human anatomy exam 4

sensation

conscious awareness of the stimuli

transduction

converting stimuli to impulses

perception

brain assigning meaning

sensory receptors

sensory nerve endings that respond to stimuli

(general & special senses)

general senses

temperature, pain, touch, pressure, vibration, proprioception

special senses

gustation, olfaction, vision, equilibrium, and hearing

chemoreceptors

detect specific molecules dissolved in fluid

ex: taste & smell

thermoreceptors

detect changes in temperature

photoreceptors

detect changes in intensity, color, and position of light

mechanoreceptors

detect touch, pressure, vibration, and stretch

baroreceptors: detect pressure changes within body structures

nociceptors

detect painful stimuli

phantom pain

sensation associated with a part of the body that has been removed

ex: amputee

referred pain

pain that is felt in a location other than where the pain originates

gustation

sense of taste

gustatory cells

sensory receptors within a taste bud; detect tastants (molecules & ions) in food

**chemoreceptors

papillae

taste buds, bumps on tongue

5 taste sensations

sweet, sour, salty, bitter, umami

olfaction

sense of smell

odorants

dissolved in mucus of nasal cavity and detected

olfactory epithelium

lines superior nasal cavity

scent pathway?

olfactory receptors --> olfactory nerve --> olfactory bulb --> olfactory tract --> temporal lobe

taste pathway?

chemoreceptors (taste buds) --> facial nerve/glossopharyngeal nerve --> insula (gustatory cells

structure of taste buds

Gustatory cells are the receptors

- Have gustatory hairs (long microvilli)

- Hairs are stimulated by chemicals dissolved in saliva

extrinsic muscles of eye

Movement of each eye is controlled by 6 extrinsic eye muscles, skeletal muscle, attach to sclera and controlled by cranial nerves III, IV and VI. (oculomotor, trochlear, abducens)

eyelids

protect eyes

medial canthus

inner corner of eye

lateral canthus

outer corner of eye

lacrimal caruncle

fleshy elevation at the medial commissure; produces a whitish oily secretion

conjunctiva

lining of the eyelids and over the anterior surface of eye

does not cover cornea

pink eye

inflammation of the conjunctiva

lacrimal apparatus

the structures that produce, store, and remove tears

lacrimal fluid

tears

lacrimal gland

gland located in the upper outer region above the eyeball that secretes tears & spreads tears to eyes

lacrimal canaliculi

drain lacrimal fluid from eyes medially

lacrimal sac

structure that collects tears before emptying into the nasolacrimal duct

nasolacrimal duct

passageway for tears from the lacrimal sac into the nose

aqueous humor

fluid in the eye, found between the cornea and the lens

vitreous humor

jellylike substance found behind the lens in the posterior cavity of the eye that maintains its shape

3 eye wall layers

fibrous tunic, vascular tunic, retina

glaucoma

increased pressure in eye; too much aqueous humor

fibrous tunic in the eye is composed of:

sclera- white of the eye

cornea- clear, anterior portion most superficial

vascular tunic is composed of:

choroid- contains network of capillaries to retina

ciliary body- changes lens shape

iris- controls amount of light entering eye

the iris

Colored part of the eye; contains schincter pupillae (makes pupil smaller) & dilator pupillae (makes pupil bigger)

retina

Light sensitive layer of the eye; contains rods and cones

converts energy into nerve impulses

3 layers of the neural layer

photoreceptor cell layer, bipolar cell layer, ganglion cell layer

_____

photoreceptor cell layer= outermost; rods & cones

bipolar cell layer= synapse w/ photoreceptors & ganglion cells

ganglion cells= innermost layer of retina; leave retina & form the optic nerve (CN II)

rods vs cones

rods - 120 million, on the periphery, sense dark and light only, have rhodopsin and a high recovery time

cones - 6 million, in the fovea, sense color, 3 kinds (RGB), trichromatic theory, less numerous, lower recovery time

optic disc

blind spot on the retina lacking photoreceptors

fovea centralis

tiny pit or depression in the retina that is the region of clearest vision; highest proportion of cones, almost no rods

macula lutea

a yellowish central area of the retina that is rich in cones and that mediates clear detailed vision

optic nerve leaves back of eye; no photoreceptors here

lens

Focuses light onto retina

accommodation- ability of lens to change shape

accommodation

ability of lens to change shape to focus an image

optic chiasm

point at which optic nerve fibers cross in the brain

optic tracts

extend laterally, posteriorly from chiasm

optic radiation

extends from thalamus to occipital lob

visual acuity

the ability to see fine detail

20/20 vision normal

20/<20 vision better than normal

20/>20 vision worse than normal

myopia

nearsightedness; eye too long, cant see objects far away

treatment= shaving eye

hyperopia

farsightedness; eye too short, cant see objects close

treatment= thicker lens

astigmatism

defective curvature of the cornea or lens of the eye; light scatters

treatment= lens

emmetropia

normal vision

presbyopia

age related farsightedness; loses ability to accommodate

cataracts

clouding of the lens

diabetic retinopathy

small unstable blood vessels develop inside the eye that ruptures and creates blind spots

strabismus

misalignment of the eyes due to one set of extrinsic muscles being stronger than the other

external ear

outer structures of the ear that collect sound

auricle, external acoustic meatus, tympanic membrane

cerumen

ear wax

middle ear

auditory tube & auditory ossicles (malleus, incus, stapes)

inner ear

contains cochlea, semicircular canals, and vestibular sacs

equilibrium

awareness of head position

linear acceleration

change in velocity in a straight line

utricle & saccule

detect linear acceleration and the effects of gravity

semicircular ducts

Detect rotational movements of the head.

static equilibrium

the perception of the orientation of the head when the body is stationary

maculae

sensory receptors for static equilibrium (within utricle & saccule)

contain hair cells

otoliths

small crystals in the fluid-filled vestibular sacs of the inner ear that, when shifted by gravity, stimulate nerve cells that inform the brain of the position of the head

cochlea

converts vibrations into nerve signals (hearing)

cochlear duct

filled with endolymph

scala vestiboli & scala tympani

filled with perilymph; two chambers on either side of the cochlea duct

spiral organ/ organ of corti

receptor for hearing located within the cochlea; the organ of hearing

Path of light through the eye to the retina

Cornea → Aqueous humor → Lens → Vitreous humor → Retina

Path of visual impulses to the brain

Cornea → Aqueous humor → Lens → Vitreous humor → Retina → Transduction → Optic Nerve → Optic Chiasm → Optic Tracts → Optic radiation → Occipital lobe

auricle

external ear; collects sound waves

external auditory canal

channels sound to eardrum

tympanic membrane (eardrum)

vibrates in response to sound waves

Ossicles (malleus, incus, stapes)

three small bones that amplify sound waves (vibrations)

Eustachian tube

A narrow tube between the middle ear and the throat that serves to equalize pressure on both sides of the eardrum

Path of nerve impulses in hearing

Spiral organ (Organ of Corti in cochlea) → Cochlear nerve (branch of CN VIII) → Brainstem (cochlear nuclei) → Thalamus → Auditory cortex (temporal lobe)

pathway a tear follows

lacrimal glands → lacrimal canaliculi → Lacrimal sac → nasolacrimal duct

Loudness depends on _______ of vibration

amplitude

Louder sound sources cause tympanic membrane to vibrate ____

more

tinnitis

ringing in the ears

conductive hearing loss

hearing impairment caused by interference with sound or vibratory energy in the external canal, middle ear, or ossicles

otitis

inflammation of the ear

hormone

Chemical messengers, mostly those manufactured by the endocrine glands, that are produced in one tissue and affect another

endocrine gland

a ductless gland that secretes hormones directly into the bloodstream

target cell

cell that has a receptor for a particular hormone

Negative feedback loop in hormone secretion

levels too high= turn down secretion

return to set point

positive feedback loop in hormonal secretion

pushes the process further & stronger

compare & contrast how the nervous system and endocrine system control body function

Both: regulate body functions + maintain homeostasis

Nervous system: electrical impulses + neurotransmitters, very fast (milliseconds), short-term, precise/localized effects (nerves → muscles/glands)

Endocrine system: hormones released into bloodstream, slower (seconds-hours), long-lasting, widespread effects (target cells with receptors)

major control center of endocrine system?

hypothalamus

pituitary gland

divides into anterior & posterior lobes; also known as hypophysis