Section 4 Flashcards
General func. of the nervous system, their branches, and examples (4)
- controls internal environment; parasympathetic (autonomic nervous system); ex. altering hormone release
- voluntary movement; somatic nervous system; ex. direct movement
- spinal cord reflexes; afferent division (sensory); ex. yanking hand away when touched something HOT
- memory and learning; autonomic;
Components of periphery: stimulus, nerve sig. pathway, response of spindles and GTO; include stretch reflex
Stimulus: muscle over-stretching
Nerve sig. path: annulospiral neve fiber; sends impulse to thru dorsal root to spinal cord producing a shortening reflex of muscle
Resp. spindles: detects and responds by shortening length of extrafusal muscle fibers
Resp. GTO: sensors discharge to depress motor neuron activity to reduce force output
Org. of nervous system
CNS
Afferent (sensory)
PNS
Efferent (motor)
Autonomic (involuntary)
Sympathetic
Parasympathetic
Somatic (voluntary)
CNS descrip.
consists of the brain and spinal cord
- brain (incl. retinas)
- spinal cord
- integrative/control centers
Afferent (sensory)
division of CNS
somatic and visceral neurons
conducts impulses from receptors to CNS
PNS
Consists of nerves that transmit information to and from the CNS
- cranial nerves 3-12
- spinal nerves
Efferent (motor)
division of PNS
motor neurons
conducts impulses from CNS to effectors
Autonomic
division of efferent
involuntary
conducts impulses from CNS to cardiac muscle, smooth muscle, and glands
ex. sweating
Somatic
division of efferent
voluntary
conducts impulses from the CNS to skeletal muscle
ex. flexing
Sympathetic
division of autonomic
prepares fro excitement (HR increase)
“fight or flight”
Parasympathetic
division of autonomic
relax and digest (HR decreases)
Unipolar
a neuron that only has one neurite extending from the cell body
Are sensory neurons uni or multipolar?
Unipolar b/c sensory neurons only carry sensory processes and conduct impulses from receptor toward CNS.
Multipolar
a neuron that possesses a single axon and many dendrites to allow info from other neurons to be received.
Are somatic motor neurons uni or multipolar?
Multipolar b/c they conduct impulses from CNS to multiple receptors (skin, skeletal muscles, joints, tendons)
Describe what is meant by excitability
-ability to receive and respond to a stimulus.
Impulse (stimulus) arrives at NMJ
ACh releases saclike vesicles in terminal axons w/in synaptic cleft.
ACh changes elec. neural impulse into chem. stimulus and combines w/ transmitter-receptor complex in postsynaptic membrane.
This change in elec. property of postsynaptic membrane triggers end-plate potential that spreads from motor end-plate to extrajunctional sarcolemma of muscle.
This causes AP to travel to muscle fibers for contraction
Key components of neuron controlling skeletal muscle (6)
Cell body Dendrites Axon Myelin Sheath Schwann cells Nodes of Ranvier
Cell body
aka Soma
Contains the nucleus
Connect dendrites
Found in spinal cord grey matter
Dendrite
brings info TO cell body
consists of short neural branches that receive impulses through numerous connections and conduct them toward cell body
Axon
takes info AWAY from cell body
extends from cord to deliver the impulse to muscle