Sense Organs, Special Senses

Question 1

Types of general stimuli that trigger a response from sensory receptors (4)

Answer 1

1. Mechanical: touch, hearing, balance
2. Thermal: hot & cold
3. Electromagnetic: vision
4. Chemical: taste & smell

Question 2

Visceral sensations: What is sensed (3)? Types of stimulus used?

Answer 2

Sensed:
1. Hunger: Indicates a deficiency on nutrients.
2. Thirst: Indicates deficiency on nutrients & fluid balance.
3. Hollow-organ fullness: Hollow-organ will stretch creating a painful sensation with the exception of the bladder.

Types of stimulus:
- Chemical & mechanical

Question 3

Superficial vs Central temperature sensors

Answer 3

• Superficial: Measure skin temp. Both hot & cold.
• Central: Measure blood temp. in hypothalamus.

Question 4

Special senses (5): What is sensed and stimuli used

Answer 4

1. Taste: Tastes; Chemical.
2. Smell: Odors; Chemical.
3. Hearing: Sounds; Mechanical.
4. Equilibrium: Balance & head position; Mechanical.
5. Vision: Light; Electromagnetic.

Question 5

What are the three parts of the ear?

Answer 5

External, middle, & inner!

Question 6

External ear parts (3)

Answer 6

1. Pinna
2. External auditory canal
3. Tympanic membrane

Question 7

Pinna structure and function

Answer 7

Structure:
- Elastic cartilage & skin.
Function:
- Collects sound wave vibrations. Directs these to the external auditory canal.

Question 8

External auditory canal structure and function

Answer 8

Structure:
- Membrane-line tube beginning at the pinna.
Function:
- Carries sounds waves to to tympanic membrane.

Question 9

Tympanic membrane (eardrum) structure and function

Answer 9

Structure:
- Thin connective tissue membrane.
Function:
- Sound waves strike this & cause it to vibrate.

Question 10

Middle ear structure and parts (2)

Answer 10

Structure:
- Hollowed-out area of the temporal bone that is lined by soft tissue membranes.
Parts:
- Ossicles (small bones)
- Eustachian tube

Question 11

Ossicles structure, function, & parts (3)

Answer 11

Structure:
- Link tympanic membrane w/cochlea of inner ear.
Function:
- Act as a system of levers that transmit sound wave vibrations from the tympanic memb. to cochlea.
Parts:
1. Mallus: outermost bone; attached to tympanic memb.
2. Incus: middle bone.
3. Stapes: medial-most bone; attached to memb. that covers oval window of cochlea.

Question 12

Inner ear

Answer 12

1. Cochlea: Shell-shaped spiral cavity in the temporal bone.
   - Organ of Corti: Fluid-filled portion that makes up the receptor organ of hearing

Question 13

Eustachian tube structure and function

Answer 13

Structure:
- Connects the middle ear cavity with the pharynx.
Function:
- Equalizes air pressure on the two sides of the tympanic membrane.

Question 14

Equilibrium function and receptors location (2)

Answer 14

Function:
- Mechanical sense that maintains balance by tracking position & movements of the head.
- Involves equalib receptors & info from eyes & proprioceptors.
The receptors location:
1. Vestibule
2. Semicircular Canals

Question 15

Vestibule structure and function

Answer 15

Structure:
- Between cochlea & semicircular canals.
- Made of sac-like spaces called utricle & saccule.
Function:
- Gravity causes gelatinous matrix & otoliths to put pressure on the hair cell they’re covering.
- Movement of the head bends the sensory hairs.
- Generates nerve impulses that give the brain info about the position of the head.

Question 16

Semicircular canals structure and function
Hint: glass of water being turned

Answer 16

Structure:
- Located opposite the vestibule from the cochlea.
- Each semicircle has a bulb at the end called “ampulla.”
- Within ampulla, there is the cupula floating above it.
Function:
- When you turn a glass with water, the water lags behind the movement of the glass. Same goes for the semicir.
- Movement of fluids pulls cupula & bends the hairs.
- This generates nerve impulses & give brain info about motion.

Question 17

Layers of the eyeballs (3)

Answer 17

1. Outer fibrous layer
2. Middle vascular layer
3. Inner nervous layer (retina)

Question 18

Outer Fibrous layer of the eyeball: Name the parts (3) functions and structures

Answer 18

1. Cornea: Transparent; arrangement of collagen fiber (no blood vessels). Admits light to interior of the eye.
2. Sclera: “White” of the eye. Dense fibrous connective tissue.
3. Limbus: Junction of the cornea & sclera.

Question 19

Middle Vascular layer of the eyeball parts (4)

Answer 19

1. Choroid: Pigment & blood vessels. Tends to form tapetum.
2. Iris: Controls amount of light that enters posterior part of eye.
3. Pupil: Opening at center of iris.
4. Ciliary body: Ring shape behind iris. Muscles that adjust shape of lens to allow near/far vision.

Question 20

Tapetum

Answer 20

Highly reflective area in the rear of the eye

Question 21

Inner Nervous layer of the eyeball, “Retina”

Answer 21

Retina:
- Lines the back of the eye
- Contains the sensory receptors for vision, rods & cones.

Question 22

Major compartments of the eyeball (2)

Answer 22

1. Aqueous:
   - Split by iris into anterior & posterior chambers.
   - Contains clear watery fluid: aqueous humor.
2. Vitreous:
   - Contains clear gelatinous fluid: vitreous humor.
   - This fills whole back of eyeball behind the lens & ciliary body.

Question 23

Origin of tears, how they flow in/out of the eye

Answer 23

• Tears are produced by lacrimal glands in dorsal and ventral border of orbit, accessory lacrimal glands in 3rd eyelid.
• Drain thru upper & lower lacrimal puncta, canaliculus into lacrimal sac, into nasolacrimal duct, into nasal cavity.