key terms unit 2 Flashcards
endocrine gland
Endocrine glands are glands of the Endocrine system that secrete hormones directly into the bloodstream to a target gland or organ.
Examples: adrenal gland, pancreas, thyroid gland, hypothalamus, pituitary gland
exocrine gland
Exocrine glands are glands that secrete substances onto the surface.
Examples: sweat, salivary, mammary
peptide hormone
Peptide hormones are hormones that bind to the receptors on the surface of the cell because they are lipophobic(fat-hating)
Examples: Insulin, Glucagon, Oxytocin
steroid hormone
Steroid hormones are hormones that bind to the receptor inside the cell(nucleus or cytoplasm) because they are lipophilic(fat-loving).
Examples: Estrogen and Testosterone
cornea
A tough, clear covering over the iris and the pupil that helps protect the eye. Light bends as it passes through the cornea. This is the first step in making an image on the retina. The cornea begins bending light to make an image; the lens finishes the job.
pupil
The pupil is the dark circle in the center of your iris. It’s a hole that lets light into the inner eye. Your pupil is round, a cows pupil is oval.
aqueous humor
A clear fluid that helps the cornea keep its rounded shape.
iris
A muscle that controls how much light enters the eye. It is suspended between the cornea and the lens. Human iris’ comes in many colors.
lens
A clear, flexible structure that makes an image on the eye’s retina. The lens is flexible so that it can change shape, focusing on objects that are far away.
retina
The layer of light-sensitive cells at the back of the eye. The retina detects images focused by the cornea and the lens. The retina is connected to the brain by the optic nerve.
vitreous humor
The thick, clear jelly that helps give the eyeball its shape.
sclera
The thick, tough, white outer covering of the eyeball.
blind spot
The place where the optic nerve leaves the retina. Each eye has a blind spot where there are no light-sensitive cells.
optic nerve
The bundle of nerve fibers that carry information from the retina to the brain.
tapetum
The colorful, shiny material located behind the retina. Found in animals with good night vision, the tapetum reflects light back through the retina.
accommodation
Accommodation is the combination of reflex actions by which the lens of the eye changes to keep the distance between the center of the lens and its focal point, constant. Ciliary muscles in the eye assist adjustment of the lens.
afterimages
Afterimages are optical illusions that occur when looking away after staring at intently at a fixed image or color. The constant light stimulating the retina causes the cones in that area to become fatigued, and after looking away from the image, the less-stimulated cones, which are not fatigued still function.
astigmatism
Astigmatism is a condition in which the cornea of the lens is irregularly shaped. This shape change causes incoming light rays to converge improperly. The light rays do not focus at the specific point on the retina and can cause blurry or distorted images.
color vision
Color vision is possible because of the retina, which contains two types of photoreceptors - rods and cones. Impulses from the rods and cones pass through the nerve cells to the optic nerve.
cones
Cones are a type of photoreceptor that function in bright light and provide sharp, colorful images. There are three cones(blue, red, and green) which combine to see other colors as well. If one cone malfunctions, color blindness can occur.
depth perception
Depth perception is the ability to judge the relative distances between objects in three dimensions.
optical illusions
Optical Illusions are visual tricks that take place in the brain rather than the eye. The visual cortex of the brain decipher images sent from the eye, but surrounding objects cause the mind to interpret the image differently.
peripheral vision
Peripheral Vision is the ability to see things that fall outside of our direct line of vision. This vision is better for detecting movement than for processing sharp images and is most strong in the dark.
rods
Rods are one of our photoreceptors and function in dim light to see shades of gray.
growth hormone
The growth hormone is secreted by the pituitary gland, targets the liver and other tissues causing growth of bone, liver, or fat.
oxytocin
Oxytocin is secreted by the pituitary gland, targets the breasts, uterus, and mammary gland causing contractions and helping male reproduction.
adrenaline
Adrenaline is secreted by the adrenal glands, targets the heart causing a faster heartbeat, an increase in blood flow to the brain and muscles while helping the body to react quickly.
MSH
MSH is secreted by the pituitary gland and causes skin darkening.
FSH
FSH is secreted b the pituitary gland, targets the testes/ovaries causing pubertal maturation, regulates development, growth and reproductive processes.
LH
LH is secreted by the pituitary gland, targets the gonads causing control of the testes/ovaries.
ACTH
ACTH is secreted by the pituitary gland, targets the adrenal cortex causing regulation of the steroid hormone, cortisol.
TSH
TSH is secreted by the pituitary gland, targets the thyroid gland causing stimulation of the metabolism of tissues.
myopia
- nearsightedness
- eyeball is too long
- image lands in front of the retina
- divergent lens(concave)
hyperopia
- farsightedness
- eyeball is too short
- image lands beyond the retina
- convergent lens(convex)
