ANS Flashcards
Two types of nervous systems
CNS
PNS
what are the two divisions of the PNS
afferent
efferent
Two major division of the efferent peripheral system
Somatic
Autonomic
Somatic pathways consist of __ neuron between CNS and effector
1 neuron
Somatic neurons normally innervate _____
skeletal muscle
Autonomic pathways consist of ____ between CNS and effector
2 neurons
ANS innervates ____
smooth muscle, cardiac muscle, glands, GI neurons
ANS is activated by ______
spinal cord, brain stem (pons and medulla) and hypothalamus
Brainstem is responsible for controlling ____ of the ANS
cardio and respiratory
MAP, HR, respiratory frequency, tidal volume
Hypothalamus is responsible for controlling ____ of the ANS
Temperature regulation
water balance
feeding control
signals sent to CNS in ganglia that return immediately to the effector organ
reflex
examples of reflex are
sweating (thermo)
bladder emptying (water regulation)
smells -> digerstive enzymes (glands)
baroreceptor (MAP)
Functions of the ANS included
homeostasis control
4 F’s (fighting, fooling around, fleeing or feeding)
2 subdivisions of efferent ANS
Sympathetic
Parasympathetic
sympathetic system is also called the
thoracolumbar
Sympathetic system responses
—-responds to stress—-
fight or flight
preparing for physical activity
Parasympathetic system is also called
craniosacral
Parasympathetic system responses
—–conserves energy—–
when not in stressful situation
ANS cell bodies are located
outside the CNS
Cluster of nerve bodies found outside the CNS
ganglia or ganglion
The two neurons in the ANS are called
Preganglionic neurons
Postganglionic neurons
sympathetic ganglia lie close to the spinal cord being called ______
sympathetic trunk
75% of parasympathetic fibers are located in the _____
vagus nerves
acetylcholine (aCh) is released at
ALL preganglionic synapses
and postganglionic synapses in the parasympathetic system
(except sympathetic, sweat glands, piloerector muscles and blood vessels)
Most sympathetic postganglionic neurons secrete
norepinephrine
neurons that secrete norepinephrine are called
adrenergic
aCh is released through
exocytosis
aCh is released due to a rise in ____
calcium (intracellular )
aCh is hydrolyzed by
acetylcholinesterase
A bulbous enlargement of the postganglionic ganglia is called
varicosities
removal of neurotransmitters
3 steps
- reuptake (50%-80%)
- diffusion out of cleft
- enzymatic destruction
adrenal medulla release _____ directly into the _____
epinephrine and norepinephrine
blood stream
cells of the adrenal medulla that release neurotransmitters are called
chromaffin
chromaffin cells are like _____
sympathetic Postganglionic neurons (no axons)
norepinephrine in the blood stream last _____
5-10 times longer
receptor-dependent cells are excited or inhibited by:
- change in membrane permeability
2. enzyme is activated or inactivated
aCh actions on the heart
increase SA node permeability to K
decreasing the heart rate
norepinephrine actions on the heart
increase SA node permeability of Na
increase heart rate
The two types on ANS receptors
cholinergic (acetylcholine)
Adrenergic (epinephrine or norepinephrine)
Two types of cholinergic receptors
muscarinic
nicotinic
Muscarinic receptors operate through ___
2nd messenger system
linked to gated K+ channels
Nicotinic receptors operate through ____
opening a cation channel
cholinergic changes in the body
lower HR
lower atrial contractility
dilate coronary arties
contract smooth muscle (bronchial)
Adrenergic receptors are linked to
G-protein linked 2nd messenger
Two types of adrenergic receptors are
Alpha
Beta
alpha receptors are responsible for
systemic vasoconstriction
Beta receptors are responsible for
sympathetic cardiac stimulation
airway dilation
effects on receptors by norepinephrine
excites alpha receptors highly
excites beta receptors slightly
effects on receptors by epinephrine
excites alpha and beta equally
fight or flight term coined by
Walter cannon
sympathetic stress response on the body
increased arterial pressure increased blood flow to active muscles decreased blood flow to GI tract and kidney increased cellular metabolic rate increased blood glucose levels increased glycolysis in muscles and liver increase muscle strength (recruitment) increased mental activity increased rate of blood coagulation
some effector tissues in the ANS are innervated by other means called
non-adrenergic
non-cholinergic
(NANC)
Alpha receptor (adrenergic) function
a1 vasoconstriction
Beta receptor (adrenergic) function
b1 increased HR
b1 increased force of contraction
b2 bronchodilation
b2 vasodilation
