The Autonomic Nervous System: Flashcards
The somatic nervous system stimulates _____, whereas the ANS innervates _____.
skeletal muscles
cardiac and smooth muscle and glands
preganglionic neuron reside in …
brainstem or spinal cord
Where is the cell body of postganglionic neurons?
autonomic ganglion outside the CNS
Differ between pre and post ganglionic axons
Preganglionic axons are thin, lightly myelinated fibers, and postganglionic axons are even thinner and nonmyelinated.
All somatic motor neurons release ____ at their synapses with skeletal muscle fibers. The effect is always ____.
acetylcholine (ACh)
excitatory
all autonomic preganglionic fibers release
ACh
autonomic postganglionic fibers release two neurotransmitters:
- norepinephrine (NE) secreted by most sympathetic fibers,
- ACh secreted by parasympathetic fibers.
The ANS has two arms, parasympathetic and sympathetic:
describe them.
- The parasympathetic division promotes maintenance functions and conserves body energy
- The sympathetic division mobilizes the body during activity
Parasympathetic activity:
➢ BP and HR are regulated at low normal levels
➢ Respiratory rates are low
➢ GI tract is actively digesting food
➢ The skin is warm
➢ In the eyes, the pupils are constricted, and the lenses are accommodated for close vision
Fight-or-flight is sympathetic or parasympathetic
sympathetic
Signs of sympathetic nervous system mobilization:
➢ HR increases
➢Breathing is rapid and deep;
➢ Dry mouth
➢ Skin is cold and sweaty
➢ Pupils dilate
➢ It constricts blood vessels, shunting blood to the muscles and the vigorously working heart
➢ It stimulates the liver to release more glucose into the blood to accommodate the increased energy needs of body cells.
➢ Reduces nonessential activities, such as GI motility
➢ helps w/ far vision
The parasympathetic division as the D division:
digestion, defecation, and diuresis (urination)
The sympathetic division as the E division
exercise, excitement, emergency, embarrassment
Sites of origin differences between para and sympa
- Parasympathetic fibers are craniosacral
- sympathetic fibers are thoracolumbar
Location of their ganglia differences between para and sympa
Most parasympathetic ganglia are located in or near the visceral effector organs. Sympathetic ganglia lie close to the spinal cord.
Relative lengths of their fibers differences between para and sympa
- parasympathetic division has long preganglionic and short postganglionic fibers.
- sympathetic division preganglionic fibers are short, and the postganglionic fibers are long
The preganglionic axons extend from the CNS and synapse with postganglionic neurons located in …
terminal ganglia
Preganglionic fibers run in which cranial nerves
Oculomotor, facial, glossopharyngeal, and vagus
The cell bodies of the postganglionic neurons of oculomotor nerves are in the ____
ciliary ganglia within the eye orbits
Pterygopalatine ganglia is located
posterior to the maxillae.
The preganglionic neurons that stimulate the ____ and _____ originate in the pons
submandibular and sublingual salivary glands
Sacral Part of Parasympathetic Division serve what
the pelvic organs and the distal half of the large intestine
the sympathetic nervous system supplies the ____ in the internal body cavities
the smooth muscles, cardiac muscle, and glands
After leaving the cord via the ventral root, preganglionic sympathetic fibers pass through a ___ to enter an adjoining ___ forming part of the ____.
a white ramus communicans to enter an adjoining sympathetic trunk ganglion forming part of the sympathetic trunk.
Cholinergic fibers release what?
Ach
- include (1) all ANS preganglionic axons and (2) all parasympathetic postganglionic axons at synapses with their effectors.
Adrenergic fibers release what
NE
- include the majority of sympathetic postganglionic axons. An exception is sympathetic postganglionic fibers that secrete ACh onto sweat glands.
Two types of cholinergic receptors
nicotinic and muscarinic
Nicotinic receptors include
- All postganglionic neurons (cell bodies and dendrites), both sympathetic and parasympathetic
- cells of the adrenal medulla
- The sarcolemma of skeletal muscle cells at neuromuscular junctions
When ACh binds to nicotinic receptors, the effect is always
stimulatory, and directly opens ion channels, depolarizing the postsynaptic cell.
When ACh binds to muscarinic receptors the effect is
inhibitory or stimulatory
two major classes of adrenergic (NE-binding) receptors
alpha and beta
NE binding to the β1 receptors of cardiac muscle prods the heart into
more vigorous activity
Epinephrine binding to β2 receptors in bronchiole smooth muscle causes it to…
it to relax, dilating the bronchiole
ANS is regulated by CNS controls in the
spinal cord, brain stem, hypothalamus, and cerebral cortex.
