Control of Respiration Flashcards
Which part of the brain is the main rhythm generator for breathing?
Medulla
What are the specialised neurones that generate rhythmical breathing called?
Pre-Botzinger complex
What are the steps of neuronal stimulation that causes inspiration?
- Pre-Botzinger generates rhythm
- Excites dorsal neurones
- Fire in bursts
- Firing of neurone causes contraction of inspiratory muscle.
- When firing stops- passive expiration
Which group of neurones generate active expiration using accessory muscles?
Ventral neurones–> excite internal intercostals, abdominal muscles
Major muscles of inspiration?
- Diaphragm
2. External intercostal muscles
Accessory muscles of inspiration?
- Sternocleidomastoid
2. Scalenus
Muscles used in active expiration?
- Internal intercostals
2. Abdominal muscle
Which part of the brain terminates inspiration, allowing passive expiration?
Pons. Known as the pneuotaxic centre.
What would happen if the pneumotaxic centre was dysfunctional?
Apneusis- Prolonged inspiratory gasps with brief expiration
What is the Apneustic area responsible for?
Can prolong inspiration by exciting the inspiratory area of the medulla
What types of stimuli are the respiratory brain centres responsive to? (5)
- Higher brain centres
- Stretch receptors
- Juxta-pulmonary receptors
- Joint receptors
- Baroreceptors
What is the Hering Breuer reflex?
Pylmonary stretch receptors that inhibit inspiration.
Prevent hyper-inflation of the lungs.
What are the effects of the joint receptors?
Impilses from moving limbs that increase breathing.
Increases ventilation in exercise
What other factors can increase ventilation during exercise? (3)
- Adrenaline
- Impulses from cerebral cortex
- rise in temperature
What are the steps involved in the cough reflex? (4)
- Short breath intake
- Closure of larynx
- Contraction of abdominal muscles
- Larynx opens, expulsion of air at high speed
What is the main factor of chemical control of respiration?
Blood gas tension, especially C02
What are the two types of respiratory chemoreceptors?
- Central
2. Peripheral
Peripheral chemoreceptors detected _ and _ and _ concentration in blood
02,C02 and H+
Central chemoreceptors detectives _ concentration sonly in _ fluid
H+, Cerebrospinal
Cerebrospnal fluid impermeable to H+ and HC03-. But CO2 readily diffuses into it.
What is hypercapnia? What is its effect of ventilation ?
Abnormally high CO2 concentrations in blood.
Causes increased ventilation
Ventilation very susceptible to small change in PCO2
What is hypoxia? Effect on ventilation?
Abnormally low levels of 02 in blood.
Increases ventilation
What is the effect of high altitudes on PO2?
Reduces atmospheric pressure
P02 decreases.
How does the body deal with this initially and over time?
initally- Hyperventilation and increased CO
Over time
- RBC’S increase to carry more 02
- 2,3BPG produced which offloads more 02 to tissues
- Mitochondria increase
- Increase in capillaries and branches
