nervous system Flashcards
ganglia
many neurons
cephalization
creating a concentration of sensory organs and nervous system components at the front of the body
pathway of nervous system
sensory (sensory neurons) –> sensory input (PNS) –> integration (CNS) –> motor output (PNS) –> effector
sensory neuron
cell body in middle of axon, in PNS
interneurons
cell body near dendrites, in CNS
motor neurons
cell body near dendrites, in PNS
dendrite
receives signals from other nerves, at the top of the cell
axon hillock
connects dendrite and axon, where action potential is triggered
what is the difference between a nerve cell and other cells?
an axon
axon
the long fatty section of the nerve, where the signals are sent down
presynaptic cell
cell that is sending the signal, before the signal is sent
postsynaptic cell
cell that receives the signal
synapse
the gap/connection between two nerves
neuron vs nerve
neuron is the functional unit of a nerve, multiple neurons make up a nerve
1st step of neuronal signal transduction
stimuli is received by dendrites and cell body
2nd step of neuronal signal transduction
synaptic stimuli summoned at axon hillock where an action potential is triggered if the sum of the arriving signals is greater than the threshold
3rd step of neuronal signal transduction
action potential conducted along axon and axon terminal where neurotransmitters are released
what happens to released neurotransmitters?
they bind to receptors on postsynaptic cell membrane and potentially create a new signal
resting membrane potential of a neuron
-70 mV
action potential
the depolarization of a cell
steps of an action potential
- reaching threshold, 2. depolarization (Na+ rushes in), 3. repolarization (K+ rushes out), 4. refractory period
how does depolarization occur?
there are voltage gated sodium channels that are opened when the threshold is reached, as the membrane potential reaches 40 the channels become blocked
how does repolarization occur?
voltage gated potassium channels open and potassium will rush out of the cell
inactivation gate
closes the sodium channel so it does not keep working during repolarization
glial cell
provide chemical and physical support to other cells
myelin sheath
fatty outer layer that promotes movement of action potential
salgatory propogation
movement of signal across axon
node of ranvier
in between myelin sheath segments there are proteins where the signal is received
axon terminal
receives and passes on the signal
vesicles role in action potential
store neurotransmitters and exocytose when they should be released into synaptic cleft
why do vesicles know when to exocytose?
voltage gated Ca2+ channels open which allows Ca to rush into presynaptic membrane and triggers vesicles
what happens when the neurotransmitter (Ach) is released?
Ach binds to protein which opens ion channels for Na+ to rush into postsynaptic membrane
astrocyte
type of glial cell, huge component of the CNS
role of the astrocyte
structure neuron, repair damaged neurons with scar tissue, maintain homeostasis, creates blood brain barrier
EPSP
excitatory signals which depolarize the cell, can have temporal or spacial summation
IPSP
inhibitory signals which hyperpolarize the cell
temporal summation
multiple EPSPs arrive quickly at a single synapse and set off an action potential
spacial summation
several signals at the asme time from different EPSPs leads to action potential
afferent neurons
to CNS
efferent neurons
away from CNS
Peripheral Nervous System (PNS)
made of a network of mainly neurons, anything that is not the brain or the spinal cord
Central Nervous System (CNS)
brain and spinal cord
branches of the PNS
somatic and autonomic
Somatic reponses
voluntary/conscious: reactions, sensing and responding to environment, etc
Autonomic responses
involuntary/unconscious, sympathetic and parasympathetic systems
Sympathetic system
fight or flight (accelerates heart, stimulates glucose release, inhibition of stomach and intestines)
Parasympathetic system
rest and digest (slow heart, stimulates stomach and intestines)
