Autonomic Nervous system Flashcards

1
Q

Divisions of the Autonomic NS

A
  • sympathetic and parasympethic
  • Also afferent and efferent connections
  • innervates involuntary musucles glandular tissue
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2
Q

Function of the ANS

A
  • regulates activity of internal organs and vasculature
  • homeostasis: circulation, HR, BP, RR, digestion, secretions, temperature
  • reproduction
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3
Q

Sensory receptors of the Autonomic NS

A
  • mechanoreceptors
  • chemoreceptors
  • nocioceptors
  • thermorecepetors
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4
Q

Similarities between somatic and Autonomic NS

A
  • specialized afferents and efferents
  • reflex connections
  • ascending and descending connections to CNS
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5
Q

Differences between somatic and Autonomic NS

A

somatic

  • thalamus receives most ascending info
  • cerebral cortex is source of descending info
  • one neuron system to PNS

autonomic

  • hypothalamus receieves much of the ascending infor
  • hypothalamus is source of descending info
  • a two neuron system to PNS (a lightly myelinated axon to autonmic ganglia and unmyelinated axon to organ)
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6
Q

Afferent system

how does it enter the CNS

A

info from visceral receptors enters the CNS via two routes:

  • into spinal cord via dorsal roots
  • into brainstem via cranial nerves
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7
Q

Regulation of Autonomic NS

A
  • viseral afferent to efferents = reflex is initiated via the afferent system
  • visceral info enters the brainstem via cranial nerves to converge in the solitary nucleus
  • solitary nucleus controls areas in pons and medulla and modulates areas in the hypothalamus, thalamus and limbic system
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8
Q

the efferent system of Autonomic NS

control of the efferent system

A
  • medulla regulates the autonomic efferent system in spinal cord and vagus nerve
  • hypothalamus is the master controller of homeostasis via pituitary, brainstem, and spinal cord
  • visceral info from thalamus projects to limbic system (increase HR with anxiety)
  • connect with somatosensory nociceptive afferents as in referred pain
  • connect with somatic efferents as in muscle guarding
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9
Q

How is the CNS connected to the autonomic effectors

A
  • preganglionic from CNS to ganglion
  • post ganglionic connects ganglion with organ
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10
Q

what are the three systems within the Autonomic NS

A
  • sympathetic NS
  • parasympathetic NS
  • enteric NS
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11
Q

comparision of sympathetic and parasympathetic NS

A
  • sympathetic nervous system also known as the thoracolumbar or adrenergic system and postganglionic neurotransmitter = NE
  • parasympathetic NS is known is cranosacral and postganglionic NT = AcH
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12
Q

function of the Sympathetic NS

A
  • optimal blood supply to organs (orthostatic hypotension if this doesnt happen)
  • respose to flight or fear
  • maintain blood pressue with change of position
  • regulation of body temperature (adrenal medulla releases epi.)
  • blood flow regulation in skeletal muscules
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13
Q

Fight or flight response

A
  • sweating
  • hair cells
  • pupil dilation
  • vasoconstriction in skin and gut to increase blood flow to active muscules
  • blood glucose levels increase
  • bronchi and coronary vessels dilate
  • BP/HR increase
  • sympathetic firing decreases digestive system activity
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14
Q

Sympathetic NS efferent

preganglionic

A
  • cell bodies of preganglionic neurons are in lateral horn of spinal cord T1-L2
  • preganglionic neurons innervate adrenal medulla a specialized sympathetic ganglion
  • secretes epinephrine and norepinephrine into blood stream
  • preganglionic neurons to paravertebral ganglion where they synpase or go up or go down trunk to synpse in another ganglion
  • ganglia are interconnected and form a trunk runnign beside vertebrae
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15
Q

Sympathetic NS efferent

postganglionic

A
  • cell bodies of postganglionic neurons are in paravertebral ganglion
  • postganglionic axon enters a peripheral nerve via a rami communicant
  • then travels in a dorsal or ventral ramus to target organ
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16
Q

Sympathetic NS efferent

paravertebral ganglion

A
  • cervical paravertebral ganglion that carry the preganglionic fibers from thoracolumbar area to head, face, and UE
  • lower lumbar and sacral paravertebral ganglion descend from upper lumbar cord
17
Q

Sympathetic NS efferent

Preganglionic axons to abdominal and pelvic organs

A
  • pass through sympathetic ganglia without synpasing
  • synpases is with an organ
  • signals to GI tract: stop or slow peristalsis
  • reduce gland secretion
  • signals to seminal vesicles elicit ejaculation
18
Q

Parasympathetic NS structure

A
  • also known as cranial sacral
  • arises from CNs and spinal levels S2-S4
  • cholinergic system
  • post ganglionic NT = acH
19
Q

function of

Parasympathetic NS

A
  • releases ACh onto end organs
  • involved in more sedentary functions
  • decrease pupil size, increase gastic secretion and peristalsis, slowing heart rate
  • energe conservation and storage
20
Q

enteric NS

A
  • function is to serve the alimentary canal
  • motility of the gut can function without the CNS, though if properly functioning is modulated by sympathetic and parasympathetic systems
  • the enteric NS is entirely outside CNS inculding sensory nerves, interneurons and visceral motor neurons
21
Q

ANS clinical disorders

Horners syndrome

A
  • lesion affects the sympathetic pathway to the head
  • sympathetic activity on one side of the head is decreased
  • results in ipsilateral drooping of the upper eyelid, constriction of the pupil, skin, vasodilation with absence of sweating on the ipsilateral face and neck
22
Q

ANS clinical disorders

autonomic dysfunction: spinal shock

A
  • complete lesions above T6
  • autonomic dysreflexia
  • poor thermoregulation
  • orthostatic hypotension
23
Q

ANS clinical disorders

Autonomic dysfunction: peripheral region

A
  • peripheral nerve severed = interruption of sympathetic efferents
  • causes loss of vascular control, temperature regulation and sweating in region supplied by the peripheral nerve
  • may lead to trophic changes in the skin
  • postural orthostatic tachycardia syndrome (POTS)
24
Q

ANS clinical disorders

Autonomic dysfunction: brainstem

A
  • descendign control of heart rate, BP and respiration
  • cranial nerve nuclei = interference of pupil constriction, tear/saliva production, regulation of thoracic/abdominal viscera
25
Q

ANS clinical disorders

Autonomic dysfunction: cerebral region

A

hypothalamus damage disrupts homeostasis

26
Q

Syncope

A
  • brief loss of consciousness due to inadequate blood flow to the brain
  • high emotion
  • vasovagal attack
27
Q

types of

syncope

A
  1. neural reflexive
  2. orthostatic hypotension
  3. cardiac arrhythmias
28
Q

Syncope

neural reflexive

A
  • neurocardiogenic/vasovagal-emotional distress
  • situational-cough, sneeze, defecation, urination
  • carotid sinus hypersensitivity
29
Q

Syncope

orthostatic hypotension

A
  • decrease of at least 20mmHg systolic BP or 10 mmHg during the first 3 minutes of standing
  • gravity induced pooling of blood in the lower limbs, compromising venous return and cardiac output = decrease in arterial pressure
  • spinal cord disorders, PD, peripheral neuropathy
30
Q

tests of

autonomic function

A
  • BP regulation with position changes
  • sweat test: amout of salt in sweat
  • vasomotor test
  • valsava test: blow into closed tube with small hole