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Neuro B4 - WLB > Homeostasis (Stayin' Alive) - Trachte > Flashcards

Homeostasis (Stayin' Alive) - Trachte Flashcards

1
Q

What is usually viewed as the most important physiological function?

A

Homeostasis

-process of maintaining a relatively constant internal environment

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2
Q

What part of the brain is a key integrator of homeostatic systems?

A

Hypothalamus

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3
Q

What is the largest threat to thermoregulation?

A

Overheating

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4
Q

How does the body compensate when overheating?

A
  • Increased heat loss
    • Sweating
    • Panting
    • Posture changes
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5
Q

What is hypothermia resisted by?

A
  • Heat conservation
  • Increased heat production (shivering)
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6
Q

What are the two sources of input that relay info if the body is below/above the set point (37°C)?

A
  1. Skin temperature receptors
  2. Core temperature receptors (spinal cord)
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7
Q

To avoid too high of a temperature, local temperature sensors cause a release of what? Why?

A

Nitric Oxide (NO)

  • acts as a vasodilator
  • increases surface blood flow
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8
Q

To avoid too high of a temperature, core temperature sensors send signals to the CNS to activate what? Why?

A

Sympathetic Nerve Outflow

(both adrenergic - NE & cholinergic - ACh)

  • Increases skin blood flow
  • Increases sweating
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9
Q

To avoid too low of a temperature, cold stimulates skin sensors to increase release of what? Why?

A

Norepinephrine

  • Constricts blood skin blood vessels
  • Keep core warm
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10
Q

To avoid too low of a temperature, core temperature sensors stimulate the CNS to increase what? Why?

A

Sympathetic Nervous System Outflow

-To decrease skin blood flow

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11
Q

What elevates the internal thermostat in a fever?

A

Pyrogen = Interleukin

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12
Q

What does the hypothalamus produce in response to elevated internal thermostat (pyrogen)?

A

PGE2

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13
Q

What effect does the release of prostaglandins during a fever cause in the body?

A
  • Shivering
  • Increased metabolic rate
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14
Q

What receives input from temperature sensors elsewhere in the body, but does not actually change temperature itself?

A

Hypothalamus

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15
Q

Why do 80% of postmenapausal women have hot flashes?

A

They have an extremely narrow (unmeasurable) thermoregulatory zone.

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16
Q

What is the definition of blood pressure?

A

relationship b/t flow & resistance

BP = (Heart Rate) x (stroke volume) x

(total peripheral resistance)

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17
Q

Blood pressure is largely determined by release of what?

A

Norepinephrine release from sympathetic nerves

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18
Q

What do sympathetic nerves interact with to stimulate heart rate?

A

Beta-1 receptors

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19
Q

What do sympathetic nerves interact with to increase stroke volume?

A

Beta-1 receptors

20
Q

What do sympathetic nerves interact with to increase resistance in blood vessels?

A

Alpha-1 receptors

21
Q

What other parasympathetic nerve contributes major input in blood pressure regulation?

A

Vagus Nerve (CN X)

22
Q

The Vagus Nerve releases _______ to interact with ______ in the heart to slow heart rate.

A

Acetylcholine –> muscarinic receptors

23
Q

What kind of receptors are located in the carotid arteries and aortic arch to monitor blood pressure?

A

Stretch

24
Q

What two nerves carry the stretch receptor impulses back to the brain?

A

Glossopharyngeal & Vagus

25
Q

What nucleus in the brain receives the impulses from the stretch receptors?

A

Nucleus Tractus Solitarius

26
Q

In increased blood pressure situations, neurons from the NTS have what effect on neurons in the rostral ventrolateral medulla (a sympathoexcitatory area)?

A

Inhibit/suppress activation of sympathetic nerves and their release of NE

27
Q

When no suppression is present, neurons in the rostral ventrolateral medulla (a sympathoexcitatory area) normally have what effect?

A

Excite sympathetic preganglionic neurons in intermediolateral column of the thoracic cord

28
Q

What effect do sympathetics normally have on heart rate, stroke volume, and resistance?

A
  • RAISE BLOOD PRESSURE:
    • Increase heart rate
      • (beta-1 receptor)
    • Increase stroke volume
      • (beta-1 receptor)
    • Increase resistance
      • (alpha-1 receptor)
29
Q

What happens if blood pressure in the carotid and aorta drop?

A
  • Baroreceptors send less impulses through the glossopharyngeal/vagus nerve
  • Less stimulation of the NTS
  • Less inhibition of the rostral ventrolateral medulla
  • Greater stimulation of preganglionic sympathetics in the thoracic cord
    • Increase heart rate
    • Increase stroke volume
    • Increase resistance
30
Q

What two things produce orthostatic hypotension?

A
  1. Dehydration
  2. Autonomic dysfunction
31
Q

What are the three phases of ventilation?

A
  1. Inspiration
  2. Post-inspiration
  3. Expiration
32
Q

What two muscles function as a “pump” that is required for inspiration?

A

Diaphragm & External Intercostals

33
Q

What area of the CNS functions as a pacemaker to induce contraction of the diaphragm?

A

Pre-Boetzinger area of Ventrolateral Medulla

34
Q

What nerve innervates the diaphragm? Somatomotor or autonomic nerve? NT? Receptor?

A

Phrenic Nerve (C3-C5)

  • Somatomotor
  • ACh –> Nicotinic
35
Q

What are the two inputs into the Pre-Boetzinger area?

A
  • Parafacial respiratory center sense CO2
    • ​CA –> H+
    • excites Pre-Boetzinger area
  • Parafacial rspiratory center also directly excites muscles involved in active expiration
    • abdominal muscles
36
Q

What happens if there are no carbon dioxid sensors giving input into the Pre-Boetzinger area?

A

Hypoventilation (fatal)

-Ondine’s curse

37
Q

Urination is controlled by what two types of mechanisms?

A

Voluntary & Involuntary

38
Q

What consists of the voluntary mechanism of urination?

A
  • External Sphincter
    • skeletal muscle = VOLUNTARY
    • ACh –> Nicotinic receptors
39
Q

What consists of the involuntary mechanism of urination?

A
  • Internal sphincter and detrusor (wall)
    • Parasympathetic innervation = INVOLUNTARY
    • ACh –> muscarinic receptors
40
Q

What kind of receptors sense bladder filling?

A

Stretch

41
Q

Where afferent signals travel to in response to bladder filling?

A

Medial prefrontal cortex

(normally suppresses voiding)

42
Q

What is the net result of bladder filling?

A

Suppresses an inhibition of voiding

-i.e. encourages voiding

43
Q

What center in the CNS activates the sacral cord to stimulate preganglionic parasympathetic nerves in efferent signals for urination?

A

Pontine micturition center

44
Q

What inhibitory interneurons are also activated by efferent signals from the CNS to promote urination?

A

Inhibitory interneurons influencing motorneurons innervating the external urethral sphincter

45
Q

What relaxes and what contracts in successful urination?

A
  • Relaxation of external sphincter (voluntary)
  • Contraction of the urinary bladder (involuntary)
    • Internal sphincter
    • Detrusor (wall)
46
Q

What type of drugs can help treat incontinence?

A

Muscarinic antagonists

(block ACh from stimulating muscarinic receptors to prevent activation of involuntary muscles)

Neuro B4 - WLB (17 decks)

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