Vision physiology

Question 1

What is a bareceptor?

Answer 1

a receptor sensitive to changes in pressure, e.g., these can be found in blood vessels and detected changes in blood pressure

Question 2

What is a mechanoreceptor?

Answer 2

a receptor sensitive to mechanical stimuli such as touch and sound, e.g., Meissner’s Corpuscles

Question 3

Thermoreceptor?

Answer 3

A receptor sensitive to temperature stimuli, e.g., found in the skin, liver, skeletal msucles etc.

Question 4

Osmoreceptor

Answer 4

Receptor sensitive to sodium & water water balance levels; osmotic pressure

Question 5

photoreceptor

Answer 5

receptor sensitive to light stimuli

Question 6

Nocireceptor

Answer 6

a receptor sensitive to pain stimuli/threatning & dangerous threats

Question 7

Somatic V Visceral

Answer 7

Somatic; regards external stimuli and responses to such

Visveral; regards internal stimuli and responses to such

Question 8

somatosensory

Answer 8

relating to sensation, such as pain, temp, etc. which can occur anywhere in the body- in contrast to one localised sense organ, e.g., sight, balance, taste

Question 9

Viscera

Answer 9

refers to internal body cavities and their organs, such as the guts within the abdomen

Question 10

papillae

Answer 10

small structures (bumps) on the upper surface of the tongue which gives the muscle its characteristic rough texture/ they contain our taste buds and therefore vital in our perception of taste.

Question 11

Meissner’s Corpuscles

Answer 11

cutaneous (relating to/affecting the skin) never ending responsible for transmitting the sensations of fine, discriminative touch and vibration.

Question 12

Gustatory

Answer 12

concerned with tasting/the sense of taste, e.g., gustatory cells = taste cells

Question 13

Olfactory

Answer 13

concerned with the sense of smell, e.g., olfactory cells

Question 14

Lacrimal

Answer 14

this is a (tear-shaped) gland which has the primary function of secreting tears (fluid) onto the surface of the eyeball

Question 15

Conjunctivae

Answer 15

a thin mucous membrane which provides the eye protection via its production of both mucus and tears. It lines the inside of the eyelids and provides a covering to the sclera

Question 16

Sensory receptor

Answer 16

a structure which reacts to a physical stimulus in the environment, whether internal or external. The sensory nerve ending receives information, such as a stimulus, and conducts a process of generating nerve impulses to be transmitted to the brain for interpretation

Question 17

Nerve impulse

Answer 17

an electrical signal that travels along a nerve fibre in response to a stimulus, and serves to transmit a record of sensation from a receptor or an instruction to act as an effector

Question 18

Neurone

Answer 18

a nerve cell

Question 19

Receptive field

Answer 19

a specific region of sensory space in which an appropriate stimulus can drive an electrical response in a sensory neurone

Question 20

Nerve fibre

Answer 20

a long, slender projection of a neurone (nerve cell) which typically conducts electrical impulses (action potentials) away from one neurone’s cell body to the next

Question 21

Adaption (of sensory neurones)

Answer 21

the decline of the electric responses of a receptor neurone over time in spite of the continued presence of an appropriated stimulus of constant strength. e.g., not being aware of the sensation of our clothes on our skin, or background noise in a room we’ve been in for a period of time

Question 22

What section of the brain is smell translated

Answer 22

temporal lobe; which is also associated with memory and emotion

Question 23

where are receptor cells for smell (olfactory cells) located?

Answer 23

olfactory nasal epithelium

Question 24

Three processes involved in formation of an image of the retina

Answer 24

1.) refraction or bending of light rays
2.) formation of an inverted image on the retina for the brain to convert
3.) adjustments for close vision (accomodation)

Question 25

Conjuntivitis

Answer 25

* eye condition caused by allrgies or infection * also known as pink eye * usualluy affects both eyes * redness, swelling, gritty sensation * not contagious if caused by allergies

Question 26

Cataract

Answer 26

when lens develops cloudy patches which become bigger and interfere with eyesight. older people likely to experience this

Question 27

Myopia

Answer 27

short-sightedness. usually develops in kids 6-13 can get worse but stabalises when eye stops growing around age 20

Question 28

hyperopia/hypermetropia (long-sightedness)

Answer 28

typically affects adults over age 40 but can affect anyone

Question 29

astigamatism

Answer 29

* where eye is shaped more like a rugby ball than football * blurred vision, eye strains, headaches * common alongside myopia/hypermetropia * may cause a lazy eye * early identification is key for treatment

Question 30

amblyopia (lazy eye)

Answer 30

* childhood condition where vision does not develop properly * most common cause is imbalance in muscles which position the eyes (hence off-centred appearance) * eyes are therefore prevented from wokring completely together

Question 31

two types of photoreceptors

Answer 31

Cones; less sensitive than rods and therefore play a bigger role in our daytime vision. responsible for colour vision Rods; due to their sensitivity, therefore work more in nightvision and are responsible for black and white vision

Question 32

what is rhodopsin

Answer 32

a protein packed within rod and cone photoreceptors on the retina which is critical for light activation of rods

Question 33

what vitamin is vital for vision?

Answer 33

vitamin A- which is necessary for rhodopsin and rods to do their job efficiently. where there is a deficiency in Vit A, nightvision would be greatly affected (negatively)

Question 34

what is the macula lutea (fovea)

Answer 34

a (yellow) area of the retina responsible for sharp, detailed, central vision (also called visual aucity). here there is a high concentration of cones.

Question 35

Gluacoma

Answer 35

where increased pressure within the eye can damage the optic nerve and therefore inhibit vision. e.g., the drainage system of aqueous humour is not working and compressing the vessels.

Question 36

Visionretinopathy

Answer 36

prolonged exposure to high blood glucose (sugar) levels in the eye's blood vessels, often because of uncontrolled diabetes

Question 37

Macular Degeneration

Answer 37

A common age-related (50s & 60s) condition in which the middle part of one’s vision is affected. It does not cause total blindness but can make everyday activities such as reading and recognising faces difficult.

Question 38

What is presbyopia?

Answer 38

the gradual loss of the eyes' ability to focus on nearby objects. it is common as we age.

Question 39

what part of the eye is affected with macular degeneration?

Answer 39

The macula lutea, which is located at the centre of the retina and in line with the pupil. degeneration of photoreceptors here means that central vision is blurry & obscured.