Respiration and Breathing 2 Flashcards
What does blood flow through lungs allow
Transfer of gases to and from the respiring tissues of the body
What do gases move according to
They move down a concentration gradient
How is pulmonary circulation specialised
Gas composition of blood in pulmonary arteries and veins opposite to those in systemic circulation. Pressures in pulmonary circulation are very low. Pulmonary artery walls are thin and contain little smooth muscle. Pulmonary vascular resistance is low.
How do you work out vascular resistance
(input pressure - output pressure)/ blood flow
How do you work out alveolar ventilation rate
(tidal volume- dead space) x respiratory rate
What is alveolar rate
4 litres per minute
What is dead space
150ml
What is tidal volume
1/2L
What is respiratory rate
11/min when sitting
What is blood gas composition regulated by
Changes in alveolar ventilation rate
What is hypoventilation
When ventilation is reduced and is not meeting demands. There is not enough O2 and increased conc of CO2 as it id not removed
What is hyperventilation
Ventilation is increased above demands. Too deep/ rapid breathing. Oxygen conc increases but is limited by saturation levels. Decrease in conc of CO2
Why is hyperventilation dangerous
Decrease in conc of CO2 which increases pH making blood more alkaline
What sets the basic rhythm and pattern of breathing
The brainstem
How can ventilation be modified
Feedback from higher brain centres (cortex, hypothalamus, limbic system). Feedback from receptors in the lung (stretch, irritants). Feedback from peripheral and central chemoreceptors
What does an increase in the arterial partial pressure of CO2 result in
An increase in minute ventilation rate
What are sensitive to changes in blood chemistry
Chemoreceptors
What are the 2 types of chemorecptors
Peripheral and central
Describe peripheral receptors
Acutely sensitive to changes in arterial pressure of CO2. Small increase in PCO2 causes an immediate increase in minute ventilation
Describe central receptors
Sensitive to longer-term changes in PCO2
Which receptors are sensitive to changes in arterial PO2
Peripheral chemoreceptors
What do peripheral chemoreceptors do if arterial PO2 drops
If arterial PO2 drops below 60mmHg minute ventilation rises
When are ventilatory responses more sensitve
During hypercapnia and hypoxia
What is hypercapnia
When PCO2 is elevated
What is hypoxia
When PO2 is reduced
