Module 11: The Special Senses Flashcards Preview

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Flashcards in Module 11: The Special Senses Deck (61):
1

First-order neurons

Sensory neurons that conduct impulses from the PNS into the CNS

2

Free nerve endings

Bare dendrites
Pain, thermal, tickle, itch, some touch sensations

3

Encapsulated nerve endings

Dendrites enclosed in connective tissue capsule
Pressure, vibration, some touch sensations

4

Separate cells

Receptor cells synapse with first-order sensory neurons
Located in retina, inner ear, and taste buds

5

Meissner corpuscles (corpuscles of touch)

Capsule surrounds mass of dendrites in dermal papillae of hairless skin
Touch, pressure, slow vibrations
Rapid adaptation

6

Hair root plexuses

Free nerve endings wrapped around hair follicles in skin
Touch
Rapid adaptation

7

Merkel (tactile) discs (type I cutaneous mechanoreceptor)

Saucer-shaped free nerve endings make contact with Merkel cells in epidermis
Touch and pressure
Slow adaptation

8

Ruffini corpuscles (type II cutaneous mechanoreceptor)

Elongated capsule surrounds dendrites deep in dermis and in ligaments and tendons
Stretching of skin
Slow adaptation

9

Pacinian (lamellated) corpuscles

Oval, layered capsule surrounds dendrites
Present in dermis and subcutaneous layer, submucosal tissues, joints, periosteum, some viscera
Pressure and fast vibrations
Rapid adaptation

10

Itch and tickle receptors

Free nerve endings in skin and mucous membranes
Both slow and rapid adaptation

11

Warm receptors and cold receptors

Free nerve endings in skin and mucous membranes of mouth, vagina, anus
Initially rapid, then slow adaptation

12

Nociceptors

Free nerve endings in every body tissue except brain
Pain
Slow adaptation

13

Muscle spindles

Sensory nerve endings wrap around central area of encapsulated intrafusal muscle fibers within most skeletal muscles
Muscle length
Slow adaptation

14

Tendon organs

Capsule encloses collagen fibers and sensory nerve endings at junction of tendon and muscle
Muscle tension
Slow adaptation

15

Joint kinesthetic receptors

Pacinian corpuscles, Raffini corpuscles, tendon organs, and free nerve endings
Joint position and movement
Rapid adaptation

16

Taste buds consist of:

Supporting cells
Gustatory receptor cells
Basal cells

17

Two nerves that carry impulses from taste buds on the tongue

Cranial nerve VII – facial nerve
Cranial nerve IX – glossopharyngeal nerve

18

Nerve that carries impulses from taste buds in the epiglottis and the lower pharynx

Cranial nerve X – vagus nerve

19

Taste impulse travel pathway

Cranial nerve VII, IX and X -> medulla oblongata -> thalamus -> gustatory cortex in the insula of the brain for
interpretation

20

Lobe that interprets olfactory information

Temporal lobe

21

Orbicularis oculi muscle and corrugators muscle

Under the eyebrow
Reflex responses

22

Lacrimal apparatus

Consists of the lacrimal gland and tear ducts

23

Lacrimal gland

Size and shape of an almond
Secretes lacrimal fluid (tears), which flows across the surface of the eye toward the nose
Tears drain through small openings called lacrimal puncta into the lacrimal sac and nasolacrimal duct
Nasolacrimal ducts eventually empty into the nasal cavity

24

Lacrimal fluid

Tears moisten, lubricate, and cleanse the surface of the eye
Contain lysozyme to destroy bacteria and prevent infection

25

Extrinsic eye muscles

Muscles within the orbit to anchor the eye in place

26

Superior rectus

Rolls the eye upward

27

Inferior rectus

Rolls the eye downward

28

Lateral rectus

Turns the eye outward

29

Medial rectus

Turns the eye inward

30

Superior oblique

Rotates the eye medially

31

Inferior oblique

Rotates the eye laterally

32

Three layers of the eye

Fibrous layer
Vascular layer
Inner (nervous) layer

33

Fibrous layer of the eye

Outermost layer
Consists of the sclera and the cornea

34

Cornea

The “window of the eye”
Transparent
Helps focus light rays entering the eye

35

Vascular layer of the eye

Middle, thin layer
Consists of the choroid, ciliary body, and iris

36

Choroid

Highly vascular, brown pigmented layer located between the sclera and the retina in the posterior portion of the eye
Pigment absorbs excess light rays that might interfere with vision

37

Ciliary body

Ciliary processes within the ciliary body that secrete aqueous humor
Ciliary muscles change the shape of the lens

38

Inner (nervous) layer of the eye

Also called the retina
Found only in the posterior portion of the eye
Light-sensitive layer consisting of sensory receptive cells called rods and cones

39

Rods

120 million in each retina
Function in dim light
Do not detect fine detail or color
Detect motion

40

Cones

6.5 million in each retina
Function in bright light
Detect fine detail
Responsible for color vision

41

Aqueous humor

Located in front of the lens in the anterior chamber (cavity)
Continually produced by the ciliary body
Also drains continually through the canals of Schlemm
Maintains intraocular pressure, thus helping the anterior portion of the eye hold its spherical shape
Provides nourishment for the cornea

42

Vitreous humour

Located behind the lens in the posterior chamber (cavity)
Formed during the embryonic stage and lasts a lifetime
Supports the eyeball
Pushes the retina against the choroid layer, ensuring that the retina receives a good supply of blood

43

Light pathway

Cornea, aqueous humor, lens, vitreous humour, retina, neurons, optic disk, optic nerve, optic chiasma, occipital lobe

44

Hyperopia

Farsightedness (the inability to focus on nearby objects)
Light rays focus behind the retina
Usually caused by an eyeball that is too short

45

Myopia

Nearsightedness (inability to focus on distant objects)
Light rays focus in front of the retina
Usually caused by an eyeball that is too long

46

Glaucoma

Caused by intraocular pressure when the drainage of aqueous humor has been blocked
The damage may eventually lead to blindness

47

Outer ear

Pinna (auricle) and auditory canal
Secretes cerumen (earwax), which is produced by the
ceruminous glands (modified sweat glands)
Cerumen guards the ear against the entrance of foreign materials

48

Pinna

Cartilaginous flap
Leads into the external auditory canal and ends at the tympanic membrane (eardrum)

49

Auditory canal

Filled with air and lined with fine hairs

50

Middle ear

Small air-filled chamber that contains the tympanic membrane, ossicles, and the phyaryngotympanic tube (formerly called Eustachian tube)

51

Tympanic membrane

Composed of connective tissue, nerve tissue, and blood vessels
Separates the outer ear from the middle ear

52

Ossicles

Three small bones called the malleus, incus, and stapes

53

Malleus

Hammer

54

Incus

Anvil

55

Stapes

Stirrup

56

Pharyngotympanic tube

Auditory tube
Connects the middle ear to the pharynx (throat)
Equalizes the pressure on both sides of the tympanic membrane by permitting air to pass (by swallowing or yawning) from the throat into the middle ear

57

Inner ear

Also called the labyrinth
Intricate system of passageways hollowed out of the temporal bone
Bony labyrinth, which contains a fluid called perilymph
Membranous labyrinth, which contains a fluid called endolymph

58

Cochlea

Hearing
Shaped like a snail
Contains the receptors (“hair” cells that look like cilia) for hearing in the organ of Corti, which transmit sound waves to the brain for interpretation via the auditory nerve

59

Vestibule

Means cavity or space
Between the semicircular canals and the cochlea
Balance (equilibrium)
Contains the utricle and saccule

60

Utricle and saccule

Membranous sacs that contain hair cells that are moved by gravity as the position of the head changes
Monitors static equilibrium
Responds to linear or vertical acceleration

61

Semicircular canals

Consist of three oval-shaped canals that contain receptors that detect motion
Balance (equilibrium)
Contain hair cells (receptors)
Monitors dynamic equilibrium
Responds to rotation or angular movements