Respiration 7 Flashcards Preview

A CAPS 301 > Respiration 7 > Flashcards

Flashcards in Respiration 7 Deck (12)
Loading flashcards...
1

Where is breathing established?

Initiated in medulla
- Modified by higher structures
- Modified by sensory input from pns (chemoreceptors, chest wall, mechanoreceptors in the lungs) etc.

Kind of like that of the heart!

2

What are the different types of peripheral receptors?

Peripheral chemoreceptors (o2 decrease, co2 increase, ph decrease in blood)

Central chemoreceptors (co2 increase, pH decrease in co2)

Hering-Breuer reflex (stretch receptors in lungs)

Proprioceptors

Touch receptors

3

What are the DRG and VRG? Other areas?

Dorsal respiratory group: inspiratory neurons
- Drive diaphragm
- Get input from peripheral chemorecptors and Mechanoreceptors

Ventral respiratory group: mainly expiratory
- Silent during quiet breathing
- Drive expiratory muscles that are recruited

Other areas:
Pons: regions in pons modify VRG/DRG.
- Apneustic center: sustained inspiration, sudden expiration
- Pneumotaxic center: stop inspiration. Leads to apneusis.

Medulla generates rhyth, but it's influenced above by PONS or CORTEX or below from peripheral feedback.

4

How does info get to muscles of respiration?

Phrenic nerve: c3,4,5 supply motor output to diaphragm

Intercostal nerves exit thoracic and lumpar to supply intercostal and abdominal msucle s

Cranial nerves: supply upper airway dilator muscles motor input

5

What are feedforward and feedbackwards?

Forward: Pons, higher brain regions, motor cortex (voluntary through corticospinal tract)

Automatic through ventrolateral tract

Feedback (negative)
- chemoreceptors and mechanoreceptors

6

What's the Hering Breur reflex?

- Prevent overinflation
- Lungs breath the appropriate amount, then brain starts expiring
Mediated by vagus nerve

Works in animals and newborns but not big ppl
- our lungs would have to fill too much

7

What are central chemorecpetors?

Central Chemoreceptors
- Below medulla
- Stimulated by changes in Pco2 in aterial blood
○ 40mm Hg is normal

This is primary regulatory of breathing
Medulla sees this partial pressure and keeps it there.

If this pco2 is increased (holding breath?)
- Co2 diffuses into brain increases co2 levels in brain exracellular fluid. Becomes carbonic acid. (cause it goes into hydrogen ion)
- This is what the chemoreceptors sense.
- Sends info to medulla
- Changes rhythm of breathing to increase breathing.
- NEGATIVE FEEDBACK SYSTEM.
If this pco2 is decreased (hyperventilate)
® Same pathway but it would do the opposite thing, reduce H+ and increase in co2.
® Decrease ventilation.

If pco2 is VERY VERY HIGH (unusual or disease)
- Inhibits medulla and can't breathe anymore

This will increase peripheral chemoreceptor.

8

What is peripheral chemoreceptor?

Peripheral chemoreceptors
- Carotid and aortic bodies


"taste blood" mainly p02 and a little pco2 and arterial pH

Quickly, direct input to the structures
Separate from baroreceptors. Not stretch receptors. But in simliar location.

Carried via glossopharyngeal (CB)nerve and vagus nerve (AB) *****

9

What is the key oxygen receptor?

We regulate co2 in the blood. We don't "regulate" o2.
Arterial 02 levels have to go way way low (disease/altitude)


Peripheral chemoreceptors detect low 02 and tell them to get more in (hypoxia).
Decrease po2, increase in alveolar ventilation, correct it to normal level.
- We overventilate alveoli to make up for co2 and keep it normal
NEGATIVE FEEDBACK LOOP; the opposite is true too.

Drop in o2 results in hyperventilation
- Lower co2 below normal (below 40)
Raise 02 above normal (hyperoxia)

10

How do we sense arterial plasma pH?

- Detect PH or H ions.
- Regulates acid when its non carbon dioxide.

Detect increase in H or decrease in pH
- Send that info to medulla
- Raise ventilation
- Decrease arterial pco2
- Reduce arterial co2 hydrogen ions
- Correct for high acid.

Increase in pH in blood, hydrogen ion can't penetrate BBB.
- Can't influence central chemoreceptor.
- The NON CO2 ONE IS SENSED BY PERIPHERAL CHEMORECEPTORS.
- The co2 can cross the BBB, so that’s why it can access the chemoreceptors.
True with any bicarbonate: if you have too basic - decrease ventilation to correct
NEGATIVE FEEDBACK LOOK.

Response is also hyperventiation for acidity: overventilate alveoli (lower co2 and increase o2 both below/above regular levels)
- Alkylosis has opposite effect.


**ventilation is depedent on both peripheral and central chemoreceptors but the timing is different**
- Central does most of it (80%)

Central: responds to changes in co2 in arterial blood
Only peripheral does oxygen
pH only in the blood: peripheral
pH away from the blood: central

11

Whats congenital central hypoventilation syndrome?

Voluntary control doesn't work during sleep in Ondine's curse. Congenital central hypoventilation syndrome.

Some patients : inability to sense co2 and oxygen!!!!
That is the reason for some of them.

12

what are examples of when when acid gets into blood/

lactic acid example
diabetic ketoacidosis (kussmaul breathing)
Ventilatory response to acid is hyperventilation to reduce co2 and increase o2 beyond normal levels.
(since co2 makes H+ ions it all works out in the wash)

To basic stuff is the opposite effect.