medulla?
hormone v
Since the neurons of the adrenal medulla lack axons, how do their secretions reach their target organs?
fiber v da molecular
Is the adrenal medulla an organ
of the nervous system or an organ of the endocrine system?
of endocrine
organ
system
Visceral Sensory Neurons & Reflexes
Visceral Sensory/Afferent Division of PNS
General Senses- stretch, temperature, chemical changes, and irritation.
CNS Interpretation – of sensory information as the following “feelings”.
hunger, fullness, pain, nausea, well-being
Referred Pain – visceral pain perceived as somatic in origin (e.g., pain in left arm during heart attack)
Visceral Reflex Arc
Defecation Reflex (Stretch and Contraction) – rectum stretched by feces, smooth muscles of colon/large
intestine contract and …
Generalized Visceral Reflex Arc
Stimulus → Sensory Receptor of Sensory Fiber → Dorsal Root Ganglion → Integration Center (maybe
interneuron involved or not; (i.e., CNS may or may not be involved) → preganglionic neuron → autonomic
ganglion → postganglionic axon → effector organ → response
Questions
Are the stimuli sensed by the visceral sensory/afferent division of the PNS considered to be parasympathetic or
because it deals
sympathetic stimuli and why or why not?
"
houde
keeping
"
parasympathetic
-
w/
Is the CNS always involved in visceral reflex arcs?
yer
What is the difference between a ganglionic neuron and a postganglionic fiber?
Differentiate between sympathetic postganglionic fibers and parasympathetic postganglionic fibers.
What is the difference between norepinephrine secreted by sympathetic postganglionic axons and the
sympathetic ganglionic neurons of the adrenal medulla?
26
Levels of ANS Control by CNS
Cerebral Cortex
Meditation
Frightful Experience
Amygdala of Limbic System
Emotions (e.g., fear).
Hypothalamus
Integration Center of ANS
Reticular Formation of Brain Stem
Cardiac Center – heart rate.
Vasomotor Center – blood pressure.
Medullary Respiratory Center – respiration.
Spinal Cord
Defecation Reflex – also subject to conscious inhibition from brain.
Discussion Questions
Have you ever observed a traumatic event unfold (real or fictional) and noticed certain physiological changes
(e.g., sweaty palms, increased heart rate, change in rate or depth of breathing)? What was happening to you?
Yeo
I war
getting
into a car accident heavier
breathing
Have you ever been awakened by an unsettling dream and experienced physiological effects? What was
incr eared heart rate from
happening to you?
,
yer
away
,
.
running
27
Chpt. 16 (Special Senses)
Why is it important to study special senses?
Overview
Special Senses
Chemical Senses – chemoreceptors respond to chemicals; chemicals must be dissolved in fluid (e.g., saliva
or mucus).
Taste/Gustation & Smell/Olfaction
Sight, Hearing, & Equilibrium
Special Sensory Receptors – localized/confined to the head.
Receptor Cells – not free endings of sensory neurons; described as “neuron-like” epithelial cells or small
peripheral neurons.
Complex Sensory Organs (e.g., eyes and ears) vs. Distinctive Epithelial Structures (e.g., tastebuds and
olfactory epithelium).
Cranial Nerves – some receive sensory information from special sensory receptors.
Olfactory Nerve/CN I – smell.
Optic Nerve/CN II – sight.
Vestibulocochlear Nerve/CN VIII – hearing and equilibrium.
Facial Nerve/CN VII & Glossopharyngeal Nerve/CN IX & Vagus Nerve/CN X – taste.
Questions
Are special senses somatic, visceral, or both?
visceral
attached to each other
are
they
Why do you
suppose
our special senses are confined to the head?
How are gustation and olfaction related?
because it's near the brain
Which cranial nerve receives olfactory information?
CNI
CNE
Which cranial nerve receives visual information?
Which cranial nerve receives auditory information?
CN Vh1
Which cranial nerves receive gustatory information?
CNX
28
Taste/Gustation
Taste Buds – taste receptors are found within taste buds.
Mucosa of Mouth & Pharynx – location of taste buds.
10,000 – the majority of taste buds are found on the tongue, but not all of them.
Papillae
Fungiform Papillae – relatively small; located over the entire surface of the tongue; most numerous.
Vallate Papillae – relatively large; located near the back of the tongue; least numerous; form a “V-shape”.
50-100 Epithelial Cells – make up an individual taste bud.
Gustatory Cells – receptor cells.
Supporting Cells – insulate/protect gustatory cells; very numerous.
Basal Cells (Undifferentiated) – will replace gustatory cells or supporting cells.
Taste Pore – near the center of the taste bud; where microvilli from gustatory cells absorb taste molecules.
Tastes – sweet, sour, salty, bitter & umami (“deliciousness”/“savory”).
Sensory Pathway
Tastebuds (Sensory Receptors) => Sensory Fibers of CN VII, CN IX, CN X => Solitary Nucleus of
Medulla Oblongata => Thalamus => Gustatory Area of Cerebral Cortex
Questions
Where are the gustatory receptors located?
Where are theTongue
taste buds located?
Muara of Mouth da
Pharynx
What type of tissue composes
a taste bud?
epithelial
What structural
feature of gustatory cells allows for more efficient sampling of tastes?
taste budr
Which cranial nerves receive gustatory information?
CN V l l CN IX , da CN k
What parts of, the brain
receive gustatory information?
Medulla oblongata , that amur , da cerebral cortex
Are you aware of tastes? If so, how?
29
Smell/Olfaction
Olfactory Epithelium – olfactory receptors are located within the epithelia that cover the Superior Nasal
Conchae & Superior Nasal Septum.
Sniffing – draws more air and intensifies smell.
Pseudostratified Columnar Epithelium – olfactory epithelium.
Olfactory Receptor Cells
Bipolar Neurons
Olfactory Cilia – apical dendrite projections; act as receptors; largely immotile.
Supporting Cells – secrete mucus.
Mucus – captures and dissolves scent molecules.
Basal Cells (Undifferentiated) – form new olfactory receptor cells.
Olfactory Glands – also secrete mucus.
Filaments of Olfactory Nerve – axons of CN I.
Olfactory Bulb – a part of the forebrain.
Mitral Cells – neurons that synapse with CN I axons.
Glomeruli – present between CN I filaments and mitral cells; where synapses occur.
Questions
The olfactory epithelium is located where within the nasal cavity?
epithelia
The superior
nasal conchae are a part of what bone?
What type of neurons forms the olfactory receptor cells?
Bipolar
What is one function of mucus that coats the olfactory epithelium?
dissolves scent molecular
How would you describe the olfactory epithelium?
Axons of which cranial nerve receive olfactory information from the olfactory receptor cells?
CNI
Is the olfactory bulb CN I?
yer
Is the olfactory tract CN I?
NO
30
Sight/Vision – dominant special sense in humans; accounts for 70% of sensory receptors & 40% of cerebral cortex.
Accessory Structures
Eyebrows – shade the eyes and prevent sweat from the forehead from reaching the eyes.
Eyelids/Palpebrae – upper and lower; close to protect the eyes.
Eyelashes – help to protect the eyes as a filter and through reflexive blinking.
Conjunctiva – is a transparent mucus membrane that covers the inner surfaces of the eyelids and anterior
surface of the eye; forms the white sclera; blood vessels are present within, responsible for “bloodshot”
eyes.
Lacrimal Apparatus – keeps the surface of the eye moist with tears/lacrimal fluid.
Extrinsic Eye Muscles – 6 skeletal muscles that move the eye.
Anatomy of the Eye
The eye has anterior & posterior poles.
Tunics – three layers
Fibrous Tunic – outer layer; corresponds to the dura mater of the brain.
Sclera – white.
Cornea – transparent.
Vascular Tunic – middle layer.
Choroid – highly vascular, dark-pigmented membrane; corresponds to arachnoid mater and pia mater.
Ciliary Body – thickened ring of tissue continuous with the choroid anteriorly; encircles the lens.
Iris – visible colored part of the eye located between the cornea and lens.
Sensory Tunic – inner layer.
Retina – where photoreceptors are located.
Cavities/Chambers – anterior and posterior.
Humors
Aqueous Humor – watery fluid found within the anterior chamber of the eye.
Vitreous Humor – relatively viscous fluid found within the posterior chamber of the eye.
Lens – focuses light on the retina; is capable of changing shape.
Discussion Question
What are the functional differences between eyebrows and eyelids? Briefly discuss the differences between the
three tunics of the eye and name some of their components.
31
Sensory Tunic/Retina
Layers – the retina is composed of two layers.
Pigmented Layer – outer layer; lies against the choroid; composed of melanocytes.
Melanocytes – produce melanin, which absorbs incoming light to prevent scattering.
Neural Layer – the inner layer of the retina, relatively thick; contains photoreceptors.
Photoreceptor Cells
Rods – the most numerous; very sensitive to light; allow vision in dim light.
Cones – bright light; color vision; three types of cones.
Blue, Red, & Green – sensitive to different wavelengths of light.
Ganglion Cells – axons of which form Optic Nerve/CN II.
Regional Specializations of the Retina
Ora Serrata Retinae – location where the neural layer of the retina ends anteriorly.
Macula Lutea – located at the posterior pole; appears yellow; lots of cones; central vision best.
Fovea Centralis – located in the center of the macula lutea; contains only cones; maximum visual acuity
(i.e., sharpest daylight images).
Optic Disc/Papilla – where the axons of the ganglion cells converge to form Optic Nerve/CNII; blind spot.
Visual Pathways & Development
Main Visual Pathway
Photoreceptors (Retina) => Optic Nerve => Optic Chiasma => Optic Tract => Thalamus => Visual
Cortex of Occipital Lobe of Cerebrum
Other Pathways
Superior Colliculi – reflex nuclei controlling extrinsic eye muscles.
Pretectal Nuclei
Pupillary Light Reflex – change diameter of pupil.
Suprachiasmatic Nucleus of Hypothalamus – “timer” that runs daily biorhythms associated with
daylight/dark cycles.
Development
Eyes form as outpocketings of brain (optic vesicles → optic cups).
Questions
Briefly differentiate between the two layers of the retina.
layers composed of melanocytes Neural contains
pigmented
photo recpterr
Briefly differentiate between rods and cones.
rod virion in dim light w her color virion in bright
lighter
Why is it best to view an object nearly “dead-center” during daylight hours?
Fovea Centralia works bert at this time
What is the optic disc?
-
-
-
-
.
blind rpot
32
Hearing & Equilibrium
Ear
Outer/External Ear
Auricle/Pinna
Elastic Cartilage – flexible cartilage.
External Acoustic/Auditory Meatus – canal through which sound waves travel.
Cerumen/Earwax – produced by ceruminous glands.
Tympanic Membrane – “ear drum”; medial boundary of external ear; lateral boundary of middle ear.
Middle Ear
Medial Boundary
Oval Window – deep to stapes.
Round Window – inferior to stapes.
Mastoid Antrum – superior to stapes.
Pharyngotympanic/Auditory/Eustachian Tube – connects middle ear to pharynx.
Middle Ear Ossicles – transmit vibrations to inner ear.
Malleus, Incus, Stapes – from most lateral to most medial.
Inner Ear/Labyrinth – sometime referred to as the “maze”.
Bony Labyrinth – three parts composed of bone.
Semicircular Canals – house semicircular ducts.
Vestibule – houses utricle & saccule.
Vestibular Nerve – innervates vestibule; balance.
Cochlea – houses cochlear duct.
Cochlear Nerve – innervates cochlea; hearing.
Membranous Labyrinth
Semicircular Ducts – sense rotational acceleration.
Cupula – hairs of epithelial cells form a cap-like structure that bends.
Utricle & Saccule – senses static equilibrium and linear acceleration.
Macula – sensory epithelium within utricle and saccule; monitors static equilibrium and linear
acceleration.
Otoliths – “ear stones”.
Cochlear Duct – senses sound/hearing.
Hair Cells – act as receptors; bent by vibrations.
33
Auditory Pathway
Cochlear Nerve => Medulla => Midbrain => Cerebral Cortex (Primary Auditory Cortex)
Equilibrium Pathway
Vestibular Nerve => Brain Stem (Medulla & Cerebellum)
Also, Minor Equilibrium Pathway to Cerebrum
Questions
Briefly differentiate among the different functions of the external, middle, & inner ear.
external Cannae roundwaves travel ; middle transmit round waves wear 's inner Veni circular canal r
-
-
-
-
What serves as the medial boundary of the external ear?
tympanic membrane
What serves as the lateral boundary of the middle ear?
,
Veftibule , &
cochlea
Mal
leur
Name the three
middle ear ossicles from lateral to medial?
Mal leur , Incur , an rtaper
What are the two branches of CN VIII?
What is the function of the semicircular canals?
houreremi circular ductr
What is the function of the semicircular ducts?
rotational acceleration
What is the function of the otoliths?
earvto
her
What is the function
of the cochlea?
house cochlear duct
What is the function of the cochlear duct?
venire round hearing
I
Why is it important for the auditory
pathway to lead to the primary auditory cortex?
I
no iverlrounar
recognize
Why is it important
for the equilibrium pathway to be sent primarily to the brain stem (medulla & cerebellum)?
for balance
to
Additional Questions
120. Briefly describe the basic functions of the nervous system. Provide an example of how these basic functions
receptors monitor changer t falling temperature)
pro carving da interpreting
integration
are performed. ffipnuluv change temperature change) sensory
whiner )
Motor output response whererings
121. What are the basic structural subdivisions of the nervous system?
-
-
-
-
to
decide
-
Central New our System Brain darprnalwrd Peripheral Nerwurilystem
Urania , Ipina , da
Ganglia
122. Briefly differentiate among the terms: afferent, efferent, motor, sensory, somatic,
and visceral. Briefly
differentiate between “inner tube” senses and “outer tube” senses. Use 2 words to differentiate somatic motor and
visceral motor. afferent hennery signals toward efferent I motor signals away VO Matic external ventral body cavity viceroy w/ in
ventral
cavity
inner tube taste das meth outer tube body veneer VOMatic motor skeletal murder Vivceral Motor umooth marae body
123. What are the 2 main types of cells in nervous tissue? Which type is “excitable”?
Neuwnrda
cells neurons excitable
124. Briefly describe the special characteristics of neurons. Differentiate between axons and dendrites.
-
-
-
-
-
-
"
"
-
-
-
-
Supporting
extreme longevity
lifetime don't divide do
-
-
not
undergo
cell division
High
Metabolic Rate
-
lot of Oz
AXON conduct
-
signal away
Dendrite r
-
conduct
signal toward
125. What is a synapse? What molecules are released at synaptic junctions? Differentiate between presynaptic and
postsynaptic neurons. What are the 2 most common types of synapses? What are the 3 less common types of
synapses? synapses neuron communication neuro tram Mitter presynaptic electrical signals toward
-
postsynaptic
-
-
electrical signals away Axo dendritic da Ando Matic Axoaxowio , denaro dendritic
, da denaro somatic
34
126. List the structural classes of neurons. Which is most common? List the functional classes of neurons. Which is
Afferent efferent , da Association
Arrogation
most common? Multipolar Bipolar da Unipolar ; Multipolar
,
,
,
127. Briefly differentiate among astrocytes, ependymal cells, microglial cells, and oligodendrocytes. Where are these
form
cells found? astrocytes recycle neurotransmitter microglia cells defense cells oligodendrocytes
myelin heat her
-
-
-
CNVvupporeiongcel.ir
128. What is the function of myelin? What is the function of the Nodes of Ranvier? Briefly differentiate between
oligodendrocytes and Schwann cells. Myelin u peed impulse conduction gaps in myelin unearth
Schwann Vurrondaxonv oligodendrocytes cellular procurer
129. Briefly differentiate among axons, nerve fascicles, and nerves. Which connective tissues surround each?
-
-
nerve
-
-
collection of nerve fiber (epineurium)
nerve
f- avoider
-
group
of axons (perineurium
axons
-
impure generaterrbendoneunui
130. Briefly differentiate among the terms: neuron, nerve fiber, and nerve.
neurone 'll IN Nerve fiber = axon Nerve -_ collection of wngaxonr
131. Briefly describe the components of a typical reflex arc. What are the 2 main types of effector organs?
Chain of neuron r 's muscle du glander
132. Briefly differentiate between gray matter and white matter. What is unique about gray matter in the brain versus
spinal cord? Why use the directional term rostral? gray neuron cell bodier White no cell bodies
-
-
associated w/ the head
133. List the basic structural components of the brain. What are the 2 functional systems of the brain?
Greb at Hemisphere diencephalon , Brainstem , cerebellum , 4 rent rider limbic dgreoticulareyrtemr
134. What are the 3 primary vesicles of the brain from most rostral to most caudal? What are their secondary
vesicles? What are adult brain structures are derived from the secondary brain vesicles? What are the respective
expansions of the central canal within each secondary vesicle? Prosencephalon telencephalonda diencephalon (cerebrum)
Cerebral aqueduct thalamus hypothalamus du Epithalamion)
(FOR brain , midbrain 14 hindbrain) Metencephalon
Rhombencephalon metencephalon du Myelencephalon lponrda medulla oblongata
135. List the basic structural components of the brain again. What are the 3 components of the brain stem?
,
-
,
-
-
Cerebral Hemisphere , diencephalon
,
Brainstem (Midbrain , pong medulla oblongata
cerebellum
136. Briefly differentiate fissures, sulci, and gyri of the cerebrum. Name the cerebral lobes. Why do their names
make sense? firm rev-deepeutgroover.ru/oi-vmallergroovergyri-foldo/ridger Frontal parietal occipital da temporal
Became of their placement on the skull
137. List the motor areas of the cerebral cortex and briefly describe their functional roles.
,
primary
-
skilled
voluntary Premotor
-
complex
frontal eye field
-
voluntary
eye
Broca's Area
-
,
,
vpeeoh production
138. List the sensory areas of the cerebral cortex and briefly describe their functional roles.
primary somatosensory general aromatic venvory
-
info
Primary Vimal venrory info
-
.
.
eye
Primary Auditory
-
inner ear
Gustatory
-
taste budr
Vevtibular
139. List the association areas of the cerebral cortex and briefly describe their functional roles.
movement Auditory
tomatorenvory underhand veneration Vimal analyzing colors forma in
-
-
-
rata visceral
round 4
memories
of paotooundr
-
balance
olfactory smell
-
General interpretation
-
integrate
veneration
info Wernicke 'r
-
.
recognized underjpteaendn
140. What is lateralization? Briefly differentiate between the primary motor cortex and the primary somatosensory
cortex with respect to the body map. Why do the proportions of the human body appear distorted on the body
killed voluntary somatosensory general somatic vehvory info
map? motor V
-
-
-
141. Briefly differentiate between association fibers, commissural fibers, and projection fibers. What is the corpus
callosum?
142. Briefly describe the functions of the basal ganglia and the basal forebrain nuclei. What is the connection of
Alzheimer’s to deep gray matter?
143. List the 3 components of the diencephalon and briefly describe the functions of each. Why is the
hypothalamus sometimes referred to as the “master gland”?
144. List the 3 components of the brain stem and briefly describe the functions of each.
145. Briefly describe the functions of the cerebellum?
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146. Briefly differentiate between limbic and reticular systems. Why is the hippocampus so important? What is the
function of the amygdala?
147. Briefly differentiate among dura mater, arachnoid mater, and pia mater.
148. What is the function of the spinal cord? What are reflex arcs? What bony structures protect the spinal cord?
What is the epidural space?
149. Briefly describe spinal cord gray matter. To which region are lateral horns restricted? Briefly differentiate
among spinal cord ascending, commissural, and descending fibers.
150. Briefly differentiate between sensory receptors and motor endings. What two types of effector organs do
efferent neurons innervate? How does somatic motor innervation differ from visceral motor innervation with
respect to control?
151. List the basic structural components of the brain. What are the 2 functional systems of the brain?
152. Briefly differentiate between nerves and ganglia. How many pairs of cranial nerves do you have? How many
pairs of spinal nerves do you have? Briefly differentiate between sensory nerves, motor nerves, and mixed nerves.
153. What are the 3 types of sensory receptors based on location? What are the 5 types of sensory receptors based
on type of stimulus detected? What are the 3 types of sensory receptors based on structure?
154. Briefly differentiate between motor innervation of skeletal muscles and smooth muscles. What is acetylcholine?
155. List all 12 pairs of cranial nerves and correlate to forebrain, midbrain, pons, and medulla oblongata. Which 3
cranial nerves are considered to be purely sensory? Which 5 cranial nerves are considered to be primarily motor?
Which 3 cranial nerves innervate extrinsic eye muscles?
156. Briefly differentiate between dorsal roots and ventral roots. How are dorsal rami and ventral rami similar?
What are the relationships among rami communicantes, sympathetic trunk ganglia, and ventral rami?
157. How does the visceral motor division of the PNS differ from the somatic motor division of the PNS in terms
of the number of motor neurons involved?
158. Briefly differentiate between sympathetic and parasympathetic division of the ANS with respect to organs
innervated, neurotransmitters released, and the morphology of preganglionic and ganglionic neuron axons.
159. Briefly describe the morphology of the adrenal medulla. What 2 hormones are produced and secreted? Is the
adrenal medulla a part of the nervous system, endocrine system, or both? Why?
160. What is referred pain? Briefly describe a visceral reflex arc. What are the two types of effector organs involved
in visceral reflex arcs? How might the CNS exert conscious control over the ANS?
161. Briefly describe the structure of a taste bud. What is the function of gustatory cell microvilli? Which cranial
nerves are involved in gustation? Briefly differentiate between fungiform and vallate papillae.
162. Briefly describe the olfactory epithelium with respect to location and type of epithelium. What are olfactory
cilia? Is the olfactory bulb synonymous with CN I?
163. Briefly describe the functions the conjunctiva, eyebrows, extrinsic eye muscles, eyelashes, lacrimal apparatus,
and palpebrae. Briefly differentiate between the 3 tunics of the eye and list their components. What are the 2
36
chambers of the eye and which humors are found in each? What is the function of the lens? What are the 2 layers of
the retina? Briefly differentiate between rods and cones. What are the macula lutea, optic disc, and ora serrata
retinae? Briefly describe the main visual pathway. Briefly describe development of the eyes.
164. Briefly differentiate among inner, middle, and outer ear. What is the tympanic membrane? Name the middle
ear ossicles and describe their function. Briefly differentiate between bony and membranous labyrinths. What is the
primary difference between semicircular ducts, utricle and saccule, and cochlear duct? What is the primary
difference between the cochlear nerve and the vestibular nerve? What cranial nerve do they form?
37