Lecture 15- Respiratory 3 Flashcards
How is CO2 transported in the body?
-Dissolved in blood 10% -Bound to globin portion of Hb 30% - Forms carbamino Hb (HbCO2) =Reduced Hb > affinity for CO2 than HbO2 - Transported as bicarbonate (HCO3- )=combines with water 60% -Carbonic anhydrase catalyses the reaction in red blood cell CO2 + H2O=H2CO3 (carbonic acid)=H+ HCO3-
Describe the picture of how is CO2 transported:
-to prevent the bicarbonate built up it is dissociated and pushed into the plasma shunted out in swap for Cl- ions
1 to 1 swap
chloride shift
-O2 is dropping as it goes out to the tissue cell while the CO2 goes in from the tissue cell and is taken up by the Hb
What happens to CO2 in the lungs (pic)?
most CO2 in bicarb will be shunted in for Cl- that will drive the the reaction to go to H2CO3 and wtare and CO2 which can then leave
What are the respiratory centers in the brain?
brain stem
medullary respiratory center= controls inspiration and expiration (dorsal does only the inspiration) so control of the process of breathing in and out, how long for so determining the Tidal volume
- how to get it right? feeding in from a few areas= pre-botzinger area=time keeper the rthytmicity = vital in normal breathing
-pons respiratory centers:apnestic cntr-increasing and decreasing inspiratory neurons= overriding effect when imalance in gas to emergency button sort of
How is respiration controlled?
Your respiratory rate changes. When active, for example, your respiratory rate goes up; when less active, or sleeping, the rate goes down. Also, even though the respiratory muscles are voluntary, you can’t consciously control them when you’re sleeping. So, how is respiratory rate altered & how is respiration controlled when you’re not consciously thinking about respiration?
The rhythmicity center of the medulla:
controls automatic breathing consists of interacting neurons that fire either during inspiration (I neurons) or expiration (E neurons) I neurons - stimulate neurons that innervate respiratory muscles (to bring about inspiration) E neurons - inhibit I neurons (to 'shut down' the I neurons & bring about expiration) Apneustic center (located in the pons) - stimulate I neurons (to promote inspiration) Pneumotaxic center (also located in the pons) - inhibits apneustic center & inhibits inspiration
Factors involved in increasing respiratory rate
Chemoreceptors - located in aorta & carotid arteries (peripheral chemoreceptors) & in the medulla (central chemoreceptors)
Chemoreceptors (stimulated more by increased CO2 levels than by decreased O2 levels) > stimulate Rhythmicity Area > Result = increased rate of respiration
-Heavy exercise ==> greatly increases respiratory rate
Mechanism?
NOT increased CO2
Possible factors:
reflexes originating from body movements (proprioceptors)
increase in body temperature
epinephrine release (during exercise)
impulses from the cerebral cortex (may simultaneously stimulate rhythmicity area & motor neurons)
How are higher brain centers connected to respiration control?
feeding in to the area in the brain stem
- Emotions & pain sympathetic nerves in hypothalamus E.g. rise in temperature, anger
- links to the autonomic nervous system though it’s not part of it
holding breath= even in animals but not as much control
race horses= when really excited in races and stop breathing (only small percentage) = they stop and start breathing once they relax
-in giving birth= can stop breathing etc
What is Hering-Breuer reflex?
Respiratory system mechano/stretch receptors monitor degree of inflation ␣ Over-inflation of lungs results in inhibition of breathing (Hering-Breuer reflex)
-also feedback from lungs= then inhibition of lungs if breathing too much= hering-breuer reflex
Where do the respiratory centers in the brain get their feedback from?
What is the chemical control of respiration?
- Changes in arterial PO2 =Only important during an emergency(will have effect on tidal volume, but only works when in very low O2 conditions= only emergencies)
- Changes in arterial PCO2= Most dominant mechanism for regulating ventilation on a minute-to- minute basis(CO2 is the important regulator
can assume that rise in CO2 means drop in O2 so we breathe in more so it’s leveled out= works most of the time
but shortfalls if CO2 rich environment)
- Changes in arterial H+ unrelated to CO2 =Special circumstances & metabolic conditions =Important in regulating acid-base balance in the body
What are the effects of hyperventilation & hypoventilation on arterial PO2 and PCO2?
What are the Peripheral chemoreceptors?
aortic arch= nerve endisng that attach to aortic bodies and carotid bodies(carotid artery goes to the brain)
brain is the most sensitive to the change in oxygen
-detect changes in arterial PO2, H+, and PCO2 levels
What are the Central chemoreceptors?
What happens when PO2 decreases?
What is the Role of decreased arterial PO2?
What is the role if increased PCO2?
What is the Role of increased H+ (non-CO2 induced)?
