Ls 2 Lecture 13

Front 1

Excitatory Ligand-Gated Channels

Back 1

permeable to cations (Na+, K+)

produce depolarizations (EPSP's) excitatory postsynaptic potentials

ex. receptors for ach, glutamate, serotonin

Front 2

Inhibitory Ligand-Gated Channels

Back 2

permeable to anions (Cl-)

produce hyperpolarizations (inhibitory postsynaptic potentials IPSP's)

ex. receptors for glycine, GABA

Front 3

Metabotropic Receptor

Back 3

NOT an ion channel but activates a G protein

-in turn activates an ion channel in many cases via a change in concentration of a second messenger such as cyclic nucleotide or Ca 2+

olfactory receptors, taste for bitter and sweet receptors, all photoreceptors

Front 4

Ionotropic Sensory Receptors

Back 4

mechanoreceptors, electroreceptros, temperature receptors, some kinds of taste receptors (salt detectors)

-sensory stimulus gates a channel directly

Front 5

What is the most important mechanoreceptor in the skin?

Back 5

merkel's disks

detect touch

Front 6

What are the cells that detect hearing called?

Back 6

hair cells of vestibule

Front 7

How did scientists learn to control membrane potential?

Back 7

pipette is inserted into the cell to record potential

pipette is moved back and forth to stimulate cell

intracellular recording made from hair cells while stimulating cells with an external stimulus probe

depolarization when they move the bundle in one direction, when you move it in the other direction = hyperpolarization

Front 8

True of False: metabotropic processes take longer than ionotropic

Back 8

true

takes time for g protein enzyme process

Front 9

What does the vestibular system tell you?

Back 9

how your head is oriented and your body is accelerating

Front 10

Semicircular Canals

Back 10

fluid filled

3 on each side of head

have hair cells in cupula (?)

as you move, fluid sloshes and touches hair bundles
-hair bundles change membrane potential and stimulate nerve cells

Front 11

What are hair cells of the semicircular canals stimulated by?

Back 11

rotational acceleration, caused by movement of the head

Front 12

Otolith Organs

Back 12

adjacent to semicircular canals

called utriculus and sacculus

detect linear acceleration and the position of the head with respect to gravity

Front 13

Basilar Membrane

Back 13

starts out narrow then at end o cochlea, becomes broad and floppy

makes mechanical compliance change

Front 14

What affect to sounds have on ear?

Back 14

produce a traveling wave down the baisilar membrane whose amplitude for different sound frequencies is greatest at different places along the length of the cochlea

low frequency causes floppy membrane to move

high frequency causes stiff membrane to move

Front 15

Olfactory Receptor

Back 15

smell

metabotropic sense

Front 16

Transduction cascade

Back 16

1) receptor
2) G protein
3) effector molecule (adenylyl cyclase)
4) second messenger cAMP
5) channel (second messenger gated)

cells do produce action potentials

Front 17

Olfactory Receptor Molecules

Back 17

1000 different olfactory receptor molecule genes that are functional in the mouse genome (300-350 in man)

each cell expresses only a single type of receptor molecule gene

each receptor molecule is sensitive to a wide variety of odors, specificity is different for each receptor molecule

many receptors cells in epithelium express the same receptor molecule and all these cells synapse together onto the same group of cells in the CNS

(each receptor molecule has its own group of cells)

Front 18

Photoreceptor is for what sense?

Back 18

sight

rods- detect dim light, green

cone- detects brighter light, color vision, blue, yellow, red?

Front 19

11 cis retinal

Back 19

red molecule in center of 7 alpha helixes

= chormophore

combines with opsin (protein) to form rhodopsin

light changes 11 cis to all trans

reaction is called a photoisomerization

Front 20

Rhodopsin

Back 20

binds to binding site, convalently attached to protein

works in photoreceptor

Front 21

Retinal

Back 21

a chomophore

actually absorbs the light

alpha helixes shift when retinal unkinks, causes activation of the cascade

bind cyclic nucelotides which opens the channel in the dark

Front 22

cGMP gated channels

Back 22

open in darkness because cGMP is high in dark

closing of channels causes the membrane potential of the photoreceptor to hyperpolarize and decreases release of transmitter

Na+ channels are open in dark, unstimulated, so membrane potential is very depolarized and stays at ~35 mV. If stimulate with light, decreases cAMP and activate photophosphodiesterase, channels close. membrane potential hyperpolarizes.

neurotransmitter always released in darkness.

cell doesn't produce an action potential

Front 23

In nose the stimulation causes a _____ in cAMP

in eyes the stimulation causes a _____in cAMp

Back 23

rise


fall