Nakamura Human Anatomy Ch 15

Question 1

Somatic motor system vs autonomic nervous system

Answer 1

Somatic
-One motor neuron extends from the CNS to skeletal muscle
-Axons are well myelinated, conduct impulses rapidly
Autonomic
-Chain of two motor neurons
-Preganglionic neuron
-postganglionic neuron
-Conduction is slower due to thinly or unmyelinated axons

Question 2

Divisions of the autonomic nervous system

Answer 2

Sympathetic and parasympathetic divisions
–Chains of two motor neurons
•Innervate mostly the same structures
•Cause opposite effects

Question 3

Sympathetic division

Answer 3

“fight, flight, or fright”

• Activated during exercise, excitement, and emergencies
• Sympathetic axons: highly branched, Influences many organs
• postganglionic release neurotransmitter norepinephrine (adrenergic)

Question 4

Parasympathetic division

Answer 4

“rest and digest”

• Concerned with conserving energy
• Parasympathetic axons: few branches, Localized effect
• preganglionic nerve fiber longer, postganglionic shorter
• postganglionic releases neurotransmitter acetylcholine

Question 5

Parasympathetic

Preganglionic fibers run via:

Answer 5

-Oculomotor nerve (III) (located in the midbrain, innervate smooth muscles in the eye)
–Facial nerve (VII) (located in the pons, stimulate secretion of glands in the head)
–Glossopharyngeal nerve (IX) (emerges from the medulla, stimulate secretion of glands in the head)
–Vagus nerve (X) (Located in dorsal motor nucleus in the medulla, innervate visceral organs of the thorax and most of the abdomen,
stimulates digestion, reduction in heart rate and blood pressure)

Question 6

Path of the vagus nerve

Answer 6

Sends branches through Autonomic nerve plexuses
-Cardiac plexus
•Pulmonary plexus
•Esophageal plexus
•Celiac plexus
•Superior mesenteric plexus

Question 7

Parasympathetic

Sacral outflow

Answer 7

Emerges from S2-S4
•Innervates organs of the pelvis and lower abdomen
•Preganglionic cell bodies
–Located in visceral motor region of spinal gray matter
•Axons run in ventral roots to ventral rami
–Form splanchnic nerves
–Run through the inferior hypogastric plexus

Question 8

Basic organization of the sympathetic division

Answer 8

Issues from T1-L2
–Preganglionic fibers form the lateral gray horn
–Supplies visceral organs and structures of superficial body regions
–Contains more ganglia than the parasympathetic division

Question 9

Sympathetic trunk ganglia

Answer 9

-Located on both sides of the vertebral column

•Linked by short nerves into sympathetic trunks

Question 10

.White rami (sympathetic )

Answer 10

-White rami communicantes between each spinal nerve (T1-L2) and the sympathetic trunk
•White rami are the pre-ganglionic fibers which are myelinated

Question 11

Grey rami (sympathetic)

Answer 11

•Grey rami are the postganglionic sympathatic fibers which are unmyelinated communicante to all spinal nerves

Question 12

Pre vertebral ganglia (sympathetic)

Answer 12

-Unpaired, not segmentally arranged
-Occur only in abdomen and pelvis
•Lie anterior to the vertebral column
•Main ganglia
–Celiac, superior mesenteric, inferior mesenteric, inferior hypogastric ganglia

Question 13

Sympathetic pathways to the abdominal organs

Answer 13

-Preganglionic fibers originate in spinal cord (T5-L2)
-Synapse in prevertebral ganglia
•Inhibit activity of muscles and glands in visceral organs

Question 14

Sympathetic pathways to the pelvic organs

Answer 14

• Preganglionic fibers originate in spinal cord (T10 –L2)
• Some preganglionic fibers synapse in sympathetic trunk
• Some preganglionic fibers synapse in prevertebral ganglia
• Postganglionic fibers to pelvic organs

Question 15

The role of the adrenal medulla in the sympathetic division

Answer 15

-Major organ of the sympathetic nervous system
-Constitutes largest sympathetic ganglia
•Secretes great quantities of norepinephrine and adrenaline
•Stimulated to secrete by preganglionic sympathetic fibers

Question 16

Central control of the ANS

Answer 16

-Control by the brain stem and spinal cord
–Reticular formation exerts most direct influence
•Medulla oblongata
•Periaqueductal gray matter (midbrain)
–Control by the hypothalamus and amygdala
•Hypothalamus: the main integration center of the ANS
•Amygdala: main limbic region for emotions
–Control by the cerebral cortex

Question 17

The autonomic nervous system

Answer 17

• system of motor neurons
  –Innervates smooth muscle, cardiac muscle, and glands
  –Regulates visceral functions
  •Heart rate, blood pressure, digestion, urination
  –The general visceral motor division of the PNS