L15 Stimulated Excitable Cells

Question 1

excitable cells respond to ____ stimuli

Answer 1

specific

Question 2

which neurons have integral membrane proteins?

Answer 2

efferent neurons

interneurons

Question 3

what is the function of the integral binding proteins?

Answer 3

chemoreceptors with binding sites for NTs - ACh, glutamine, GABA etc.

Question 4

what do afferent neurons have?

Answer 4

membrane receptor responding to specific type of stimulus

Question 5

what are sensory stimuli converted into?

Answer 5

local graded changes of membrane potential

Question 6

local grade potential spread ___ with ____

Answer 6

passively

decrement

Question 7

a stimulus to the sensory end of the afferent neuron produces a _______

Answer 7

local depolarization

*adjacent areas are also depolarized but spread is less effective

Question 8

where is a change in conductance seen?

Answer 8

only in the stimulated region!

Question 9

what has a length constant?

Answer 9

every cable-like structure

Question 10

when a charge is spreading, it is continually ____ in quantity

Answer 10

diminishing

Question 11

define length constant

Answer 11

indicates how far a current will spread along the inside of a neurite and thereby influence the voltage along that distance

Question 12

the length constant (lambda) increases with increasing values of ?

Answer 12

radius of cylinder

resistance across cell surface - is membrane leaky or not…

Question 13

what monitors the length of muscles fibers?

Answer 13

afferent neurons

Question 14

what are muscle spindles made of?

Answer 14

intrafusal fibers

Question 15

what is stimulated by stretching of muscle?

Answer 15

intrafusal fibers in muscle spindles

golgi tendon organ

Question 16

what does the golgi tension organ monitor when it receives a stimulus? ?

Answer 16

tension

Question 17

what does muscle spinal measure when it receives a stimulus?

Answer 17

length

Question 18

most muscle afferent neurons are what?

Answer 18

mechanoreceptors

Question 19

what do muscle spindle afferents have?

Answer 19

stretch gated ion channels

Question 20

what mainly pass through the stretch gated ion channels in the non-contractile central region of the intrafusal fiber?

Answer 20

cations - mainly Na

pass through channels = depolarization

Question 21

what does stretch produce in the afferent neuron?

Answer 21

graded receptor potential

Question 22

what happens in the dark to cGMP and Na+ Channels

Answer 22

we have plenty of cGMP

open Na+ channels

Question 23

what happens in the light to cGMP and Na+ channels?

Answer 23

less cGMP because its broken down
closed Na+ channels =
HYPERPOLARIZATION
= reduce the amount of GLUTAMATE into retinal bipolar cells

*the more light, the more hyper polarization!

Question 24

what is the rods receptor potential?

Answer 24

graded hyperpolarization

Question 25

what happens when odorant molecules bind to receptors?

Answer 25

increase cAMP *bind odorant molecules --> activate G protein ---> ride in Adenylate cyclase ---> increase cAMP

Question 26

what happens with an increase in cAMP?

Answer 26

cation channels open - | entry of Na+ and Ca2+ into cell = depolarization

Question 27

what does the rise in Ca2+ in the olfactory neuron cause?

Answer 27

causes Cl- channels to open - cl- leave the cell = more depolarization!

Question 28

change in membrane potential is linearly related to the ?

Answer 28

magnitude of the current pulse

Question 29

what is the purpose of a graded potential?

Answer 29

to drive the axon hillock or initiation zone to threshold membrane potential - to gen. AP!

Question 30

where is the impulse initiation zone in multipolar neurons?

Answer 30

axon hillock

Question 31

where is the impulse initiation zone in pseudounipolar and bipolar neurons?

Answer 31

near the sensory endings of afferent neurons

Question 32

where is the impulse initiation zone in skeletal muscle fibers?

Answer 32

close to the central region that receives ACh released by the motor neuron

Question 33

impulse initiation zones have a high density of what?

Answer 33

voltage-gated Na+ channels

Question 34

what is idiopathic focal dystonia?

Answer 34

abnormalities of posture, involuntary movements and muscular spasm likely to be caused by a physical property of specialized stretch receptors present in skeletal muscle spindles. these are responsible for signaling about body position and muscular effort

Question 35

what is anosmia?

Answer 35

head injury that severs/compresses the axons of the olfactory neurons in the elderly due to degen. loss of fraction of the population of olfactory neurons occasionally congenital and sometimes hereditary

Question 36

what is night blindness?

Answer 36

rods are responsible for our vision in low light levels cones are excellent for day vision and color detection vitamin A deficiency = lack of rhodopsin

Question 37

where are graded potentials found (hyperpolarization and depolarization?)

Answer 37

- afferent fibers in muscle spindles - rods of retina - olfactory neurons in nasal cavity