3 - Autonomic Nervous System Flashcards
The sympathetic and parasympathetic nervous system affect cardiac pump function in 3 ways.
- Changing chronotropism (HR)
- Changing inotropism (strength)
- Changing blood flow
Are far the most important regulators of the peripheral circulation.
SNS nerves
ANS can be subdivided by neurotransmitter secreted at the effector cell (3)
- Acetylcholine (SNS)
2. Epinephrine & NE (PNS)
Is a substance that interacts with a receptor to evoke a biologic response.
Agonist
Is a substance that interferes with the triggering of the response at a receptor site by an agonist.
Antagonist
The ANS reflex comprises the (4)
- Sensors
- Afferent pathways
- CNS integration
- Efferent pathways
Includes the part of the central and peripheral NS concerned with involuntary regulation of cardiac muscle, smooth muscle and glandular and visceral functions.
ANS
These structures are the first link in the reflex arcs of the ANS, and may relay visceral pain or changes in vessel stretch.
Afferent fibers
Is the highest level of ANS integration.
Cerebral cortex
What is the principal site of ANS organizaton?
Hypothalamus
SNS functions are controlled by nuclei in which part of the hypothalamus?
Posterolateral
PNS functions are governed by nuclei in which part of the hypothalamus?
Midline and anterior
Which part of the hypothalamus is in charge of regulation of temperature?
Anterior
Is the part which regulate water metabolism and are anatomically and functionally and associated with the posterior lobe of the pituitary.
Supraoptic hypothalamic nuclei
Together with the hypothalamus, these two structures integrate momentary hemodynamic adjustments and and maintain the sequence and automaticity of ventilation.
- Medulla
2. Pons
This area that is located within the medulla oblongata, is the primary area for relay of afferent chemoreceptor and baroreceptor information from the glossopharyngeal and vagus nerves.
Nucleus tractus solitarius (NTS)
Nerves related:
N = NINE (glossopharyngeal)
T = TEN (vagus)
S = SEVEN (less facial)
These 2 tissues are only innervated by the SNS fibers (2)
- Sweat glands
2. Spleen
EFFERENT SOMATIC MOTOR SYSTEM
Is composed of a cell body in the ventral gray matter of the spinal cord (unipolar) with its cell body in the ventral gray matter. Its myelinated axons extends directly to the voluntary striated muscle unit.
ANS efferent motor system
Is a two unit (bipolar) chain from the CNS to the effector organ. The first neuron of both the SNS and PNS originates within the CNS but does not make direct contact with the effector organ. Instead, it relays the impulse to a second station, known as the ANS ganglion, which contains the second ANS (postganglionic) neuron. Its axons contact the effector organ.
PREGANGLIONIC FIBERS both subdivisions are myelinated and are conducted at a speed of?
3 to 5 m/s
POSTGANGLIONIC FIBERS are unmyelinated and conduct impulses at a slower speed of?
2 m/s
3 classifications of nerve fibers
- Myelinated somatic
- Myelinated visceral (preganglionic autonomic)
- Unmyelinated
3 GROUPS of nerve fibers
- A
- B
- C
5 types of A nerve fibers
- Alpha
- Beta
- Gamma
- Delta
- Epsilon
Conduction velocity of A (alpha and beta) nerve fibers
120 m/s
Conduction velocity of A (gamma and delta) nerve fibers?
5-40 m/s (pain fibers)
Conduction velocity of A epsilon nerve fibers?
5 m/s
Conduction velocity of B nerve fibers?
3 - 15 m/s
Conduction velocity of C nerve fibers?
0.5 - 0.2 m/s (pain fibers)
The efferent SNS referred to as _____ located in what level of the vertebrae?
Thoracolumbar nervous
T1-T12 and L1-L3
Upon entering the paravertebral ganglia of the lateral sympathetic chain, the preganglionic fiber may follow one of three courses. (3)
- Synapse with postganglionic fibers in ganglia at level of exit
- Course upward or downward in the trunk of the SNS chain to synapse in ganglia at other levels
- Track for variable distances through the sympathetic chain and exit without synapsing to terminate in an outlying, unpaired, SNS collateral ganglion.
Preganglionic fibers pass directly thru what structure without synapsing in a ganglion.
Adrenal medulla
Collateral ganglia of these 2 ganglia are formed by the convergence of preganglionic fibers with MANY POSTGANGLIONIC neuronal bodies.
Celiac
Inferior mesenteric ganglia
SNS ganglia are almost ALWAYS closer to?
The spinal cord than the organs
Many of the postganglionic fibers pass from the lateral SNS chain back to the spinal nerves forming what structure?
They are distributed distally to these structures (3)
These nerves are called?
Gray communicating rami
- Sweat glands
- Pilomotor muscle
- Blood vessels (skin and muscle)
Unmyelinated C type fibers
The first 4 or 5 thoracic spinal segments generate preganglionic fibers that hat ascend in the neck to form three paired ganglia. (3)
- Superior cervical
- Middle cervical
- Cervicothoracic
Cervicothoracic ganglion is also called?
This is formed by the fusion of what 2 ganglia?
Stellate ganglion
- Inferior cervical
- 1st thoracic
Postganglionic neurons outnumber the preganglionic neurons in an average ratio of?
20:1 to 30:1
The preganglionic cell bodies of the parasympathetic NS ORIGINATE in 2 areas.
- Brainstem
2. Sacral segments
Parasympathetic preganglionic are found in what cranial nerves (4)
(1973) 9 10 7 3
This cranial nerve has the most extensive distribution of all the PNS.
Vagus nerve