Ch. 41: Neural Signaling Flashcards
a change in an organisms environment
stimulus
hormones that are regulated and produced to trigger chemical rxn
endocrine system
neurons send electrical signals to target cells to trigger rxns
nervous system
reception..transmission..integration..action
RTIA (response to a stimulus)
the process of detecing a simulus
reception
sending messages to a neuron
transmission
sorting and interpreting incomig sensory info and determining the appropriate response
integration
the physical/physiological response that an effector carries
action
specialized cells in the nervous system
- receive stimuli
- produce & transmit electrical signals (action potentials)
- have 3 main parts:
-cell body, axon, dendrites
neurons
contains nucleus, organelles, and bulk of cytoplasm
cell body
long extension from the neuron that conducts nerve impulses away from the cell body
axon
short, highly branched processes specialized to receive stimuli
dendrites
“nerve glue” cells
neuroglia (glial cells)
phagocytic cells that remove debris and waste
microglia
star-shaped cells that support neurons physically/metabolically
astrocytes
line fluid-filled spaces in the brain & spinal cord & produce cerebrospinal fluid
ependymal cells
form a myelin sheath around the axon which insulates axons and speeds up the rate of impulse transmission
oligodendrocytes
similar to oli but form myelin sheaths in the peripheral nervous system
schwann cells
group of cell bodies
ganglion
used to transmit info along axons
- inside is negatively charged (-70mv) (ions can’t cross membranes)
neural signals
the plasma membrane of a __ doesn’t get an impulse and is polarized
resting neuron (the neural signals category)
the voltage of a resting neuron is
negative (-70mv)
- selective permeable (no ions)
- sodium-potassium pumps (sodium channels open is first = depolarization; potassium channels open is second = repolarization)
- passive ion channels
- large intracellular anions (can’t cross plasma membrane/contribute negative charge)
how does a neuron maintain a negative resting potential
opening of Na channels/make less negative
depolarization
making more negative back to resting potential
repolarization
below resting potential
hyperpolarization
action potential (ALL OR NONE)
-55mv
resting potential
-70mv
small period of time where neuron can’t respond
refractory period
voltage reaches threshold, voltagte gated Na channels open, Na goes into cell and K channel opens slowly in response
depolarization to repolarization
- resting potential
- threshold
- depolarization phase
- repolarization phase
- undershoot
action potential cycle
wave of action potential along an axon
impulse
- contiguous conduction
- smooth/in unmyelinated neurons - saltatory conduction
- depolarization jumps
neural impulse transmission
space between neurons
1. chemical __
- have a synaptic cleft
- involve the release of
neurotransmitters
synapse
__ terminal release neurotransmitters
synaptic
chemical that transmit signals from one neuron to another neuron or to an effector
neurotransmitters
- nerve impulse (action potential) reaches axon terminal and calcium channels open and Ca flow into the cell from the outside
- Ca ions stimulate fusion os synaptic vesicles with the pre-synaptic membrane which release a neuro transmitter into the synaptic cleft
- the neurotransmitter diffuses across the cleft and binds to receptors int he post-syn membrane
- this initiates the opening of sodium or potassium channels n the dendrites of post-synaptic neuron which changes the membranes potential (depolar/hyperpolar
- the neurotransmitter chemical is broken down by an enzyme which release sit from the binding sites and the new cycle begins (ex: acetylcholine is broken down by acetylcholinesterase) (ase=enzyme)
- Ca is returned to the outside of the presyn membrane by a calcium pump
steps in synaptic transmission
point at which a muscle and neuron meet (neuromuscular junction)
motor end plate (sending messages to effectors)
- acetylcholine: excititory in skeletal muscle , inhibitory in cardia muscles (most important)
- norepinephrine, 3. dopamine, 4. seratonin, 5. endorphins
neurotransmitters
depolarization (less negative) by opening of Na channel that lead to Na influx (increase) (never reach threshold)
EPSP
hypolarization (more negative) by opening of K channels that lead to K efflux (decrease)
IPSP
allow CNS (central nervous system) to integrate incoming info from various sources (brain, spinal cord, etc…)
neural circuits
opposite of neural circuits
neural circuits divergence
