Lab 11: Special Senses

Question 1

Sensation

Answer 1

conscious/subconscious awareness of changes in internal/external environment.

Question 2

General Senses

Answer 2

• somatic senses - touch, pressure, pain, temperature and proprioception
• visceral senses - provides information about internal organs

Question 3

Special Senses

Answer 3

• vision, hearing, equilibrium, taste and smell

* distinct receptor cells restricted to the head

Question 4

Adipose tissue function in eye

Answer 4

padding and insulation within the orbit to protect the eye.

Question 5

Sclera

Answer 5

•“white of the eye”
•Function:  
- protects/shapes eyeball 
- provides sturdy anchoring site for extrinsic eye muscles
- oppose pulling forces of eye muscles

Question 6

Cornea

Answer 6

• transparent, anterior portion of sclera
•Function:
- allows light to enter eye
- helps bend (refract) light rays so they focus on photoreceptors in retina.

Question 7

Extrinsic eye muscles

Answer 7

• skeletal muscles provide rotary movements of the eye
• focus the eye for optimum vision
• anchor the eye in the bony orbit
• flat bands on the surface of the eye.

Question 8

The wall of the eye is composed of three layers/tunics:

Answer 8

• Outer Layer (Fibrous Tunic): sclera and the cornea.
• Middle Layer (Vascular Tunic): iris, the ciliary body and the choroid
• Inner Layer: retina

Question 9

Iris

Answer 9

Function: Controls light that can enter back of eye

Question 10

Lens

Answer 10

Function: flexible, changes shape to focus light

Question 11

What is this fluid found in the anterior cavity in relation to the lens?
What is the function of this fluid?

Answer 11

• Aqueous Humor
• Clear, continuously fomred
• Function: forms a fluid cushion, maintain constant intraocular pressure, supply oxygen and nutrients to lens/cornea and carry away metabolic waste

Question 12

What is this fluid found in the posterior cavity in relation to the lens?
What is the function of this fluid?

Answer 12

• Vitreous Humor
• Jelly like fluid, formed during embryonic life and lasts a lifetime
• Functions: help stabilize shape of eye, supports lens/retina, contributes to intraocular pressure

Question 13

Ciliary Body

Answer 13

= ciliary processes + ciliary muscles
• ciliary muscles: control lens shape
• ciliary processes: contain capillaries that produce aqueous humor

Question 14

Choroid

Answer 14

• highly vascular and darkly pigmented tissue

* Function: absorb excess light rays to prevent reflection, can deliver oxygen and nutrients to retnia

Question 15

Retnia

Answer 15

Two Layers
• Outer pigmented layer - absorbs light
• Inner Neural layer - photoreceptors (rods & cones) + bipolar cells + ganglion cells.

Question 16

Optic Disc

Answer 16

• ‘blind spot’
• Light focused on this area cannot be seen because it lacks photoreceptors
• where the optic nerve/blood vessles leave eye

Question 17

Photoreceptors types

Answer 17

Cones:
• stimulated by bright light
• produce colour vision.

Rods:
• absent in fovea, more on periphery of retina
• stimulated by dimmer light
•produce shades of black, white and grey.

Question 18

Macula Lutea

Answer 18

• The central portion of the macula lutea has a small depression known as the fovea centralis.

Question 19

Fovea Centralis

Answer 19

• area of greatest visual acuity (sharpness of vision)

* contains only cones

Question 20

Glaucoma

Answer 20

• develops if drainage of aqueous humor is blocked

* intraoccular pressure increases

Question 21

Cataract

Answer 21

• Clouding of the lens

Question 22

Accommodation

Answer 22

lens of the eye must become more rounded or convex in shape in order to view objects at close range

Question 23

How do we see far (3)

Answer 23

• ciliary muscles relax
• suspensory ligaments stretch
• lens flattens

Question 24

How do we see near (3)

Answer 24

• cilliary muscles contract (close = ciliary = contract)
• suspensory ligaments relax
• lens buldges

Question 25

near point

Answer 25

* The closest distance at which an object appears to be in sharp focus * change due to loss of lens elasticity

Question 26

Visual acuity

Answer 26

degree of "sharpness" of eyesight.

Question 27

Hyperopia (Hypermetropia)

Answer 27

* can see far * short eyeball + flat lens * Fix = converging lens (convex)

Question 28

Myopia

Answer 28

* can see close * long eyeball + curved lens * Fix = diverging lens (concave)

Question 29

Astigmatism

Answer 29

* Astigmatism: cornea or lens has irregularities in the surface curvature * objects may be in focus in one axis and blurred in another axis.

Question 30

The ear is divided into 3 main regions

Answer 30

* External ear: collects/channels sound waves inward * Middle ear: transfers sound vibrations to oval window * Internal ear: contains receptors for hearing/equilibrium.

Question 31

External Ear

Answer 31

Two parts: auricle/pinna + external auditory canal/meatus

Question 32

Auricle/pinna

Answer 32

•external ear, flap of skin/elastic cartilage | Function: Collects/directs sound waves into external auditory canal

Question 33

External auditory canal/meatus

Answer 33

•external ear • ceruminous (wax) glands to trap forign bodies and repel insects Function: conduct airborne sound to tympanic membrane.

Question 34

Tympanic Membrane

Answer 34

•external ear | Function - vibrates at frequency/amplitude of the sound that reaches it.

Question 35

Middle Ear

Answer 35

* Air filled cavity in temporal bone * Auditory ossicles: Bones of axiel skeleton, malleus, incus stapes Functions: transmits and magnifies vibrations fo tympanic membrane to oval window (stapes sits here). * Auditory Tube

Question 36

Auditory (pharyngotympanic) tube or eustachian tube

Answer 36

* middle ear * goes to nasal pharynx. * Funciton: used to equalize pressure on both sides of tympanic membrane to prevent it from rupturing.

Question 37

Inner Ear

Answer 37

Outer bony labyrinth - contains perilymph fluid. - cochlea + vestibule + semicircular canals Inner membranous labyrinth - contains endolymph fluid - cochlear duct + saccule and utricle + semicircular ducts

Question 38

cochlear duct

Answer 38

* contains organ of Corti, the receptor organ for hearing. * Special receptors (hair cells) convert sound waves into nervous impulses that are carried by the cochlear branch to the auditory area of cerebral cortex.

Question 39

saccule and utricle

Answer 39

• Hair cells contain receptors to detect static equilibrium

Question 40

semicircular ducts

Answer 40

* receptors for maintaining dynamic equilibrium | * Ampulla: contains equilibrium receptors (crista ampularis) where we detect dynamic equilibrium

Question 41

Static vs. Dynamic Equilibrium:

Answer 41

Static Equilibrium: the position of head with respect to respect to gravity and linear acceleration. Saccule and utricle. Dynamic equilibrium: position of head during rotational movement. Semicircular ducts.

Question 42

Smell

Answer 42

* chemical sense * Receptors = neurons * Impulses from olfactory nerve (I) --> olfactory bulbs --> olfactory tracts --> primary olfactory area of cerebral cortex in temporal lobe.

Question 43

Olfactory Adaptation

Answer 43

an adaptation of olfactory receptors to a certain smell.  After you smell something for a while you stop detecting the smell.

Question 44

Taste

Answer 44

* chemical sense | * receptors = modified skin cells

Question 45

taste bud

Answer 45

* oval structure containing taste cells, supporting cells and basal cells * Taste buds generally respond to a mixture of the five basic tastes. * a single taste cell has receptors for only one of the basic taste sensations.

Question 46

Five primary or basic

Answer 46

* sweet - organic substances (sugars, alcohols, some amino acids) * sour - hydrogen ions (citric acid of lemon juice) * bitter - nitrogen (caffeine, quinine, and nicotine) * salt - metal ions (sodium and potassium) * umami (savoury beef) - glutamate or other amino acids * may also be a possible sixth taste that accounts for a liking of fatty foods * all areas of the tongue can detect all five taste sensations.