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2 divisions of the PNS
1. Sensory (afferent)division 2. Motor (efferent) divsion
Sensory (afferent) division
Sensory neurons – carry impulses from all senses to the central nervous system
Motor (efferent) division
Transmits impulses from the central nervous system to effector organs
Senses controlled by mechanical stimuli
Hearing Touch
Senses controlled by chemical stimuli
Smell Taste
Senses controlled by electromagnetic stimuli
Vision
The three parts of the ear
outer, middle and inner ear
Parts of ear involved only with hearing
outer and middle ear
Part of ear the functions in both hearing and equilibrium
inner ear
Receptors for hearing and balance:
Respond to separate stimuli Are activated independently
Parts of the outer ear
The auricle (pinna) –visible ear External auditory canal
Middle Ear (Tympanic Cavity)
A small, air-filled, mucosa-lined cavity
What is the middle ear bordered by?
the eardrum, oval window, and round window
Tympanic membrane is also known as what?
eardrum
Tympanic membrane:
- Thin membrane that vibrates in response to sound - Transfers sound energy to the middle ear ossicles - Boundary between outer and middle ears
Ossicles
- malleus (hammer) - incus (anvil) - stapes (stirrup)
Components of middle ear
-Tympanic membrane (eardrum) -Ossicles -Eustachian tube
Eustachian tube connects what?
the middle ear to the nasopharynx
Eustachian tube functtion
Equalizes pressure in the middle ear cavity with the external air pressure
Primary structure of the inner ear
Cochlea
Sound vibrations beat against what part of the ear?
eardrum
The _______ pushes against the ossicles, malleus, incus, and stapes, which presses fluid in the _______ against the oval and round windows
eardrum; inner ear The fluid movement moves the hair cells Moving hair cells stimulates the cochlear nerve that sends impulses to the brain
measure of sound energy
Decibels
Any sound above ___ decibels (db) may cause some hearing loss if the exposure is prolonged
90
But most portable music players can produce sounds up to ___ db.
130
What constricts the flow of blood to the hair cells of the auditory system?
smoking
What provides sense of balance?
semicircular canal
Anatomy of Maculae
Maculae respond to tilting the head forward-backward and side-to-side
Anatomy of Cristae
Cristae respond to rotational or dynamic movement
Sense organ for the sense of touch
skin
three major regions or layers of the skin
Epidermis Dermis Hypodermis
Epidermis
outermost superficial region
Dermis
middle region
Hypodermis
deepest region
Function of Epidermis
-Waterproofing -Protection from abrasion and penetration
Epidermis Characteristics
Consists of four or five layers Deepest epidermal layer firmly attached to the dermis Outermost layer of keratinized cells
What accounts for approximately 80% of the thickness of the skin?
Dermis
Collagen fibers does what?
adds strength and resiliency to the skin
Elastin fibers deos what?
provide stretch-recoil properties
Hypodermis characteristics
Subcutaneous layer deep in the skin Composed of adipose and areolar connective tissue
Three pigments contribute to skin color
Melanin Carotene Hemoglobin
Melanin
yellow to reddish-brown to black pigment, responsible for dark skin colors
Carotene
yellow to orange pigment, most obvious in the palms and soles of the feet
Hemoglobin
reddish pigment responsible for the pinkish hue of the skin
Sensitivity of the skin determined by:
- Types of sensory neurons in a particular area - Numbers of sensory neurons in the area
(T or F)Stimulated neurons always send message to the same part of the brain
True
The organ of smell is the ______ ________
olfactory epithelium
What are Olfactory receptor cells called?
rods
Humans able to detect up to ______ different odors
10,000
Impulses are sent to
olfactory cortex, limbic system and hypothalamus
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