Final Exam Terms (Part 2)

Chapters 8, 12, and 13

receptor cells

specialized cells that convert input into a signal (release of a neurotransmitter)

photoreceptor cells

vision; capture photons and generate a chemical or electrical signal (rods and cones)

mechanoreceptors

audition and balance receptors

chemoreceptors

olfaction and gustation receptors

receptor potentials

graded potentials for specialized sense that must be strong enough to trigger an action potential

sensory coding

the signal received by receptor cells must be transduced to a signal that can be relayed and understood by the brain, allowing CNS to determine duration, intensity, and precise location of that stimulus

action potential frequency

the number of action potentials fired per unit time; determines coding

sensory adaptation

ability of a sensory receptor to become less sensitive in the continued presence of a stimulus

fibrous tunic

strong, outermost layer of the eye (cornea and sclera)

vascular tunic (uvea)

medial layer of the eye containing the choroid, ciliary body and arteries, and iris

nervous tunic

innermost layer of the eye containing nerve cells (retinal layer)

first task of the eye

capture and focus light; done by cornea, pupil, lens, and iris (fibrous and vascular tunics)

second task of the eye

turn signal into one that can be relayed to and understood by the brain; done by retina and optic nerve (nervous tunic)

accessory structures

do not play direct role in vision, but protect eye and provide necessary functions to facilitate vision

list of accessory structures

eyebrows, eyelashes, eyelid, conjunctiva, lacrimal apparatus, and tear duct

lacrimal gland

produces tears

lacrimal puncta

drains tears into the nose

dilator and sphincter papillae

intrinsic muscles of the eye that cause the pupil to dilate or constrict

ciliary muscle

adjusts shape of lens to control focus (accommodation)

aqueous humor

anterior cavity of the eye filled with clear, watery fluid

vitreous humor

posterior cavity

lens

the transparent structure behind the pupil that changes shape to help focus images on the retina

glaucoma

increased intraocular pressure results in damage to the retina and optic nerve with loss of vision

focal point

the point at which rays parallel to the optical axis reflect and meet (convex lenses are useful for this)

fovea centralis

area consisting of a small depression in the retina containing the most cones and where vision is most acute

RPE cells

retinal pigment epithelial cells (closest to choroid); contain melanin to trap light and recycle Vitamin A

horizontal cells

between photoreceptors and bipolar cells

bipolar cells

between the horizontal and amacrine cells; receive information from the retinal cells and distribute information to the ganglion cells

amacrine cells

between bipolar and ganglion cells; contact bipolar and ganglion cells

ganglion cells

closest to vitreous humor; axons form optic nerve and lead to the brain

photosensitive ganglion cells

respond to light and are capable of adjusting iris size and circadian rhythms, even in retinas without rods and cones

outer segments

region on photoreceptor cells that can capture light and initiate a second messenger cascade that is transduced into an electrical signal

diabetic retinopathy

swelling, leaking, and loss of small blood vessels that supply the retina

outer segment of a rod

stacked, tightly packed disc-like organelles surrounded by plasma membrane; capture photons and contain protein opsin and chromophore 11-cis-retinal

outer segment of a cone

tightly packed invaginations of the plasma membrane; capture photons and contain protein opsin and chromophore 11-cis-retinal

rhodopsin

photopigment that absorbs light but cannot discriminate color

scotopic conditions

low light; best for rods

photopic conditions

bright light; best for cones

visual transduction

conversion of light to neural signals by visual receptors

CNG cation channels

cyclic nucleotide-gated cation channels; allows influx of Na+ and Ca2+ into the outer segment and efflux of K+ from inner segment, creating the circulating dark current

visual transduction cascade

molecular change within the cell when photons are captured; chromophore undergoes isomerization, transferring all-trans-retinal to rhodopsin

tunnel vision

arises from a pituitary tumor placing pressure on optic chiasm and generating visual defects

astigmatism

caused by a malformed cornea or lens that causes a refractive error

strabismus

caused by the lack of parallel light paths entering the eyes because of the misalignment of one or both eyes

color blindness

results from a lack or dysfunction of one of the three cone pigments

cataracts

caused by a clouding of the eye lens dur to alterations in the crystalline proteins in the eye

night blindness

occurs when rod cells cannot properly adapt to dark conditions, leaving a person blind; caused by Vitamin A deficiency

optic chiasm

where optic nerves from each eye meet at base of brain

two main goals of the ear

to detect soundwaves or changes in head position; to transform the stimulus into a form that is recognizable by the brain

external ear

visible portion of ear (auricle/pinna and external acoustic meatus/ear canal); accomplishes first task

tympanic membrane

eardrum; separates external and middle ear

auditory ossicles

3 small bones behind eardrum (malleus, incus, and stapes); amplify vibrations of tympanic membrane onto oval window

Eustachian tube

auditory tube; connects middle ear with nasopharynx and equalize pressure across the eardrum

semicircular canals

in the inner ear; important for balance

cochlea

contains hair cells; responds to sound vibrations

round window

allows fluid in cochlea to move/vibrate

membranes and ducts in the cochlea

scala vestibuli, cochlear duct, scala tympani, tectorial membrane, organ of Corti, and basilar membrane

frequency tuned

how the hair cells in the basilar membrane detect specific frequencies of sound

vestibular system

manages balance; in inner ear and consists of semicircular canals, utricle, and saccule

ITD

interaural time difference; detects difference in time between the arrival of the same sound to each ear; localization of sound

IID

interaural intensity difference; detects the difference in sound intensity at each ear; localization of sound

olfactory membrane

detects smell; has sensory receptors that are proteins that interact with volatile and foodborne chemicals

olfactory tract

olfactory nerve --> olfactory cortex --> limbic system

gustatory system

stimuli are detected by receptors found within the papillae on surface of the tongue; has sensory receptors that are proteins that interact with volatile and foodborne chemicals

gustatory tract

facial and glossopharyngeal nerves --> gustatory cortex

blood

liquid connective tissue consisting of plasma and formed elements

functions of blood

transport of blood gases, nutrients, ions, and hormones through vessels; buffering of pH, temp, and osmolarity; defense against pathogens and waste; and clotting of blood

plasma

mostly water, but contains ions, soluble and insoluble proteins, wastes, and some dissolved gases; blood without the cells

albumins

highly abundant plasma protein produced by the liver; regulate osmolarity and function as carrier molecules

globulins

second most abundant plasma proteins; produced by liver and immune system cells; function as carrier molecules. Immunoglobulin forms the structural basis of antibodies

formed elements

erythrocytes, leukocytes, and platelets; form buffy coat

erythrocytes

anucleate, biconcave discs that mature from myeloid stem cells in the bond marrow; as they mature, the produce increasing amounts of hemoglobin

hematocrit

the percent of the volume of whole blood that is composed of red blood cells as determined by separation of red blood cells from the plasma usually by centrifugation

erythropoiesis

formation of new RBCs; takes place in kidneys and is driven by hormone erythropoietin

hemoglobin

globular tetrameric protein consisting of 4 subunits, each containing a heme group with an ion molecule at its center

Bohr effect

O2 is more readily released upon CO2 binding to hemoglobin

Haldane effect

CO2 more readily binds to deoxygenated hemoglobin

leukocytes

white blood cells, fight infection; have organelles and nuclei

neutrophils

cytotoxic cells that release hydrolytic enzymes known as defensin; have multilobed nuclei

eosinophils

work primarily on non-bacterial pathogens and trigger inflammation; have bi-lobed nuclei

basophils

regulate inflammation and allergic responses; have bi-lobed nuclei

monocytes

macrophages that engulf foreign pathogens; have U-shaped nuclei

lymphocytes

either T-cells (cytotoxic) or B-cells (antibody producing); coordinate specific immune responses; have a single nucleus

leukopoiesis

formation of white blood cells; begins with hematopoietic stem cells in the bone marrow

myeloid stem cells

commits to a RBC fate by transforming into a proerythroblast, commits to platelet fate by forming megalokaryocyte that will shed platelets as it matures, OR commits to a WBC fate by transforming into a myeloblast

antigens

proteins within nucleated cells that can be recognized by the immune system

diapedesis/extravasation

leukocytes becoming thin and elongated to slip between adjacent endothelial cells

blood doping

injecting extra red blood cells before competition to improve performance

hemostasis

process of blood clotting

thrombocyte

platelet; fragments of a megakaryocyte that is found in the bone marrow

vascular spasm phase

when endothelial cells in the blood vessel become damaged and release tissue factors that activate platelets, and the vessels reflexively constrict

platelet phase

activation of platelets, which release signaling molecules that activate more platelets. The positive feedback loop allows activated platelets, which aggregate, to from a plug to stop blood loss

coagulation phase

reinforces the platelet plug by activating the enzyme thrombin; thrombin converts the soluble plasma protein fibrinogen into an insoluble form called fibrin, which binds together the platelet plug with other cells

clot retraction

platelets begin to contract in order to make the clot more compact and pull the edges of the wound closer together

thrombus

a blood clot formed in an undamaged vessel that can obstruct blood flow

plasmin

breaks down fibrin in a process known as fibrinolysis

heparin

can inhibit blood clot formation by initiating thrombin (anticoagulant process)

granulocytes

contain membrane-bound cytoplasmic granules that give the cytoplasm a spotted appearance; neutrophils, eosinophils, and basophils

agranulocytes

lack granules in the cytoplasm; lymphocytes and monocytes

blood type

determined by carbohydrate markers present on the plasma membrane of erythrocytes (antigens)