Nervous system Flashcards
how many neurons in a brain?
how many synapses per neuron?
100 billion neurons
100-1000 synapses
what are neurons?
specialized cells
- long living + irreplaceable (your don’t grow new neurons)
- neuroplasticity: new connections
- neurogenesis: stem cells
billions of tiny information processors (excite or inhibit)
what do neurons do?
carry messages through HNS
transmit electrochemical info
- action potential aka nerve impulse
soma
cell body
nucleus/metabolic function
dendrites
receive signals (branches)
axons
long slender tail, tube like, miniature cable carries info away from the soma terminal buttons (which release neurotransmitters)
myelin sheath
white fatty coating
insulation/speed
MS signals slow-loss of coordination
glial cells
neurons are held in place by glial cells
surround, support, nourish, protect
more than half the brains volume
**performs pruning (cleaning waste, dead neurons)
insulates fro efficient transmission
involved in modulation, amplification of sensory experimences (chronic pain)
transmission of electrical impulses
- permeability (axon letting +ions in)
- electrically charged neuron fires action potential = message sent across synapse
firing of neuron steps
electrically charged neuron fires action potential = message sent across synapse
- resting potential
- neuron is stimulated. action potential fire
(all of nothing, inhibitory/excitatory) - refractory period
- resting potential
synapse
junction point between two neurons
more synapses than grains of sand on a beach
synapse structures
Axon Terminal (buttons)
Synaptic Vesicles
Neurotransmitters
Synaptic Gap/Cleft
Nervous system, study slide 18, 24, 27, 31 (chap 2)
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central nervous system (cns)
brain and spinal chord
protected by skull and spine
peripheral nervous system (pns)
somatic and autonomic nervous systems
links body and brain
when does the nervous system form?
what is the nervous system?
within 7h of sperm penetrating egg
controls & coordinates every function of the body
how do cns and pns interact?
CNS integrates sensory info collected by the PNS from all over the body and responds to it
CNS components and def of components
- brain
- brainstem: primitive brain, handles functions critical for survival
- spinal cord: extension of brain, protected by spine + spinal fluid
types of nervous systems in PNS
- somatic nervous system (sensory and skeletal)
- autonomic nervous system
- -sympathtic
- -parasympathetic
somatic nervous system
- connects CNS to the muscles in the body
- transmits sensation information
autonomic nervous system
- involuntary basic life functions
- communicates with glands, smooth and cardiac muscle
sympathetic nervous system
arouses body + motivates response for fight or flight
parasympathetic nervous system
resting, digesting, repair
homeostasis
reflexes (knee-jerk reflex) is controlled by what? what happens?
spinal cord and PNS can initiate movement on their own
response to stimuli immediately ‘reflected back’ to muscle which contracts before the brain gets wind of it
