Ch. 21 Brain Structure and Function Flashcards
nervous system
receives and interprets messages and decides how to respond
neurons
carry electrical and chemical messages. bundles into nerves
effectors
responsive tissue to nerve impulses
nerve impulse
chemical changes as ion concentrations change to pass message
neurotransmitters
chemicals released from nerve cell
sensory neurons
carry info to CNS. input detected by sensory receptors
sensory receptors
neurons or other cells that communicate with sensory neaurons. when stimulated, signals are generated and carried to brain.
general senses
temperature, pain, pressure, and body position. proprioception. scattered in body
special senses
smell, taste, equilibrium, hearing, and vision. gound in sense organs in head
motor neurons
carry info away from CNS to effector tissues
interneurons
between sensory and motor neurons
spinal cord
main nerve pathway. contains reflex arc
reflex
automatic response to stimuli
reflex arc
prewired circuit of neurons to allow quick reactions to dangerous stimuli
peripheral nervous system (PNS)
network of nerves outside brain and spinal cord
glial cells
10x more than neurons in brain. dont carry messages. supply nutrients to neurons, help them repair, and attack invading bacteria
cerebrum
fills whole upper skull. 2 hemispheres, each with 4 lobes.
temporal lobe
processes auditory and olfactory information. important for memory and emotion
occipital lobe
processes visual information from eyes
parietal lobe
processes touch and involved in self awareness
frontal lobe
processes voluntary movements. planning and organizing future expressive behavior
cerebral cortex
wrinkled outer surface of cerebrum
corpus callosum
bundle of nerve fibers that communicates between hemispheres
caudate nuclei
paired structures in each hemisphere. part of pathway coordinating movement
thalamus
relays info between cerebrum and spinal cord. first to receive messages signaling sensations. thalamus suppresses some and enhances others, then are relayed to cerebrum where is processes signals and responds. located between hemispheres
hypothalamus
located under thalamus. control center for sex drive, pleasure, pain, hunger, thirst, BP, temp. releases hormaones that regulate sperm and egg production and menstrual cycle
cerebellum
controls balance, muscle movement, coordination. ensures smooth contractions and relaxations. under hemispheres of cerebrum. has hemispheres as well
brain stem
below thalamus and hypothalamus. governs reflexes and spontaneous functions like heartbeat, resp, swallowing, and coughing
midbrain
adjusts sensitivity of eyes to light and ears to sound
pons
bridge. allows messages to travel between cord and brain
medulla oblongata
controls heart rate. conveys info from cord to parts of brain
left hemisphere
controls right side of body, speech, reading, and ability to solve math problems
right hemisphere
controls left side of body, spatial perception (understanding shape and form), and musical and artistic creations
reticular formation
in medulla. network of neurons radiating toward cerebral cortex. function as filter for sensory input. decides what stimuli require response. prevents brain from reacting to repetitive stimuli (traffic sounds or music while sleeping)
dendrites
branches off of neuron cell body
neuron cell body
contains nucleus
terminal boutons
knobby structures at end of neuron
axon
long wire like. protected by myelin sheath
myelin sheath
formed by schwann cells. mostly lipids
white matter
brain tissue composed of myelinated cells
nodes of ranvier
small patches uncovered by myelin in between schwann cells. impulse jumps from node to node and 200 mph
gray matter
brain tissue of unmyelinated cells
action potential
transmitting signal through breif reversal of electrical charge of nerve cell membrane. wave of electrical current through neuron
polarization
resting neuron has different charge accross membrane. higher K+ inside than Na+ on outside
sodium potassium pump
uses ATP to move 3 Na+ out of cell for every 2 K+ put back inside. returns potassium into cell to maintain gradient
depolarization
decrease of charge difference. activates Na+ channels and lets Na+ enter cel and lowers negative state of polarization. if a critical point is reached, channels open completely and Na+ rushes into cell, eliminating charge difference.
repolarization
Na+ channels close and K+ channel open, allowing K+ out of cell, making inside of cell more negative than outside
synapse
space between neurons
vesicles
sacs at end of terminal boutons filled with neurotransmitters
synaptic transmission
when signal reaches end of presynaptic neuron, wesicle releases neurotransmitters that diffuse across synapse to specific receptors on membrane of postsynaptic neuron.
once across synapse and in receptor, stimulates rapid change in uptake of Na+ causing depolarization and generating an action potential
cycle occurs until signal reaches effector tissue
reuptake
reabsorption of neurotransmitters. presynaptic cell allows reentry and reuses them
neurotransmitters after signal has passed
broken down by enzymes in synapse or taken up by presynaptic cell through reuptake to ensure stimulation stops on postsynaptic cell
alzheimers
impaired function of neurotransmitter acetylcholine in some neurons
depression
thought to be imbalance of neurotransmitters serotonin, dopamine, and norepinephrine
parkinson’s
malfunctioning of neurons that produce dopamine. loss of dopamine causes cells to fire without regulation
ADD
decreased dopamine levels. dopamine suppresses responsiveness to new stimuli. may also have increased number of reuptake receptors on presynaptic neuron and remove dopamine quickly
ritalin
decreases impact of reuptake receptors, letting dopamine stay in synapse longer
Adderall and dexedrine
increase levels of dopamine
