Intro To Nervous System Flashcards
CNS
brain and spinal cord
PNS
autonomic nervous system and motor pathways
Main goal of information pathway
sense changes in the environment and respond appropriately
Afferent Peripheral
at/towards CNS, how sensory information is received and transmitted into animals body
Integration
takes place in CNS
Efferent Peripheral
away from CNS, carries signals through nerves to muscles (motor response pathway) or internal organs (autonomic nervous systems) to elicit response
Neurons
what transmit electrical signals
cell body
houses nucleus
plasma membrane
surrounds cell
dendrites
finger-like projections originating from neuron cell body that receives sensory stimuli/signals (neurotransmitters) from other neurons
Action potential
generation of electrical signals sent in one direction down nerve axon to axon terminal (triggered by activation of dendrites)
Synapse
connection between two neurons, or a neuron or another cell, at axon terminal. Responsible for transmitting electrical signals across neurons through the entire body
myelin sheath
layer of fat covering axon, helps action potentials move faster down the axon
glial cells
surround neurons (not part of the neuron), support and insulate neurons
oligodendrocytes and Schwann cells
glial cells that produce myelin for the CNS and PNS
Steps of Action Potentials (4)
1) Rest. Higher sodium concentration outside the neuron compared to inside where there is a higher potassium concentration. Sodium-potassium ATPase pump maintains levels using energy to pump ions against the concentration gradients. Sodium and potassium ions in neurons plasma membrane closed, ions can’t flow down concentration gradients. Resting membrane potential of -70mV
2) dendrite stimulated. Sodium channels open and it rushes into the neuron towards a lower concentration inside the neuron (down concentration gradient). Depolarization: membrane potential to +30mV
3) membrane potential reaches +40mV, potassium channels open, rushes out of neuron towards a lower potassium concentration outside the cell (down concentration gradient). Repolarization: membrane potential is -90mV
4) sodium-potassium pump moves sodium back outside the cell and potassium inside of the cell to reestablish resting membrane potential of -70mV
Locations of action potential in order
dendrites, axon, axon terminal, release of neurotransmitters at synapse
all-or-nothing
when triggered, action potentials always reach +40mV.
neurotransmitters
chemicals released from neuron in response to an action potential
presynaptic neuron
neuron releasing the neurotransmitter
synaptic cleft
space between presynaptic and postsynaptic neuron that the neurotransmitter travels
Receptors
where neurotransmitters bind on the post-synaptic neuron
Ach and NE (E too)
Acetylcholine
Ach, excitatory or inhibitory depending on location of release
Norepinephrine
NE, fight or flight, response of the sympathetic nervous system
afferent sensory
action potentials activated here, PNS, synapse and release neurotransmitters to nerves in integrating CNS
efferent peripheral nervous system
action potentials via neurotransmitters sent to activate muscles or organs for an appropriate response
