chapter 11 Flashcards
homeostasis
state of relative stability within the body
nervous system
Brain, spinal cord and nerves, control sensory input, integration, and motor output.
Central nervous system
Brain, spinal cord it integrates and processes information sent by nervous system
Peripheral nervous system
Motor neurons, and sensory neurons
Somatic system
five senses
autonomic system
smooth and cardiac muscles
parasympathetic system
rest
sympathetic system
stress (fight - or - flight)
Neurons
basic structural and functional units of nervous system specialized to respond to physical and chemical stimuli, to conduct electrochemical signals, release chemicals that regulate various body processes.
Glial cells
More than neurons 10 to 1. nourish the neuron, remove their waste and defend against infections (supporting framework)
sensory neurons
Gather info from sensory receptors and transmit these impulses to control nervous system.
motor neuron
transports information from the central nervous system to other parts of the body.
interneuron
entirely in central nervous system.
reflex arc
Sudden, unlearned, involuntary response to certain stimuli. contains simple connections of neurons
Sensory receptors in the skin senses and sends a stimuli to sensory neuron, which then activates the interneuron, which then activates the motor neuron to instruct the muscle to contract and withdraw the hand.
dendrite
Short, branching terminals that receive nerve impulses from other neurons or sensory receptors. have high surface area and relays impulse to the cell body.
cell body
Contains nucleus, site of cell’s metabolic reactions. processes input from dendrite, if input is large enough it relays impulse to axon where action potential takes place.
axon
Axon conducts impulses away from the cell body. They are pretty long depending on the type of neuron and they communicate with corresponding cells, glands with releasing chemicals in the surrounding fluid.
mylein sheath
Axon enclosed in fatty, insulating layer, white in color and it protects the neuron and speeds the rate of nerve impulse transmission.
Schwann cells
Type of glial cells, form myelin by wrapping themselves around the axon.
Resting membrane potential
Potential difference across the membrane of a resting neuron. -70mv
Polarization
Process of generating the resting membrane potential
-large protein stuck inside the cell
-leaky potassium channels
-sodium/potassium pump (pumps 3 sodium out while pimping 2 potassium in)
-impermeable to small ions like chloride
Action potential
When the node of ranvier gets depolarized to less than -55 mv, threshold potential is reached so the impulse goes all the way up. (all of none)
Depolarization
If transmembrane potential becomes less then -70 mv.
Threshold potential
The potential difference of -55 which has to be reached before generating an action potential
nerve impulse
series of action potentials.
Whole process
when an impulse is received by the dendrite of the neuron and is then transmitted to the cell body, if the impulse is great enough it is sent to the axon, where some sodium channels start to open, if the impulse is high enough and threshold level of -55 mv is reached then more sodium channels open and the impulse goes all the way up creating an action potential. Sodium channels then close and potassium channels open and potassium is moved to the outside of the membrane called repolarization. Even more of the potassium channels open and hyperpolarization occurs makes it up to -90 mv. then potassium channels close and the sodium potassium pump does its work. this period is called the refractory period and no action potential can be generated.
Saltatory conduction
action potential jump from one node of Ranvier to another.
Multiple sclerosis
autoimmune disease which breaks down its own mylein
Synapse
connection between two neurons or neuron and effector.
neuromuscular junction
synapse between motor neuron and muscle cell
Synapse process
Impulse travels the lengths of axon and reaches the synapse terminal. the presynaptic neuron releases the neurotransmitters in the synaptic cleft from the synaptic vesicles. Neurotransmitters then go in to synaptic cleft and attach to specific receptor proteins on the postsynaptic membrane.
Excitatory and inhibitory synapse response
excitatory - opens sodium channels
inhibitory - opens potassium channels
Acetylcholine
a neurotransmitter broken down by enzyme called acetylcholinesterase and it returns it to presynaptic vesicles.
