Lecture 22- The Nervous System Flashcards
Nervous system consists of
- circuits
- neurons
- supporting cells
Neurons
process and transmit information through electrical and chemical signals
action potential
rapid, temporary change in membrane potential
Membrane potential
Voltage difference across a cell membrane
Membrane potential results from ____
the unequal distribution of ions inside and outside the cell
Three phases of action potential
- depolarization phase
- repolarization phase
- Hyperpolarization phase
Depolarization phase
the initial change in the membrane potential, making the charge closer to 0
repolarization phase
returning the charge to the resting potential
hyperpolarization phase
charge becomes more negative that resting potential
resting potential
the normal negative charge of the membrane potential
if the depolarization phase doesn’t reach the _____ then no signal is sent
threshold potential
SImplest animals with nervous systems possess interconnected neurons arranged in _____
nerve nets
More complex animals have _____
nerves
Cephalization
the clustering of sensory organs at the front end of the body
Which type of animals exhibit cephalization?
bilaterally symmetrical
the components of the nervous system in vertebrates
- CNS: Brain and spinal cord
- PNS: nerves and ganglia
The brain and spinal cord contain:
- white matter
- gray matter
Gray matter consists of
- neuron cell bodies
- dendrites
- unmyelinated axons
white matter consists of
bundles of myelinated axons
Myelin
fatty sheet surrounding the axon (facilitates sending the signal faster)
purpose of the PNS?
transmits info to and from the CNS
PNS regulates
movement and internal movement
Components of PNS
afferent and efferent neurons
efferent neurons
neurons transmit information away from the CNS to the body
Afferent neurons
neurons transmit info to the CNS
The two efferent components of the PNS
- motor system
- autonomic nervous system
Motor system of the PNS
carries signals to skeletal muscles
autonomic nervous system of PNS
carries signals to smooth and cardiac muscles
Two autonomic nervous system divisions
- sympathetic
- parasympathetic
sympathetic nervous system
arousal and energy generation (fight or flight)
parasympathetic nervous system
calming and return to self-maintenance (rest and digest)
