Lecture 21- control of breathing Flashcards

1
Q

Where are central chemoreceptors found?

A

just beneath the surface of the medulla

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2
Q

What are central chemoreceptors stimulated by?

A

High CO2, low pH in the CSF.

OXYGEN HAS NO EFFECT

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3
Q

Why doesn’t the csf resist pH changes from the blood?

A

CO2 is lipid soluble so crosses the blood-brain barrier. The CSF is only weakly buffered so the pH changes as the blood does.

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4
Q

What do peripheral chemoreceptors detect?

A

Changes in pH, PCO2 and PO2

peripheral do detect oxygen changes

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5
Q

Where are peripheral chemoreceptors found? What is each innervated by?

A
  1. Carotid body- (at bifurcations of carotid arteries)- innervated by carotid sinus nerve via glossapharyngeal.
  2. Aortic Bodies- above and below the aortic arch- innervated by the vagus nerve.
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6
Q

What are the 3 parts of local control of gas transport that work together?

A
  1. PO2 and PCO2 in active tissue- vasodilation etc.
  2. Lung perfusion- vasoconstrcition in low O2 part of lungs
  3. Alveolar ventilation- Bronchodilatioin when high CO2 so it’s exhaled.
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7
Q

what is repiratory acidosis?

A

When pH is below 7.35. Because of very high carbon dioxide levels

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8
Q

What is respiratory alkalosis?

A

pH above 7.45. Because of hyperventialtion, very low CO2 levels

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9
Q

What are the dangers of breathing oxygen- rich gases?

A

PO2 too high. Generates free radicals- leads to coma and death

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10
Q

What are the 3 types of mechanoreceptors?

A
  1. Slowly adapting stretch receptors. Hering-Breuer reflex.
  2. Rapidly adapting stretch recpetors. Coughing reflex
  3. C-fibres receptors (J receptors)- chemical/mechanical stimuli, sends signals, brachoconstriction.
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11
Q

What are the main parts of the central controlller for breathing?

A
  1. Rythmicity centre (medulla)- controls automatic breathing
  2. PONS- (pneumotaxic and apneustic centres) modify firing patterns of medulla
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12
Q

What are DRG and VRG and what do they do?

A

Dorsal respiratory group and ventral respiratory group.

DRG fires I neurons during in Inspiration

VRG fires _E _and I** neurons during **expiration

I neurons set rythm for quiet inspiration (stimulate muscles). E neurons, passive process. E neurons inhibit I neurons.

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13
Q

What are the parts of the PONS?

A
  1. Apneustic centre- promotes inspiration, stimulates the I neurons- increases intensity of inspiration
  2. Pneumotaxic centre- inhibits apneustic centre- stops inhalation, promotes exhalation
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