Patch Clamp and Sensory Transduction

Question 1

What is electrophysiology?

Answer 1

Branch of neuroscience that explores the electrical activity of living neurons

Question 2

How does a patch clamp work?

Answer 2

Use a pipette over a channel to get continuous environment, which is measured

Question 3

What is a gigaseal?

Answer 3

Large resistance (seal) between the pipette and the cell membrane (due to suction)

Question 4

What is the importance of the gigaseal?

Answer 4

No current through the seal; only current through the channel

Question 5

What are the five forces that form a gigaseal?

Answer 5

Membrane tension, cytoskeletal stresses, electroosmotic forces, viscosity, and adhesion energy

Question 6

How does membrane tension contribute to a gigaseal?

Answer 6

Hydrostatic pressure of the liquid forces membrane to the sides

Question 7

How does cytoskeletal stresses contribute to a gigaseal?

Answer 7

Cytoskeleton pushes against the pipette wall

Question 8

How does an electroosmotic drag force contribute to a gigaseal?

Answer 8

Voltage dependent creep (movement of charged fluids)

Question 9

How does viscosity contribute to a gigaseal?

Answer 9

Fluid resistance and stickiness of the membrane

Question 10

How does adhesion energy contribute to a gigaseal?

Answer 10

Interaction between membrane and glass pipette

Question 11

What is cell attached recording?

Answer 11

Pipette makes contact with cell membrane, but is not ruptured

Question 12

What can be measured with a cell attached recording?

Answer 12

Measure action potentials due to one channel

Question 13

How come the cell attached recording cannot record the whole cell?

Answer 13

No control of intracellular environment

Question 14

What is whole cell recording?

Answer 14

Pipette breaks cell membrane, has contact with intracellular environment

Question 15

How come the whole cell recording can record the whole cell?

Answer 15

Has control of intracellular environment

Question 16

What is inside out recording?

Answer 16

Cytosolic surface of the membrane is exposed (pipette raptures membrane)

Question 17

What experiments can be done with inside out recording?

Answer 17

Modify intracellular environment, and record response outside the cell

Question 18

What is outside out recording?

Answer 18

Extracellular surface is exposed (pipette raptures membrane)

Question 19

What experiments can be done with outside out recording?

Answer 19

Modify extracellular environment, and record response inside the cell

Question 20

What is a voltage gated channel?

Answer 20

Opens in response to membrane potential

Question 21

What is a ligand gated channel?

Answer 21

Opens in response to ligand binding

Question 22

What is a chemically gated channel?

Answer 22

Opens in response to intracellular signals

Question 23

What is a mechanically gated channel?

Answer 23

Opens in response to pressure changes

Question 24

What is the advantage of the patch clamp technique?

Answer 24

Look at only one channel (high resolution)

Question 25

What do sensory neurons do?

Answer 25

Convert sensory stimuli into electrical voltages

Question 26

What is a graded potential?

Answer 26

Change in membrane potential, but does not reach threshold (does not start an action potential)

Question 27

What is the first step of sensory transduction?

Answer 27

Reception

Question 28

What happens in reception (sensory transduction)?

Answer 28

Sensory receptor cells are stimulated

Question 29

What is the second step of sensory transduction?

Answer 29

Transduction

Question 30

What happens in transduction (sensory transduction)?

Answer 30

Transforming chemical stimuli into neural impulses

Question 31

What processes happen in transduction (sensory transduction)?

Answer 31

Coding and transmission

Question 32

What happens in coding (sensory transduction)?

Answer 32

Correspondence between parameters of the stimulus and the parameters of the firing

Question 33

What happens in transmission (sensory transduction)?

Answer 33

Deliver neural information to the brain to be processed

Question 34

What are some examples of coding in sensory transduction?

Answer 34

Frequency encoding and amplitude encoding

Question 35

What is the third step of sensory transduction?

Answer 35

Processing by the brain (and action)

Question 36

What are mechanoreceptors?

Answer 36

Receptors that respond to mechanical stimuli

Question 37

What are photoreceptors?

Answer 37

Receptors that respond to light

Question 38

What are chemically-sensitive receptors?

Answer 38

Receptors that respond to chemicals

Question 39

What are thermoreceptors?

Answer 39

Receptors that respond to temperature

Question 40

What are nociceptors?

Answer 40

Receptors that respond to pain

Question 41

What is a receptor?

Answer 41

A protein structure that receives and transduces signals

Question 42

What is a channel?

Answer 42

A protein structure that allows ions or other molecules to flow through it

Question 43

What is the purpose of the small bones in the ear?

Answer 43

Amplify the sound signal

Question 44

What ions are prevalent in hair cell liquid?

Answer 44

Potassium and calcium

Question 45

How do the channels open on hair cells?

Answer 45

Channels are connected together, and displacement opens the channels

Question 46

What happens when a hair cell is depolarized?

Answer 46

Glutamate is released, which sends a signal to the brain

Question 47

How come we can not hear super high frequencies?

Answer 47

Hair cells cannot move fast enough to encode the frequency (not enough time to depolarize)

Question 48

How do cochlear implants work?

Answer 48

Use a microphone to record sound, which can be converted to an electrical signal to stimulate the hair cells

Question 49

What mechanoreceptors are found in the skin?

Answer 49

Merkel receptors, Meissner corpuscle, Pacinian corpuscle, and Ruffini cylinder

Question 50

What are slow adapting cells?

Answer 50

Fire for a long time

Question 51

What are rapid adapting cells?

Answer 51

Adapt quickly

Question 52

What is a receptor field?

Answer 52

The area that a receptor can perceive information

Question 53

What is the relationship between receptor field and resolution?

Answer 53

An increased receptor field leads to a decrease in resolution

Question 54

Which receptors have a larger receptive field?

Answer 54

Deep receptors

Question 55

Which receptors have a smaller receptive field?

Answer 55

Surface receptors

Question 56

What is the purpose of the fluid in Pacinian corpuscles?

Answer 56

Adaptation and high pass filtering

Question 57

How can specific channels be studied (based on chemicals)?

Answer 57

Use specific channel blockers

Question 58

How can adaptation be used in experimental design?

Answer 58

Remove effects from other receptors

Question 59

What does two-point discrimination reveal?

Answer 59

How closely innervated an area is with receptors

Question 60

Where is sensory information processed in the brain?

Answer 60

Somatosensory cortex

Question 61

What is the homunculus?

Answer 61

Body map of the brain (processing space in sensory cortex)

Question 62

What areas are the most represented in the homunculus?

Answer 62

Hands and lips

Question 63

If an area of the body is sensitive to sensory information, what impact would that have in the sensory cortex?

Answer 63

Large area devoted for processing

Question 64

What is phantom limb syndrome?

Answer 64

Sensory input in a lost limb

Question 65

What is the cause of phantom limb syndrome?

Answer 65

Reorganization of sensory cortex and homunculus

Question 66

How does sensory information travel to the brain?

Answer 66

Through dorsal root ganglia

Question 67

What do the two pathways of transmission in sensory transduction relay?

Answer 67

Location/touch, and temperature/pain

Question 68

Why do braile people sometimes experience confusion about which finger is touched?

Answer 68

Reorganization of sensory cortex; an area of the brain was stimulated when it shouldn't have

Question 69

What is TRPV1 (pain receptor) activated by?

Answer 69

Capsaicin (chili peppers) and temperature