Chapter 15 - The Autonomic Nervous System and Visceral Reflexes

Total Flash Cards » 40
 
1. 

A motor nervous system that controls glands, cardiac and smooth muscle to maintain homeostasis, actions are involuntary

 

ANS - Autonomic

 
2. 

Slower than somatic reflexes, include a visceral reflex arc, Example Elevated BP; baroreceptors stretch receptors (aorta & carotid), glossopharyngeal n., medulla, vagus n., heart pacemaker cells

 

Visceral Reflexes

 
3. 

(receptor, afferent neurons, interneurons, efferent neurons, effectors),

 

Visceral reflex arc

 
4. 

Mainly adapts body for activity, (“fight or flight”)

 

Sympathetic

 
5. 

Mainly a calming effect, reduced energy expenditure, normal body maintenance (“rest & digest”)

 

Parasympathetic

 
6. 

Background rate of activity from both divisions

 

Autonomic Tone

 
7. 

Control nuclei in hypothalamus and other brain stem regions, motor neurons in SC, peripheral ganglia and fibers in cranial and spinal nerves, pathway involves 2 neurons

 

Neural Pathways

 
8. 

Soma in brainstem or SC, ends in ganglion

 

Preganglionic

 
9. 

Begins in ganglion and extends to target cells

 

Post ganglionic

 
10. 

Short preganglionic and long postganglionic fibers, cell bodies in lateral horns and nearby gray matter of SC, fibers exit via spinal nerves T1 to L2 and go to nearby sympathetic chain ganglia, interconnected by nerve cords there are typically 3 cervical, 11 thoracic, 4 lumbar, 4 sacral, 1 coccygeal

 

Sympathetic Division; also called thoracolumbar,

 
11. 

Small myelinated, enter ganglia via white communicating rami

 

Preganglionic

 
12. 

Unmyelinated, exit ganglia by gray communicating rami or other route

 

Postganglionic

 
13. 

Enter ganglia, take one of 3 paths (end and synapse, go up or down the chain, pass through chain to another ganglia nearer target), fibers leave chain by: spinal n. (effectors in muscles and body wall), sympathetic n. (effectors in head and thoracic cavity), and splanchnic n. (effectors in abdominopelvic cavity), neural convergence and divergence are present

 

Preganglionic

 
14. 

secretes steroid hormones

 

Adrenal Cortex

 
15. 

modified postganglionic sympathetic neurons, secretes hormones epinephrine (85%) and norepinephrine (15%) into blood stream

 

Adrenal Medulla

 
16. 

Also called craniosacral division, long preganglionic and short postganglionic fibers, cell bodies in brain stem and segments S2 to S4

 

Parasympathetic Division

 
17. 

preganglionic fibers end in terminal ganglia in or near target, little divergence more selective

 

SC

 
18. 

exit via 4 cranial nerves, III Oculomotor, VII Facial, IX Glossopharyngeal, X Vagus

 

Preganglionic (brainstem)

 
19. 

(lens and pupil of eye)

 

III Oculomotor

 
20. 

(tear, salivary, nasal glands)

 

VII Facial

 
21. 

(parotid salivary glands

 

IX Glossopharyngeal

 
22. 

contains 90% of all PS preganglionic fibers, (heart, bronchi, blood vessels to lungs, esophagus, liver, pancreas, stomach, small intestine, kidney & ureter, proximal half of colon)

 

X Vagus

 
23. 

form Pelvic Splanchnic ns.: (distal half colon, rectum, bladder, reproductive organs)

 

Preganglionic (sacral cord)

 
24. 

Within walls of digestive tract, innervates smooth muscle and glands, regulates motility of esophagus, stomach, intestines and secretion of digestive enzymes and acid, interacts with ANS

 

Enteric Nervous System

 
25. 

Secrete ACh, released by all Sym & Parasym PG fibers & Parasym POG fibers, a few Sym POG fibers

 

Cholinergic Fibers

 
26. 

all cardiac muscle, smooth muscle, and glands, two types, work via 2nd messenger systems

 

Muscarinic Receptors

 
27. 

all synapses in autonomic ganglia, cells in adrenal medulla, at neuromuscular junction, always excitatory, work via ligand-gated ion channels

 

Nicotinic Receptors

 
28. 

Secrete NE, released by almost all POG Sym fibers

 

Adrenergic Fibers

 
29. 

usually excitatory, two subclasses cause different effects, α1 (suppress synthesis of cAMP), α2 (use Ca+2 as 2nd messenger)

 

α-Adrenergic Receptors

 
30. 

usually inhibitory, two subclasses cause different effects, β1 & β2 (use cAMP as 2nd messenger), many drugs are designed to be receptor selective

 

β-Adrenergic Receptors

 
31. 

tend to last longer due to lingering effects of NE.

 

Sympathetic Effects

 
32. 

Most viscera receive dual innervation

 

Dual Innervation

 
33. 

.

 

.

 
34. 

cardiac, digestive, pupils,

 

Antagonistic Effects

 
35. 

salivary glands

 

Cooperative Effects

 
36. 

partial constriction of vessels due to baseline sympathetic innervation

 

Vasomotor Tone

 
37. 

Limbic system provides a pathway connecting sensory and mental experiences with the ANS

 

Cerebral Cortex

 
38. 

Major control center of the ANS, includes hunger, thirst, thermoregulation, emotions, and sexuality, output is mainly to more caudal areas of brainstem and then to cranial nerves and spinal cord.

 

Hypothalamus

 
39. 

House numerous ANS nuclei many in the reticular formation, for cardiac, vasomotor, salivation, swallowing, sweating, GI secretion, bladder control, pupil control, and others, output is via spinal cord and cranial nerves III, VII, IX, X

 

Midbrain, Pons and Medulla Oblongata:

 
40. 

Autonomic reflexes like micturation, defecation, erection, and ejaculation are integrated in the spinal cord

 

Spinal Cord