anant exam 3 Flashcards
effectors of ANS
smooth muscle, cardiac muscle, glands
preganglionic neurons
- cell body in CNS, axons enter PNS
- axons contribute to cranial and spinal nerves
- lightly myelinated
- slow conduction velocity
- neurons are cholinergic (Ach)
postganglionic neurons
- neurons completely in PNS
- cell bodies form peripheral ganglia
- nonmyelinated
- very slow conduction velocity
- either cholinergic (Ach) or adrenergic (Epi or NEpi)
- axons synapse with effector organ
SYMPATHETIC preganglionic neurons
- cell body in thoracic and lumbar spinal cord ( T1-L1)
- short preganglionic axon
- ALL are cholinergic (Ach)
SYMPATHETIC postganglionic neurons
- cell bodies in sympathetic chain ganglia (paravertebral) or collateral (prevertebral) ganglion
- long postganglionic axons
- MOST are adrenergic (Epi or NEpi)
somatic vs autonomic nervous sytem
somatic: effectors are skeletal muscles, motor neurons exert direct control over skeletal muscles.
autonomic: effectors are viscera, motor neurons synapse on visceral motor neurons in autonomic ganglia and ganglionic neurons control visceral effectors
sympathtic nervous system
(thoracolumbar) activated during fight or flight conditions, preganglionic fibers are short and post ganglionic fibers are long
sympathtic responces
- heightened mental alertness
- increased metabolic rate
- reduced digestive and urinary functions
- activation of energy reserves
- increased respiration & dilation to airways
- increased hr and bp
- sweat
parasympathetic nervous system
craniosacral, rest and digest, preganglioni fibers are long and post ganglionic fibers are short
parasympathetic responces
- decreased metabolic rate
- decreased HR and BP
- increased salivation and digestive secretions
- increased blood flow in digestive system
- stim of urination and defection
sympathetic chain ganglia
located on both sides of the vertebral column, control effectors in the body wall, inside thoracic cavity, and in head & limbs
collateral ganglia
anterior to vertebral bodies, contain ganglionic neurons that innervate tissues and organs in the abdominopelvic cavity
adrenal medullae
modified sympathetic ganglion, have very short axans
where are preganglionic sympathtic fibers found?
ventral roots of spinal segments T1-L2
innervation of adrenal medullae
secretes E and NE, preganglionic fibers innervate directly
cholinergic receptors
synapses that use Ach as a transmitter, effect is always excitatory, most are preganglionic
adrenergic
neurons release NE, most are sympathetic ganglionic.
alpha receptors
activates enzymes on the inside of the plasma membrane, more common, adrenergic
beta receptors
located on plasma membranes of cells of many organs, adrenergic
nicotinic receptors
cholinergic receptor, at neuromuscular junctions, opens chemically gated channels, PARASYMP
muscarinic
g proteins, can be excitatory or inhibitory, changes K membrane permeability, occurs at all nuromuscular or neuroglandular junctions, PARASYMP
preganglionic PARASYMPATHETIC neurons occur in….
- midbrain, pons, and medulla.
- associated with cranial nerves III, VII, IX, X
- in lateral gray horns of S2-S4
parasympathetic stimulation is specific/ localized and long lasting. (t/f)
FALSE. they are localized but last BRIEFLY
what nerves do parasympathetic leave the brain in?
III, VII, IX, X, also in s2-s4
wha neurotransmitter do sympathetic neurons release?
preganglionic: Ach
postganglionic: mostly NE but some release Ach or NO
what neurotransmitters do parasympathetic neurons release?
always releases Ach
dual innervation
some vital organs recieve both sympathetic and parasympathetic innervation
parasympathetic ganglionic neurons are located ___ their target organs
within or next to
the vagus nerve provides 75percent of parasymp outflow. (t/f)
true
sympathetic division contains __ set(s) of chain ganglia
2
how many collateral ganglia does the sympathetic division have?
3
exocrine gland
a gland that secretes onto epithelial surfaces or into a duct connected to the exterior
endocrine gland
a gland that secretes secretions into extracellular fluid
direct communication
occurs between two cells, transports ions through gap junctions, limited yo adjacent cells
paracrine communication
transports paracrine factors through extracellular fluid, limited to a local area
endocrine communication
transmits hormones through the bloodstream, extends to other tissues of the body