BIOL 2020
HUMAN
ANATOMY &
PHYSIOLOGY II
Dr. Tyler Evans
Email: tyler.evans@csueastbay.edu
Office: S Sci 350
Office Hours: F 8:30-11:30 or by appointment
Website: http://evanslabcsueb.weebly.com/
Phone: 510-885-3475
LAST LECTURE
CHAPTER 5
• these are all properties of your skin
• the skin and its associated components including sweat and oil glands, hair
and nails make up a complex system of organs called the INTEGUMENTARY
SYSTEM
Fig 5.1 pg 151
LAST LECTURE
CHAPTER 5
LAYERS OF THE EPIDERMIS AND DERMIS
stratum corneum
stratum granulosum
stratum spinosum
stratum basale
Fig 5.2 pg 153
LAST LECTURE
SKIN COLOR
• three pigments contribute to skin color: MELANIN, CAROTENE and
HEMOGLOBIN
• only melanin is actually made in the skin
• melanin is a polymer of the amino acid TYROSINE and its formation is catalyzed
by the enzyme TYROSINASE
Granules of melanin pigment
called MELANOSOMES
accumulate in the layers of
skin above the dermis
LAST LECTURE
APPENDAGES OF THE SKIN
• skin appendages are derivatives of the epidermis and
include:
1. Hair and hair follicles
2. Nails
3. Sweat glands
4. Sebaceous (oil) glands
Fig 5.1 pg 151
LAST LECTURE
SEVEN FUNCTIONS OF THE INTEGUMENTARY SYSTEM
1. CHEMICAL BARRIER
2. PHYSICAL BARRIER
3. BODY TEMPERATURE REGULATION
4. CUTANEOUS SENSATION
5. METABOLIC FUNCTIONS
6. BLOOD RESERVOIR
7. EXCRETION
TODAY’S LECTURE:
FUNDAMENTALS OF THE NERVOUS SYSTEM
AND NERVOUS TISSUE
CHAPTER 11
THE NERVOUS SYSTEM
• the nervous system is the master controlling and communication system of the
body
• the nervous system has three overlapping functions:
• 1. SENSORY INPUT: uses millions of receptors to monitor changes both inside
and outside the body
• 2. INTEGRATION: processes and interprets sensory input
• 3. MOTOR OUTPUT: activates organs (e.g. muscle and glands) to appropriately
respond
Fig 11.1 pg 387
THE NERVOUS SYSTEM
ORGANIZATION
• We have only one highly integrated nervous system, but it is divided into several
parts with specific functions:
1.
2.
CENTRAL NERVOUS SYSTEM (CNS): consists of the brain and spinal cord and is
the integrating and control center for the nervous system
PERIPHERAL NERVOUS SYSTEM (PNS): links body parts to the CNS and consists
mainly of nerves that extend out from the brain and spinal cord
• PNS has two subdivisions:
a. SENSORY DIVISION: conveys nerve signals to the CNS from receptors in
the body
b. MOTOR DIVISION: transmits nerve signals from the CNS to muscles and
glands.
i. SOMATIC NERVOUS SYSTEM: connects to skeletal muscles
ii. AUTONOMIC NERVOUS SYSTEM: connects to smooth muscles,
cardiac muscles, and glands
 SYMPATHETIC DIVISION: stimulates systems
 PARASYMPATHETIC DIVISION: conserves energy
Fig 11.2 pg 388
THE NERVOUS SYSTEM
CELL TYPES
• although highly complex, the nervous system is made of two principal cell types:
1. NEURONS: excitable cells capable of transmitting electrical signals
2. NEUROGLIA: supporting cells that surround more delicate neurons
TYPES OF NEUROGLIA:
a.
b.
c.
d.
ASTROCYTES: support, brace and anchor neurons
• called SATELLITE CELLS in the PNS
MICROGLIA: repair damages neurons and prevent
against infection
EPENDYMAL CELLS: line cavities of the central
nervous system separating cerebrospinal fluid from
nervous tissue
• can be ciliated to help circulate the fluid
OLIGODENDROCYTES: wrap around neurons to
produce an insulating cover called MYELIN SHEATH
• in the PNS, SCHWANN CELLS produce myelin
sheath
Fig 11.3 pg 390
THE NERVOUS SYSTEM
TYPES OF NEURONS
• neurons are the structural units of the CNS: they have extreme longevity (entire
lifetime), once formed they do not divide and required a large amount of energy
• while neurons come in many cell types, they share common features
e.g. vertebrate motor neuron
THE NERVOUS SYSTEM
TYPES OF NEURONS
INTERNEURONS connect other neurons
of the CNS
can lack a clearly defined axon because
are only transmitting signals over short
distances between other neurons.
SENSORY NEURONS transmit signals
from receptors on skin or internal organs
to the CNS
EFFERENT or MOTOR NEURONS: carry
impulses away from the CNS to muscles
and glands
• long axons of sensory and efferent
neurons help transmit signals over
greater distances
THE NERVOUS SYSTEM
TYPES OF NEURONS
• although most neurons have the same basic components, each of these
components has been modified best perform specific tasks
• structure dictates function
• most neurons have DENDRITES, a CELL BODY (SOMA) and an AXON, but details
of each structure are variable
• this diversity allows neurons to perform different tasks in the nervous system
THE NERVOUS SYSTEM
MYELIN SHEATH
• many axons, particularly long or thick ones, are covered with a whitish and fatty
MYELIN SHEATH
• protects and electrically insulates axons (i.e.
prevents signals from decaying) and increases the
speed of signal transmission down axons
• SCHWANN CELLS wrap themselves around the
axon many times and then squeeze the cytoplasm
out so that just the plasma membrane remains
• gaps between individual Schwann cells form
NODES OF RANVIER
• in the CNS, OLIGODENDROCYTES form the myelin
sheath, but use a similar process
• regions of the brain that contain a lot of
myelinated axons appear white and is called
WHITE MATTER
• unmyelinated axons from GREY MATTER
Fig 11.5 pg 392
THE NERVOUS SYSTEM
MEMBRANE POTENTIALS
• when a neuron is activated, an electrical signal called a POTENTIAL travels down its
axon,
• these signals underlie virtually every function in the nervous system
• recall, that integral proteins in cell membranes called ION CHANNEL PROTEINS
control the movement of charged particles across the membrane and this
generates an ELECTROCHEMICAL GRADIENT.
• when channel proteins open, ions move down their concentration gradient
creating an electrical charge
• changes in membrane potential produce two types of electrical signals:
1. GRADED POTENTIALS: weak and operate over a short distances
2. ACTION POTENTIALS: strong and operate over longer distances
THE NERVOUS SYSTEM
•
•
•
•
ACTION POTENTIALS
only neurons and muscle cells can generate action potentials (AP)
an AP is a brief reversal of membrane charge (from about -70 mV to +30 mV)
unlike graded potentials, action potentials do not degrade over distance
AP are created by the movements of sodium (Na+) and potassium (K+) across the
membrane via integral proteins. The sequence of events are as follows:
1. RESTING STATE: Na+ and K+ protein channels are closed
2. DEPOLARIZATION: Na+ channels open and Na+ rushes into cells, which
triggers the opening of even more Na+ channels in a POSITIVE FEEDBACK
MECHANISM
3. REPOLARIZATION: Na+ channels close and K+ channels open and K+ rushes
out of cells, which works to restore the resting membrane potential
4. HYPERPOLARIZATION: K+ remain open for longer than required and excessive
K+ moves out of cells causing a temporary drop below the resting state
• resting state is returned as Na+ channels close
• Na+, K+ ATPase then works to restore the correct number of Na+ and K+ ions
to each side of the membrane
THE NERVOUS SYSTEM
ACTION POTENTIALS
Changes in potential
Changes in permeability
(i.e. opening or closing of
ion channels)
Fig 11.11 pg 402-403
THE NERVOUS SYSTEM
CONDUCTION VELOCITY
• conduction velocities vary between neurons:
• larger diameter axons propagate signals faster than smaller ones
• myelinated axons propagate signals faster than non-myelinated axons
• myelination prevents signal from spreading onto adjacent cell membranes and
the signal confined only to the single axon
• In MULTIPLE
SCLEROSIS, the body’s
immune system
destroys myelin
sheath and the signal
degrades and impairs
movement
Fig 11.15 pg 406
THE NERVOUS SYSTEM
THE SYNAPSE
• a SYNAPSE is the junction that connects one neuron to another or to an effector
organ like a muscle or gland
• synapses occur in two varieties:
1. ELECTRICAL SYNAPSES: are less common and occur via proteins connections
called CONNEXONS that connect the cytoplasm of adjacent cells and allow the
movement of small molecules between cells
• conduction across electrical synapses is very fast
THE NERVOUS SYSTEM
SYNAPTIC TRANSMISSION
• synapses occur in two varieties:
2. CHEMICAL SYNAPSES: are specialized to allow the release and reception of
NEUROTRANSMITTERS, a large group of chemicals that exert a variety of effects on
the body
• chemical synapses consists of a AXON TERMINAL on the pre-synaptic
neuron which are packed with synaptic vesicles that contain
neurotransmitters and a RECEPTOR REGION on the post-synaptic neuron.
• these structures are separated by a gap called the SYNPATIC CLEFT
• when an AP arrives at the axon terminal, it triggers calcium (Ca+2) channels
to open. Ca+2 rushes into the cell where it acts as a signal for synaptic
vesicles to unload their neurotransmitters into the cleft
• neurotransmitters diffuses across the cleft and binds to receptors on
integral membrane proteins of the post-synaptic neuron.
• different types of neurotransmitter effect different channel proteins and
therefore result in different outcomes either EXCITATORY or INHIBITORY
THE NERVOUS SYSTEM
SYNAPTIC TRANSMISSION
Fig 11.17 pg 409
THE CENTRAL NERVOUS SYSTEM
CHAPTER 12: THE BRAIN
• recall, CNS consists of the BRAIN and SPINAL CORD and is the integrating and
control center for the nervous system
• four regions in the adult brain:
1. CEREBRAL HEMISPHERES
2. DIENCEPHALON
3. BRAIN STEM
4. CEREBELLUM (includes midbrain, pons and medulla oblongata)
Fig 12.2 pg 430
THE CENTRAL NERVOUS SYSTEM
THE BRAIN
• the CEREBRAL HEMISPHERES form
the most conspicuous parts of the
brain, together accounting for 83% of
the total mass
• elevated ridges are called GYRI,
which are separated by grooves
called SULCI
• several sulci divide each hemisphere
into five LOBES:
• FRONTAL LOBE: occurs at the
anterior (front) of the skull
• PARIETAL LOBE
• TEMPORAL LOBE
• OCCIPITAL LOBE: occurs at the
posterior (back) of the skull
• INSULA: buried underneath frontal
and temporal lobes
Fig 12.4 pg 432
THE CENTRAL NERVOUS SYSTEM
THE BRAIN
• the CEREBRAL CORTEX is where the conscious mind is found and allows
communication, memory and learning
• composed of GREY MATTER and accounts for 40% of the brain’s mass
Fig 12.4 pg 432
THE CENTRAL NERVOUS SYSTEM
THE BRAIN
• the CEREBRAL CORTEX is where the conscious mind is found and allows
communication, memory and learning
• composed of GREY MATTER and accounts for 40% of the brain’s mass
Fig 12.4 pg 432
THE CENTRAL NERVOUS SYSTEM
THE BRAIN
• the CEREBRAL CORTEX is where the conscious mind is found and allows
communication, memory and learning
• composed of GREY MATTER and accounts for 40% of the brain’s mass
Fig 12.4 pg 432
1.
2.
3.
• the cerebral cortex is divided into three functional areas (actually a
simplification as not each area acts entirely alone):
MOTOR AREAS: control voluntary movement
SENSORY AREAS: concerned with the conscious awareness of sensation
ASSOCIATION AREAS: where individual perceptions are integrated into a more
unified process
THE CENTRAL NERVOUS SYSTEM
MOTOR AREAS
• MOTOR AREAS of the cerebral cortex lie in the posterior sections of the frontal
lobes and comprise four areas:
1.
PRIMARY MOTOR CORTEX: large neurons called PYRIMIDAL CELLS allow this
region to control the movement of skeletal muscles
• sub-regions of the motor cortex control specific body areas (e.g. feet, arms,
etc.)
2.
PRE-MOTOR CORTEX: coordinates the movement of several muscle groups into
complex tasks (e.g. playing a musical instrument)
3.
BROCA’S AREA: directs muscles involved in speech production
4.
FRONTAL EYE FIELD: controls the voluntary movement of the eyes
THE CENTRAL NERVOUS SYSTEM
MOTOR AREAS
• MOTOR AREAS of the cerebral cortex lie in the posterior sections of the frontal
lobes and comprise four areas:
Fig 12.6 pg 434
THE CENTRAL NERVOUS SYSTEM
SENSORY AREAS
• SENSORY AREAS concerned with the conscious awareness of sensation and
comprise eight areas:
1.
2.
3.
4.
5.
6.
7.
PRIMARY SOMATOSENSORY CORTEX: receive input from touch
SOMATOSENSORY ASSOCIATION CORTEX: integrate sensory information to
understand an object being felt
VISUAL AREAS: largest sensory area and receives input from the retina
AUDITORY AREAS: detect sound energy exiting inner ear
VESTIBULAR CORTEX: conscious awareness of balance
OLFACTORY CORTEX: is connected to odor receptors in nose via long axons and
is involved in smell
GUSTATORY CORTEX: region involved in taste
VISCERAL SENSORY AREA: detects sensations like an upset stomach, full
bladder and need for air when holding breath
THE CENTRAL NERVOUS SYSTEM
SENSORY AREAS
• SENSORY AREAS concerned with the conscious awareness of sensation and
comprise eight areas:
Fig 12.6 pg 434
THE CENTRAL NERVOUS SYSTEM
ASSOCIATION AREAS
ASSOCIATION AREAS where individual perceptions are integrated into a more
unified process
• gives meaning to the information we receive, allows us to store it memory, and
decide what action to take
• damage to the association area
impairs judgment and causes a loss
of inhibitions
• also cause failure to recognize parts
of their body as belonging to
themselves
THE CENTRAL NERVOUS SYSTEM
WHITE MATTER
• WHITE MATTER underlies grey matter and is responsible for communication
within the CNS and contain three nerve fiber types:
1. ASSOCIATION FIBERS: connect different parts of the same hemisphere
2. COMMISSURAL FIBERS: allows both hemispheres to function as a whole
3. PROJECTION FIBERS: processes sensory information
Fig 12.8 pg 438
THE CENTRAL NERVOUS SYSTEM
DIENCEPHALON
• up until now we have been describing parts of the cerebral hemispheres
• the DIENCEPHALON is the next major brain region and lies at the core of the
forebrain. It consists largely of three paired structures:
1. THALAMUS: sensory information converges here information is sorted out and
edited (i.e. what is important)
2. HYPOTHALAMUS: controls the viscera (internal organs) and is very important in
maintaining homeostasis, such as body temperature, food intake and thirst.
3. EPITHALAMUS: regulates sleep/wake cycles
Fig 12.8 pg 440
THE CENTRAL NERVOUS SYSTEM
BRAIN STEM
• the brain stem produces the programmed actions required for survival.
• also associated with 10 of the 12 pairs of cranial nerves.
• there are three brain stem regions:
1. MIDBRAIN: functions associated with pain suppression, fight or flight response
and hearing
2. PONS: composed of nerve fibers
3. MEDULLA OBLONGATA: crucial role as an autonomic reflex center, including
a. CARDIOVASCULAR CENTER: adjusts heart contraction force and rate
b. RESPIRATORY CENTER: generates respiratory rhythm
c. OTHER CENTERS: vomiting, hiccuping, swallowing, coughing and sneezing
Fig 12.13 pg 444
THE CENTRAL NERVOUS SYSTEM
BRAIN STEM-FACIAL NERVES (FOR LAB ONLY)
Fig 12.13 pg 444
THE CENTRAL NERVOUS SYSTEM
CEREBELLUM
• the CEREBELLUM provides the precise timing and appropriate patterns of skeletal
muscle contraction for smooth movement (e.g. driving, typing, etc)
• activity occurs subconsciously, we are not aware of it
• damage to the cerebellum results in clumsy unsure movements
Fig 12.15 pg 448
THE CENTRAL NERVOUS SYSTEM
LIMBIC SYSTEM
• refers to a group of structure located on the medial aspect of each hemisphere
• limbic system is our emotional brain, especially the AMYGDALOID BODY (involved
in fear responses) and CINGULATE GYRUS (involved in facial expressions)
Fig 12.16 pg 449
THE CENTRAL NERVOUS SYSTEM
BRAIN PATHOLOGIES
• single most common nervous system disorder and third leading cause of death
in the U.S. are CEREBROVASCULAR ACCIDENTS, also called STROKES
• occurs when blood circulation to the brain is blocked and brain tissue dies
• mostly commonly a blot clot that blocks an artery to the brain. Clots form on
the walls of arteries narrowed by ATHEROSCLEROSIS
• those affected can be partially paralyzed and have difficulty with speech
THE CENTRAL NERVOUS SYSTEM
BRAIN PATHOLOGIES
• up to 50% of people over 85 years of age have ALZHEIMER’S DISEASE
• memory loss, shortened life span, disorientation, confusion and irritability
• caused by accumulations of BETA-AMYLOID PEPTIDES that disrupt brain function
THE CENTRAL NERVOUS SYSTEM
THE SPINAL CORD
• the spinal cord is enclosed in the vertebral column and
provides a two-way conduction pathway to/from the
brain
• surrounded by a protective membrane called DURA
MATER and CEREBROSPINAL FLUID
• 31 pairs of spinal nerve fibers attach via foramen
(holes) in vertebrae
• these fibers connect to motor and sensory
neurons that control movement and the senses
Fig 12.28 pg 467
Fig 12.26 pg 465
THE CENTRAL NERVOUS SYSTEM
SPINAL CORD TRAUMA
• damage to the spinal cord results in PARALYSIS (loss of motor function) or
PARATHESIAS (abnormal sensations)
• severing of the spinal cord results in total motor and sensory loss in body regions
inferior (below) this site of damage
• if damage occurs in thoracic or lumbar regions both lower limbs are
impaired called PARAPLEGIA
• if damage occurs in the cervical section all four limbs are affected and this is
referred to as QUADRIPLEGIA
• POLIOMYELITIS inflammation of the spinal cord from ingesting water
contaminated with poliovirus. The virus destroys neurons of the spinal cord
leading to motor impairment and paralysis
• eradicated with vaccines, but infection rates increasing as parents choose
not to vaccinate their children
• AMYOTROPHIC LATERAL SCLEROSIS: neuromuscular conditions caused by
destruction of neurons of the spinal cord and patient loses ability to speak,
swallow and breathe
• also called Lou Gehrig’s disease
FOR REVIEW TONIGHT
•
understand the organization of the nervous system
•
understand the structure and function of nerve cells
•
understand how action potentials are generated and the
events occurring at the synapse
•
understand the structure and function of the four major
regions of the brain (i.e. CEREBRAL HEMISPHERES,
DIENCEPHALON, BRAIN STEM, CEREBELLUM)
NEXT LECTURE
SPECIAL SENSES
CHAPTER 15