A&P HW 9-11 for EXAM 3

Which of the following statements regarding glial cells is false?

Glial cells produce action potentials for skeletal muscles.

Sam is curling very heavy weights and suddenly drops them. Which reflex forced this action by Sam to prevent tendon damage?

Golgi tendon reflex

Which portion of a reflex arc is most likely to be located entirely within the central nervous system?

Interneuron

The ______has two functional subdivisions, the sensory division and the motor division.

PNS

Suppose both excitatory and inhibitory neurons synapse with a single postsynaptic neuron. What determines if an action potential is initiated in the postsynaptic neuron?

The number of EPSPs in relation to the number of IPSPs

The two kinds of long, thin protein filaments contained in a myofibril are _____ myofilaments or thin myofilaments and ____ myofilaments or thick myofilaments.

actin; myosin

in order for muscle relaxation to occur

active sites on acting must be blocked

Baby Z was diagnosed with the hypoxic encephalopathy, which affects the blood brain barrier, what cells are affected

astrocytes

When someone taps you on your shoulder, they stimulate the __________ nerve.

axillary

Smooth muscle and cardiac muscle are similar in that they both

are under involuntary control

Arrange these events in order: 1. The sarcoplasmic reticulum releases Ca+2 2. The sarcoplasmic reticulum takes up Ca+2 3. Ca+2 ions diffuse into the sarcoplasm 4. An action potential moves down the T tubule 5. The sarcomere shortens6. The muscle relaxes

4, 1, 3, 5, 2, 6

Skeletal muscle

Constitutes 40% of the body's weight; voluntarily controlled

lateral horn

Contains cell bodies of multipolar neurons of the autonomic nervous system

ventral horn

Contains cell bodies of multipolar neurons that innervate skeletal muscle

dorsal horn

Contains neurons that receive sensory information from the neurons of the dorsal root

The ANS is subdivided into two divisions: the ____ division which is most active during physical activity and the ____ division which regulates resting functions.

sympathetic; parasympathetic

as a result of calcium ions diffusing into the presynaptic cell,

synaptic vessels migrate to the plasma membrane and release acetylcholine

what type of potential causes a graded potential great enough to initiate an action potential

threshold

A collection of axons inside the CNS is called a ____ whereas outside the CNS it is called a _____.

tract; nerve

During muscle contraction, calcium ions bind to ___________.

troponin

________ is composed of three subunits: one that binds to actin, a second that binds to tropomyosin, and a third that has a binding site for Ca2+.

troponin

in excitation contraction coupling Ca 2+ binds to

troponin

A muscle fiber is a highly specialized skeletal muscle cell that are long and cylindrical with several nuclei located near the plasma membrane.

true

A power stroke is the process when the myosin heads pivot towards the M-line sliding the actin over the myosin.

true

Absolute refractory period cannot produce a secondary action potential.

true

Active tension is when force is applied when lifting an object.

true

An action potential is an electrical impulse that is often associated with contractility and neuron stimulation.

true

Cardiac muscle is involuntary and auto rhythmic.

true

Gaps in myelin sheath are called nodes of Ranvier and they are not wrapped in myelin.

true

In chemical synapses the action potentials in the presynaptic terminal cause the release of neurotransmitters that diffuse across the synaptic cleft to bind to specific receptors on the postsynaptic membrane.

true

Most researchers believe MS results from a combination of genetic and environmental factors. One peculiar observation regarding environment is the fact that the incidence increases as one gets farther from the equator.

true

Muscle tissue has four major functional properties: contractility, excitability, extensibility, and elasticity.

true

The Golgi tendon reflex causes a muscle to relax after an intense stretch.

true

The following are all functions of the nervous system: maintaining homeostasis, receiving sensory input, integrating information, controlling muscles and glands, and establishing and maintaining mental activity.

true

The vertebral column originates from the foramen magnum.

true

depolarization results in EPSP, hyperpolarization results in IPSP

true

what is not a property of the myosin head

bind to troponin

A local anesthetic such as Novocaine decreases membrane permeability to Na+. The use of this anesthetic will

block sensory input into the CNS.

novacane decreases permeability to Na+. The use of this medication will

block sensory input to the CNS

The ____ nervous system consists of the brain and the spinal cord whereas the ___ nervous system consists of cranial nerves, spinal nerves, and ganglia.

central; peripheral

region of the spinal cord gives rise to eight pairs of spinal nerves.

cervical

The five major plexuses are: the ____ plexus (C1-C4), the ____ plexus (C5-T1), the ____ plexus (L1-L4), the ____ plexus (L40S4), and the _____ plexus (S5 and the coccygeal nerve).

cervical; BRACHIAL; lumbar; sacral; COCCYGEAL

The sensory (afferent) division of the peripheral nervous system

conveys action potentials to the CNS.

Response to a withdrawal reflex; causes extension of the opposite limb

cross extensor reflex

reflex occurs on the opposite side of the body from the stimulus.

crossed extensor

think pair share How do these factors influence RMP?

decrease extracellular K- hyperpolarization increase extracellular K- depolarization open k gated channels- hyperpolarization open na gated channels- depolarization open ca gated channels- depolarization open cl gated channels- hyperpolarization

Acetylcholine binds to a membrane bound receptor and causes ligand-gated sodium channels to open and results in

depolarization

ependymal cells

function in the production and circulation of CSF

Cell bodies of the peripheral nervous system are located in

ganglia

Prevents contracting muscles from applying tension to tendons

golgi tendon reflex

Not all muscle contractions are of equal force. Therefore, muscles respond to stimuli in a _____ fashion

graded

Frank has a microbial infection attacking his brain. Which cell type would you expect to proliferate and be most active during this time?

microglia

Depolarization occurs because

more sodium ions diffuse into the cell than potassium ions diffuse out of it.

The ______division of the PNS is divided into the somatic nervous system and the autonomic nervous system.

motor

ventral

motor

the ventral root of the spinal nerve contains

motor fibers

The specialized nerve cells responsible for stimulating skeletal muscle contraction are called

motor neurons

If the ventral root of a spinal nerve were cut, the regions innervated by that spinal nerve would experience complete loss of __________.

movement

Multiple sclerosis is a neurological disorder in which myelin sheaths in the CNS are destroyed. Which of the following neuroglial cells is being damaged in multiple sclerosis?

oligodendrocyte

2. The cells of the nervous system that produce myelin are the

oligodendrocytes.

The ventral root of a spinal nerve contains __________.

only motor fibers

the ventral root of a spinal nerve contains

only motor fibers

The Na+/K+ pump allows the movement of 3 Na+ ____ of the cell and 2 K+ ____ the cell.

out; into

surrounds groups of axons to form nerve fascicles.

perineurium

Skeletal muscle fibers

possess striations

The process of________involves an increase in the_______of muscle fibers involved

recruitment;number

A decrease in the number of voltage-gated Ca2+ ion channels in the presynaptic terminal would

reduce or inhibit transmission across the synapse.

is an automatic response to a stimulus produced by a reflex arc and occurs without conscious thought.

reflex

1. A time when there is a decrease in the sensitivity of the plasma membrane to further stimulation

refractory period (middle of the graph)

The time when a stronger-than-threshold stimulus is needed to initiate another action potential

relative refractory period (hyper polarization)

withdrawal reflex

removes body part from painful stimulus

an increase in permeability to Na+ will

result in EPSP

The ventral rami of different spinal nerves (called the ___) join with each other to form a ___.

roots; plexus

Spinal nerves exiting the spinal cord from the level of L4 to S4 form the __________ plexus.

sacral

The ______ is the plasma membrane of a muscle fib

sarcolemma

The ____ is the basic structural and functional unit of skeletal muscle because it is the smallest portion of skeletal muscle capable of contracting.

sarcomere

satellite cells

support cells in the PNS that surround the neuronal cell bodies

Endomysium is a delicate network of loose connective tissue that

surrounds each muscle fiber

The endoneurium

surrounds individual axons and their Schwann cells.

The muscles of the back contract to straighten so that you sit at a more erect posture and subsequently the muscles are suddenly stretched as you nod off. Which of the following best represents the sequence of events when you start to nod off? (1) Muscles of the back are stretched.(2) The muscle spindle is stretched.(3) Action potentials in sensory neurons of the muscle spindles increase.(4) Action potentials in alpha motor neurons of skeletal muscle fibers increase.(5) Skeletal muscle of the back contract.

1, 2, 3, 4, 5

Put the following events of excitation-contraction coupling in the correct order.

1. A nerve impulse causes ACh to be released at a neuromuscular junction. 2. The T tubules carry the action potential to the interior of the muscle fiber. 3. Calcium ions are released into the sarcoplasm. 4. Calcium ions bind to troponin molecules on the actin myofilaments. 5. The troponin-tropomysin complex moves, exposing active sites on the actin myofilaments. 6. The heads of myosin myofilaments bind to sites on the actin myofilaments, forming cross-bridges.

Place the boxes in the numbered boxes, 1 through 8, according to the order in which these events occur. Start with acetylcholine binding to lignad-gated sodium channels.

1. Acetylocholine binds ligand-gated sodium channels. 2. sodium ions enter the cell, initiating an action potential 3. an action potential travels down the sarcolemma and T tubules 4.calcium ions are released from the sarcoplasmic reticulum 5.Calcium binds to troponin, causing tropomyosin to move 6. myosin binds to actin 7. myosin cross-bridges alternately swing and detach using ATP energy 8. myosin filaments continue to slide actin toward the M-line

From superficial to deep, put the following meninges and their related spaces in the correct order.

1. dura mater 2. subdural space 3. arachnoid mater 4. subarachnoid space 5. pia mater

Reflexes function in

1. removing the body from painful stimuli. 2. keeping the body from falling. 3. maintaining blood pressure. 4. maintaining blood CO2 levels.

Place the steps of the muscle action potential in the appropriate order.

1.an action potential arrives at the presynaptic terminal2. voltage-gated Ca+2 channels in the presynaptic membrane open3. calcium ions enter the presynaptic terminal4. the neurotransmitter acetylcholine (ACh) is released from presynaptic vessicles5. ACh is released and diffuses into the synaptic cleft6. ACh bings to and opens ligand-gated Na+ channels on the postsynaptic membrane7. Na+ enters the postsynaptic cell8. Postsynaptic membrane begins to depolarize9. If depolarization passes threshold, an action potential is generated along the postsynaptic membrane10. ACh unbinds from the ligand-gated Na+ channels, which then close11. the enzyme acetylcholinesterase removes acetylcholine from the synaptic cleft

There are ___cranial nerves and ___ pairs of spinal nerves.

12; 31

Place the following parts of a reflex arc in the correct order beginning with the sensory receptor. (1) motor neuron (2) interneuron (3) effector (4) sensory neuron (5) sensory receptor

5, 4, 2, 1, 3

There are ____ spinal nerve pairs that exit the vertebral column in the cervical region, ____ in the thoracic region, ____ in the lumbar region, ____ in sacral region, and ____ in the coccygeal region which makes a total of _____ spinal nerves.

8; 12; 5; 5; 1; 31

A _____ is the area of skin supplied with sensory innervation by a pair of spinal nerves.

A DERMATOME

think pair share Myasthenia Gravis is a disease characterized by production of antibodies to the ACh receptors, thus destroying and reducing number of receptors. Which mechanism do you expect drug for this disease to target?

A class of drugs that can block the action of AChesterase enzyme is used to treat this disease. The drugs thus increase the level of ACh in the synaptic cleft, so that it can bind more effectively to the remaining ACh receptors. This will result in improved neuromuscular transmission and muscle contraction.

Epineurium

A layer of dense connective tissue surrounding a nerve

Extensibility

A muscle can stretch beyond its normal resting length and still contract.

Elasticity

A muscle recoils to its original resting length after having been stretched.

Excitability

A muscle responds to a stimulus

Contractility

A muscle shortens forcefully.

Synaptic vesicles contain _____, a neurotransmitter, that when released from a presynaptic membrane diffuses across the synaptic cleft and alters the activity of the postsynaptic cell.

ACETYLCHOLINE

______pathways typically consist of two neurons, with their cell bodies (somas) located in the CNS and PNS, respectively.

ANS

think pair share • Students in a vet school are given the following hypothetical problem: a dog ingests organophosphate poison, and the students must act to save its life. Organophosphate poisons bind to and inhibit Acetylcholinesterase. • How might this affect the dog adversely?• Which one of the following should the students inject into the animal to save it? oCurare (blocks Acetylcholine receptors)oAcetylcholine

As the poison inhibits that enzyme, ACh levels increase in the synaptic cleft, which leads to overproduction of AP, tetanus of muscles and eventual respiratory failure • Injecting ACh would make matters worse • Curare is the best antidote as it blocks the effect of ACh

Stimulation of the Golgi tendon organs result in which of the following changes in the reflex arc?

Both "stimulation of an inhibitory neuron" and "decreased action potentials in alpha motor neurons" are correct.

Which of the following statements regarding the sliding filament model is false?

Both actin and myosin myofilaments shorten during contraction.

Each voltage-gated Na+ channel has two voltage sensitive gates: an activation gate and an inactivation gate. Which of the following would occur during depolarization?

Both activation and inactivation gates are open.

The ______ is in the inferior cervical region and corresponds to the location where nerve fibers that supply the upper limbs enter and leave the spinal cord whereas the______ is in the inferior thoracic, lumbar, and superior sacral regions and corresponds to the location where nerve fibers that supply the lower limbs enter or leave the spinal cord.

CERVICAL ENLARGEMENT; LUMBOSACRAL ENLARGEMENT

Endoneurium

Delicate layer of connective tissue surrounding a single axon and its Schwann cell sheath

Which of the following situations occurs in electrically excitable cells?

Depolarization causes voltage-gated Na+ channels to open.

Which of the following situations occurs in electrically excitable cells?

Depolarization causes voltage-gated sodium ion channels to open.

Depolarization of postsynaptic membrane

EPSP

membrane becomes more permeable to Na+

EPSP

The mechanism by which an action potential causes contraction of a muscle fiber is called _____and it occurs because of the anatomical association between the T tubules and the sarcoplasmic reticulum.

EXCITATION-CONTRACTION COUPLING

What space, found between the vertebral wall and the dura mater, is the area for injecting anesthesia for childbirth?

Epidural space

Which of the following is true about skeletal muscle?

Every muscle fiber receives a branch of an axon from the nerve.

A cross-bridge is formed when actin binds to tropomyosin.

FALSE the correct answer is: myosin binds to actin.

Which structure anchors the thecal sac and conus medullaris to the coccyx?

Filum terminale

Oligodendrocytes

Form myelin sheath in CNS

cardiac muscle

Found only in the heart; involuntarily controlled

a membrane potential becomes more negative

IPSP

hyperpolarization of the postsynaptic membrane

IPSP

the membrane becomes more permeable to Cl- or K+

IPSP

think pair share Explain what would happen if presynaptic action potentials in an axon release insufficient acetylcholine.

If insufficient Ach released, then can't depolarize skeletal muscle fiber to threshold, and no action potential will be produced because of which muscle cannot contract.

Which of the following helps explain the increased tension seen in multiple wave summation?

Increased concentration of Ca2+ around the myofibrils

Where do we see the following solute in increased concentration- inside or outside the cell?

K+- inside Na+- outside Proteins- inside Cl- - outside

While moving a large box in his garage, Carl hurt his back. Within hours, the pain in his back was radiating down the medial side of his left thigh and knee. It was especially difficult for Carl to flex his left hip and extend his left knee. He could not stand the pain, so he went to the emergency room. Radiographs and an MRI revealed a bulging intervertebral disk.Using a dermatome map, indicate which spinal nerve was most likely affected?

L3

Classify each of the following according to whether it belongs to the lag, contraction, or relaxation phase of a muscle twitch.

LAG PHASE:- Ca++ bings to troponin- local depolarization of the muscle fiber- the action potential produced propagates into the T tubules CONTRACTION:- Ca++ released from sarcoplasmic reticulum- actin myofilaments slide past myosin myofilaments- cross-bridges form RELAXATION:- Ca++ is actively transported into the sarcoplasmic reticulum- muscle fibers lengthen

The _____ phase of a muscle twitch is the gap between the time of stimulus application to the motor neuron and the beginning of contraction, the ____ phase is the time during which contraction occurs, and the ____ phase is the time during which relaxation occurs.

LAG or LATENT; contraction; relaxation

Perineurium

Layer of connective tissue surrounding a nerve fascicle

Which of the following actions is caused by contraction of skeletal muscle?

Moving your feet in walking

Which of the following is mismatched?

Myosin myofilaments - thin myofilaments

A _____ consists of the axon terminals and the area of the muscle fiber sarcolemma they innervate.

NEUROMUSCULAR JUNCTION or SYNAPSE

Which of the following is true?

Optimal actin and myosin overlap will produce maximal contraction.

Damage to which of these nerves would be most life-threatening?

Phrenic nerves

Which of the following is true during the resting membrane potential?

Potassium is concentrated primarily inside the cell.

Arrange these structures as they participate in excitation-contraction.

Sarcolemma, T tubules, sarcoplasmic reticulum, Ca2+

Which of the following events occurs during the lag phase of a muscle twitch?

The action potential is propagated from presynaptic to postsynaptic membrane.

What is found in the lateral gray horns of the spinal cord?

The cell bodies of autonomic motor neurons

Smooth muscle

The most widely distributed muscle type; involuntarily controlled

Which of the following is responsible for problem-solving skills?

central nervous system

Which of the following statements concerning the structure of spinal nerves is true?

The ventral root contains motor or efferent fibers.

The_____ removes a limb or another body part from a painful stimulus.

WITHDRAWAL reflex (FLEXOR reflex)

think pair share You are about to have a dental procedure and the dentist numbs you up with an injection of lidocaine, a local anesthetic that prevents voltage-gated Na+ channels from opening. Explain why this mechanism would block the conduction of pain signals from your teeth to your brain.

When the voltage-gated Na+ channels cannot open, there can be no inflow of Na+, no depolarization of the plasma membrane, no generation of action potentials at that point. • Therefore, the pain fibers would be unable to conduct signals to the CNS beyond the point where the lidocaine is applied.

An isotonic contraction is described as

a muscle produces constant tension during contraction.

In which of the following situations does a resting membrane potential exist?

a relaxed muscle fiber

A recently depolarized area of a cell membrane cannot generate an action potential because of the

absolute refractory period

The time when there is complete insensitivity of the plasma membrane to another stimulus

absolute refractory period (peak of graph)

_____ attaches to receptor sites on the motor endplate and stimulates muscle contraction

acetylcholine

in excitation coupling, myosin binds to exposed sites on

actin

1. In Alzheimer's disease, there is a loss of cholinergic signal transmission in the brain, and patients are given a cholinergic _________blank. 2. In myasthenia gravis, antibodies may reduce the ability of acetylcholine to bind its receptors in skeletal muscle. These patients may benefit from therapy with drugs that are cholinergic_________blank. 3. A farm worker severely poisoned by an insecticide that prevents acetylcholine function will benefit from receiving a cholinergic _________blank.

agonist; agonist; agonist

increasing permeability of Cl- to the membrane will cause

an IPSP

When a neurotransmitter binds to its receptor and increases the permeability of the postsynaptic membrane to Na+,

an excitatory postsynaptic potential (EPSP) will result.

Movement away from the cell body is called ___ whereas movement toward the cell body is called ____.

anterograde; retrograde

Voltage gated Na+ ion channels have two voltage sensitive gates. which will occur during depolarization

both activation and inactivation gates opened

Spinal nerves C5-T1 make up the __________ plexus.

brachial

spinal nerves C5-T1 form the _____ plexus

brachial

When an action potential reaches the presynaptic terminal,

calcium ions diffuse into the presynaptic terminal through voltage-gated ion channels.

Neurotransmitters

cause the production of action potentials in the postsynaptic membrane.

Protein synthesis in neurons occurs in __________.

cell bodies or soma

At the highest state of depolarization Na+ channels _____ and K+ channels are _____.

close; opening

in the spinal cord, white matter is organized into _____ and gray matter is organized into____

columns and horns

In the spinal cord, white matter is organized into

columns and the gray matter into horns.

the absolute refractory period ensures

completion of repolarization before another AP

The absolute refractory period assures

completion of repolarization before another action potential.

T tubules

conduct action potentials deep into the muscle fiber.

T tubules

conducts APs deep in muscle fibers

The somatic nervous system directs _______activities.

conscious

Lack of acetylcholinesterase in the synaptic cleft would result in

continuous stimulation of postsynaptic membrane

Both actin and myosin myofilaments shorten during contraction.

continuous stimulation of the postsynaptic membrane.

cannot enter a muscle fiber in response to a stimulus,

contraction cannot occur

If Ca 2+ ions cannot transport back into the sarcoplasmic reticulum, what will result?

contraction with no relaxation

An increase in the force of the_______of the muscle fibers in a muscle is accomplished through______

contraction; summation

is the tapered end of the spinal cord.

conus medullaris

the motor (efferent) division of the PNS

conveys AP from CNS to effectors

Movement of sodium ions into the muscle cell at the neuromuscular junction causes _____________.

depolarization of the muscle cell membrane

The ____ phase of the action potential is when the inside of the cell becomes positively charged and the ____ phase is the return of the membrane potential to its resting value.

depolarization; repolarization

When traveling along an axon, the cell membrane immediately ahead of an action potential depolarizes because of _________

diffusion of sodium current

The ____ nervous system is an independent subdivision of the PNS that is integrated with the ANS.

enteric

WHICH ORDER IS CORRECT

excitability AP excitation contraction cross bridge relaxation

When depolarization of the postsynaptic cell occurs, the response is stimulatory, and the resulting graded potential is called an ___ postsynaptic potential whereas ____ postsynaptic potential is hyperpolarization in the postsynaptic membrane, which causes the membrane potential to move away from threshold.

excitatory; inhibitory

Acetylcholine is released at the adrenergic synapse and norepinephrine is released at the cholinergic synapse

false

Fast-twitch muscle fibers (type I) have a better-developed blood supply, have more mitochondria and are more fatigue-resistant than slow-twitch muscle fibers (type II).

false

Receptor molecules in synapses are not specific for particular ligands. FALSE They are specific

false

Reflexes can operate as isolated entities only and never integrate with the brain.

false

Schwann cells form myelin sheaths around axons of multiple neurons. FALSE: only one axon

false

The simplest reflex arcs involve interneurons.

false

as Na + enters the membrane, the cell becomes more negative

false

during resting membrane potential, sodium is primarily concentrated inside the cell

false

Each actin myofilament is composed of two strands of ______ actin, a series of ______ molecules, and a series of ____ molecules.

fibrous; tropomyosin; troponin

limits the up and down movements of the spinal cord.

filum terminale

schwann cells

form myelin sheaths in PNS

A neuron is receiving a stimulus which gets stronger and stronger. The result is

frequency of occurrence of action potentials increases.

decreasing extracellular K+ will cause

hyperpolarization

occurs when the membrane potential becomes more negative and is the movement of the membrane potential further away from zero

hyperpolarization

Mr. Miller has been hospitalized for the flu. The flu virus increases membrane permeability to K+. You would expect his cells to __________.

hyperpolarize

the flu causes your membrane ti be more permeable to K+ ions this means the cell would

hyperpolarize

which of the following is mismatched?

i band has actin and myosin filaments

The portion of a sarcomere that contains actin myofilaments only is the ____ whereas the ______is the portion of the sarcomere where only myosin myofilaments are present.

i band; h-zone

Curare blocks acetylcholine receptors at the motor end plate. This would result in

inability of the muscle fiber to respond to nervous stimulation.

Complete tetanus

is the condition in which stimuli occur so rapidly that there are no intervening relaxations.

multiple wave summation occurs because of

increased frequency of AP on plasma membrane

raven is a world class sprinter, which of the descriptions about her muscle fibers is true

increased glycogen deposits

a local potential

increases or decreases in direct proportion to the stimulus strength.

Triggers of acute episodes of MS include

infections pregnancy stress

decreasing the number of voltage gated Ca 2+ ions in the presynaptic terminal will

inhibit or reduce transmission across synapse

Local hyperpolarization in a synapse is called a/an __________.

inhibitory postsynaptic potential

Golgi tendon reflex

initiated by excessive force in the tendon receptors embedded in collagen of tendons

stretch reflex

initiated by increase in muscle length muscle spindles

A neuromodulator

is a substance released from neurons that influences the sensitivity of neurons to neurotransmitters.

The conus medullaris

is a tapered, cone like region immediately inferior to the lumbar enlargement.

1. Myelin is critical to nervous system function because

it provides insulation around axons so as to greatly speed up neural impulses.

what effect does acetylcholine have on the postsynaptic neuron

ligand-gated sodium ion channels open and sodium diffuses in

If the ventral root of a spinal nerve were cut, the region innervated by spinal nerves would experience

loss of movement

region of the spinal cord gives rise to five pairs of spinal nerves.

lumbar

Microglia

macrophages of the cns

The ____ are connective tissue membranes that surround the spinal cord and brain and include the dura mater, arachnoid mater, and the pia mater.

meninges

astrocytes

multi-functioning cells involved with neurogenesis, scar formation, BBB maintenance, etc

The motor neurons responsible for making a fist are __________.

multipolar

___ neurons have many dendrites and a single axon, ___ neurons have one dendrite and one axon, and ____ neurons have a single process extending from the cell body, which divides into two branches a short distance from the cell body.

multipolar; bipolar; pseudo unipolar

The _____ _____ surrounds individual muscles and groups of muscles, the _____ is dense irregular collagenous connective tissue that surrounds muscles, the _____ is a connective tissue layer that surrounds fascicles, the _____surrounds muscle fibers.

muscle fascia; epimysium; perimysium; endomysium

Energy produced when ATP is converted to ADP and phosphate is stored in ___________.

myosin heads

In excitation-contraction coupling,

myosin heads bind to exposed active sites on actin.

During the resting membrane state in the neuron the inside of the neuron is _____ while the outside is ____.

negative; positive

If you cut bundles of axons and their myelin sheaths in the PNS, you cut __________.

nerves

bundles of axons in the PNS are known as ______________

nerves

are substances released from neurons that influence the likelihood of an action potential being produced in the postsynaptic cell.

neuromodulators

The basic structural unit of the nervous system is the ____ whereas the basic functional unit of the nervous system is the ___ which includes: a sensory receptor, a sensory neuron, an interneuron, a motor neuron, and an effector organ.

neuron; reflex arc

Cells of the nervous system are called ____ and they send electrical messages from their cell body to other cells with long extensions called axons.

neurons

____ receive stimuli, conduct action potentials, and transmit signals to other neurons or effector organs whereas ___ cells support and protect neurons and perform other functions.

neurons; glial

In this stage, the actin myofilaments slide past the myosin myofilaments releasing ADP

power stroke

When the myosin head flexes into a bend, pulling the actin filament along with it, this is called the

power stroke

The adaptive significance of the crossed extensor reflex when a person steps on a tack is to

prevent the person from falling down.

if a RMP is -60 mv and the TP is -40 mv a membrane potential of -30 mv will

produce an action potential

in some cells an AP occurs because

prolonged elevated permeability to K+ ions

A myofilament is the

protein strand composed of actin or myosin.

complete tetanus

rapid stimuli with no intervening

allows the coordinated contraction of flexor muscles and relaxation of the opposing extensor muscles.

reciprocal innervation

dorsal

sensory

there are five components of a reflex arc, which is the correct order

sensory receptor sensory neuron interneuron motor neuron effector organ

In the PNS, the sensory division transmits action potentials from

sensory receptors to the CNS

The PNS is subdivided into two divisions: the ___ division which is also called afferent ("toward") division and the ____ division which is also called efferent ("away") division.

sensory; motor

The dorsal roots contain axons of ____ neurons whereas the ventral roots contain the axons of ____ neurons.

sensory; motor

____ neurons conduct action potentials toward the CNS, ____ neurons conduct actions potentials away from the CNS toward muscles or glands, and ____ conduct action potentials within the CNS from one neuron to another.

sensory; motor; interneurons

Hypertrophy of skeletal muscles from weight lifting is caused by an increase in the

size of muscle fibers

The cell bodies of _____motor neurons are located in the CNS and their axons connect with skeletal muscle cells.

somatic

The motor division is divided into two subdivisions: a voluntary (conscious) division called the ____ nervous system and an involuntary (unconscious) division called the ___ nervous system.

somatic; autonomic

10 APs arrive simultaneously at different presynaptic terminals. this will cause what to occur

spatial summation

When two action potentials arrive simultaneously at two different presynaptic terminals that synapse with the same postsynaptic neuron,

spatial summation occurs.

spatial summation relates to the ___ of a stimulus and temporal summation relates to the ___ of a stimulus

strength; frequency

The ____ reflex occurs when muscles contract in response to a stretching force and is a monosynaptic reflex.

stretch

The simplest reflex where muscles contract in response to excessive stretch

stretch reflex

The autonomic nervous system controls _______activities.

subconscious

In order for muscle relaxation to occur,

the active sites on actin must be blocked.

Hyperpolarization, or afterpotential, occurs because

the increased potassium ion permeability lasts slightly longer than the time required to bring the membrane potential back to its resting level.

The symptoms of MS can come and go. This is because

the oligodendrocytes are constantly renewing their myelin sheaths, so they are able to temporarily repair some of the damage.

Excitation-contraction coupling begins with

the production of an action potential in the sarcolemma.

is the major communication link between the brain and the PNS inferior to the head and is composed of cervical, thoracic, lumbar, and sacral segments.

the spinal cord

The plasma membrane of a neuron is more permeable to K+ because

there are more leak ion channels for K+ than Na+.

The plasma membrane of an excitable cell is more permeable to K+ because

there are more leak ion channels for K+ than Na+.

In some cells, an afterpotential occurs because

there is prolonged, elevated permeability to K+ during repolarization.

Which of the following is NOT a property of the myosin head?

they bind to troponin

region of the spinal cord gives rise to twelve pairs of spinal nerves.

thoracic

an action potential arriving at the presynaptic terminal causes

voltage-gated calcium ion channels to open, and calcium ions to diffuse into the cell

A reflex that protects limbs by removing them from painful stimuli is the __________ reflex.

withdrawal

a reflex that protects limbs by removing them from painful stimuli is the ____ reflex

withdrawal

Removes a body part from a painful stimulus

withdrawal reflex

a reflex that protects the limbs by removing them from painful stimuli is the

withdrawal reflex

think pair share What would happen if Acetylcholine was allowed to accumulate in the synaptic cleft?

• If acetylcholine wasn't degraded in the synaptic cleft, it would act as a constant stimulus at the post synaptic terminal, producing many APs and continuous contraction of the muscle fiber.

think pair share Loss of sensation in a dermatomal pattern can provide information about location of nerve damage. Predict the possible site of nerve damage for patient who suffered whiplash injury in an automobile accident and subsequently developed anesthesia (no sensation) in the left arm, forearm, and hand.

• The body areas in figure 12.15 are color coded and labeled for the nerve innervation. To answer this question, look at the left arm, forearm, and hand to see which nerves are indicated. • In the figure, it is apparent that nerves C5-T1 are damaged. C5 and T1 innervate the left arm, C6 and T1 innervate the forearm, and C7 and C8 innervate the hand.