Chapter 9: ANS Flashcards

1
Q

What does the ANS do?

A

It manages our physiology by regulating organs/organ systems and their smooth muscle and glands

  • innervates organs NOT under voluntary control
  • cardiac muscle, smooth muscle, organs, blood vessels, glands
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2
Q

Name the 2 divisions of the ANS and what they are associated with.

A
  1. Sympathetic: fight or flight
  2. Parasympathetic: rest and digest

They usually have antagonistic effects on each other

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3
Q

Discuss the autonomic neurons.

A
  1. Somatic motor neurons: cell bodies in spinal cord and 1 neuron traveling from spinal cord to effector
    ie. voluntary, skeletal muscle
  2. Autnomic motor neurons: 2 sets of neurons in PNS; preganglionic neuron and postganglionic neuron
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4
Q

Discuss the sympathetic division of the ANS.

A
  • “Thoracolumbar division”
  • preganglionic axons exit T1 - L2
  • Short preganglionic axons and long post ganglionic axons (pre. synpase right outside spinal cord - paravertebral ganglia)
  • travel with spinal nerves
  • most act as a unit = mass activation (makes sense b/c fight or flight)
  • white rami communicantes: myelinated axons exit spinal cord ventral root and diverge onto white rami communicantes (on ramp to super highway)
  • gray rami communicantes: unmyelinated axons; postganglionic neurons; return to spinal nerves and travel to effectors (off ramp)
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5
Q

Discuss the parasympathetic division of the ANS.

A
  • “Craniosacral division”
  • Preganglionic axons exit midbrain, medulla, pons, and S2 - S4
  • Preganglionic axons long; Postganglionic axons are short and innervate organs
  • Do NOT travel with spinal nerves

ie. vagus nerve

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6
Q

Be able to discuss an example of the antagonistic effects of the sympathetic and parasympathetic divisions of the ANS.

A

ie. Heart Rate:
If symp division is activated, HR increase
If parasymp division activated, HR decreases

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7
Q

Discuss ANS neurotransmitters.

A

ALL PREganglionic = ACh
Parasymp POSTganglionic = ACh
Symp POSTganglionic = Norepinephrine

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8
Q

Discuss the 3 ways Symp and Parasymp divisions can work together.

A
  1. Usually antagonistic (i.e. HR, pupil dilation)
  2. Complementary (cause similar effects to same target)
    ie. salivation:
    - Parasymp stimulates watery saliva
    - Symp constricts blood vessels so secretion is thicker
    Therefore, overload of parasymp = a lot of drooling but overload of symp = cotton mouth
  3. Cooperative (produce diff effects that work together to produce desired effect)
    ie. micturition:
    Parasymp aids in detrusor muscle contraction
    Symp activity on internal urethral sphincter decreases to allow it to relax and the bladder to empty.
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9
Q

Discuss the control of the ANS by the higher brain centers.

A

Hypothalamus - MAJOR regulatory center of the ANS
- body temp, hunger, thirst

Medulla - directly controls activity of ANS
- cardiovascular, pulmonary, urinary, reproductive, and digestive systems

Limbic system - autonomic responses during emotional states (blushing, pallor, fainting, sweating, racing HR)

Also influence from cerebral cortex and cerebellum

(Hypothalamus tells medulla what to do but medulla has more direct contact/control over the body)

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10
Q

Discuss organs WITHOUT dual innervation.

A
  • Only innervated by simp division:
  • So they are regulated by increase or decrease of symp nerve activity
  • Important for body temp regulation.

Other examples:

  • Adrenal medulla
  • Arrector pili muscles
  • Sweat glands in skin
  • Most blood vessels
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