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nervous system

detects and interprets information from the surrounding environment, controls most body function

endocrine system

controls body functions through the use of chemical messengers called hormones

circulatory system

brings needed materials to the cells and carriers away waste materials

lymphatic system

recaptures and filters fluid from the tissues and returns it to the blood stream

respiratory system

takes oxygen into the body and releases carbon dioxide

digestive system

takes food into the body, breaks it down, and absorbs the nutrients from the food

urinary system

removes wastes from the blood

skeletal system

supports the body, protects it, and allows movement

muscular system

makes it possible for the body to move


protects the body and helps regulate body temperature

reproductive system

produces the cells necessary to produce offspring


nerve cells


neuron cell body


anything that sticks off something else


a neuron has several of these to receive messages


a neuron transmits an impulse down this

dendrite to cell body to axon

the direction in which an impulse travels through a neuron


when a neuron is resting, the inside of the neuron is negatively charged compared to outside the neuron

resting membrane potential

-70mV in most cells, a polarized cell maintains this when not transmitting

sodium-potassium pump

this uses a molecule of ATP to move three Na+ out of the cell and two K+ into the cell

leak channels

allow potassium to leak outside the cell to lower the charge inside the cell

voltage-gated channels

channels that open when the cell reaches a charge higher than its resting membrane potential, usually around -50mV

threshold potential

the voltage a cell must reach to fire an impulse


true or false: potassium voltage-gated channels open before sodium voltage-gated channels

action potential

from -70mV to -50mV to +35mV to -90mV to -70mV


the membrane potential moves in the positive direction


the membrane potential returns to its resting value

Schwann cells

special cells that wrap the axon to increase transmission speed

myelin sheath

this increases the speed at which an impulse can travel down the axon

nodes of ranvier

the gaps between Schwann cells

saltatory conduction

jumping conduction over the myelin sheath

refractory period

the amount of time in which a neuron is unable to fire another action potential which keeps the impulse from travelling in two directions


a neuron-to-neuron or neuron-to-organ junction


special chemicals which pass an impulse from one impulse to another


a neurotransmitter that, among its functions, triggers muscle contraction

synaptic cleft

the space between the axon of the first neuron and the dendrites of the second neuron


when a cell depolarizes toward the threshold


when a neuron moves away from threshold


the combining of inhibitory and stimulatory inputs

central nervous system

the brain and spinal cord make up the

peripheral nervous system

the nervous system excluding the brain and spinal cord

sensory neurons

involved in sending information to the CNS from the sensory organs of the body

motor neurons

involved in sending information from the CNS to the organs of the body


are completely within the brain and spinal cord, and often connect sensory and motor neurons

spinal cord

part of the nervous system involved in primitive, reflex actions


our conscious mind, where voluntary actions occur, such as movement, speech, and problem solving, where we have conscious awareness of sensations


part of the brain which coordinates muscle movement and balance


part of the brain in which involuntary acts originate, such as breathing and blood pressure regulation, and is a primitive area


this part of the body maintains homeostasis by monitoring hormone levels, electrolyte balance, temperature, etc.

somatic nervous system

the voluntary system of the PNS which controls skeletal muscles

autonomic nervous system

the involuntary system of the PNS which controls vital organs

sympathetic division

this part of the ANS helps prepare the body for stress by increasing heartbeat, blood pressure, etc. the neurotransmitter used is norepinephrine.

parasympathetic division

this part of the ANS is most active when you are at rest, and moves blood to the digestive organs, decreases heartbeat, and uses acetylcholine


chemicals made by glands, secreted into the blood, and has slow effects on targetted organs

peptide hormones

long distance messengers made of amino acids which must bind to receptors outside the cell, cause effects rapidly by turning enzymes in the cell on or off, and include insulin, prolactin, and glucagon

steroid hormones

long distance messengers made from cholesterol which can easily cross cell membranes and bind to receptors inside the cell, they are more slow, and cause their effects by binding to DNA and changing which genes are transcribed

pituitary gland

the master gland which is controlled by the hypothalamus and is divided into anterior and posterior

growth, thyroid stimulating, adrenocorticotropic, follicle stimulating, luteinizing, prolactin

six hormones that the anterior pituitary gland makes and secretes

growth hormone

targets all tissues and organs and causes them to grow, important in children, but stimulates cell-turnover rate in adults

thyroid stimulating hormone

causes the thyroid to secrete thyroid hormones

adrenocorticotropic hormone

stimulates the outer layer of the adrenal gland to secrete hormones

follicle stimulating hormone

targets the gonads: causes maturation of ova and release of ova and causes testes to make sperm

luteinizing hormone

targets the gonads, causing the ovaries to develop a corpus luteum and the testes to make testosterone


is released only after childbirth and stimulates the mammary glands to make breast milk

oxytocin, antidiuretic

two hormones secreted by the posterior pituitary gland


this hormone causes the uterus to contract during childbirth and causes the mammary glands to release milk

antidiuretic hormone

causes the kidneys to retain water, and is also known as vasopressin

thyroxine, calcitonin

two hormones secreted by the thyroid


this hormone affects body cell's by increasing their rate of metabolism, meaning they work harder and use more energy


activates special cells in bone that remove calcium from the blood and use it to build new bone. it reduces blood calcium levels.

parathyroid hormone

activates special cells in bone to dissolve the bone to release calcium into the blood

epinephrine, norepinephrine

two hormones secreted by the adrenal medulla that increase and prolong the effects of the sympathetic nervous system

glucocorticoids, mineralocorticoids, sex steroids

three types of steroids secreted by the adrenal cortex


steroid hormone that causes the liver to produce glucose from fats and to release the glucose into the blood, which is known as gluconeogenesis (cortisol)


this hormone-type is primarily aldosterone, which causes the kidney to retain sodium, which removes sodium from the urine and return it to the body


organ which secretes hormones and digestive enzymes

insulin, glucagon

two hormones secreted by the pancreas


this hormone is secreted when blood glucose levels are high, such as after a meal, by allowing cells to take glucose out of the body


this hormone is released when blood glucose is low, and causes the liver to break down glycogen and release free glucose into the blood


the male and female primary sex organs: testis and ovary

androgens, testosterone

male sex steroids produced by the testes, which develop male secondary sex characteristics during puberty and maintain them in adulthood

estrogens, progesterone, estradiol

three hormones produced by the ovaries, which are responsible for developing female secondary sex characteristics during puberty and maintaining them in adulthood


hormone which stimulates the growth of the uterine lining in the first half of the menstrual cycle


hormone which enhances and maintains the lining of the uterine during the second half of the menstrual cycle

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