14 Flashcards
What motor neurons does the ANS consist of?
Motor neurons that innervate smooth and cardiac muscles and glands
What does the autonomic nervous system do?
Makes adjustments to ensure optimal support for body activities
TF: ANS operates via conscious control
False
Subconscious
What are the other names for the ANS?
Involuntary nervous system
General Visceral motor system
What do the Somatic and Autonomic nervous systems differ in?
Effectors
Efferent pathways and ganglia
Target organ responses to neurotransmitters
What do somatic and autonomic nervous systems have the same?
Both have motor fibers
What are the effectors in the somatic nervous system
Skeletal muscles
What are the effectors in the ANS?
Cardiac muscle
Smooth muscle
Glands
Where are the cell bodies in the somatic nervous system?
In the Cns
What kind of fibers are found in the somatic nervous systems?
Group A (thick myelinated) fibers that extend in spinal or cranial nerve to skeletal muscle
What kind of efferent pathway does the ANS use?
A two neuron chain
(preganglionic neuron in the CNS)
(postganglionic neuron in the autonomic ganglion outside the CNS)
What axon in the ANS is nonmyelinated?
The postganglionic axon that extends to effector organs
What kind of axon in the ANS has a think lightly myelinated one?
Preganglionic axon
What do all somatic motor neurons release? (neurotransmitter)
ACh
Acetylcholine
What kind of effects come from the somatic nervous system?
Stimulatory effects
What fibers in the ANS release ACh?
Preganglionic fibers
What do the postganglionic fibers in the ANS release?
Norepinephrine or ACh at the effectors
What kind of effects come from ANS?
Stimulatory or inhibitory
What kind of receptors are at the ganglion in the Sympathetic and parasympathetic divisions of the ANS?
Nicotinic (ACh)
What kind of receptors are near the effectors of the parasympathetic division in the ANS?
Muscularinic receptors (ACh)
What kind of receptors are found at the end of a postganglionic axon in the sympathetic nervous system?
Adrenergic receptors (NE)
What nerves contain both somatic and autonomic fibers?
Most spinal and cranial nerves
What are the two divisions of the ANS?
Sympathetic and parasympathetic
What does dual innervation mean?
Almost all organs served by both divisions of the ANS but have opposite effects
What maintains homeostasis between the two divisions of the ANS?
Dynamic antagonism (always opposing one another)
What is the role of the parasympathetic division of the ANS?
Promotes maintenance activities and conserve body energy
What does the parasympathetic division direct in the body?
Digestion
Diuresis
Defecation
When does the parasympathetic division take control of a person?
As the person is resting
Reading
Relaxing
After a meal
What happens to blood pressure, heart rate and respiratory rates when the body is in the parasympathetic control?
They are low
What kind of activity does the gastrointestinal tract have in the parasympathetic control?
High Activity (increase digestion)
What happens to the pupils while the parasympathetic division is in control and why?
They constrict to accommodate for close vision
What is the role of the sympathetic system?
Mobilize the body during activity
Fight or flight
What causes the sympathetic division to take control?
Exercise
Excitement
Emergency
Embarassment
What happens to the heart rate when the body is taken over by sympathetic control?
It increases
What happens to the skin when the body is under sympathetic control?
It becomes cold and sweaty
What happens to the pupils when the body is under the sympathetic control?
They dilate along with the bronchioles
What happens to the mouth when the body is under sympathetic control?
It becomes dry
What happens to the body during vigorous physical activity?
It shunts blood to skeletal muscles and heart
It dilates bronchioles
Causes the liver to release glucagon
What division of the ANS has long preganglionic fibers from the brain stem and sacrum?
Parasympathetic (Craniosacral)
What is longer in the parasympathetic division, the preganglionic or postganglionic fiber?
Preganglionic fiber
Where do the parasympathetic preganglionic fiber synapse with postganglionic neurons?
In the terminl ganglia close to or within target organs
Where are the cell bodies of the parasympathetic preganglionic nerve fibers of the cranial division?
Cell bodies in the brain stem
What nerves are found in the cranial part of parasympathetic division?
Oculomotor nerve (CIII) Facial nerves (VII) Glossopharyngeal nerves (IX) Vagus nerve (X)
What do oculomotor nerves serve?
The smooth muscle of the eye via ciliary ganglia
What do facial nerves do?
Stimulate large glands in the head via pterygopalatine ganglia and submandibular ganglia
What do glossopharyngeal nerves serve?
Parotid salivary glands via otic ganglia
What do vagus nerves serve?
Neck and nerve plexuses for all thoracic and abdominal viscera (almost all) via cardiac, pulmonary, and esophageal plexuses
What does the sacral part of the parasympathetic division serve?
The pelvic organs and distal half of large intestine
Where are the preganglionic neurons in the sympathetic division (thoracolumbar)?
in the spinal cord segments T1-L2
What do preganglionic fibers of the sympathetic division enter?
The sympathetic trunk (paravertebral) ganglia
What do paravertebral ganglia of the sympathetic truck vary in?
Size
Position
Number
How many paravertebral ganglia are in the sympathetic trunk?
23
How many paravertebral ganglia are cervical?
3
How many paravertebral ganglia are thoracic?
11
How many paravertebral ganglia are lumbar?
4
How many paravertebral ganglia are sacral?
4
How many paravertebral ganglia are coccygeal?
1
What are the three fates that could happen when the short preganglionic fiber enters sympathetic trunk ganglion?
- Synapse with ganglionic neuron in same trunk ganglion
- Ascend or descend sympathetic trunk to synapse in another trunk ganglion
- Pass through trunk ganglion and emerge without synapsing (only in abdomen and pelvis)
What kind of sympathetic fibers pass directly to adrenal medulla without synapsing?
Some preganglionic fibers
What happens in the medulla when the preganglionic fiber passes directly to the adrenal medulla?
Medulla is stimulated and medullary cells secrete norepinephrine and epinephrine into blood
TF: Sympathetic ganglia and adrenal medulla arise from same tissue?
True
What is the misplaced sympathetic ganglion?
Adrenal medulla
What is the difference in somatic reflex arcs and visceral reflex arcs?
They have the same components but the visceral reflex arc has 2 neurons in the motor pathway
What causes the phenomenon called referred pain?
When visceral pain afferents travel along the same pathways as somatic pain fibers (heart pain in left arm0
What kind of fibers release ACh?
Cholinergic fibers
What are all ANS preganglionic axons (what kind of fibers)?
Cholinergic fibers
What are all parasympathetic postganglionic axons at effector synapse?
Cholinergic fibers
What do adrenergic fibers release?
Norepinephrine
What are most sympathetic postganglionic axons?
Adrenergic fibers
What kind of sympathetic postganglionic axons are not adrenergic?
The ones at sweat glands
What are two major classes for adrenergic receptors?
Alpha (1,2)
Beta (1,2,3)
What are the two types of receptors that bind Ach?
Nicotinic
Muscarinic
Where are nicotinic receptors found?
On sarcolemma of skeletal muscle cells at NMJ
All postganglionic neurons
Hormone producing cells of adrenal medulla
What effect does ACh have at nicotinic receptors?
Always stimulatory
What does ACh do at nicotinic receptors?
Opens ion channels
Depolarizes postsynaptic cell
Where are muscarinic receptors found?
On all effector cells stimulated by post ganglionic cholinergic fibers (release ACh)
What effect does ACh have at muscarinic receptors?
Can be either inhibitory or excitatory
What does beta 1 receptors do?
Increase heart rate and force of contraction
Causes the kidney to secrete renin
What do Beta 2 receptors do?
Causes the bronchioles in the lungs to dialate
What do beta 3 receptors do?
Lipolysis in adipose tissue
What do alpha 1 receptors do?
Serve and stimulate all sympathetic target organelles except the heart (pupil size)
What do alpha 2 receptors do?
Affect blood platelets
Inhibit NE and insulin production
Promote vasodilation
What type of drug is atropine?
Anticholinergic
What does atropine do?
Blocks muscarinic ACh receptors
When do you use atropine?
Used to prevent salivation during surgery
To dilate pupils for examination
What does Neostigmine inhibit?
Acetylcholinesterase
It breaks down ACh
What is neostigmine used to treat?
Myasthenia gravis
What do over the counter drugs for colds, allergies and nasal congestion stimulate?
Alpha - adrenergic receptors
What do most visceral organs have?
Dual innervation
What does dynamic antagonism allow for?
Precise control of visceral activity
What division controls blood pressure during rest and activity?
The sympathetic division
What is the vascular system innervated by?
The sympathetic division
What does sympathetic tone do?
Keeps blood vessels in continual state of partial constriction (vasomotor tone)
How do sympathetic fibers cause constriction of blood vessels and blood pressure to rise?
Fire more rapidly
What do alpha blocker drugs do?
Interfere with vasomotor fibers to reduce hypertension
What does the parasympathetic division normally dominate?
The heart
Smooth muscle of digestive and urinary tract organs
activate most glands except for adrenal and sweat
When does the sympathetic division override the parasympathetic division?
During times of stress
What division slows the heart and speeds up the digestive and urinary tracts?
Parasympathetic division
When is cooperative effects best seen in the body?
The control of external genetalia
What do the parasympathetic fibers do during cooperative effects on the external genetalia?
Cause vasodilation
Erection of penis or clitoris
What do the sympathetic fibers do during cooperative effects on the external genetalia?
Cause ejaculation of semen in males
Reflex contraction of females vagina
What parts of the body only receive sympathetic fibers?
Adrenal medulla sweat glands arrector pili muscles kidneys most blood vessels
What does the sympathetic division control?
Thermoregulatory responses to heat
Release of renin from kidneys
Metabolic effects
What division raises blood glucose levels?
Sympathetic division
What division of the ANS is short lived and highly localized?
Parasympathetic division
Why is the parasympathetic division so short lived?
ACh is quickly destroyed by acetylcholinesterase
What is the main integrative center of ANS activity?
Hypothalamus
What controls go into the hypothalamus?
Subconscious cerebral input via the limbic (emotional) system structures on hypothalamic centers
TF: Hypothalamus controls are only direct through the reticular system
FALSE
It is direct and indirect through the reticular system
What are the main controls of the hypothalamus?
Heart activity and blood pressure Body temp water balance Endocrine activity Emotional stages Biological drives Reactions to fear and fight or flight system
What allows for cortical influence on ANS?
Connections of hypothalamus to limbic lobe
TF: Voluntary cortical control of visceral activities is possible
True
What is biofeedback?
Awareness of physiological conditions with goal of consciously influencing them (breathing to slow heart rate)
What is hypertension and what causes it?
High blood pressure
Overactive sympathetic vasoconstrictor response to stress
What disease causes exaggerated vasoconstriction in fingers and toes which leads to pale and cyanotic skin which is painful?
Raynaud’s Disease
What disease is caused by uncontrolled activation of autonomic neurons in quadriplegics and those with spinal cord injuries above T6?
Autonomic dystrflexia
Causes blood pressure to skyrocket
What causes ANS deficiency to decline?
Old age
Structural changes to preganglionic axon terminals
What is orthostatic hypotension?
Low blood pressure after position change
Pressure receptors less responsive to BP changes
Cardiovascular centers fail to maintain healthy blood pressure
What are the 4 effects of age on ANS?
Constipation
Dry eyes
Frequent eye infections
Orthostatic hypotension
