UNIT 3 - Handout (Anatomy of Special Senses)

Question 1

special senses

Answer 1

• smell
• taste
• hear
• vision
• equilibrium

Question 2

Neural pathways for the special senses are also MORE COMPLEX than those for the general senses.

Answer 2

As with general senses, physiologic processes of these special senses also involve detection of environmental stimuli and conversion of these stimuli to signals that the brain can interpret.

Question 3

occupies the superior part of the nasal cavity, covering the inferior surface of the cribriform plate and extending along the superior nasal concha

Answer 3

olfactory epithelium

Question 4

3 KINDS OF CELLS OF OLFACTORY EPITHELIUM

Answer 4

1. olfactory receptor cells
2. supporting cells
3. basal cells

Question 5

• First-order neurons of the olfactory pathway
• Bipolar neuron with an exposed knob shaped dendrite
• Axon projecting through the cribriform plate that ends in the olfactory bulb

a. _________: non-motile, site of olfactory transduction
b. _________: within cilia detecting odorants

Answer 5

1. OLFACTORY RECEPTOR CELLS

a. olfactory cilia
b. olfactory receptors

Question 6

• _______________ of the mucous membrane lining the nose.
• Provide physical support, nourishment, and electrical insulation for the olfactory receptor cells
• Help detoxify chemicals that come in contact with the olfactory epithelium

Answer 6

2. SUPPORTING CELLS
   - columnar epithelial cells

Question 7

• Stem cells located between the bases of the supporting cells
• Continually undergo cell division to produce new olfactory receptor cells, which live for only a month or so before being replaced

Answer 7

basal cell

Question 8

• found within the connective tissue that supports the olfactory epithelium
• Produce mucus that is carried to the surface of the epithelium by ducts
• Secretion moistens the surface of the olfactory epithelium and dissolves odorants so that transduction can occur.

Answer 8

olfactory glands (bowman’s glands)

Question 9

• parasympathetic neurons within branches of the facial (VII) nerve
• Impulses in these nerves in turn stimulate the _______ glands in the eyes and nasal mucous glands

Answer 9

innervation of olfactory glands and supporting cells

• lacrimal

Question 10

• react to odorant molecules in the same way that most sensory receptors react to their specific stimuli: a ________ (______) develops and triggers one or more nerve impulses.

This process, called ____________, occurs in the following way: Binding of an odorant to an olfactory receptor protein in an
olfactory cilium stimulates a membrane protein called a _________.

• The G protein, in turn, activates the enzyme __________ to produce a substance called ______________.
• The cAMP opens a sodium ion (Na+) channel that allows Na+ to enter the cytosol, which causes a depolarizing generator potential to form in the membrane of the olfactory receptor cell.
• If the depolarization reaches threshold, an action potential is generated along the axon of the olfactory receptor cell.

Answer 10

OLFACTORY RECEPTOR CELLS

• generator potential (depolarization)
• olfactory transduction; G protein
• adenylate cyclase; cyclic adenosine monophosphate (cAMP).

-

Question 11

__________: reduced ability to smell, affects half of those over age 65 and 75% of those over age 80.

• also can be caused by neurological changes, such as a head injury, Alzheimer’s disease, or Parkinson’s disease; certain drugs, such as antihistamines, analgesics, or steroids; and the damaging effects of smoking.

Answer 11

hyposmia

Question 12

• where receptors for sensation of taste are located
• Most of the nearly 10,000 taste buds of a young adult are on the tongue, but some are found on the ________ (posterior portion of the roof of the mouth), ________ (throat), and ________ (cartilage lid over voice box).
• The number of taste buds declines with age.

Answer 12

TASTE BUDS

• soft palate
• pharynx
• epiglottis

Question 13

3 KINDS OF EPITHELIAL CELLS

Answer 13

1. supporting cells
2. gustatory receptor cells
3. basal cells

Question 14

• Contains microvilli and surround 50 gustatory receptor cells in each taste bud

Answer 14

supporting cells

Question 15

• Life span of about 10 days
• ___________ (gustatory hairs) project from each gustatory receptor cell to the external surface through the taste pore, an opening in the taste bud

Answer 15

gustatory receptor cells
- Gustatory microvilli

Question 16

• Stem cells found at the periphery of the taste bud near the connective tissue layer, produce supporting cells, which then develop into gustatory receptor cells.

Answer 16

basal cells

Question 17

• elevations on the tongue where taste buds are found increase the surface area and provide a rough texture to the upper surface of the tongue

3 TYPES

Answer 17

PAPPILAE

1. circular vallate papillae (wall-like) or circumvallate papillae
2. fungiform papillae (mushroom-like)
3. foliate papillae (leaflike)

Question 18

• Form an inverted V-shaped row at the back of the tongue
• About 12 very large papillae
• Each of these papillae houses 100–300 taste buds.

Answer 18

CIRCULAR VALLATE PAPILLAE (WALL-LIKE) or CIRCUMVALLATE PAPILLAE

Question 19

Mushroom-shaped elevations scattered over the entire surface of the tongue that contain about five taste buds each

Answer 19

FUNGIFORM PAPILLAE (MUSHROOM-LIKE)

Question 20

Located in small trenches on the lateral margins of the tongue, but most of their taste buds degenerate in early childhood

Answer 20

FOLIATE PAPILLAE (LEAFLIKE)

Question 21

• Contain tactile receptors but no taste buds.
• increase friction between the tongue and food, making it easier for the tongue to move food in the oral cavity.

Answer 21

filiform papillae (threadlike)

Question 22

(1)

Chemicals that stimulate gustatory receptor cells are known as ________.

Once it is dissolved in saliva, it can make contact with the plasma membranes of the _______, which are the sites of taste transduction.

The result is a receptor potential that stimulates exocytosis of _________ from the release of neurotransmitter.

The hydrogen ions (H+) in sour tastants may flow into gustatory receptor cells via H+ channels.

Answer 22

• tastants
• gustatory microvilli
• ## synaptic vesicles

Question 23

(2)

• also influence opening and closing of other types of ion channels.
• Again, the result is _______ & _______of neurotransmitter.
• Other tastants, responsible for stimulating sweet, bitter, and umami tastes, DO NOT themselves enter gustatory receptor cells.
• rather, they BIND to receptors on the plasma membrane that are linked to G proteins.
• The G proteins then activate several different chemicals known as _________ inside the gustatory receptor cell.
• Different second messengers cause depolarization in different ways, but the result is the same—_____________

Answer 23

• depolarization and the liberation
• second messengers
• release of neurotransmitter

Question 24

If all tastants cause release of neurotransmitter from many gustatory receptor cells, why do foods taste different?

Answer 24

• answer is thought to lie in the patterns of nerve impulses in groups of first-order taste neurons that synapse with the gustatory receptor cells.
• Different tastes arise from activation of different groups of taste neurons.
• although each individual gustatory receptor cell responds to more than one of the five primary tastes, it may respond more strongly to some tastants than to others.

Question 25

- Measures about ___cm (__ in.) in diameter. - Of its total surface area, only the anterior 1/6 is exposed; the remainder is recessed and protected by the orbit, into which it fits.

Answer 25

eyeball

Question 26

3 layers of eyeball wall

Answer 26

1. fibrous tunic - cornea - sclera 2. vascular tunic - choroid - ciliary body - iris 3. retina (inner tunic) - pigmented layer - neural (sensory) layer

Question 27

superficial layer of the eyeball and consists of the anterior cornea and posterior sclera

Answer 27

1. FIBROUS TUNIC - cornea - sclera --> sclera venous sinus or (canal of Schlemm)

Question 28

- a transparent coat that covers the colored iris - Focus light onto the _____ - Outer surface consists of NONKERATINIZED _______________ - Middle coat of the cornea consists of ________ and ________ - Inner surface is _____________

Answer 28

CORNEA - retina - stratified squamous epithelium - collagen fibers and fibroblasts - simple squamous epithelium

Question 29

- “white” of the eye, a layer of _____________ made up mostly of _______ and ______ - Covers the entire eyeball except the cornea - Gives shape to the eyeball, makes it more rigid, protects its inner parts - Serves as a site of attachment for the _______ eye muscles ____________: junction of Sclera and Cornea

Answer 29

SCLERA - dense connective tissue - collagen fibers and fibroblasts - extrinsic SCLERAL VENOUS SINUS (CANAL OF SCHLEMM)

Question 30

middle layer of the eyeball

Answer 30

2. VASCULAR TUNIC a. choroid b. ciliary body - ciliary processes - ciliary muscle (a circular band of smooth muscle) c. iris

Question 31

- posterior portion of the vascular tunic, lines most of the internal surface of the _____ - Provide nutrients to the posterior surface of the _____ - Contains melanocytes that produce the pigment _______, which causes this layer to appear dark brown in color. - Melanin in the choroid absorbs stray light rays, which prevents reflection and scattering of light within the eyeball.

Answer 31

CHOROID - sclera - retina - melanin

Question 32

- anterior portion of vascular tonic - Extends from the _________ to a point just posterior to the junction of the sclera and cornea - Appears dark brown in color because it contains melanin producing ___________

Answer 32

CILIARY BODY - Ora serrata - melanocytes

Question 34

parts of ciliary body

Answer 34

- ciliary processes - ciliary muscle (a circular band of smooth muscle)

Question 35

- protrusions or folds on the internal surface of the ciliary body - Contain blood capillaries that secrete __________ - __________: extensions of ciliary processes that consist of thin, hollow fibrils that resemble _____________ attached to lens

Answer 35

CILIARY PROCESSES - aqueous humor - Zonular fibers or suspensory ligament - elastic connective tissue fibers

Question 36

- Contraction or relaxation of the ciliary muscle changes the tightness of the _________, which alters the shape of the lens, adapting it for near or far vision.

Answer 36

CILIARY MUSCLE (A CIRCULAR BAND OF SMOOTH MUSCLE) - zonular fibers

Question 37

- colored portion of the eyeball, shaped like a flattened donut - Suspended between the cornea and the lens and is attached at its outer margin to the ciliary processes. - It consists of ________, and _______ and __________ - The amount of melanin in it determines the eye color. - Principal function is to regulate the amount of light entering the eyeball through the _______

Answer 37

IRIS - melanocytes and circular and radial smooth muscle fibers. - pupil

Question 38

Pupillary reaction to: _________ ANS stimulated: ___________ Reaction: ___________ stimulate the ________ or ________ of the iris to contract, causing a decrease in the size of the pupil (_________)

Answer 38

Pupillary reaction to: bright light ANS stimulated: parasympathetic Reaction: - Oculomotor (III) nerve - circular muscles or sphincter pupillae - (constriction)

Question 39

Pupillary reaction to: _________ ANS stimulated: _________ Reaction: Stimulate the _______ or _______ of the iris to contract, causing an increase in the pupil’s size (__________).

Answer 39

Pupillary reaction to: dim light ANS stimulated: sympathetic Reaction: - radial muscles or dilator pupillae - (dilation)

Question 40

_________: third and inner layer of the eyeball a. ___________: sheet of melanin-containing epithelial cells located between the choroid and the neural part of the retina b. ___________: multilayered outgrowth of the brain that processes visual data extensively before sending nerve impulses into axons that form the optic nerve.

Answer 40

3. RETINA (INNER TUNIC) a. Pigmented layer b. Neural (Sensory) layer

Question 41

10 LAYERS OF THE RETINA

Answer 41

1. retinal pigment epithelium (RPE) 2. photoreceptors: rods and cones - Each retina has about 6 million cones and 120 million rods - Rods allow us to see in dim light, and do not provide color vision - Cones produce color vision. three types of cones present in the retina: (1) Blue cones - sensitive to blue light (2) Green cones - sensitive to green light (3) Red cones, which are sensitive to red light. 3. external limiting membrane (ELM) 4. outer nuclear layer (ONL) 5. outer plexiform layer (OPL) 6. inner nuclear layer (INL) - nuclei of horizontal and bipolar cells and amacrine cells 7. inner plexiform layer (IPL) 8. ganglion cell layer (GCL) 9. nerve fiber layer (NFL) 10. inner limiting membrane