BIO 141 Unit 4 Learning Objectives
Upon your successful completion of this unit, you will be able to do the following.
Chapter 10 – Muscle Tissue
1. Name the 3 types of muscle tissue, their locations, whether they are
voluntary or involuntary and whether or not they are striated.
a. Skeletal – long, cylindrical striated muscle fibers, cells are multinucleated. Found attached by connective tissue to the skeleton,
controlled voluntarily, produces movement of the body
b. Cardiac – short, wide, branching striated cardiac muscle cells with
intercalated discs; cells have a single nucleus or two nuclei. Found
at the heart. Involuntarily controlled, produces beating of the heart
c. Smooth – thin smooth muscle cells, generally joined by gap
junctions; cells have a single nucleus. Found at walls of hollow
organs as well as in the skin and the eyes. Controlled involuntarily.
Changes diameter of hollow organs, causes hairs to stand erect, and
adjusts the shape of the lens and the size of the pupil of the eye
2. Describe the five properties of muscle cells.
a. Contractility – the ability of cells to contract.
b. Excitability – muscle cells are excitable, or responsive, to the
presence of various stimuli from chemical signals from the nervous
or endocrine systems, mechanical stretch signals, or local electrical
signals
c. Conductivity – when a muscle cell is excited, the electrical changes
across the plasma membrane do not stay in one place. Instead they
are conducted along the entire length of the plasma membrane
d. Distensibility – a property of a cell by which it can be stretched
without sustaining damage
e. Elasticity – a property of a cell by which it will return to its resting
length after it has been stretched
3. Given a diagram, identify the following structures of a skeletal muscle fiber,
a. Sarcoplasmic reticulum.
b. T tubules.
c. Terminal cisternae.
d. Triad
e. Sarcomere.
f. Mitochondria.
g. Myofibrils.
h. Sarcolemma and sarcoplasm.
4. Describe the functions of the following structures of a skeletal muscle fiber,
a. Sarcoplasmic reticulum – the specialized smooth endoplasmic
reticulum of a muscle fiber that stores calcium ions. Surrounds each
myofibril
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b. T-tubules – transverse tubules, hollow inward extensions of the
muscle fiber sarcolemma that surround myofibrils; filled with
extracellular fluid. Terminal cisternae flank each side of a t-tubule. A
triad consists of a t-tubule and two adjacent terminal cisternae
c. Sarcomere - the functional unit of muscle contraction, consists of the
area of the myofibril from one z-disc to another, i.e. consists of two
half I-bands and one A-band
d. Sarcolemma – the plasma membrane of a muscle fiber (lemma =
husk or shell)
e. Sarcoplasm – the cytoplasm of a muscle fiber. (Sarco = flesh)
f. Glycogen.
g. Mitochondria.
h. Myoglobin.
i. Myofibrils – long, cylindrical organelles composed of muscle proteins
in a muscle fiber called myofilaments. Makes up 50-80% of the
muscle cell’s volume.
j. Myofilaments – consist of
• Contractile proteins which produce tension
• Regulatory proteins which control when the muscle fiber can
contract
• Structural proteins which hold the myofilaments in their
proper places and ensure the structural stability of the
myofibril and the muscle fiber
5. List the protein components of the thick and thin filaments and explain how
the thin and thick filaments are organized into the sarcomere.
a. Thick filaments – composed of contractile protein Myosin (a clubshaped contractile protein found in muscle fibers and cells that are
motile
b. Thin filaments – composed of both contractile and regulatory
proteins, Actin (a bead-shaped contractile protein found in muscle
fibers and motile cells) that can bind to a myosin head, Tropomyosin
(a filamentous regulatory protein that covers the active sites of Actin
subunits in a thin filament), and Troponin (a regulatory protein with
three subunits that binds tropomyosin and calcium ions in a thin
filament
c. They are arranged alternating between double-sided thick filaments
and thin filaments thus creating the striations we see in these muscle
fibers
6. Briefly describe the structure of a sarcomere with reference to the arrangement
of the thick and thin filaments in relation to the following,
a. Sarcomere – the functional unit of muscle contraction, consists of
the area of the myofibril from one z-disc to another, i.e. consists of
two half I-bands and one A-band
b. I band – the component of the sarcomere that appears lighter
because it contains only thin fibers.
c. A band – the component of the sarcomere that appears darker
because it contains thick filaments and areas in which the thick and
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thin filaments overlap
d. H zone – the middle section of the A-band with only thick filaments
e. M line – the dark line in the middle of the A-band, consists of
structural proteins that hold the thick filaments in place and serve as
an anchoring point for the elastic filaments
f. Z disc – the dark line in the middle of the I-bands that contains structural
proteins that anchor the thin filaments in place and to one another and
serve as an attachment point for elastic filaments. Also attach myofibrils
to one another across the whole diameter of the muscle fiber
g. Connectin (Titin).
h. Dystrophin.
7. Structure of muscle: Muscle fascia surrounds the whole muscle and
anchors it to the surround tissues > deep to the fascia is the epimysium
which surrounds the whole muscle and blends with a deeper layer called
the perimysium > which forms tendons and surrounds fascicles of muscle
fibers > muscle fibers are made up of myofibrils > which are composed of
myofilaments > composed of sarcomeres
8. Briefly describe the thin filaments of myofilaments in terms of,
a. functions of proteins actin, troponin, and tropomyosin.
b. myosin binding site on actin.
c. molecular structures of thin filaments.
9. Briefly describe the thick filaments of myofilaments in terms of,
a. myosin protein.
b. myosin head binding site with actin.
c. myosin head with ATP hydrolysis.
d. molecular structures of thick filaments.
10. Describe the events that occur within the muscle fiber in terms of,
a. Calcium binding to troponin – causes the Troponin to shift pulling the
Tropomyosin and exposing the active site on the Actin
b. Removal of tropomyosin – Tropomyosin is moved and exposes the
active site on Actin
c. Exposure of myosin binding site on the thin filament – Exposure of
Actin when Troponin shifts after binding with Calcium ion
d. Hydrolysis of ATP – ATP hydrolysis “cocks” the myosin head 90
degrees when it then attaches to Actin active site
e. Crossbridge formation (attach) – attachment of “cocked” myosin
head to exposed actin
f. Power stroke leading to sliding of actin and myosin (muscle contraction)
(pivot) – the detachment of phosphate from ATP causes myosin
to pull the attached actin closer to the center of the sarcomere
g. Release of myosin head (detach) – a 2nd ATP breaks the attachment
of myosin to actin at the end of the power stroke
h. Reset myosin head (return) after releasing from the actin, the myosin
head returns to its normal position until “re-cocked” by another ATP
i. During this cycle, what happens to the relative lengths of the I band, A
band, and H zone of the sarcomere in a relaxed versus a contracted
muscle – the I-band and H-zone decrease and the A-band increases
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as the muscle contracts
11. Describe the connective tissues that enclose individual muscle fibers, the
fascicle and the entire muscle.
12. Describe the events, including movement of ions where relevant, that occur
at the neuromuscular junction in terms of,
a. Motor neuron – a neuron that transmits motor impulses from the
central nervous system to a muscle or gland cells
• An action potential arrives at the axon terminal and triggers
voltage gated Ca2+ channels in the axon terminal to open.
Calcium ions follow their electrochemical gradient and enter
the axon terminal
b. Action potential (nerve impulse).
c. Synaptic vesicles.
• The entry of calcium ions into the axon terminal triggers
exocytosis of synaptic vesicles. The synaptic vesicles
release Acetylcholine into the synaptic cleft b/w the motor
neuron and motor end plate
d. Neurotransmitter acetylcholine (ACh) – a neurotransmitter involved
in a wide variety of processes, including those of the autonomic
nervous system and muscle contraction
e. Synaptic cleft – the small space b/w the axon terminal of a
presynaptic neuron and its target cell
• The binding of ACh in the synaptic cleft to ligand-gated ACh
receptors on the motor end plates allows sodium ions to
follow their electrochemical gradient and enter the muscle
fiber
f. Removal of ACh by enzyme acetylcholinesterase.
• ACh is quickly broken down by acetylcholinesterase which
causes the ligand-gated ion channels to close allowing for
repolarization of the motor end plate (as Ca2+ ions are
released once the action potential reaches the SR) to repeat
the process
13. Using concepts of resting membrane potential, depolarization and
repolarization, describe the events that occur on the muscle membrane
(sarcolemma) in terms of,
a. Motor end plate with ACh receptor – acetylcholine binds to ACh
receptors embedded in the motor end plate
b. Binding of ACh with ACh receptor – binding of ACh to ACh receptors
opens chemically gated ion channels allowing interchange of Na+
and K+ ions creating local depolarization on the motor end plate
Excitation
c. Action potential generation on sarcolemma – the local depolarization
at the motor end plate is propagated along the sarcolemma down
the T-tubules until it gets to the terminal cisternae
d. Calcium release from sarcoplasmic reticulum – the action potential
causes the release of calcium ions from the terminal cisternae into
the cytosol Excitation-Contraction Coupling
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14. List and describe the events that occur at the neuromuscular junction leading to
the stimulation of muscle contraction in a muscle fiber.
a. An action potential arrives at the axon terminal and acetylcholine
is released across the synaptic cleft
b. Results in the depolarization of the motor end plate on the muscle
fiber
c. The action potential then propagates along the sarcolemma and
down T-tubules leading to contraction of the sarcomeres
15. Trace the path of the action potential from the neuromuscular junction, down
the T-tubules, and its effect on the sarcoplasmic reticulum.
16. List and describe the steps that occur when intracellular calcium levels rise in a
muscle cell.
a. Calcium ions bind to troponin – 3 sub-units of troponin, one binds
calcium ions, one binds actin and one binds tropomyosin. Ca2+
ions released from the SR bind to the troponin sub-unit
b. Tropomyosin moves, and the active sites of actin are exposed –
troponin shifts its position after binding with the calcium ion
shifting tropomyosin away from the active sites and allowing the
myosin on thick filaments to attach to the active sites on the actin
c. Myosin binds to Actin – creating a crossbridge cycle and the
myosin pulls the thin filament closer to the M line of the
sarcomere Contraction
17. List the events that allow muscle relaxation to occur in terms of,
a. ACH receptor close – receptors close as Acetylcholinesterase
degrades ACh in the synaptic cleft and repolarization occurs
b. Calcium channel on the sarcoplasmic reticulum close – repolarization
occurs and the calcium ion channels in the SR close
c. ATP formation at the myosin head.
d. Movement of calcium back into the sarcoplasmic reticulum – active
transport pumps in the SR membrane consume ATP and pump
Calcium ions back into the SR
e. Removal of ACh from the synaptic cleft by enzyme acetyl cholinesterase.
f. Reformation of troponin-tropomyosin complex to cover myosin binding
site on actin - as the number of Calcium ions returns to resting
level Calcium ions dissociate from Troponin causing to shift back
pulling the Tropomyosin back over the active sites on Actin
18. Describe the three different pathways that are used for generating ATP in muscle
cells,
a. Aerobic cellular respiration (long-term means of supplying ATP).
• Oxidative catabolism, it is the continuation from the end
products of glycolysis (i.e. pyruvates). Produces much more
ATP than other two methods. After about 1 minute of continued
muscle activity nearly all ATP for muscles is produced
aerobically
b. Anaerobic respiration (short-term means of supplying ATP).
• AKA glycolysis – glucose is broken down to produce (2) ATP
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per molecule of glucose and two molecules of pyruvate.
Muscles can get glucose directly from the bloodstream or from
glycogen. Stored glycogen and glycolysis allows for ~30-40sec
of muscle activity
c. Creatine-phosphate complex formation (immediate means of supplying
ATP).
• Creatine phosphate, with the help of creatine kinase,
donates a phosphate group to ADP to form ATP. Allows
for ~10sec of muscle activity
19. Describe the role of myoglobin.
a. Myoglobin binds oxygen in the muscle cells to increase the
amount of oxygen immediately available for aerobic respiration
20. Describe the 3 distinct phases of a muscle twitch on a myogram; latent
period, contraction period, relaxation period.
a. Latent period – the 1-2ms time it takes for the action potential to
spread through the sarcolemma. Begins with the start of the
action potential and up to the start of the crossbridge cycle
b. Contraction period – the period marked by rapid increase in
tension as crossbridge cycles occur repeatedly.
c. Relaxation period – period in which tension decreases due to the
decreasing calcium ion concentration in the cytosol. Takes the
Ca/K pumps b/w 10-100ms to pump calcium ions back into the
SR
21. Describe how changes in the strength of the stimulus and the frequency of the
stimulus can alter the response of the muscle, and how it can lead to tetany.
a. Increasing strength and frequency of stimulus increases tension
because the Ca/K pumps can’t pump all the released Calcium
ions back into the SR membrane
b. Unfused tetany – a type of wave summation in which a muscle
fiber is stimulated rapidly and only allowed to partially relax
between contractions, building up more and more until a level of
maximal tension is reached. Happens when the fiber is
stimulated ~50 times per second
c. Fused tetany – a type of wave summation in which a muscle
fiber is stimulated rapidly and the muscle fiber is not allowed to
relax between contractions, so the tension remains constant at a
maximal level. Happens when the fiber is stimulated 80-100
times per second
22. Explain how a fast-twitch fiber differs from a slow-twitch fiber, and how an
oxidative fiber differs from a glycolytic fiber.
a. Fast Twitch – skeletal muscle fibers with high myosin ATPase
activity that proceed more rapidly through their crossbridge
cycles; generate rapid but generally short-duration
contractions. Ex muscles that move the eyeballs
b. Slow Twitch – skeletal muscle fibers with low myosin ATPase
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activity that proceed relatively slowly through their
crossbridge cycles; generate slower but generally longer
lasting contractions. Ex muscles in the back that control
posture
c. Type I fibers – slow twitch oxidative fibers (use oxidative
catabolism), also called “red muscle” because high levels of
myoglobin makes them red. Generally small diameter, slow
less forceful but extended periods of contractions
d. Type II fibers – fast twitch fibers, often larger in diameter and
more rapid contractions, rely heavily on glycolytic energy
sources and have less myoglobin, fewer mitochondria, and
less extensive blood supply. Also called “white muscle”
• Type IIa – fast oxidative glycolytic; used in walking or
writing
• Type IIx – fast glycolytic; used in heavy lifting or
sprinting
23. Define motor unit. What is the significance of motor unit recruitment?
a. Motor unit – the group of muscle fibers innervated by a single motor
neuron. Slow motor units are tied to type I fibers, fast motor units to
type II
b. Recruitment – an increase in the number of motor units of a skeletal
muscle that are stimulated in order to produce a contraction with
greater tension. Slow motor units are typically activated first, then
fast motor units
24. Describe the inverse relationship between the size of a motor unit and the
degree of control of skeletal muscles in an organ or body part.
a. Average unit consists of 150 muscle fibers but can vary
widely depending on degree of motor control needed for the
muscle. Higher control = lower number so that more neurons
are controlling the muscle fibers
25. Define muscle tone.
a. The small amount of tension produced by a muscle at rest due to the
involuntary activation of motor units by the brain and spinal cord.
Important to maintain erect posture, stabilize joints, generate heat
and ensure the muscle is ready to respond if movement is initiated.
b. Hypotonia – abnormally low muscle tone
c. Hypertonia – abnormally high muscle tone (can occur during
shivering to generate heat)
26. Define isometric and isotonic contractions
a. Isotonic concentric contraction – aka miometric (mio = shorter), a
type of muscle contraction in which the tension generated is greater
than that of the external load, and so the muscle cell shortens with
the contraction. Ex. when you are lifting a weight up, muscles flex
and shorten when they generate enough force to lift the weight
b. Isotonic eccentric contraction – aka pliometric (plio = longer), a type
of muscle contraction in which the tension generated is less than
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that of the external load, and so the muscle cell lengthens with the
contraction. Ex. when you’re putting the weight back down, the force
generated by the muscles becomes less than the load of the weight,
but your motor units are still generating tension even though the
sarcomeres are stretching and lengthening
c. Isometric contractions – a type of muscle contraction in which the
tension generated is equal to that of the external load, and so the
muscle cell remains at a constant length. Ex. lifting and holding a
weight in place. Tension is still being generated to hold the weight in
the air but the muscles are neither shortening or lengthening
27. Define muscle hypertrophy.
a. An increase in cell size. In the case of muscle training, occurs during
resistance (strength training) and is a result of increased number of
myofibrils and increased diameter of myofibrils
28. Define muscle and explain what causes muscle fatigue.
a. Muscle fatigue – an inability to maintain a given level of intensity of a
particular exercise. Occurs due to
• Depletion of key metabolites such as creatine phosphate,
glycogen, and blood glucose
• Decreased availability of oxygen to muscle fibers, the
amount of oxygen bound to myoglobin may be depleted, the
amount of oxygen taken in by the lungs may be inadequate
• Accumulation of certain chemicals for ex. calcium ions
accumulate in the mitochondria where they interfere with the
mitochondrial ability to carry out oxidative catabolism
• Environmental conditions like extreme heat disrupt the
body’s homeostasis leading to more rapid muscle fatigue,
sweating may cause an electrolyte imbalance etc.
29. Define excess post-exercise oxygen consumption (EPOC)
a. The persisting increased rate of breathing during the recovery period
after completing exercise to bring your body back to the pre-exercise
state. Activities needed to bring it back to original state include
• Heat dissipation
• Restoration of intracellular and extracellular ion
concentrations
• Correction of blood pH
30. Explain where smooth muscle is located throughout the body and how they
differ from skeletal muscle.
a. Widely distributed throughout the body, much is found lining hollow
organs but also present at arrector pili muscles in the dermis and the
iris of the eye
b. Function in peristalsis – rhythmic contractions to propel material
through the hollow organs
c. Form sphincters
d. Regulation of flow by contracting or loosening. Occurs in blood
vessels and the airway passages
e. They have a different arrangement of myosin and actin compared to
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the skeletal muscles. They lack striations and sarcomeres giving
them their “smooth” appearance
f. Actin are arranged obliquely and are anchored to dense bodies.
Several thin filaments radiate from dense bodies and surround thick
filaments. Overall the ratio of thin to thick is higher in smooth
muscles
g. Thin filaments in smooth muscle don’t have troponin, and myosin
heads are arranged differently
h. Smooth muscles don’t have motor end plates, the SR is less
extensive and T-tubules are absent
31. Define single-unit and multiunit innervation in smooth muscle.
a. Single-unit – AKA visceral smooth muscle, smooth muscle cells that
contract together as a single unit. Is the predominant type of smooth
muscle in the body and is found in nearly all hollow organs
b. Multi-unit smooth muscle – found in locations as the muscles in the
eye and the arrector pili muscles in the dermis. Consists of individual
muscle cells whose plasma membranes are not joined by gap
junctions allowing each cell to contract independently
32. Explain the cellular arrangement of filaments in a smooth muscle cell.
a. Myosin is sandwiched b/w two outer layers of actin
33. List and explain the sequence of five steps in smooth muscle contraction.
a. Calcium ions bind a protein in the cytosol called calmodulin
b. The calcium ion-Cam complex activates an enzyme associated with
myosin called myosin light-chain kinase (MLCK)
c. MLCK causes the activation of myosin ATPase
d. Crossbridge cycles then ensue
Chapter 09 – Muscular System: Axial and Appendicular Muscles
Please refer to the list of muscles provided in the Muscles Table attached to the unit.
You should be able to identify and explain the actions of all the muscles listed in the
table. In addition, you should know the origin and insertion of the muscles.
1. Define the terms origin and insertion of a skeletal muscle.
a. Origin – the less moveable attachment point of a muscle on a bone
b. Insertion – the end of a muscle attached to the structure that will be
moved when the muscle contracts
2. Differentiate between agonists, antagonists, synergists and fixators.
a. Agonists - a muscle that provides the principal force required in a
movement; also known as the prime mover
b. Antagonists – a muscle generally located on the opposite side of a
joint from its agonist that opposes or slows the action of the agonist
c. Synergists – a muscle that works together with the agonist to make
the movement more efficient and smooth
d. Fixators – a muscle that holds a bone in place, allowing other
muscles to move the bone and joint more effectively
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3. List the eight characteristics of muscles that may be used for naming skeletal
muscles, and provide examples for each. (Refer to Table 9.1 Common Terms in
Muscle Anatomy)
a. Muscle Size
•
Brevis – short. Ex fibularis brevis
•
Longus – long. Ex adductor longus
•
Vastus – wide/large. Ex vastus lateralis muscle
b. Muscle Location
•
Anterior – toward the front
•
External – toward the outside
•
Infra – below
•
Intercostal – between the ribs
•
Internal – toward the inside
•
Posterior – toward the back
•
Profundus – deep
•
Superficialis – nearer the surface
•
Supra – above
c. Muscle Action
•
Abductor – pulls away from the midline
•
Adductor – pulls toward the midline
•
Depressor – pulls down
•
Erector – holds erect or straight
•
Extensor – increases the angle between the bones
•
Flexor – decreases the angle between bones
•
Levator – raises a body part
•
Pronator – turns palm anteriorly
•
Supinator – turns palm anteriorly
d. Body Region
•
Abdominis – abdominal area
•
Brachii – arm areas
•
Capitis – head area
•
Carpi – wrist area
•
Cervicis – neck area
•
Digitorum/digitti – related to fingers/toe
•
Femoris – femur or thigh
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0
•
Gluteal – buttocks
•
Hallucis – great toe
•
Oculi – eye area
•
Oris – Mouth area
•
Pectoralis – chest area
•
Pollicis – thumb
e. Muscle Fiber Orientation
f.
•
Oblique – at an angle
•
Orbicular – circular
•
Rectus – straight
•
Transversus – across transverse
Muscle Heads
•
Biceps – three heads
•
Quadriceps – 4 heads
•
Tricaps – three headed
g. Muscle Shape
•
Deltoid – triangular
•
Minimus/minimi – smallest
•
Minor – small
•
Quadratus – shaped like a rectangle
•
Rhomboid – shaped like a rhombus
•
Serratus – serrated or jagged
• Trapezius -shaped like a trapezoid
4. Given a diagram/picture, identify a muscle and explain its action. (Refer to the
list of muscles provided in the Muscles Table attached to the unit).
5. Six main fascicle patterns:
a. Parallel – muscle has evenly spaced fascicles attaching to a tendon that
is about the same width as the muscle. Produces a straplike muscle, ex.
sartorius muscle in the thigh
b. Convergent – muscle is broad at one end and uniformly tapers to a
single tendon, triangular muscles such as the pectoralis major muscle in
the chest, usually have a convergent fascicle arrangement
c. Pennate – muscle has fibers and fascicles that attach to the tendon at an
angle in such a way that the muscle resembles a feather. Uni pennate
has as ingle tendon, bipennate has a single tendon but the fascicles
angle out from both sides of the tendon, multipennate is usually several
tendons like several feathers joined together
d. Circular – muscle encircles a structure, such as the opening of the eye,
to close or constrict it when it contracts, often referred to as sphincters
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e. Spiral – muscle may wrap around a bone or have the twisted appearance
of a towel wrung out to dry
f. Fusiform – muscle is thicker in its belly, or middle region, and tapered at
its ends
Chapter 11 – Nervous System: Nervous Tissue
1. Describe the three general functions of the nervous system.
2. List the two structural divisions of the nervous system.
a. Central nervous system – made up of the brain and spinal cord
b. Peripheral nervous system – made up of nerves (12) cranial and
(31) spinal
3. List the organs that comprise the two structural divisions of the nervous system.
4. Describe the functional divisions of the nervous system somatic sensory,
visceral sensory, somatic motor, visceral motor
a. Sensory input taken in by afferent division of PNS, integrated by
CNS, and output is by efferent division of PNS
b. Somatic sensory – a subdivision of the PNS that provides sensory
innervation to the skin, muscles and joints
c. Visceral sensory – transmit signals from viscera (organs)
d. Somatic motor – provides motor innervation to the skeletal muscles.
AKA voluntary motor division
e. Visceral motor division – division of the PNS that controls
homeostatic responses of the organs, autonomic
5. Given a diagram or histological image of a neuron, identify the following
features,
a. cell body.
b. chromatophilic substance (Nissl bodies).
c. dendrites.
d. axon.
e. axon hillock.
f. collateral
g. neurofibril node (node of Ranvier).
h. synaptic knobs.
i. synaptic vesicles.
6. Briefly explain the functions of the following,
a. cell body.
b. chromatophilic substance (Nissl bodies).
c. dendrites.
d. axon.
e. synaptic vesicles.
7. Describe the structural and functional classification of neurons.
Structural
a. Multipolar neurons – single axon, multiple highly branched dendrites
b. Bipolar neurons – one acon, one dendrite
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c. Pseudounipolar neuron – begin as bipolar neurons but their
processes fuse and give rise to a single axon, axon splits into two
processes, one peripheral and one central
Functional
d. Sensory/afferent neurons – carry signals toward the CNS, generally
pseudounipolar or bipolar
e. Interneurons – carry signals within the CNS, multipolar
f. Motor neuron – carry signals away from the CNS, multipolar
8. Differentiate the function and location of the three different functional classes of
neurons.
a. Receptive region – cell body
b. Conducting region – along the axon
c. Secretory region – at the terminal end of the axon
9. Explain how glial cells differ in function from neurons.
a. Supporting cell of nervous tissue, can still undergo mitosis,
maintains the environment, protects neurons, and assists in their
proper functioning
10. List the different types of glial cells in the central nervous system (CNS) and
peripheral nervous system (PNS).
CNS
a. Astrocytes – most numerous, anchor neurons and blood
vessels, regulate the ECM, facilitate formation of the blood
brain barrier, repair damaged tissue
b. Oligodendrocytes – myelinate certain axons
c. Microglia – act as phagocytes
d. Ependymal cells – line cavities, cilia circulate cerebrospinal
fluid around brain and spinal cord, some secrete fluid
PNS
e. Schwann cells – myelinate certain axons in the PNS
f. Satellite cells – surround and support cell bodies
11. Describe the role of astrocytes in the formation of the blood-brain barrier.
12. Describe the functions of the following glial cells,
a. ependymal cells.
b. microglia.
c. oligodendrocytes.
d. Schwann cells
e. satellite cells.
13. Describe the role, composition of myelin and its location along a neuron.
a. Same composition as other cells since it is made up of
oligodendrocytes and schwann cells
b. Insulates the electric current in the axon because it has high lipid
content (hydrophobic) keeps the ions in
c. Covered sections of axon are called internodes
d. Exposed gap is node of Ranvier
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14. Describe the difference between gray and white matter.
a. White matter is myelinated axons
b. Gray matter is unmyelinated cell bodies and dendrites
15. Describe the process of regeneration of neurons in the PNS.
a. In the CNS - Doesn’t occur often, no chemical growth factors
present, oligodendrocytes may inhibit neuronal growth, astrocytes
grow and fill up empty spaces
b. In the PNS – occurs only if the cell body is intact
16. Briefly explain the 2 main classes channels found on neurons.
17. Describe the 3 types of gated channels.
18. Explain the relative concentrations of Na+, K+, Ca+, and across the plasma
membrane of a resting nerve cell (review resting membrane potential).
19. Define a graded potential.
20. Define the terms hyperpolarization and depolarization with reference to ionic
movement.
21. Differentiate between excitatory postsynaptic potentials (EPSP) and inhibitory
postsynaptic potentials (IPSP) in terms of ionic movement.
22. Define threshold membrane potential.
23. Describe the two types of summation of graded potentials.
24. Explain the all or none law and how it applies to the generation of an action
potential in the initial segment.
25. Explain the events of an action potential with the reference to ionic movement
and opening and closing of the channels along the neuronal membrane. (Refer to
Figure 11.13
26. Given a graph of an action potential, label the following stages,
a. resting membrane potential.
b. threshold potential.
c. depolarization.
d. repolarization.
e. hyperpolarization.
27. Define absolute and relative refractory periods.
28. Differentiate between saltatory and continuous conduction.
29. Describe how fiber size and degree of myelination affect conduction
velocity.
30. Describe the differences between electrical and chemical synapses.
31. Define a neurotransmitter and state where it is released from a neuron.
a. What is the role of calcium in this process?
32. State the functions of the following neurotransmitters,
a. Norepinephrine.
b. Acetyl choline.
c. dopamine.
d. GABA .
e. Glutamate.
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f. Serotonin.
33. Describe the relationship between neurotransmitters, receptors and the
process of degrading the neurotransmitter.
34. Describe the difference between converging and diverging circuits.
a. What is a neuronal pool
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