Nervous system: sensory function vision and olfaction

Question 1

what are the 5 special senses?

Answer 1

1. olfaction
2. gustation (taste)
3. vision
4. hearing
5. equilibrium

Question 2

where are the olfactory neurons located?

Answer 2

offactory epithelium = roof of nasal cavity

Question 3

what happens when you sniff?

Answer 3

swirling air currents created by nasal conchae of ethmoid bone when you sniff

Question 4

what layer do odor molecules dissolve?

Answer 4

mucus layer

Question 5

what do the odor molecules bind to?

Answer 5

bind to chemoreceptors on cillia of olfactory neurons which leads to depolarization

Question 6

what happens after depolarization of odor molecules?

Answer 6

mitral cells integrate input and convey to olfactory nerve which leads to temporal lobe, frontal lobe, amygdala, and hypothalamus

Question 7

what membrane covers the inner surface of the eyelid and outer surface of the eye

Answer 7

mucous membrane the conjunctiva which protects/moistens

Question 8

what does the fibrous tunic consist of?

Answer 8

sclera=white of eye
cornea= transparent covering continuous with sclera which bends light rays
cornea is avascular and is easily transplanted

Question 9

what is the vascular tunic (uvea)consist of?

Answer 9

choroid= contains extensive capillary network
isis= pigmented c.t smooth muscle here constricts/dilates pupil
ciliary body= ring of smooth muscle anchored to lens by suspensory ligaments

Question 10

functions of ciliary body?

Answer 10

changes shape of lens to focus: lens become more rounded when ciliary muscle contracts: secretes aqueous humor

Question 11

what does the neural tunic consist of?

Answer 11

retina= contains bipolar sensory
photoreceptors= rods+cones
Macula= highest concentration of cones
fovea= area within macula where vision is sharpest images are focused here when you directly look at an object
optic disc= blind spot where optic nerve emerges has no photoreceptors

Question 12

what are the two cavities of the eye?

Answer 12

anterior cavity and posterior cavity

Question 13

what does the anterior chamber consist of?

Answer 13

anterior chamber and posterior chamber
aqueous humor

Question 14

what is aqueous humor?

Answer 14

secreted by ciliary body and is recycled into blood via scleral venous sinus

Question 15

what does the posterior cavity consist of?

Answer 15

vitreous humor/body which is gelatinous which stabilizes the eye shape and supports the retina

Question 16

what is the function of the lens?

Answer 16

to focus an image on the retina

Question 17

how does the lens focus the image on the retina?

Answer 17

accommodation (changing the shape off the lens by contraction of smooth muscle in ciliary body )
lens made of special fibres called lens fibres

Question 18

how does the shape of the eye corelate to how we see?

Answer 18

lens becomes more rounded to focus on near objects
lens is convev in shape bends the light rays to converge at focal point (focuses image on retina)

Question 19

what do lens fibres contain?

Answer 19

transparent proteins called crystallins

Question 20

what does the cornea do?

Answer 20

bend light rays to focus image on retina

Question 21

what does the anterior cavity contain?

Answer 21

fluid called aqueous humor

Question 22

what is the suspensory ligaments?

Answer 22

attaches ciliary muscles to the lens

Question 23

what is the iris

Answer 23

contains melanin which is coloured part of eye

Question 24

what is the posterior cavity?

Answer 24

contains jelly-like vitreous body

Question 25

what is the ciliary body?

Answer 25

smooth muscles here contracts to make lens more rounded

Question 26

what is the cornea?

Answer 26

transparent part of the fibrous tunic

Question 27

what is the sclera?

Answer 27

white part of the eye

Question 28

what is the optic disc?

Answer 28

part of the retina which contains no photoreceptors

Question 29

what is the retina?

Answer 29

contains photoreceptors rods and cones and sensory neurons

Question 30

what is the fovea?

Answer 30

highest concentration of cones in the eye

Question 31

what are the extraocular muscles?

Answer 31

moves the eye in the orbit of the skull

Question 32

what is the choroid?

Answer 32

part of vascular tunic that supplies retina with oxygen and nutrients

Question 33

where are photoreceptors found?

Answer 33

rods and cones

Question 34

what types of light detection do rods and cones let in?

Answer 34

rods= dim light
cones= bright light and colours

Question 35

how do cones respond differently?

Answer 35

respond to different wavelengths and colours of light
blue cones
red cones
and green cones

Question 36

where are cones concentrated?

Answer 36

fovea which lies in neural tunic

Question 37

how does the fovea help us see?

Answer 37

when you look directly at something it is projected onto the fovea and you see colours and detail most clearly

Question 38

what do rods and cones contain?

Answer 38

photopigments

Question 39

what are photopigments?

Answer 39

pigments in photoreceptors that absorb light energy

Question 40

what are the two photopigments?

Answer 40

rhodopsin= in rods
iodpsin= in cones

Question 41

what does rhodopsin contain?

Answer 41

contains protein apsin and molecule retinal made from vitamin A

Question 42

what does retinol do?

Answer 42

absorbs light energy and changes shape from cis-retinal to trans-retinal

Question 43

what does opsin do?

Answer 43

activates a g protein transducen

Question 44

what does the activated transducen activate?

Answer 44

activates a second messenger which causes na channels to close stopping the release of the neurotransmitter

Question 45

what do the photoreceptors synapse with?

Answer 45

synpase with bipolar sensory neuron in the retina

Question 46

what is the neurotransmitter at synapse?

Answer 46

it is glutamate and it is inhibitory