Ch. 12

generation of action potential: 2. when the sodium channel activation gates open the plasma membrane becomes more permeable to ____ driven by the large electrochemical gradient, sodium ions rush into the cytoplasm and rapid depolarization occurs. the inner membrane surface now contains more ___ ions than ___ ions and the transmembrane potential has changed from -60 to 10+

Na+ + ions than - ions

In the neuron: _____ contain rough ER and free ribosomes -they give the brain a gray color to areas containing neuron cell bodies

Nissl bodies

_______ delivers sensory info to the CNS and carries motor commands to peripheral tissues and systems

PNS

____________ principle states that If a stimulus exceeds threshold amount: - the action potenial is the same no matter how large the stimulus

all or none principle

The concentrations of which two ions are highest outside the cell. a. Na+ and Cl- b. K+ and Cl- c. Na+ and A- (negatively charged proteins) d. K+ and A- (negatively charged proteins)

a

The resting membrane potential depends on two factors that influence the magnitude and direction of Na+ and K+ diffusion across the plasma membrane. Identify these two factors. a. The presence of concentration gradients and leak channels b. The presence of concentration gradients and voltage-gated channels c. The presence of a resting membrane potential and leak channels d. The presence of concentration gradients and Na+-K+ pumps

a

What separates the presynaptic and postsynaptic cells at a chemical synapse? a. synaptic cleft b. chemically gated ion channels c. vesicles filled with neurotransmitter d. calcium channels

a

the base, or initial segment of the axon in a multipolar neuron joins the cell body at a thickened region known as the _________

axon hillock

The Na+-K+ pump actively transports both sodium and potassium ions across the membrane to compensate for their constant leakage. In which direction is each ion pumped? a. Both Na+ and K+ are pumped into the cell. b. Na+ is pumped out of the cell and K+ is pumped into the cell. c. K+ is pumped out of the cell and Na+ is pumped into the cell. d. Both Na+ and K+ are pumped out of the cell.

b

Which ion triggers synaptic vesicles to discharge neurotransmitter into the synaptic cleft? a. sodium b. calcium c. magnesium d. potassium

b

the neural cells responsible for analysis of sensory inputs ad coordination of motor output are a neuroglia b interneurons c sensory neurons d motor neurons

b

Ions are unequally distributed across the plasma membrane of all cells. This ion distribution creates an electrical potential difference across the membrane. What is the name given to this potential difference? a. Threshold potential b. Positive membrane potential c. Resting membrane potential (RMP) d. Action potential

c

What happens just after an axon is depolarized to threshold? a. Some potassium channels open. b. All potassium channels open. c. Some sodium channels open. d. All sodium channels open.

c

Which answer best describes the relative refractory period in the neuron? Choose the correct answer. a. The neuron's membrane potential is -70 mV. b. The neuron cannot generate another action potential under extreme stimulation. c. The resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state. d. Potassium ions are entering the neuron through open membrane channels.

c

Which of the following channels is most directly responsible for the properties of the axon that lead to action potential generation? Choose the best answer. a. Leak potassium channels b. Ligand-gated sodium channels c. Voltage-gated sodium channels d. Voltage-gated potassium channels e. Leak sodium channels f. Ligand-gated potassium channels

c

Which type of ion channel is always open? a. voltage-gated b. mechanically gated c. passive d. chemically gated

c

regulations by the nervous system provides a relatively slow, but long lasting responses to stimuli b swift long lasting repsosnses to stimuli c swift but brief responses to stimuli d relatively slow short-lived responses to stimuli

c

In which cell does a graded potential occur? a. adipocytes b. epithelial cells c. neurons d. It occurs in all the cell types listed.

d

Neuroglia perform all of these functions EXCEPT __________. a. regulate extracellular fluid composition b. secrete CSF c. provide supportive framework d. release neurotransmitters

d

Which of the following is an example of a presynaptic cell? a. a secretory cell b. a Schwann cell c. a muscle cell d. a neuron

d

phagocytic cells in neural tissue of the CNS are a astrocytes b ependymal cels c oligodendrocytes d microglia

d

in information processing the neurotransmitters released at a synapse may have either ______ or _______ effects. the effects on the axons initial segment reflects a summation of the stimuli that arrive at any moment

excitatory or inhibitor

___ is a temporary localized change in resting potential caused by stimulus

graded potential

a typical stimulus produces a temporary localized change in the resting potential the effect which decreases with distance is called _______

graded potential

comparing graded potential and action potential: depolarizing or hyperpolarzing

graded potential

comparing graded potential and action potential: passive spread from site to stimulation

graded potential

in a ________ potential the depolarization radiated in all directions away from the source of stimulation.

graded potential

generation of action potential: 4. the voltage gates sodium channels remain inactivated until the membrane has repolarized to near threshold levels. At this time they remain there normal status: closed but capable of opening . the K+ channels begin closing as the membrane reaches resting potential. until all of these K+ channels have closed, potassium ions continue to leave the cell. this produces a brief ________

hyper polarization

the loos of positive ions produces __________ , an increase in the negativity of the resting potential -70 to -80 or more

hyper polarization

when opening a gated K channel the rate of K outflow increases and the interior of the cell loose + ions, the inside of the cell becomes more negative and the loos of + ions produces _______

hyper polarization

12-9 ______ is At the simplest level (individual neurons) • Many dendrites receive neurotransmiKer messages simultaneously • Some excitatory, some inhibitory

information processing

_____ division of the ANS slows heart rate

parasympathetic division

_________ Moves action potentials generated in axon hillock • Along entire length of axon • A series of repeated actions, not passive flow

propagation

_______ controls skeletal muscle contractions -voluntary contractions under conscious control

somatic nervous system (SNS)

______ occurs when sources of stimulation arrive simultaneously but at different locations. local currents spread the depolarizing effects, and areas of overlap experience the combined effects

spatial summation

_______ occurs on a membrane that receives two depolarizing stimuli from the same source in rapid succession.

temporal summation

the transmembrane potential at which an action potential begins is called the _________

threshold

_____ fibers - Myelinated - Large diameter - High speed (140 m/sec) - Carry rapid informa8on to/from CNS - For example, posi8on, balance, touch, and motor impulses

type A fibers

the first step in generating an action potential is opening of ___________ channels at one site usually the initial segment of axon the movement of sodium ions into axon depolarizes the adjacent sites and triggers the opening of additional channels the result is a chain reaction that spreads across the surface of the membrane. that way the action potential is propagated along the length of axon

voltage gated sodium channels

generation of action potential: 1. the stimulus that initiates an action potential is a ______ ____ large enough to open voltage gated sodium channels. the opening of the channels occurs at the transmembrane potential known as the _______

graded depolarization threshold

______ Also called local potentials -are Changes in transmembrane potential that cannot spread far from site of stimulation

graded potential

an stimulus that opens a gated channel produces a _______ potential

graded potential

comparing graded potential and action potential: effect on membrane potential decreases with distance from stimulation site

graded potential

comparing graded potential and action potential: no refractory period

graded potential

comparing graded potential and action potential: amount of depolarization or hyperoolarization depends on intenstiy of stimulus

graded potential

comparing graded potential and action potential: no threshold value

graded potential

comparing graded potential and action potential: occur in most plasma membranes

graded potential

Three Requirements for Transmembrane Potential

- Concentration gradient of ions (Na+, K+) - Selectively permeable through channels - Maintains charge difference across membrane (resting potenial -70 mV)

12-1 __________ Consists of the spinal cord and brain - Contains neural tissue, connective tissues, and blood vessels

CNS

any shift from resting potential toward a more positive potential is called __________

depolarization

in graded potentials _____ is a shift in transmembrane poten8al toward 0 mV: -movement of Na+ through channel - produces local current

depolarization

If a signal from a sending neuron makes the receiving neuron more negative inside, a. the sending neuron becomes more positive inside. b. the receiving neuron immediately generates an action potential. c. the receiving neuron is more likely to generate an action potential. d. the sending neuron becomes more negative inside. e. the receiving neuron is less likely to generate an action potential.

e

in the neuron: _____ is a long cytoplasmic process capable of propagating an electrical impulse known as action potential

axon

Net effect on _______ determines if action potential is produced

axon hillock

On average, the resting membrane potential is -70 mV. What does the sign and magnitude of this value tell you? a. The inside surface of the plasma membrane is much more positively charged than the inside surface. b. The inside surface of the plasma membrane is much more negatively charged than the outside surface. c. There is no electrical potential difference between the inside and the outside surfaces of the plasma membrane. d. The outside surface of the plasma membrane is much more negatively charged than the inside surface.

b

Saltatory propagation occurs in _________ axons, in which action potentials _________. Select the best answer. a. unmyelinated; move from one node of Ranvier to another b. myelinated; move from one node of Ranvier to another c. myelinated; move continuously along the axon toward the axon hillock d. unmyelinated; spread by depolarizing the adjacent region of the axon membrane

b

The membranes of neurons at rest are very permeable to _____ but only slightly permeable to _____. a. Na+; Cl- b. K+; Na+ c. K+; Cl- d. Na+; K+

b

What is the primary role of the enzyme acetylcholinesterase (AChE) at a cholinergic synapse? a. AChE binds to ACh receptors, causing them to open. b. AChE degrades acetylcholine in the synaptic cleft. c. AChE depolarizes the postsynaptic cell. d. AChE releases acetylcholine into the synaptic cleft.

b

When you take a pain reliever, which of the following best describes, in general terms, how this affects the threshold of neurons? a. Taking a pain reliever decreases the threshold. b. Taking a pain reliever increases the threshold. c. Taking a pain reliever does not affect the threshold of neurons. d. Taking a pain reliever affects the all-or-none principle of neurons. So, neurons reaching threshold send an action potential at 50%.

b

Where on the neuron is the action potential initiated? Choose the best answer. a. Dendrite b. Initial segment c. Axon d. Cell body

b

if the resting membrane protenial is -70 and the threshold is -55 a membrane potential of -60 will a produce an action potential b make it easier to produce an action potential c make it harder to produce an action potential d hyperpolaizre the membrane

b

the resting potential of an undisturbed cell exists because (2)

1. the cytosol differs from extracellular fluid in chemical and ionic composition 2. the plasma membrane is selectively permeable

in saltatory propagation ______ insulates axon, prevents con8nuous propaga8on

Myelin

_____ is responsible for integrating, processing, and coordinating sensory data and motor commands sensory data conveys info about conditions inside and outside body motor commands: control activities of peripheral organs (e.g., skeletal muscles)

CNS

the function of _____ is for higher functions of brain: intelligence, memory, learning, emotion

CNS

when you stumble the _____ integrates info about your balance and the position of your limbs and then coordinates your recovery by sending motor commands to appropriate skeletal muscle -without conscious efforts

CNS

______ synapse is Any synapse that releases ACh

Cholinergic Synapse

there are two methods of propagating action potentials: ________ : unmyelinated axons _________: myelinated axons

Continuous propagation Saltatory propagation

Events that occur at a cholinergic synapse are listed here, but they are arranged in an incorrect order. Choose the correct order of these events below. (a) Calcium influx triggers exocytosis of ACh. (b) An action potential depolarizes the synaptic terminal. (c) ACh is removed by AChE. (d) ACh binds to receptors on the postsynaptic membrane. a. b→ a→ d→ c b. c→ d→ b→ a c. a→ b→ d→ c d. b→ a→ c→ d

a

Female gymnasts can contort their bodies in many different ways and land on a 4" beam with accuracy. Which fiber type is responsible for this ability? a. Type A fibers b. Type B fibers c. Type C d. Type D fibers

a

Sodium and potassium ions can diffuse across the plasma membranes of all cells because of the presence of what type of channel? a. Leak channels b. Sodium-potassium ATPases c. Ligand-gated channels d. Voltage-gated channels

a

The sodium-potassium exchange pump stabilizes resting potential of the neuron membrane at about __________. a. -70 mV b. +66 mV c. -20 mV d. -90 mV

a

Tumors that originate within the central nervous system (CNS) are due to __________. a. uncontrolled divisions of neuroglia b. a lack of centrioles within neuronal cell bodies c. uncontrolled division of neurons in adults d. all of the above

a

What is the role of neurotransmitter at a chemical synapse? a. Neurotransmitter binds to receptors on the postsynaptic cell membrane. b. Neurotransmitter causes calcium to enter the presynaptic cell. c. Neurotransmitter causes vesicles to fuse with the presynaptic membrane. d. Neurotransmitter causes an action potential in the presynaptic cell

a

What type of channel in the postsynaptic membrane binds neurotransmitter? a. a chemically gated channel b.a voltage-gated channel c. a mechanically gated channel d. a leakage channel

a

Which of the following best describes the role of calcium in synaptic activity? a. Calcium influx into the synaptic terminal causes vesicle fusion with the plasma membrane and the release of neurotransmitter. b. Calcium diffuses across the synaptic cleft and binds to chemically gated channels on the postsynaptic cell. c. Calcium breaks down acetylcholine. d. Calcium influx into the axon causes an action potential to propagate into the synaptic terminal.

a

receptors the bind acetylcholine at the postsnypatic membrane are a chemically gated channels b voltage gated channels c passive channels d mechanically gated channels

a

a _____ is an electrical impulse produced by graded potential propagates along surface of axon to synapse

action potential

if the graded potential is large enough it triggers an __________ in the membrane of the axon. -its an electrical impulse that is propagated along the surface of an axon and does not diminishes it moves away from its source, travels to one or more synapse

action potential

the initial stimulus of a _______ potential starts with a graded depolariza8on of axon hillock large enough (10 to 15 mV) to change resting potential (-70 mV) to threshold level of voltage-gated sodium channels (-60 to -55 mV)

action potential

events at a Cholinergic Synapse: _____ arrives and depolarizes synaptic knob _______ ions enter synaptic terminal, trigger exocytosis of Ach (release) ACh binds to receptors (Na+), depolarizes the ________ (initiation of action potential is threshold is released at initial segment) Ach is removed by Ache and breaks into _____ and _____ (probation of action potential)

action potential Calcium postsynaptic membrane acetate and choline

comparing graded potential and action potential: always depolarizing

action potentials

comparing graded potential and action potential: action potential at one site depolarizes adjacent to threshold

action potentials

comparing graded potential and action potential: all or none; all simuli that exceed threshold produce identical action potentials

action potentials

comparing graded potential and action potential: depolarization to threshold must occur before action potential begins

action potentials

comparing graded potential and action potential: occur only in excitable membranes of specialized cells such as neurons and muscle cells

action potentials

comparing graded potential and action potential: propagated along entire membrane surface without decrease in strength

action potentials

comparing graded potential and action potential: refractory period occurs

action potentials

_______ division of the PNS brings sensory info to the CNS from receptors in peripheral tissues and organs

afferent division

_______ provides automatic regulation of smooth muscle, cardiac muscle, glandular secretions, and adipose tissue at a subconscious level

autonomic nervous system (ANS)

Demyelination results from issues associated with myelin producing cells. Which of the following is an example of a myelin producing cell in the central nervous system (CNS)? a. ependymal cells b. schwann cells c. oligodendrocytes d. astrocytes

c

The generation of an action potential in a neuron requires the presence what type of membrane channels? Select the best answer. a. chemically gated channels b. leakage channels c. voltage-gated channels d. membrane channels are not required

c

The plasma membrane is much more permeable to K+ than to Na+. Why? a. There are many more voltage-gated K+ channels than voltage-gated Na+ channels. b. Ligand-gated cation channels favor a greater influx of Na+ than K+. c. There are many more K+ leak channels than Na+ leak channels in the plasma membrane. d. The Na+-K+ pumps transport more K+ into cells than Na+ out of cells.

c

What is the value for the resting membrane potential for most neurons? a. -90 mV b. +30 mV c. -70 mV

c

When neurotransmitter molecules bind to receptors in the plasma membrane of the receiving neuron, a. vesicles in the synaptic terminal fuse to the plasma membrane of the sending neuron. b. the receiving neuron becomes more negative inside. c. ion channels in the plasma membrane of the receiving neuron open. d. the receiving neuron becomes more positive inside. e. ion channels in the plasma membrane of the sending neuron open.

c

______ propagation cannot occur along mylenated axon because myelin increases resistance to the flow of ions across the membrane

continuous propagation

_______ propagation moves across the surface of the membrane in a series of steps

continuous propagation

A molecule that carries information across a synaptic cleft is a a. synaptic cleft. b. sending neuron. c. synapse. d. neurotransmitter. e. receiving neuron.

d

Demyelination disorders such as Multiple Sclerosis and Guillain-Barre Syndrome are particularly dangerous because they __________. a. reduce the size of the axon diameter b. block sodium channels and thus interfere with action potential transmission c. facilitate retrograde action potential transmission d. decrease the speed of action potential transmission

d

During depolarization, which gradient(s) move(s) Na+ into the cell? a. Na+ does not move into the cell. Na+ moves out of the cell. b. only the chemical gradient c. only the electrical gradient d. both the electrical and chemical gradients

d

During propagation of the action potential, __________. a. the axon hillock depolarizes the initial segment b. after threshold is reached, sodium channels open rapidly c. local currents depolarize a spot adjacent to the active zone d. All of the listed responses are correct.

d

Josh and a bunch of friends decided to see how many people they could squeeze into a small car for a charity event. Once inside, Josh felt it get hot, smelly, and like the air was getting squished out of his lungs. He also noticed aches and pains in his joints. Which of the following statements best describes the type of sensory neurons involved? a His interoceptors were monitoring his respiratory system. b. His exteroceptors were bringing in information from the outside world. c. The proprioceptors were monitoring the position of his skeletal muscles and joints. d. The interoceptors, exteroceptors, and proprioceptors were all monitoring his condition.

d

The most abundant intracellular cation is __________ while the most abundant extracellular anion is __________. a. potassium; protein anions b. sodium; chloride c. sodium; protein anions d. potassium; chloride

d

What mechanism releases neurotransmitter from presynaptic neurons? a. pinocytosis b. phagocytosis c. endocytosis d. exocytosis

d

What prevents the Na+ and K+ gradients from dissipating? a. Na+ cotransporter b. Na+ and K+ leaks c. H+-K+ ATPase d. Na+-K+ ATPase

d

When a person has a stroke, blood leaks into the brain tissue. Which type of neuroglia cells would repair the damage? a. oligodendrocytes b. ependymal cells c. satellite cells d. astrocytes

d

When calcium ions enter the synaptic terminal, a. the inside of the receiving neuron becomes more negative. b. they cause an action potential in the sending neuron. c. neurotransmitter molecules are quickly removed from the synaptic cleft. d. they cause vesicles containing neurotransmitter molecules to fuse to the plasma membrane of the sending neuron. e. the inside of the receiving neuron becomes more positive.

d

The small space between the sending neuron and the receiving neuron is the a. neurotransmitter. b. synaptic terminal. c. vesicle. d. calcium channel. e. synaptic cleft.

e

_____ division of the PNS carries motor commands from the CNS to muscles, glands and adipose tissue

efferent division

an action potential that reaches an ______ synapses is always propagates to the next cell but at a ______ synapses an arriving action potential may or may not release enough neurotransmitters to bring the post synaptic neuron to threshold

electrical chemical

_____ synapses occurs in areas of brain, eye, ciliary ganglia -rare

electrical synapses

in a ________ synapse pre synaptic and post synaptic membranes are locked together at gap junction s - Allow ions to pass between cells - Produce continuous local current and action potential propagation

electrical synapses

in _________ information is relayed in the form of action potentials in general, the degree of sensory stimulation or the strength of the motor repose is proportional to the frequency of action potential

information processing

the response of the post synaptic cell ultimately depends on what the stimulated receptors do and what other stimuli are influencing the cell at the same time. the integration of stimuli at the level of indiv. cell is the simplest form of _________ in the nervous system

information processing

_____ greatly increases the propagation speed of action potentials this is not the only thing that affects action potential speed , ______ ,effects it also

myelin axon diameter, the large the diameter the lower the resistance

a synapse between a neuron and a muscle cell is called a __________

neuromuscular junction

12-2 the cell body of the neuron contains a large round nucleus with a prominent nucleolus. the cytoplasm surrounding the nucleus is the _______

perikaryon

the process of restoring the normal resting potential after depolarization is called _________ -sodium K pump

repolarization

12-3, 12-4 the ______ is the transmembrane potential of a resting cell -all neural activities begin with a change in the _______ of a neuron

resting potential

12-6 which propagation is faster and uses less energy ? saltatory or continuous?

saltatory

______ propagation Local current "jumps" from node to node

saltatory propagation

______ propagation uses less energy

saltatory propagation

in ______ propagation Depolariza8on occurs only at nodes

saltatory propagation

generation of action potential: 3. as the transmembrane potential approaches +30 MV the inactivation gates of the voltage gates Na changes close. this step is known as ________ and it coincides with the opening of voltage gated ________. + K ions move out of the cytosol shifting the transmembrane potential back toward resting levels -repolarization beings

sodium channel inactivation potassium channels

____ diviosn of the ANS accelerates heart rate

sympathetic division

to get from the CNS to a visceral effector such as a smooth muscle cell a signal must travel along one axon and be relayed across a ______ and then travel along a second _____ to its final distention

synapse axon

12-7 ________ is where Action potentials (nerve impulses) Are transmited from presynaptic neuron To postsynaptic neuron (or other postsynap8c cell) Across a synapse

synaptic activity

________ is the activity when the presynaptic cell releases neurotransmitters at presynaptic membrane it produces graded potentials in postsynaptic membrane

synaptic activity p. 386

______ plays a key role in communication with another cell

synaptic terminals

_____ fibers - Myelinated - Medium diameter - Medium speed (18 m/sec) - Carry intermediate signals - For example, sensory informa8on, peripheral effectors

type B fibers

_____ fibers - Unmyelinated - Small diameter - Slow speed (1 m/sec) - Carry slower informa8on - For example, involuntary muscle, gland controls

type C fibers