Ch 9

Question 1

Somatic Nervous System

Answer 1

• somatic neurons have cell bodies in spinal cord and just one neuron traveling from spinal cord to effector (neuromuscular junction)
• somatic motor neurons release only ACh which is always excitatory

Question 2

Autonomic Nervous System

Answer 2

Sympathetic and Parasympathetic divisions

• two neurons in PNS
  1. first has cell bodies in brain or spinal cord and synapses in autonomic ganglion
  2. second has cell bodies in ganglion and synapses on the effector

-autonomic neurons release mainly ACh and norepinephrine and may be excitatory or inhibitory (ex. raise or lower HR)

Question 3

Autonomic Neurons

Answer 3

• innervate organs not under voluntary control
• effectors include:
• -> cardiac muscle, smooth muscle of visceral organs/blood vessels, glands
• part of PNS
• autonomic neurons can stimulate or inhibit, depending on organ and receptors
• -> preganglionic and postganglionic
• -> autonomic ganglia are located in head, neck, and abdomen as well s in chains along either side of spinal cord

Question 4

Preganglionic neurons

Answer 4

originate in the midbrain or hindbrain or from the thoracic, lumbar, or sacral spinal cord

Question 5

Postganglionic neurons

Answer 5

originate in ganglion

Question 6

Sympathetic Division

Answer 6

preganglionic neurons come from thoracic and lumbar regions (thoracolumbar)
-preganglionic neurons synapse in sympathetic ganglia that run parallel to spinal cord (paravertebral ganglia) –> connected forming sympathetic chain of ganglia

Question 7

Adrenal Glands

Answer 7

• adrenal medulla secretes epinephrine and norepinephrine when stimulated by sympathetic nervous system
• directly innervated by preganglionic sympathetic neurons

Question 8

Parasympathetic Division

Answer 8

preganglionic neurons come from the brain or sacral region of the spinal cord (craniosacral division)

• synapse on ganglia located near/or in effector organs called terminal ganglia
• preganglionic neurons do NOT travel w/somatic neurons
• terminal ganglia supply very short postganglionic neurons to then effectors

Question 9

Occulomotor Nerve

Answer 9

• MOTOR NERVE
• preganglionic fibers exit midbrain and synapse on ciliary ganglion
• postganglionic givers innervate the ciliary muscle of the eye

Question 10

Vagus Nerve

Answer 10

• MOTOR/SENSORY NERVE

- preganglionic fibers exit medulla, branch into several plexi and nerves, and travel to ganglia within effector organs

Question 11

Sympathetic Functions

Answer 11

• “fight or flight” –> release of norepinephrine from postganglionic neurons and secretion of epinephrines from adrenal medulla
• prepares body fro intense activity: increases HR/glucose levels
• regulates heart, blood vessels, and other organs

Question 12

Parasympathetic Functions

Answer 12

antagonistic to sympathetic

• “rest and digest” –> release of ACh from postganglionic neurons
• slows HR and increases digestive activities

Question 13

Cholinergic

Answer 13

ACh is used by all preganglionic neurons (sym, para)

• released from most parasympathetic postganglionic neurons
• some sympathetic postganglionic neurons (innervate sweat glands and skeletal muscle blood vessels) release ACh

Question 14

Adrenergic

Answer 14

-norepinephrine is neurotransmitter released by most postganglionic neurons

Question 15

Vericosities

Answer 15

swellings on axons of postganglionic neurons that release neurotransmitter along length of axon
-sympathetic/ parasympathetic neurons innervate the same tissues, but release different neurotransmitter

Question 16

Adrenergic Stimulation

Answer 16

• can be epinephrine in blood OR norepinephrine from sympathetic nerves
• can stimulate or inhibit depending on receptors

Question 17

Adrenergic Stimulation examples

Answer 17

heart, dilatory muscles of the iris, smooth muscles of many blood vessels

Question 18

Adrenergic Inhibition examples

Answer 18

bronchioles in lungs, other blood vessels

–> inhibits contraction and causes dilation of these structures (ex. skeletal muscles)

Question 19

Alpha Adrenergic Receptors

Answer 19

A1 and A2 (sympathetic)

• ->alpha receptors are more sensitive to norepinephrine
• postganglionic neuron
• eye, skin, skeletal muscle, stomach/intestine, liver

Question 20

Beta Adrenergic Receptors

Answer 20

B1 and B2 (sympathetic)

• ->beta receptors are more sensitive to blood epinephrine
• adrenal medulla
• heart, skeletal muscle, lungs, liver

Question 21

Cholinergic Stimulation

Answer 21

• ACh released from preganglionic neurons of both sympathetic/parasympathetic division is STIMULATORY
• ACh from postganglionic neurons of the parasympathetic division is usually stimulatory, but some are inhibitory (depending on receptors)
• ->generally sympathetic and parasympathetic effects are opposite

Question 22

Cholinergic Receptors: Nicotinic

Answer 22

found in autonomic ganglia

• stimulated by ACh from preganglionic neurons
• serve as ligand-gated ion channels for Na and K

Question 23

Cholinergic Receptors: Muscarinic

Answer 23

found in visceral organs

• stimulated by release of ACh from postganglionic neurons
• five types
• stimulatory or inhibitory
• openings of K or Ca channels

Question 24

Organs with Dual Intervention

Answer 24

• most visceral organs are innervated by both sympathetic and parasympathetic neurons
• divisions most often oppose each other
• complementary effects occur when both divisions produce similar effects on same target

Question 25

Dual Intervention

Answer 25

Opposition: 1. heart rate: sym increases, para decreases 2. digestive functions: sym decreases, para increases 3. pupil diameter: sym dilates, para constricts Complement: 1. salivary gland secretion: - sym constricts blood vessels = thicker secretion - para stimulates watery secretion

Question 26

Organs w/o dual intervention

Answer 26

only sympathetic - adrenal medulla - arrector pili muscles in skin - sweat glands in skin - most blood vessels - regulated by increase and decrease in sym nerve activity - important for body temp regulation through blood vessels and sweat glands