Sense Organs

Question 1

What are the functions of the tongue?

Answer 1

The tongue’s functions are:

• Swallowing
• Perception (can detect taste, texture, pain, pressure, heat, etc)
• Speech
• Respiration
• jaw development

Question 2

What are the extrinsic and intrinsic muscles function in the tongue?

Answer 2

The extrinsic muscles in the tongue:

• Move the tongue in and out of the mouth
• Move the tongue from side to side

The intrinsic muscles of the tongue:
- Alter the shape of the tongue

Question 3

What are taste buds?

Answer 3

• Taste buds are modified epithelial cells that act as taste receptors.
• Most are associated with nipple like projections called papillae
• About 3000 taste buds are on the tongue
• There are 4 primary taste sensations: sweet, sour, salty, and bitter

Question 4

What are Von Ebner’s glands?

Answer 4

Von Ebner’s glands surround the papillae and secrete salivary lipase, beginning the process of lipid breakdown (hydrolysis) in the mouth

Question 5

What does the eye analyze?

Answer 5

The eye analyzes form, light intensity, and color

Question 6

What is the sclera?

Answer 6

The sclera is the white part of the eye

• Tough connective tissue made up of collagen bundles
• It is avascular
• Has sensory receptors for pain

Question 7

What is the cornea?

Answer 7

The Cornea allows light into the eye

• avascular
• When light hits the cornea, it bends (refracts) the incoming light into the lens of the eye.

Question 8

What is the choroid?

Answer 8

Highly vascular thin layer that lines most of the internal sclera surface.
- Melanocytes containing pigments are here which can absorb the light that photoreceptors have not and prevents light scattering in the eye

Question 9

What is the Iris?

Answer 9

The Iris is the colored portion of the eye and is continuous with the choroid.

Question 10

What is the Pupil?

Answer 10

The pupil is the opening in the center of the iris that controls how much light enters the eye.

• Sympathetic stimulation: dilates pupil
• Parasympathetic stimulation: constricts pupil

Question 11

What is the Lens?

Answer 11

The lens is located behind the pupil

• It focuses light onto the retina.
• The ciliary muscle will change the shape of the lens

Question 12

What is the ciliary muscle?

Answer 12

The ciliary muscle is a muscle in the eye that changes the shape of the lens.

• For distant viewing it relaxes and flattens the lens
• For close up viewing it contracts and the lens becomes more spherical

Question 13

What is the Retina?

Answer 13

The retina is the posterior portion of the eye that contains the photoreceptors.

Question 14

What are rods?

Answer 14

Rods are a type of photoreceptor

• Dim light
• Black and white vision

Question 15

What are cones?

Answer 15

Cones are a type of photoreceptor

• Provide color vision
• Respond well to daylight
• provide visual acuity (ability to perceive numbers and letters at a distance)
• concentrated in the center of the retina in a depression called the fovea centralis.

Question 16

What is the Fovea Centralis?

Answer 16

The Fovea Centralis is a depression in the center of the retina where the largest concentration of cones is.

• This is the area of keenest vision
• There are no rods here
• NB: Common DAT question

Question 17

How do rods and cones vary from animal to animal?

Answer 17

Animals all have a different breakdown of rods vs cones.

- Nocturnal animals have a larger proportion of rods for night time vision

Question 18

What is the optic disc?

Answer 18

The optic disc is the area of the eye where the optic nerve leaves.

• There are no photoreceptors here, so it’s a physiological blind spot
• It’s insensitive to light here.

Question 19

What is the vitreous humor?

Answer 19

Vitreous humor is a jellylike substance that maintains eyeball shape

• makes up 80% of the eye
• Very few cells are found here
• Phagocytes are found here to help clean up cellular debris

Question 20

What is aqueous humor?

Answer 20

Aqueous humor is a clear, slightly alkaline fluid found in the anterior and posterior eye chambers.

• It resembles blood plasma, but has less protein and glucose.
• It is involved with water removal
• It brings O2 and nutrients to the eye

Question 21

What is rhodopsin?

Answer 21

Rhodopsin (aka Visual Purple) is a pigment-containing sensory protein that converts light into an electrical signal.

• This pigment is found in Rods
• Very sensitive to light, and allows us to see in dim light
• When rhodopsin absorbs light, it isomerizes its conformation from cis to trans. This conformational change causes an electrical signal to be sent to the brain and a visual image is seen
• Much is still not understood about this mechanism

Question 22

What organisms can perceive sound?

Answer 22

Many arthropods and most vertebrates can perceive sound.

Question 23

What is sound?

Answer 23

Sound is a wave of compressed air

Question 24

What is the external ear?

Answer 24

The external ear consists of the:

• Pinna: The outer ear that you touch
• Auditory Canal: Collects the sound waves that enter the ear
• Tympanic membrane (ear drum): Sound waves are channelled here via the auditory canal. The tympanic membrane vibrates in response to the sound wave.

Question 25

What is the Pinna?

Answer 25

The Pinna is the outer ear portion that you can touch. It funnels sound into the auditory canal.

Question 26

What is the auditory canal?

Answer 26

The auditory canal is a part of the external ear that funnels sound inward to the tympanic membrane from the pinna.

Question 27

What is the tympanic membrane?

Answer 27

The tympanic membrane is the ear drum. - It is a part of the external ear - It vibrates in response to sound waves - It transfers the vibrations to the three bones of the middle ear: Malleus, Incus, Stapes

Question 28

What are the three bones of the Middle Ear?

Answer 28

The three bones of the middle ear are the Malleus, Incus, and Stapes. - They receive vibrations from the tympanic membrane and transfer it to the oval window. - Superficial to Deep the bones are Malleus, Incus, Stapes (More incoming sound)

Question 29

What is the middle ear?

Answer 29

The middle ear consists of: - The bridge of bones (Malleus, Incus, Stapes) that transfers vibrations from the tympanic membrane to the oval window. - The oval window is a membrane that cause vibrations to move to the inner ear. - The Eustachian tube connects the middle ear to the nasopharynx and ensures that pressure is equalized on either side of the tympanic membrane.

Question 30

What is the Eustachian tube?

Answer 30

The Eustachian tube connects the middle ear with the nasopharynx, enabling equal pressure on both sides of the tympanic membrane.

Question 31

What is the oval window?

Answer 31

The oval window is a membrane that receives vibrations from the Malleus, Incus, and Stapes and transfers the vibrations to the inner ear.

Question 32

What is the inner ear?

Answer 32

The inner ear consists of fluid-filled channels in the bones of the skull - The Cochlea is one of these channels and is involved with hearing. - The Utricle is a semicircular canal involved with balance - The Saccule is another semicircular canal involved with balance

Question 33

What is the Cochlea?

Answer 33

The Cochlea is a fluid filled channel in the bones of the skull. - It is a snail like structure - Contains a sensory response called the Organ of Corti that holds the hair cells, the nerve receptors of hearing. These are the mechanoreceptors of the ear.

Question 34

What do the Utricle and Saccule do?

Answer 34

The Utricle and Saccule are fluid filled canals that use hairlike structures to detect movement and help with balance. - Saccule detects movement in the vertical plane - Utricle detects movement in the horizontal plane

Question 35

How is sound transferred from the inner ear to nerve impulses to the brain?

Answer 35

- The oval window transmits vibrations to the cochlea. - The fluid in the cochlea stimulate tiny hair cells - The signals from these hair cells are changed into nerve impulses. - The nerve impulses are transferred to the brain via the auditory nerve.

Question 36

What could cause deafness?

Answer 36

There are several things that can cause deafness: - Cochlea damage - Auditory nerve damage - Vibration transmittance to the inner ear is hindered - Loud sounds

Question 37

How do insects detect sound?

Answer 37

Insects use a tympanic membrane which allows sound waves to vibrate and receptor cells convert the sound waves into nerve impulses

Question 38

How do fish detect sound?

Answer 38

- Fish lack a tympanic membrane and cochlea. - Many fish conduct sound waves through a series of bones. - Mechanoreceptors are able to detect sound waves which are converted into neuronal signals.