Exam 2 Slides

Question 1

Action Potential

Answer 1

Triggered by stimulus exceeding threshold potential/ gated ion channels open and close

Question 2

Absolute Refractory Period:

Answer 2

No stimulus of any strength can produce an action potential
- Due to inactivated Na+ channels

Question 3

Relative Refractory period:

Answer 3

Strong stimulus can produce another AP, but with smaller amplitude
- Due to still open K+ channels

Question 4

What happens to membrane potential during continuous stimulation?

Answer 4

Excitability of membrane decreases with time (threshold increases)
- Is Due to changes in sensitivity of membrane channels to depolarization
- This physiological change is called accommodation

Question 5

Length constant:

Answer 5

distance over which a graded potential shows a 63% drop in amplitude.

Question 6

Spreading of electrical signal is due to?

Answer 6

cable properties of nerve membrane.

Question 7

The larger the length constant?

Answer 7

the further away a new AP will be generated, and the faster the propagation of APs.

Question 8

Synapse:

Answer 8

connection between two neurons or a neuron and an effector cell

Question 9

Electrical Synapse

Answer 9

Rapid transmission of signals. Faster than in chemical synapses!
- Used to synchronize electrical activity in groups of cells: e.g. vertebrate heart, oscillations and brain rhythms.

Question 10

Chemical synapse: fast transmission

Answer 10

1. NT release close to receptors.
2. Receptors directly open ion channels (ionotropic).
3. Small vesicles

Question 11

Chemical synapse: slow transmission

Answer 11

1. NT release distant from receptors.
2. Receptors indirectly open ion channels (metabotropic).
3. Large vesicles

Question 12

Active zone:

Answer 12

area of NT release

Question 13

Acetylcholine

Answer 13

Primary neurotransmitter at vertebrate neuromuscular junction

Question 14

If depolarization exceeds threshold

Answer 14

Yes AP

Question 15

If depolarization does not exceed threshold

Answer 15

No AP

Question 16

Change in membrane potential is a

Answer 16

graded potential

Question 17

If ion current depolarizes the membrane?

Answer 17

excitatory
- stimulates an AP in the postsynaptic cell

Question 18

If ion current hyperpolarizes the membrane?

Answer 18

inhibitory
- prevents an AP in the postsynaptic cell

Question 19

Opening Na+ or Ca2+ channels results in a graded depolarization called an?

Answer 19

excitatory postsynaptic potential

Question 20

Opening K+ or Cl− channels results in a graded hyperpolarization called an

Answer 20

inhibitory postsynaptic potential

Question 21

EPSPs move membrane potential

Answer 21

closer to threshold
- EPSPs from several neurons may be needed to actually produce action potential

Question 22

IPSPs move membrane potential

Answer 22

farther from threshold
- Can counter EPSPs from other neurons

Question 23

Summation of EPSPs and IPSPs at initial segment of axon dose what?

Answer 23

determines whether action potential occurs.

Question 24

Presynaptic Inhibition

Answer 24

Inhibitory synapse on top of an excitatory synapse

Question 25

Strychnine dose what?

Answer 25

binds to and blocks glycine receptors in the spinal cord.

Question 26

Function of Sensory System

Answer 26

1. Signal detection 2.Discrimination of some aspects of the sensory input

Question 27

Receptor cell sends

Answer 27

- intensity of stimulus frequency of APs - location of stimulus receptive field

Question 28

Receptive Field

Answer 28

Area of skin that, when stimulated, changes the firing rate of a neuron

Question 29

The more receptors, the

Answer 29

smaller the field, the larger the brain area for processing.

Question 30

Sensory Acuity

Answer 30

Ability to detect details

Question 31

Degree of convergence of primary neurons on secondary neurons determines?

Answer 31

size of receptive field.

Question 32

Range fractionation:

Answer 32

different cells with different but overlapping sensitivities, extending dynamic range

Question 33

Phasic response:

Answer 33

Firing activity only when stimulus strength changes (on/off)

Question 34

Tonic response:

Answer 34

Firing activity continues for the duration of the stimulus

Question 35

Lateral Inhibition can occur with?

Answer 35

a group of adjacent receptor cells, such as found in the eye.

Question 36

Olfactory

Answer 36

pathways from the nose project directly to the cortex

Question 37

More brain area means

Answer 37

more information processing and relatively more important

Question 38

Stimulus energy is “converted” to

Answer 38

action potential energy.

Question 39

Signals are interpreted as sight, sound, taste, depending on

Answer 39

which sensory cells send the signal and which tissue in CNS receives it!

Question 40

GUSTATION is what sense

Answer 40

Taste

Question 41

Salty

Answer 41

Na+ entry: depolarization: NT release

Question 42

Sour

Answer 42

H+ entry: depolarization: NT release.

Question 43

Sweet and umami

Answer 43

Sugar or glutamate binds to receptor: closing K+ channels: depolarization: NT release.

Question 44

Bitter

Answer 44

Quinine binds to receptor: Ca2+ entry : NT release

Question 45

Labeled-Line Coding:

Answer 45

each receptor responds to limited range of stimuli and sends direct line to brain.

Question 46

Across-Fiber Pattern or Ensemble Coding:

Answer 46

each receptor responds to wider range of stimuli and contributes to perception of each of them.

Question 47

Cone cells:

Answer 47

less sensitive, distinguish colors.

Question 48

Neural pathways for vision

Answer 48

Object on right goes to brain on left: Information crosses over!

Question 49

Hair cells modulate release of NT:

Answer 49

Change in AP frequency above spontaneous frequency.

Question 50

Actin

Answer 50

thin filament

Question 51

Myosin

Answer 51

thick filament

Question 52

Sarcomere:

Answer 52

functional unit of contraction Z disk to Z disk

Question 53

Sliding Filament Theory

Answer 53

Thin actin filaments slide past the thick myosin filaments - More overlap, shorter sarcomere

Question 54

Myosin structure

Answer 54

- Myosin heads stick out from the thick filament. - Myosin connect with actin and sliding of the filaments occurs.

Question 55

Cross bridge function

Answer 55

- Myosin cross bridge binds to actin - Power stroke slides actin past myosin - Cross bridge releases actin

Question 56

T tubules

Answer 56

Narrow tunnels formed from the plasma membrane (sarcolemma) Extend into center of cell

Question 57

Muscle relaxation

Answer 57

Nerve action potentials stop Muscle action potentials stop Calcium-release channels close Ca2+ pumps move Ca2+ back into SR (active transport) No more Ca2+ is available to bind to troponin complex Tropomyosin moves over myosin-binding sites on actin, no cross-bridges possible.