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Bio 106 Ch `4 and 6.3
The Nervous system and integumentary systems from Human Biology by Colleen Belk
50
Biology
Undergraduate 1
03/02/2011

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Term
Integumentary system
Definition
composed of the skin and accessory organs, protects the body from invasion by harmful pathogens, chemicals, and ultraviolet lights. Also prevents water loss from the body and helps regulate temperature.
Term
epidermis
Definition
outer, nonvascular layer of skin composed of stratified squamous epithelial cells
Term
melanocytes
Definition
specialized cells in the epidermis that produce melanin, which absorbs ultraviolet light and gives different humans different skin colors.
Term
dermis
Definition
located beneath the epidermis, composed of dense fibrous connective tissue. rich in collagen and elastin.
Term
nails
Definition
develop in pocketlike folds of the skin near the tips of fingers and toes, grow from the white, half-moon region of epithelial cells at the base of the nail.
Term
hairs
Definition
produced only by mammals, grows in length when new cells are produced by cell division of the epidermal cells that form the root of the hair. Hair cells produce keratin as they are pushed farther from the root.
Term
sebaceous glands
Definition
oil-producing glands that grow out from the epithelium that surrounds a hair. their secretions lubricate the hair and skin.
Term
sweat glands
Definition
present in all regions of the skin. help regulate body temperature, because sweat absorbs body heat.
Term
subcutaneous layer
Definition
also called hypodermis. composed of loose connective tisue and adipose tissue. thicker in women because they store more body fat than men.
Term
nervous system
Definition
receives and interprets the millions of signals received from the environment.
Term
neurons
Definition
cells that carry electrical and chemical messages back and forth between the brain and other parts of the body
Term
neuroglia
Definition
specialized cells that support and nourish the neurons. they don't carry messages, but supply nutrients to neurons, repair brain after injury, and attack invading bacteria
Term
effectors
Definition
cells of muscles and glands that respond to neural signals.
Term
sensory receptors
Definition
neurons or other cells that detect changes in conditions inside or outside the body.
Term
two main division of the nervous system
Definition
CNS- central nervous system and PNS- peripheral nervous system
Term
central nervous system
Definition
brain and spinal cord
Term
peripheral nervous system
Definition
network of nerves that radiates out from the brain and spinal cord extending throughout the body
Term
dendrites
Definition
short extensions of neurons that send signals to the cell body
Term
cell body
Definition
nucleus and organelles of the neuron
Term
axon
Definition
long wirelike body that conducts signals from the dendrites
Term
terminal boutons
Definition
where axons terminate
Term
3 categories of neurons
Definition
sensory, motor, and interneurons
Term
sensory neurons
Definition
carry sensory input toward the cns
Term
motor neurons
Definition
carry information away from the cns toward effectors
Term
interneurons
Definition
link sensory and motor neurons within the brain or spinal cord
Term
myelin sheath
Definition
protective layer around axons in the pns, formed by neuroglial cells
Term
Schwann cells
Definition
the neuroglial cells that make up the myelin sheath and wrap themselves around the axon
Term
white matter
Definition
cns tissue, white because of the myelin substance in the plasma in the schwann cells
Term
gray matter
Definition
cns tissue w/no myelinated axons
Term
nerves
Definition
bundles of myelinated axons in the pns
Term
nerve tracts
Definition
when myelinated axons of white matter are bundled together in the CNS
Term
nodes of ranvier
Definition
spaces between the schwann cells that interrupt the myelin sheath, leaving tiny unmyelinated patches
Term
nerve impulses
Definition
electrical charges that carry information along nerve cells
Term
resting potential
Definition
the net negative charge inside the cytoplasm of the axon compared to the outside when the axon is not conductin and impulse.
Term
sodium-potassium pump
Definition
a protein in the cell membrane that actively transports sodium out of the cell and potassium into the cell. 3 Na+ out for every 2 K+ in. Maintains the difference in ions in the cell
Term
action potential
Definition
brief reversal of electrical charge of the axon that transmits a signal along the length of the axon. the more intense the stimulus, the more often the axon fires/begins an action potential
Term
depolarization
Definition
if sodium rushing into the cell reaches a critical level, many of the sodium channels open and sodium floods the cell, quickly eliminating the charge difference across the cell.
Term
repolarization
Definition
when potassium ions diffuse out of the cell, and the inside of the cell again becomes more negative than the outside.
Term
refactory perioud
Definition
after an action potential, affected portion of the axon keeps sodium gates closed, preventing another action potential
Term
synapse
Definition
the region between 2 neurons
Term
presynaptic neuron
Definition
the neuron transmitting the action potential
Term
postsynaptic neuron
Definition
the neuron in a synapse that receives the action potential
Term
neurotransmitter
Definition
chemicals that are released when an electrical impulse arrives at the terminal bouton of a nerve cell
Term
reuptake
Definition
when neurotransmitter receptors on the presynaptic cell permit the neurotransmitter to reenter the cell, allowing the neuron that released the neurotransmitter to use it again
Term
alzheimer's disease
Definition
stems from impaired function of acetylcholine
Term
acetylcholine
Definition
an important neurotransmitter at nerve-muscle synapses
Term
acetylcholinesterase
Definition
an enzyme that breaks down acetylcholine, drugs that inhibit this enzyme temporarily improve mental function for alzheimer's patients.
Term
parkinson's disease
Definition
caused by malfunctioning of neurons that produce dopamine, which controls emotions and complex movements
Term
integration
Definition
the process by which individual neurons sum up the overall message of contrasting inhibitory and excitatory signals.
Term
integration
Definition
the process by which individual neurons sum up the overall message of contrasting inhibitory and excitatory signals.
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