respi phys Flashcards
what is tidal volume?
volume of air inhaled/exhaled during quiet breathing
what is forced expiratory volume (FEV1)?
amount of air expired in the first 1s
what is forced vital capacity?
maximum volume of air exhaled after maximal inspiration
what are the factors affecting ventilation?
- area of lungs available for diffusion
- thickness of alveoli epithelium
- diffusion constant of gas
- partial pressures of gas
- V/Q matching
what are the 4 variables in Fick’s Law?
- area of lungs available for diffusion
- thickness of alveoli epithelium
- diffusion constant (solubility) of gas
- partial pressures of gas
how is O2 transported in the blood?
- reversibly bound to haemoglobin (MAIN)
- dissolved in plasma
how will an increase in pH affect the O2/Hb dissociation curve?
shift left
increase pH –> decreased [H+] –> less O2 offloaded –> increased O2 affinity
how will an increase in 2-3,DPG affect the O2/Hb dissociation curve?
shift right
how will CO affect the O2/Hb dissociation curve?
shift left
how is CO2 transported in the blood?
- as bicarbonate ions in plasma
- bound to Hb
- dissolved in plasma
Does the ventral respiratory group (VRG) or dorsal respiratory group (DRG) modulate rhythm?
DRG
how does the pneumotaxic centre of the pons regulate ventilation?
inhibits inspiration
how does the apneustic centre of the pons regulate ventilation?
stimulates inspiration
Does the ventral respiratory group (VRG) or dorsal respiratory group (DRG) generate rhythm?
VRG
what is the hering breuer reflex?
stretch receptors stimulated by lung expansion –> send inhibitory inputs to medulla to prevent overinflation of lungs
where are central chemoreceptors located at?
medulla of brain
where are peripheral chemoreceptors located at?
carotid bodies and aortic arch
what changes to PCO2, PO2 and [H+] do peripheral chemoreceptors respond to?
- increase pCO2 (respiratory acidosis)
- decrease pO2 (hypoxia)
- increase [H+] (metabolic acidosis)
what is the haldane effect?
Hb has higher affinity for CO2 when not oxygenated
what is dead space?
inhaled air does not get to gas exchanging areas
A group of 15‐year‐old boys are having a competition to see how long they can hold their breath.
They find that they can hold their breath longer if they hyperventilate before each attempt.
What is the explanation for this phenomenon?
A. They load extra oxygen which reduces their respiratory drive.
B. They open previously non‐functioning alveoli.
C. There is a reflex fall in metabolic rate that reduces O2 consumption.
D. They lower arterial PCO2 which reduces their respiratory drive.
E. It decreases their blood pH which reduces their respiratory drive.
D. They lower arterial PCO2 which reduces their respiratory drive.
