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Physiology > Exam 2: Ch 9 ANS > Flashcards

Exam 2: Ch 9 ANS Flashcards

1
Q

 Autonomic nervous system (ANS)

A

manages our physiology by regulating cardiac & smooth muscles & glands that are not under voluntary control

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2
Q

 Neurons that conduct impulses away from CNS =

A

= motor = efferent

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3
Q

 2 types of Efferent neurons

A
  1. somatic pathway

2. autonomic pathway

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4
Q

somatic pathway

A

have cell bodies in CNS and send axons to skeletal muscle for voluntary control

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5
Q

Somatic = skeletal muscle

The pathway

A

(sensory neuron → CNS → motor out put neurons→ effector organ)

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6
Q

autonomic pathway =

A

sensory neuron → CNS → preganglionic neuron → postganglionic neuron → effector organ)

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7
Q

Autonomic ganglion

A

collection of cell bodies outside of CNS; located in head, neck, abdomen, and parallel to the spinal cord

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8
Q

Preganglionic fibers

A

originate in midbrain, hindbrain, upper thoracic to 4th sacral level of spinal cord

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9
Q

 ANS Control of Muscle:

Skeletal muscle

A

 Skeletal muscle is paralyzed without innervation,

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10
Q

ANS Control of Muscle:

smooth muscle and cardiac muscle

A

maintains resting tone (tension or contracts) in absence of nerve stimulation; ex. Heart

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11
Q

denervation hypersensitivity

A

 Smooth & cardiac muscle become more sensitive when ANS input is cut

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12
Q

 Some types of muscle are spontaneously active & contract rhythmically without ANS input

A

 ANS input simply increases or decreases intrinsic activity but recall that ACh always excites skeletal muscle

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13
Q

Feature: effector organs:

- somatic and Autonomic motor?

A

somatic motor: skeletal muscles

autonomic motor: cardiac muscle, smooth muscles, and glands

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14
Q

Feature: presence of ganglia

- somatic and Autonomic motor?

A

somatic motor: no ganglia

autonomic motor: cell bodies of postganglionic autonomic fibers located in paravertebral (collateral) and terminal ganglia

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15
Q

Feature: number of neurons from CNS to effecgtor

- somatic and Autonomic motor?

A

somatic motor: One

autonomic motor: two

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16
Q

Feature: type of neuromuscular junction

- somatic and Autonomic motor?

A

somatic motor: specialized motor end plate

autonomic motor: none; all areas of smooth muscle cells contain receptor proteins for neurotransmitters

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17
Q

Feature: effect of nerve impulse on muscle

- somatic and Autonomic motor?

A

somatic motor: excitatory only

autonomic motor: either excitatory or inhibitory

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18
Q

Feature: type of nerve fibers

- somatic and Autonomic motor?

A

somatic motor: fast-conducting and myelinated

autonomic motor: slow-conductin: preganglionic fibers lightly myelinated but thing: postganglionic fibers unmyelinated and very thin

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19
Q

Feature: effect of denervation

- somatic and Autonomic motor?

A

somatic motor: flaccid paralysis and atrophy

autonomic motor: Muscle tone and function persist: target cells show denervation hypersensitivity

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20
Q

2 divisions of ANS

A

sympathetic & parasympathetic divisions

- usually have antagonistic effects and coordinate physiology

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21
Q

 Both sympathetic and parasympathetic systems

• Consist of preganglionic neurons originating in CNS

A
  • Preganglionic sympathetic fibers

* Preganglionic parasympathetic fibers

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22
Q

 Both sympathetic and parasympathetic systems

• Consist of postganglionic neurons originating outside the CNS in ganglia

A
  • Postgagnlionic sympathetic fibers

* Postgagnlionic parasympathetic fibers

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23
Q

 Preganglionic fibers of sympathetic division

A

originate in the spinal cord between thoracic and lumbar levels

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24
Q

 Sympathetic division mediates

A

“fight, flight, & stress” reactions mostly through the release of norepinephrine from postganglionic fibers and epinephrine from the adrenal medulla

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25
 Preganglionic fibers of parasympathetic division
originate in the brain and in the sacral levels of the spinal cord
26
 Parasympathetic division mediates
"rest & digest" reactions through the release of Ach from postganglionic fibers
27
 The 2 divisions must be balanced to
maintain homeostasis
28
Sympathetic Division of the ANS is also called
thoracolumbar division because its preganglionic neurons exit spinal cord from T1 to L2
29
 Most sympathetic fibers then separate from somatic motor neurons and synapse on
postganglionic neurons within a double row of ganglia called the paravertebral ganglia
30
sympathetic chain of ganglia
chain of interconnected ganglia paralleling spinal cord formed by paravertebral ganglia
31
• Mylenated preganglionic sympathetic axons exit the
the spinal cord in the ventral roots of spinal nerves but diverge within short pathways called white rami communicantes
32
• Axons within each ramus enter
sympathetic chain of ganglia where they travel to ganglia at different levels and synapse with postganglionic symapthetic neurons
33
Axons of postganglionic neurons are
unmylenated and form the gray rami communicates as they return to spinal nerves
34
 Since sympathetic axons form a component of spinal nerves they are
widely distributed to skeletal muscles and skin where they innervate blood vessels and other involuntary effectors
35
 Divergence
occurs in the sympathetic chain of ganglia as preganglionic neurons branch to synapse with postganglionic neurons located in ganglia at different levels in the chain
36
 Convergence
occurs where a postganglionic neuron receives input from a large number of preganglionic neurons
37
 Divergence & convergence together cause
the sympathetic division to mostly act as a unit (mass activation)
38
Some preganglionic neurons that exit the spinal cord below the diaphram
do not synapse in the symapthetic chain of ganglia
39
 Beyond the sympathetic chain these preganglionic fibers form
splanchnic nerves and synapse in collateral ganglion (preventral ganglia)
40
 Postganglionic fibers that arise from collateral ganglia innervate
organs of the digestive, urinary, and reproductive systems
41
 Sympathoadrenal System
 Paired adrenal glands located on top of the
42
 Paired adrenal glands located on top of the kidneys are composed of 2 parts:
1. outer adrenal cortex (secretes steroid hormones) and | 2. inner adrenal medulla (mostly secretes epinephrine 85% (adrenaline) and norepinephrine (less ~ 15%))
43
 The adrenal medulla appears to be
a modified symapthetic ganglion because it has the same embryonic origin as the postganglionic sympathetic neurons
44
 Cells of adrenal medulla are innervated by
by preganglionic sympathetic fibers
45
 Cells of adrenal medulla are Stimulated during
mass activation of sympathetic division of ANS
46
 Parasympathetic Division of the ANS is also called
because long preganglionic parasympathetic fibers originate in midbrain, medulla, pons, & 2nd – 4th sacral region of spinal column
47
 Preganglionic parasympathetic fibers synapse on
postganglionic parasympathetic fibers in parasympathetic ganglia called terminal ganglia located next to or within target organ
48
 Postganglionic fibers have
short axons that innervate targets
49
Most parasympathetic fibers do NOT
do NOT travel with spinal nerves as do the sympathetic fibers thus, cutaneous effectors (blood vessels, sweat glands, arrector pili muscles) receive sympathetic but NOT parasympathetic innervation
50
 The long vagus nerve carries most
most parasympathetic fibers
51
 The long vagus nerve innervates
 Innervates heart, lungs, esophagus, stomach, pancreas, liver, small intestine, and upper half of the large intestine
52
 Preganglionic fibers from S2-4
innervate lower half of large intestine, rectum, urinary & reproductive systems
53
 4 of 12 pairs of cranial nerves contain
preganglionic parasympathetic fibers. |  Oculomotor (III), facial (VII), and glossopharyngeal (IX) synapse with ganglia located in the head.
54
Fibers in the vagus nerve (X) synapse in terminal ganglia spread throughout
the body (heart, lungs, esophagus, stomach, pancreas, liver, small intestine, and upper ½ of large intestine
55
ANS Neurotransmitters
 Both sympathetic & parasympathetic preganglionic fibers release ACh
56
 Parasympathetic postganglionic fibers also
ACh |  Called cholinergic synapses = all preganglionic fibers
57
 Most postganglionic sympathetic fibers release
norepinephrine (noradenaline); called adrenergic synapses |  A small number release Ach
58
Where postganglionic autonomic neurons enter into their target organs they have
have many swellings called varicosities, which release NTs along a length of axon  This forms unusual synapses synapses en passant
59
 Adrenergic stimulation
by epinephrine release into the blood or norepinephrine release at a synapse
60
 Adrenergic stimulation causes
causes both excitation & inhibition depending on tissue |  Because of different subtypes of receptors for same NT
61
 Many useful drugs have been developed to
affect ANS receptors
62
agonists
 Drugs that promote actions of a NT
63
antagonists
 Drugs that inhibit actions of a NT
64
 ACh is used at
all motor neuron synapses (excitatory) on skeletal muscle, all preganglionic neurons (excitatory), & parasympathetic postganglionic neurons (usually excitatory)
65
 Cholinergic Stimulation |  Cholinergic receptors have 2 subtypes:
Nicotinic | muscarinic
66
Nicotinic receptors are stimulated by
by nicotine and Ach and are always excitatory; located in NMJs and autonomic ganglia (released by preganglionic neurons); blocked by curare
67
 Muscarinic receptors are stimulated by
by ACh and muscarine (from poisonous mushrooms) and can be excitatory or inhibitory; released by postganglionic parasympathetic neurons;
68
Muscarinic receptors are blocked by
atropine = belladonna
69
“nonadrenergic, noncholinergic fibers”
 Some postganglionic neurons do not use norepinephrine or Ach
70
nonadrenergic, noncholinergic fibers” |  Appear to use
ATP) adenosinetriphosphate, (VIP) vasoactive intestinal peptide, or (NO) nitric oxide as NTs • NO produces smooth muscle relaxation in many tissues (stomach, urinary bladder, small intestine)
71
 Most visceral organs receive
dual innervation (supplied by both sympathetic & parasympathetic fibers)
72
2 branches are usually antagonistic
effects on heart rate (sympathetic innervation ↑ HR and parasympathetic innervation ↓HR) or digestive tract where sympathetic innervation inhibits movement and parasympathetic innervation increases movement and secretions
73
 Can be complementary (cause similar effects) such as with
such as with salivation • parasympathetic fibers cause watery saliva secretion and secretions of other glands in the digestive tract  sympathetic nerves stimulate constriction of blood vessels throughout the digestive tract thus there is a decrease blood flow to salivary glands causing thicker saliva
74
 Or cooperative or synergistic
(produce different effects that work together to cause desired effect) eg., reproductive system: erection and vaginal secretions are stimulated by the parasympathetic division and orgasm and ejaculation are cause by sympathetic division
75
 Organs Without Dual Innervation |  Most organs receive dual innervation but some only receive sympathetic innervation and regulation is achieved by
increasing or decreasing firing rate
76
 Adrenal medulla, arrector pili muscle, sweat glands, & most blood vessels receive only
sympathetic innervation
77
 Medulla oblongata most directly controls activity of
ANS by receiving afferent information via CNX (vagus)
78
 Medulla oblongata has centers for control of
of cardiovascular, pulmonary, urinary, reproductive, & digestive systems
79
 Hypothalamus has centers for control of
body temperature, hunger, thirst, the pituitary gland, the cerebral cortex and limbic system (emotions), & can regulate medulla oblongata!!
80
 Limbic system is responsible for
visceral responses that reflect emotional states
81
 Cerebral cortex & cerebellum
also influence ANS

Physiology (27 decks)

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