unit 3 test

what is conjunctiva made up of?

thin, protective mucus membrane made up of nonkeratinized stratified squamous epithelium with goblet cells

what is at the base of hair follicles of the eyelashes?

sebaceous glands

what do sebaceous ciliary glands do?

lubricate hair follicles

what does an infection of sebaceous ciliary gland cause?

sty

what are the muscles that move the eye?

superior rectus, inferior rectus, lateral rectus, medial rectus, superior oblique, inferior oblique

explain the flow of tears

lacrimal gland (secretes tears into..) --> excretory lacrimal ducts (distribute tears over surface of eyeball) --> superior or inferior lacrimal canaliculi (drains tears into..) --> lacrimal sac (drains tears into..) --> nasolacrimal duct (drains tears into..) --> nasal cavity

where is the cornea located and what is its function? (1)

a transparent coat that covers the iris, initial segment where light bends

what is known as the "white" of the eye?

sclera

what is the choroid? where is it found?

highly vascularized, posterior portion of vascular layer between sclera and retina

what is the ciliary body? where is it found?

anterior portion of vascular layer that's found behind the iris and under the lens

what is the iris?

colored portion of the eye that regulates the size of the pupil

what does the pupil do?

regulates the amount of light entering the eye

where is the lens located and what does it contain?

behind the iris and contains protein crystallin

what does the anterior segment contain?

aqueous humor

what does the posterior segment contain?

vitreous humor

what do rods allow us to do?

allow us to see dim light, dim light is shades of black, white, and grays

what does loss of rod vision cause?

night vision

what do cones do? what stimulates them?

produce color vision, brighter light stimulates them

what does cone loss cause?

can produce color blindness

what are cataracts?

loss of transparency of the lens causing blindness, the lens becomes cloudy due to changes in the structure of the lens proteins

what is the fovea centralis and where is it located? what does it contain?

small depression in the center of macula where visual acuity is the highest, only contains cones

what happens during constriction of the pupil?

narrowing of diameter of the hole through which light enters the eye due to contraction of the circular muscles of the iris

how do people with myopia see?

can see close objects but not far objects (nearsightedness)

how do people with hyperopia see?

can see far objects but not close ones (farsightedness or hypermetropia)

what is the term for a normal eye?

emmetropic eye

insert pic

1. outer segments 2. inner segments 3. pigmented layer of retina 4. rod 5. cone 6. synaptic terminals 7. horizontal cell 8. bipolar cell 9. amacrine cell 10. ganglion cell 11. optic (2) nerve axons 12. retinal blood vessels 13. photoreceptor cell layer 14. outer synaptic layer 15. bipolar cell layer 16. inner synaptic layer 17. ganglion cell layer

which part of the body has the largest amount of sensory receptors?

the eye

what are the 3 layers of retinal neurons?

photoreceptor cell layer, bipolar cell layer, ganglion cell layer

what does the photoreceptor layer contain?

rods and cones

what does the bipolar cell layer contain?

bipolar neurons, amacrine cells, horizontal cells

what does the ganglion cell layer contain?

axons that come together to form the optic nerve

where does visual processing occur?

occipital lobes

what is the only sense not fully developed at birth?

sight

when do the eyes begin to develop?

22 days after fertilization

what is binocular vision and what does it allow?

when both eyes focus on only one set of objects, allows for the perception of depth and 3D objects

what happens during convergence?

2 eyeballs move medially so that both are directed toward the object being viewed (crossing eyes)

what happens during phototransduction?

series of steps that turns rods off when in light

where is the olfactory epithelium located?

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

how many types of lingual papillae contain taste buds?

3

what are vallate papillae? how many taste buds per papillae are there?

12 very large, circular vallate papillae that form an inverted V-shaped row at back of tongue, 100-300 taste buds per papillae

what are fungiform papillae? how many taste buds per papillae?

mushroom shaped elevations over entire surface of tongue that have 5 taste buds per papillae

what are foliate papillae? what happens to their taste buds during early childhood?

located in small trenches on lateral margins of tongue, most taste buds degenerate in early childhood

where are filiform papillae located and how do they differ from other papillae?

on entire tongue, they contain receptors but no taste buds

besides the tongue, where else can taste buds be found?

soft palate, pharynx, epiglottis

what is the formal term for the eardrum? and what is its function?

tympanic membrane, a thin, semi transparent partition between external acoustic meatus and middle ear, it vibrates as sound waves enter ear

what does dynamic equilibrium deal with? what is it monitored by?

balance, monitored by semicircular canals

in dynamic equilibrium, the rate of forward reaction is ___ the rate of reverse reaction.

equal to

what is the vestibule?

oval central portion of the bony labyrinth between the cochlea and semicircular canals

what does the auditory tube connect?

connects the tympanic cavity with the nasopharynx (superior portion of throat)

what are otoliths?

calcium carbonate crystals that cover entire surface of the otolithic membrane

where is the cochlea located and what does it contain?

bony spiral canal like snails shell that's anterior to vestibule, contains hearing receptors

what is the cochlear duct?

continuation of the membranous labyrinth into the cochlea that is filled with endolymph

where does the scala vestibuli end?

at the vestibular window (oval window)

where does the scala tympani located and where does it end?

under the scala vestibuli and ends at round window, part of bony labyrinth of cochlea and filled with perilymph

what causes motion sickness?

conflict among the senses with regard to motion

ex: vestibular apparatus senses angular and vertical motion while eyes and proprioceptors in muscles and joints determine the position of the body in space

gustatory microvilli (gustatory hairs) project from each...

gustatory epithelial cell to the external surface though the taste pore - receptor for taste

what are sound waves?

alternating high and low pressure regions traveling in same direction through some medium like air

what makes a sound louder?

a larger intensity (size or amplitude) of the vibration

what do ceruminous glands secrete?

earwax or cerumen that protects ear from foreign invaders or objects

name the accessory structures of the eye

eyelids, eyelashes, eyebrows, lacrimal apparatus (tear producing), extraocular muscles

what does the somatic nervous system house?

efferent neurons that go to skeletal muscle

what does the autonomic nervous system deal with?

output from CNS that goes to involuntary tissues

what does the enteric nervous system contain?

neurons that go to gastrointestinal tract

parasympathetic nervous system

rest-and-digest

sympathetic nervous system

fight-or-flight

what tissues are made up of excitable cells?

nervous and muscle tissues

what is the cell body surrounded by?

cytoplasm that includes typical cellular organelles, free ribosomes, etc.

where are nissl bodies located and what are they?

in cell body and dendrites, clusters of rough ER that makes proteins

where are microtubules found and what are their function?

axon and dendrites, assist in moving material between the cell body and axon

what are somatic spines?

bumps caused by small projections of plasma membrane which are receptor sites that bind chemical messengers with other neurons

ganglion are a collection of what outside the CNS?

cell bodies

where ganglion located?

PNS

nerve fiber (axon)

neural processes (extensions) that start from the cell body of a neuron

the most common type of neuron with several dendrites and one axon is a...

multipolar neuron

neuron with one main dendrite and one axon that can be found in retina, nasal cavity and inner ear is a...

bipolar neuron

neuron that has dendrites and one axon that is fused together to form a continuous process that emerges from cell body (aka unipolar neuron) is a...

pseudounipolar neuron

purkinje cells are found where? what do they participate in?

cerebellum and participate in motor control and learning

what are the cells found in the cerebral cortex of brain and have pyramid shaped cell bodies?

pyramidal cells

what is white matter primarily made up of?

myelinated axons

what does gray matter contain? what gives it its gray color?

neuronal cell bodies, dendrites, axon terminals, and neuroglia, unmyelinated axons gives it its gray color.

what are the 3 methods of removal of neurotransmitters?

diffusion, enzymatic degradation, and uptake by cells

explain diffusion of neurotransmitters

neurotransmitters diffuse away from synaptic cleft. once out of reach of its receptors it can no longer exert an effect

explain enzymatic degradation of neurotransmitters

some neurotransmitters are inactivated through enzymatic breakdown

explain uptake by cells in removal of neurotransmitters

many neurotransmitters are actively transported back into the neuron that released them (reuptake), others are transported into neighboring neuroglia (uptake)

how does a simple series circuit work?

presynaptic neuron stimulates a single postsynaptic neuron, the neuron then stimulates another and so on

what is divergence?

one presynaptic neuron synapses on several postsynaptic neurons at same time

explain how a diverging circuit works

the nerve impulse from a single presynaptic neuron stimulates increasing number of cells along the circuit

what is convergence?

several presynaptic neurons synapse with a single postsynaptic neuron

explain a converging circuit

the postsynaptic neuron receives nerve impulses from several different sources

what is plasticity and how does the work?

the capability to change based on experience, the changes that can occur include sprouting of new dendrites, synthesis of new proteins, and changes in synaptic contacts with other neurons

when does chromatolysis occur?

24-48 hrs after injury to a process of normal peripheral neuron, nissl bodies break up into fine granular masses

what is the pattern of a leak channel?

randomly alternate between open and closed positions

there are more __+ ion leak channels than __+ leak channels, they are also leaker than __+

K; Na; Na

the membrane has higher permeability to __+ than to __+

K; Na

when do ligand-gated channels open and close?

in response to the binding of a ligand (chemical) stimulus like NT's, hormones, and certain ions

what causes mechanically gated channels to open and close?

mechanical stimulation in the form of vibration, touch, pressure, or tissue stretching. the force distorts the channel from its resting position, opening the gate

this channel opens in response to change in membrane potential

voltage-gated channel that participate in generation and conduction of nerve impulses in the axon of neurons

astrocytes make contact with..

capillaries, neurons, and Pia matter

what forms the myelin sheath for the CNS?

oligodendrocytes

what forms the myelin sheath for PNS?

Schwann cells