B2W3 Sensory Transduction

Question 1

Taste Anatomy Breakdown

Answer 1

Papillae > Bud > Pore > Receptor

Question 2

5 Primary Taste qualities

Answer 2

Salty
Sour
Sweet
Bitter
Umami

Question 3

Taste Receptor Cells

Answer 3

Modified epithelial cells
- Only detect 1 quality of taste

Question 4

Salt and Sour Taste Pathway

Answer 4

Ionotropic Increase in Na influx

Question 5

Salt Pathway

Answer 5

Increase sodium concentration in mouth -> Na moves through always open Na channels to depolarize the cell -> Calcium entry into the cell -> Release of vesicular serotonin

Question 6

Sour Pathway

Answer 6

H+ ions activate TRPP3 channels to allow the flow of Na into the cell and inhibits K+ channels -> Causes depolarization -> Calcium entry into the cell -> Release of vesicular serotonin

Question 7

Sweet, Bitter, and Umami Pathway

Answer 7

Metabotropic Mechanism (Gaq) -> Activation of GPCR -> Subunit activates Phospholipase C -> PLC changes PIP2 into DAG and IP3 -> IP3 initiates the release of intracellular Ca from the ER -> Increased concentration of Ca opens Ca dependent Na channels -> Na flows into the cell causing depolarization -> Release of NON VESICULAR ATP

Question 8

Olfaction Cell Types

Answer 8

Basal Cells
- Stem Cells that replace dying receptor cells
Support Cells
- Produce Mucus
Olfactory Receptors
- Site of transduction

Question 9

How is odor information determined

Answer 9

Each neuron synapses differently to determine the different smells

Question 10

Olfactory Pathway

Answer 10

Odorant Molecule binds to GPCR (G Olfactory or Golf protein) -> Alpha subunit activates Adenylate Cyclase -> Adenylate Cyclase changes ATP into cAMP -> cAMP opens CNG ion channels which allows mainly Na and Ca and some K to enter the cell (it is a nonselective channel) -> Increased Ca concentration opens Ca activated Cl channels -> Cl- moves out of the cell -> results in depolarization

Question 11

Where does most focus happen in vision

Answer 11

Anterior surface of the cornea due to different refractive index
Air 1
Cornea 1.3

Question 12

Eye Accommodation

Answer 12

Increase focal power to see closer objects
Ciliary muscles contract causing zonal fibers to release tension and the lens to become rounder

Question 13

Myopia

Answer 13

Nearsightedness
Eye is too long causing images to focus in front of retina
Distant images are blurry but can see close up

Question 14

Hyperopia

Answer 14

Farsightedness
Eye is too short causing image to focus behind retina
Near images are blurry but can see far away

Question 15

Astigmatism

Answer 15

Uneven curvature of the eye
Problem focusing everything

Question 16

Pupillary Light Reflex

Answer 16

Light shone into one eye will cause both irises to constrict

Question 17

Pathway of Pupillary light reflex

Answer 17

Light activates preganglionic parasympathetic neurons which go through the Edinger-Westphal Nucleus which goes to both eyes and then synapse on ciliary ganglia which activates postganglionic parasympathetic neurons to cause pupil constriction

Question 18

Yoked pupillary response

Answer 18

Both pupils react

Question 19

Retina

Answer 19

Area in the eye containing photoreceptors

Question 20

Types of Photreceptors

Answer 20

Rods and Cones

Question 21

Rods

Answer 21

Low light black and white slow

Question 22

Cones

Answer 22

Bright light color vision fast
C for color

Question 23

Distribution along the retina

Answer 23

Fovea or center of retina
- High resolution high density of cones
- 1 to 1 ratio of photoreceptors to sensory afferent

Periphery
- Higher Density of Rods
- More sensitive to light but low spatial resolution

Question 24

Phototransduction in the dark

Answer 24

In the dark photoreceptors are depolarized and continuously release glutamate
- Large inward Na current in the outer segment and outward current of K in the inner segment

Question 25

Phototransduction in Light

Answer 25

Retinal absorbs light and undergoes a confirmational change in opsin to become Metarhodopsin II-> Metarhodopsin II activates transducin (G-Protein) -> Alpha subunit activates phosphodiesterase -> Phosphodiesterase converts cGMP into GMP -> loss of cGMP causes inward sodium channels to close -> hyperpolarizes the cell

Question 26

Rhodopsin

Answer 26

Opsin (Receptor Protein) and Retinal (Photosensitive component)

Question 27

What neurotransmitter is released by photoreceptors?

Answer 27

Glutamate