Exam 1

Question 1

For extrinsic control systems, the sensor and integrator components will ALWAYS involve

Answer 1

the nervous system and/or endocrine system system

Question 2

Which of the following transporters would be ‘electrogenic’

Answer 2

One that transports one Ca2+ out of the cell and one Na+ into the cell

Question 3

Graded potentials and action potentials

Answer 3

propagate along the plasma membrane from where they begin by current flowing along the membrane to adjacent regions that have a different membrane potential

Question 4

The rate at which Na+ diffuses across an axon’s plasma membrane can increase greatly

Answer 4

Once the threshold is reached

Question 5

Suppose that the presynaptic neurons A,B, and C converge to communicate with postsynaptic neurons neuron D. Furthermore, suppose that when neurons A and B are active, neuron D exhibits lower action potential frequency than when only B is active. When all three presynaptic neurons are active, neuron D generates no action potential. Given this, which of the following must be true?

Answer 5

Neurons A and C elicit inhibitory responses while neuron B has an excitatory response.

Question 6

During the first phase of an action potential where it approaches a ‘peak’

Answer 6

the net electrochemical force acting on Na+ is less than at the resting potential

Question 7

As interstitial fluid begins to accumulate in one area of the body, it is returned to ____ by ____

Answer 7

the plasma; lymphatic vessels

Question 8

Hypokalemia is a condition in which someone has an abnormally low concentration of K+ in the ECF. How could this condition impair neural function?

Answer 8

This could result in hyperpolarization by increasing the net electrochemical force acting on K+.

Question 9

The Nernst equation

Answer 9

predicts the membrane potential at which an ion reaches equilibrium

Question 10

Regulating the concentration of a solute within ____ is more important than its regulation within ____ because the former process will affect the solute’s concentration in all organs, whereas the latter process will not.

Answer 10

the plasma; an organ

Question 11

What sub-types of channels are preferentially found at high density in the dendrites but not within other regions of a neuron?

Answer 11

stimulus-gated channels that are not voltage-gated

Question 12

IPSP

Answer 12

reduces the probability of that postsynaptic neurons will reach threshold

Question 13

Suppose that depolarizing current #1 reaches the axon hillock such that it depolarizes this region from the resting potential (-70mv) by +30 mv for a short period of time and then shortly thereafter depolarizing current #2 reaches the axon hillock such that it depolarizes this region by +50mv. Which of the following is true?

Answer 13

Both currents will trigger action potentials, but the frequency resulting from current #1 will be less than that from current #2.

Question 14

The convergence of two or more distinct graded potentials in a neuron on the ____ results in ____

Answer 14

axon hillock; spatial summation

Question 15

The Na+/K+ pump

Answer 15

hydrolyzes ATP to move both Na+ and K+ against their favorable gradient

Question 16

Homeostasis is

Answer 16

maintained by organs and body systems that operate as negative feedback loops.

Question 17

If a 2% NaCl solution is is prepared, then the concentration of NaCl is

Answer 17

20mg/mL

Question 18

Assume than an antiporter within the red blood cell plasma membrane moves HCO3- from the plasma into the red blood cell. assume the same antiporter moves Cl- across the plasma membrane.

Answer 18

HCO3- transport is driving the unfavorable transport of Cl-

Question 19

Orthodromic conduction

Answer 19

refers to the movement of action potentials from the axon hillock to the axon terminals

Question 20

At the resting membrane potential, the net electrochemical force acting on Na+

Answer 20

is larger than either the chemical or electrical force acting on this ion

Question 21

Physiological variables such as blood pressure and O2 tend to fluctuate around a specific value referred to as

Answer 21

the set point

Question 22

Activation of the voltage-gated ____ channels trigger ____

Answer 22

Ca2+; synaptic vesicle exocytosis

Question 23

Interstitial fluid

Answer 23

has a much higher concentration of Na+ than K+

Question 24

If an ion moves across the plasma membrane from a fluid where its concentration is low to a fluid where its concentration is high, then

Answer 24

its movement must have occurred through an ion channel

Question 25

Transduction of stimulus intensity within a dendrite

Answer 25

is possible because the stimulus intensity determines the percentage of specialized gated channels which switch from the close to open state.

Question 26

Intracellular fluid

Answer 26

has a higher concentration of K+ than extracellular fluid

Question 27

The Na+/K+ pump

Answer 27

functions to maintain the Na+/K+ concentration gradients across the plasma membrane

Question 28

The plasma membrane of an unstimulated neuron

Answer 28

differs in its permeability to Na+ and K+ because of the density of leak channels

Question 29

Synaptic communication

Answer 29

involves Ca2+ influx into the axon terminal

Question 30

The velocity of action potential conduction

Answer 30

depends on the diameter of the axon

Question 31

Many neurons have Na+-Ca2+ secondary active transporters in their plasma membrane. The transporter moves Na+ from the interstitial fluid to the cytoplasm. Knowing this, Ca2+ must be transported ___ so this transporter must be a ____

Answer 31

against its favorable gradient; antiporter

Question 32

If a voltmeter that measures the plasma membrane potential reads +30mv then

Answer 32

Na+ is closer to its equilibrium potential than K+ is to its equilibrium potential

Question 33

In neurons, action potentials are first initiated

Answer 33

when a depolarizing current enters the axon hillock

Question 34

Inactivation

Answer 34

is responsible for the absolute refractory period of action potentials

Question 35

Neurons communicate information about stimulus intensity over the long distance of an axon

Answer 35

by the frequency of action potentials occuring

Question 36

Excitable cells

Answer 36

are those capable of generating action potentials

Question 37

When ONE action potential occurs presynaptically at an excitatory synapse

Answer 37

are those capable of generating action potentials

Question 38

Neurotransmitter reuptake

Answer 38

occurs by secondary active transport

Question 39

Neurotransmitter release can trigger postsynaptic responses

Answer 39

by their interaction with ligand-gated channels

Question 40

If the membrane potential measured with a voltmeter is the same as that predicted by the Nernst equation for a hypothetical X having a higher concentration inside the cell than outside the cell,

Answer 40

X+ is at equilibrium

Question 41

Which is true of action potentials

Answer 41

the magnitude of each action potential produced by a neuron is constant

Question 42

The stomach contains glands that secrete an acidic fluid and the enzyme pepsin to help digest food within the stomach lumen. The glands in the stomach are classified as

Answer 42

epithelial tissue

Question 43

Neurons that communicate information about physiological variables within the blood or internal organs

Answer 43

are classified as visceral afferents

Question 44

A physiological saline solution

Answer 44

contains 150 mM NaCl

Question 45

If a postsynaptic neuron’s activity is 50 Hz, then

Answer 45

it generates 50 action potentials per second

Question 46

A regulatory system

Answer 46

a basic stimulus-response coupling mechanism to allow organisms to sense and respond to changes in many different environmental conditions

Question 47

Neurons that propagate action potentials away from the CNS

Answer 47

are efferent neurons

Question 48

Metabotropic receptors

Answer 48

transiently interact with G proteins once activated

Question 49

A threshold potential is

Answer 49

the membrane potential at which voltage-gated channels open

Question 50

A chemical messenger released by non-excitable cells that does not enter the blood

Answer 50

is classified as a paracrine factor

Question 51

If a postsynaptic neuron hyperpolarizes in response to a neurotransmitter release, this change in membrane potential is specifically referred to as _____

Answer 51

inhibitory post synaptic potential

Question 52

Stimulus-gated channels that do not respond to changes in the membrane potential are primarily restricted to the ___ and the ____ regions of a neuron

Answer 52

dendrites; cell body

Question 53

Physiology

Answer 53

the study of all function that occur within an organism

Question 54

Antidromic conduction occurs when

Answer 54

action potentials move from axon terminals toward the axon hilock in a non-physiological direction

Question 55

Neurons that have all of their morphological components within the CNS are referred to as

Answer 55

interneurons

Question 56

Spatial summation refers to

Answer 56

action potentials that occur in two or more presynaptic neurons within a short time period
this period affects the net graded potential at the axon hillock

Question 57

Myelin sheaths are formed by ___ and ___ in which both are glial cells

Answer 57

oligodendrocytes
schwann cells

Question 58

What are factors that determine if a synapse is excitatory or inhibitory?

Answer 58

1. the type of neurotransmitter released by the presynaptic neuron
2. the type of receptor found in the presynaptic neuron
3. if the receptor is a GPCR – type of G protein in the postsynaptic neuron
4. if the receptor is a GPCR – types of ion channels

Question 59

Explain how neurons have the ability to detect stimulus, what specifically happens in the process of detection? Once detected, how do neurons intially transduce information

Answer 59

1. Neurons are able to detect stimulus due to specialized stimulus gated channels in dendrites. Closed if stimulus is not present; open if present.
2. Neurons transduce informtion about stimulus intensity and stimulus duration. Graded potential varies in magnitude and duration.
3. GP magnitude varies with intensity due to stimulus intensity. The amount of open channels affect the change in membrane permeability.
4. Stimulus duration depends on affects how long the gated channels remain open. This also affects the membrane permeability in which the the longevity of the the change and diffusion of ions.