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Physiology > Unit 2 Chapter 2: The Autonomic Nervous System > Flashcards

Unit 2 Chapter 2: The Autonomic Nervous System Flashcards

1
Q

The autonomic nervous system

A

The portion of the nervous system that controls the visceral functions (internal organs) of the body.

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2
Q

Autonomic organization of the autonomic outflow

A

Impulses initiated in visceral receptors are relayed via Afferent autonomic fibers to the CNS, and transmitted via efferent pathways to visceral effectors (plain muscles, heart, secreting glands).

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3
Q

How is the efferent pathways to the viscera of the autonomic NS different from the somatic motor nerves to the skeletal muscles?

A
  1. Each motor somatic pathway from the cord to a skeletal muscle is composed of a single fiber (one neuron system).
  2. Each autonomic, involuntary pathway is composed of two fibers, the preganglionic and the postganglionic neurons (2 neurons system).
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4
Q

Differences between somatic and autonomic reflexes

A

Somatic reflexes
1. Afferent fibers: relay at dorsal horn cells or cranial neuron.
2. Origin from CNS: anterior horn cells of the spinal cord.
3. Efferent fibers: one neuron system.
4. Myelination: mostly myelinated.
5. Chemical transmitters: acetyl choline.
Autonomic reflexes
1. Afferent fibers: relay at lateral horn cells or cranial nuclei.
2. Origin from CNS: lateral horn cell and cranial nuclei.
3. Efferent fibers: two neuron systems.
4. Myelination:
- preganglionic: myelinated B fiber.
- post ganglionic: unmyelinated C fiber.
5. Chemical transmitters: acetyl choline and noradrenaline.

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5
Q

What is a ganglion?

A

A collection of neurons outside the CNS.
It contains the mother neurons of the postganglionic nerve fibers.

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6
Q

Where are the cell bodies of the preganglionic neurons located.

A

In the lateral horn of the pineal cord or the motor nuclei of the cranial nerves.

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7
Q

Myelination of preganglionic axons

A

Mostly myelinated B fibers.

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8
Q

How many synapses are done on the postganglionic by the preganglionic axon?

A

Each preganglionic axon synapse on 8 to 9 cell bodies of postganglionic neurons located outside the CNS.

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9
Q

Myelination of the postganglionic axons

A

Mostly unmyelinated C fibers that end on the visceral effectors.

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10
Q

Functions of autonomic ganglia

A
  1. Autonomic ganglia act as distribution center.
  2. Each preganglionic fiber synapse on 8 to 9 ganglionic neurons. This way, the autonomic output is diffused.
  3. The ratio between preganglionic to the postganglionic fibers is 1:8 or 1:9.
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11
Q

Types of autonomic ganglia

A
  1. Paravertebral sympathetic chain.
  2. Collateral ganglia.
  3. Terminal ganglia.
  4. Adrenal melluda.
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12
Q

Paravertebral sympathetic chain

A
  1. For relay of sympathetic fibers only.
  2. Present in both sides of the vertebral column.
  3. A ganglion for each segment of the spinal cord.
  4. Only 3 ganglia for the cervical region: superior, middle, and inferior.
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13
Q

Collateral ganglia

A

Present midway between the spinal cord and the viscera at the origin of big vessels arising from the abdominal aorta.
- Named according to their vessel name:
1. Ganglia for the relay of the sympathetic fibers: celiac, superior mesenteric, and inferior mesenteric ganglia.
2. Ganglia for the relay of the parasympathetic fibers: cilliary, sphenopalatine, submaxillary, and Otic ganglia.

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14
Q

Terminal ganglia

A
  1. Relay for parasympathetic fibers.
  2. Near or in the visceral organ itself.
  3. The postganglionic parasympathetic fibers are very short: 1mm to several cm in length.
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15
Q

Adrenal melluda

A
  1. Preganglionic cholinergic sympathetic fibers.
  2. Considered as modified sympathetic ganglion in which the postganglionic cells (neurons) have lost their axons and secrete catecholamines directly in the blood streams.
  3. Stimulation of the adrenal medulla causes large quantities of adrenaline (80%) and noradrenaline (20%) to be released into circulating blood.
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16
Q

The sympathetic nervous system (thoraco-lumber) origin

A

The sympathetic nerves from the lateral horn cells of all thoracic and upper 3 lumber segments of the spinal cord.

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17
Q

The sympathetic nervous system (thoraco-lumber) course

A

The preganglionic sympathetic fibers leave the spinal cord with the ventral roots of the corresponding spinal nerves. Then, they pass into the ganglia of the Paravertebral sympathetic chain. Then the course can be one of the three ways.

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18
Q

Three ways

A

A. Fibers can synapse with post ganglionic neurons in the ganglion that it enters.
B. Fibers can pass up or down in the chain and synapse in one of the other ganglia:
- postganglionic fibers from the Paravertebral sympathetic chains renter the spinal nerves to supply all the other parts of the body.
- approximately 8% of the fibers in the spinal nerves are sympathetic fibers.
C. Fibers can pass through the chain without relay then pass to synapse with the neurons in collateral ganglion.

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19
Q

Functions of the sympathetic nervous system

A

Catabolic and energy consuming system:
1. Flight
2. Fear
3. Fight
4. Stress

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20
Q

Function of the sympathetic system on the head and neck origin

A

The preganglionic neurons arise from the lateral horns cells (LHC’s) of the first and second thoracic segments.

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21
Q

Function of the sympathetic system on the head and neck relay

A

They ascend to synapse with the neurons in the cervical ganglia.

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22
Q

Function of the sympathetic system on the head and neck course

A

The postganglionic fibers run in the outer coat (sheath) of the blood vessels to the various structures.

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23
Q

Functions of the sympathetic system (Eye)

A
  1. Contraction of dilator pupillae muscle which leads to the dilatation of the pupil (mydriasis).
  2. Relaxation of cilliary muscle which decreases power of the lens to see far objects.
  3. Contraction of smooth muscle of the upper eyelid which leads to the widening of palpebral fissure and increases the field of vision.
  4. Contraction of muller’s muscles in some animals which leads to forward protrusion of eyeball and exopthalmus to increase field of vision.
  5. Vasoconstriction to conjunctival.
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24
Q

Functions of the sympathetic system of the head and neck (skin)

A
  1. Secretory of sweat glands.
  2. Vasoconstriction to cutaneous blood vessels.
  3. Contraction of piloerector muscle which leads to erection of hairs.
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25
Q

Functions of the sympathetic system of the head and neck (glands)

A
  1. Salivary glands (mainly on submaxillary) which leads to tropic secretion of salvia, concentrated, small in amount and viscid.
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26
Q

Functions of the sympathetic system of the head and neck (cerebral circulation)

A
  1. Cerebral blood flow is increased due to rise of systemic arterial blood pressure while cerebral vessels are mildly constricted.
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27
Q

Functions of the sympathetic system of the head and neck (Brain)

A

Increase mental alertness.

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28
Q

Horners syndrome cause

A

Lesion on one side of the cervical sympathetic chain.

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29
Q

Horners syndrome manifestations

A

On the same side of the lesion:
1. Miosis
2. Ptosis
3. Anhydrosis
4. Warm and red skin

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30
Q

Miosis

A

Constricted pupil relative to the opposite eye.

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31
Q

Ptosis

A

Drop of the superior eyelid.

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32
Q

Anhydrosis

A

Absence of sweating on the affected side of the head and neck.

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33
Q

Warm and red skin

A

Due to dilatation of the blood vessels of the head and neck.

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34
Q

Functions of the sympathetic system on the thoracic viscera (Origin)

A

Preganglionic fibers arise from LHC’s (lateral horn cells) of the upper 4 thoracic segments.

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35
Q

Functions of the sympathetic system on the thoracic viscera (Relay)

A

Preganglionic fibers relay in the cervical ganglia and upper 4 thoracic ganglia in the paravertebral sympathetic chain.

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36
Q

Functions of the sympathetic system on the thoracic viscera (Course)

A

The postganglionic fibers then travel to the different organs.

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37
Q

Functions of the sympathetic system on the thoracic viscera (Heart)

A

Increases all cardiac properties:
1. Increases rate and force of contraction.
2. Increases excitability and rate of conduction.
Vasodilation of the coronary blood vessels (= indirect effect).

38
Q

Functions of the sympathetic system on the thoracic viscera (Lungs)

A
  1. Bronchodilatation.
  2. Vasoconstriction to pulmonary vessels.
39
Q

Functions of the sympathetic system on the abdominal viscera (Origin)

A

Preganglionic fibers rise from LHC’s in the lower 6 thoracic segments. They pass through the Paravertebral chain without relay. They leave the chain as greater splanchnic nerve.

40
Q

Functions of the sympathetic system on the abdominal viscera (Relay)

A

Fibers of the greater splanchnic nerve relay in the collateral ganglia.
Eg. Celiac or coeliac ganglia and superior mesenteric ganglia.

41
Q

Functions of the sympathetic system on the abdominal viscera (Course)

A

Postganglionic fibers run with the blood vessels to the abdominal viscera.

42
Q

Functions of the sympathetic system on the abdominal viscera (Gastrointestinal tract)

A
  1. Relaxation of plain muscles of the wall of the stomach, small intestine, and proximal part of the large intestine.
  2. Contraction of the sphincters.
    Eg. The pyloric sphincter.
43
Q

Functions of the sympathetic system on the abdominal viscera (Blood vessels)

A
  1. Vasoconstriction of the arterioles of the stomach, small intestine, and proximal part of the large intestine, kidney, pancreas, and liver.
  2. Vasodilation of some arterioles of abdominal viscera.
44
Q

Functions of the sympathetic system on the abdominal viscera (Liver)

A
  1. Stimulation of glycogenolysis thus increasing level of blood glucose.
45
Q

Functions of the sympathetic system on the abdominal viscera (Spleen)

A

Contraction of splenic capsule releasing the stored blood, rich in RBC’s, into the circulation.

46
Q

Functions of the sympathetic system on the abdominal viscera (Adrenal medulla)

A
  1. Secretes adrenaline and noradrenaline directly into the blood.
47
Q

Functions of the sympathetic system on pelvic viscera (origin)

A

Preganglionic fibers arise from the LHC’s of the 12th thoracic segments and upper 3 lumber segments. They pass through the Paravertebral chain without relay. They leave the chain as lesser splanchnic nerve.

48
Q

Functions of the sympathetic system on pelvic viscera (relay)

A

Fibers of the lessen splanchnic nerve relay in the collateral ganglia Eg. Inferior mesenteric ganglion.

49
Q

Functions of the sympathetic system on pelvic viscera (course)

A

Postganglionic fibers pass with the blood vessels to the pelvic viscera.

50
Q

Functions of the sympathetic system on pelvic viscera (functions) Gastrointestinal tract

A
  1. Relaxation of plain muscles of the wall of the distal part of the large intestinal and rectum.
  2. Contraction of the internal anal sphincter leading to retention of feces.
51
Q

Functions of the sympathetic system on pelvic viscera (functions) urinary bladder

A
  1. Relaxation of plain muscles of the wall of the urinary bladder.
  2. Contraction of internal urethral sphincter leading retention of urine.
52
Q

Functions of the sympathetic system on pelvic viscera (functions) male genital system

A

a. Vasoconstriction of blood vessels of pelvic viscera and external genital
organs in the male leading to shrinkage of the penis.
b. Contraction of Vas deferens, seminal vesicles, and prostate leading to
ejaculation of semen.

53
Q

Functions of the sympathetic system on pelvic viscera (functions) female genital organs

A
  1. Variable effects on the uterine muscles depending on the stage of menstrual cycle.
54
Q

Function of sympathetic system on limbs

A
  1. Contraction of piloerector muscles (hair erection).
  2. Skeletal muscles: increased glycogenolysis, increased strength and delay muscle fatigue.
55
Q

Functions of sympathetic system in metabolism and blood

A
  1. Basal metabolism: increased up to 100%.
  2. Increased blood glucose and lipids.
  3. Stimulates lipolysis fat cells (brown fats).
  4. Blood: enhance clotting.
56
Q

What happens to the distribution of sympathetic innervations?

A

It is only approximate and overlaps greatly.

57
Q

The parasympathetic nervous system (cranio-sacral)

A

Anabolic and energy preserving system (rest, digest, reading).

58
Q

Functions of the parasympathetic system on the head and neck

A
59
Q

the oculomotor nerve (cranial nerve III) origin

A

Preganglionic fibers arise from edinger-Westphal nucleus in the midbrain.

60
Q

the oculomotor nerve (cranial nerve III) relay

A

They relay in the cilliary ganglion.

61
Q

the oculomotor nerve (cranial nerve III) course

A

Postganglionic fibers enter the eye as short cilliary nerves.

62
Q

the oculomotor nerve (cranial nerve III) functions

A
  1. Contraction of constrictor pupillae muscle which leads to pupil constriction (miosis).
  2. Contraction of cilliary muscle which leaves to increase in the power of the lens, preparing the eye for near vision.
63
Q

The facial nerve (cranial nerve VII) origin

A

Preganglionic fibers rise from superior salivary nucleus in the lower pons.

64
Q

The facial nerve (cranial nerve VII) relay

A

Some preganglionic fibers relay in the sphenopalatine ganglion. Other fibers run in the chords tympani (branch of the facial nerve) to relay in the submandibular region.

65
Q

The facial nerve (cranial nerve VII) course

A

Postganglionic fibers from the sphenopalatine ganglion will supply the lacrimal and nasal glands. Postganglionic fibers from the submandibular ganglion will supply the submandibular and the sublingual salivary glands.

66
Q

The facial nerve (cranial nerve VII) functions

A

Secrete motor and vasodilator.

67
Q

The glossopharnygeal nerve (cranial nerve IX) Origin

A

Preganglionic fibers arise from the inferior salivary nucleus at the junction of the pons and medulla.

68
Q

The glossopharnygeal nerve (cranial nerve IX) relay

A

In the otic ganglion.

69
Q

The glossopharnygeal nerve (cranial nerve IX) course

A

Postganglionic fibers will supply the parotid gland.

70
Q

The glossopharnygeal nerve (cranial nerve IX) functions

A

Secretomotor and vasodilator fibers.

71
Q

Vagus nerve (cranial nerve X) origin

A

Preganglionic fibers arise from the vagal nucleus in the medulla oblongata.

72
Q

Vagus nerve (cranial nerve X) course

A

Preganglionic fibers run in the vagus nerve to supply the entire thoracic and abdominal viscera. They constitute of 75% of all parasympathetic fibers.

73
Q

Vagus nerve (cranial nerve X) relay

A

They relay in the terminal ganglia (inside or close to the organ).

74
Q

Vagus nerve (cranial nerve X) functions: heart.

A
  1. The vagus doesn’t supply the ventricles.
  2. Inhibition of all properties of atrial cardiac muscles only.
  3. Decrease coronary blood flow and O2 consumption.
75
Q

Vagus nerve (cranial nerve X) functions: lungs

A
  1. Broncho-constriction.
  2. Dilation of pulmonary blood vessels.
  3. Stimulation of bronchial glands.
76
Q

Vagus nerve (cranial nerve X) functions: Gastrointestinal tract

A
  1. Contraction of the plain muscles of the wall of the:
    - Esophagus
    - Stomach
    - Small intestine
    - proximal part of the large intestine
  2. Relaxation of the sphincters.
  3. Secretory to GIT glands, liver, and pancreas.
77
Q

Vagus nerve (cranial nerve X) functions: gall bladder

A
  1. Evacuation of gall bladder: contraction of the wall and relaxation of the sphincter oddi.
78
Q

Functions of the parasympathetic system on the pelvic viscera (origin)

A

Preganglionic fibers arise from the 2nd, 3rd, and 4th sacral segments.

79
Q

Functions of the parasympathetic system on the pelvic viscera (course)

A

Preganglionic fibers run as the pelvic nerve (nervi erigentes).

80
Q

Functions of the parasympathetic system on the pelvic viscera (relay)

A

They relay in the terminal ganglia (inside or close to the organ).

81
Q

Functions of the parasympathetic system on the pelvic viscera (Defecation)

A

Due to the contraction of the wall of the rectum and relaxation of internal anal sphincter.

82
Q

Functions of the parasympathetic system on the pelvic viscera (micturation)

A

Due to contraction of the wall of the bladder and relaxation of the internal urethral sphincter.

83
Q

Functions of the parasympathetic system on the pelvic viscera (erection)

A

Due to vasodilation of blood vessels of the penis.

84
Q

Functions of the parasympathetic system on the pelvic viscera (female genital organs)

A

Vasodilation

85
Q

Centers of the autonomic reflexes

A

Levels of autonomic integration within the central nervous system are variable.

86
Q

What are types of the centers of the autonomic reflexes?

A
  1. Simple reflexes: are integrated in the spinal cord.
  2. Complex reflexes: integrated at higher levels in the C.N.S.
87
Q

Simple reflexes

A

Contraction of the full bladder are integrated in the sacral segments of the spinal cord.

88
Q

More complex reflexes

A
  1. Regulate respiration and blood pressure.
  2. Integrated in the medulla oblongata.
89
Q

Reflexes that control pupillary responses

A

Integrated in the midbrain.

90
Q

Autonomic mechanisms

A
  1. Maintain chemical constancy and temperature of the internal environment.
  2. Integrated in the hypothalamus.
91
Q

Emotional and behavioral reflexes

A

Regulated by the hypothalamus with the limbic system in the cerebral cortex.

Physiology (11 decks)

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