Cardiopulmonary Circulation Flashcards
what is henry’s law?
At a constant temperature, the amount of a given gas that dissolves in a given type and volume of liquid is directly proportional to the partial pressure of that gas in equilibrium with that liquid.
what is boyle’s law?
Pressure (P) of a gas is inversely proportional to the volume (V). This law is valid under constant temperature and amount of gas
what is charles’ law?
- the volume occupied by a fixed amount of gas is directly proportional to its absolute temperature, if the pressure remains constant.
what is Fick’s law?
The rate of diffusion is proportional to both the surface area and concentration difference and is inversely proportional to the thickness of the membrane
what is Dalton’s law?
total pressure of a mixture of gases is the sum of the partial pressures of each gas in the mixture
what is Poiseille’s law?
The resistance to flow offerent by a tube is proportional to length of the tube and the viscosity of the fluid and inversely proportional to the calibre of the tube
what is the consequence of increased O2 and N2 into tissues due to increased pressure?
decompression illness
what is the consequence of too much O2?
= toxicity and seizures
Oxygen toxicity risk below 60m due to the pressure
do free dives supper decompression illness?
- don’t suffer decompensation illness as lung act as a closed circuit- no more gas can be take up
- But can exchange at alveolar surface continues so can become severely hypoxic as they ascent- lose consciousness in final 5m
what are the functions of pulmonary circulation?
- filtration system to stop venous reach
- gas exchange
- metabolism of vasoactive substances
- autonomic regulation of blood flow
what is the effect of holding breath during ascent from depth?
pulmonary barotrauma due to Boyle’s law- decrease pressure= increase vol
how does rapid decompression cause symptoms?
how does the pulmonary circulation act as a filtration system?
- The pulmonary circulation filters before systemic arteries
what is an embolus?
mass within circulation capable of causing an obstruction
what is an embolism
event characterised by obstruction of major artery
what is the normal pulmonary transit time?
0.75s
how does pulmonary circulation metabolise vasoactive substances?
what is a pulmonary shunt?
circumstances associated with bypassing the respiratory exchange surface
when might pulmonary shunts be used?
structural heart disease: problem with tissues or valves of the heart
where might pulmonary shunts be present?
- bronchial circulation
- foetal circulation
- congenital defect
- atrial septal defect (ASD) (or patent foramen ovale :PFO)
- ventricular septal defect (VSD)
what is a PFO?
- Congenital malformation in 25% of population
- Patency varies between individuals
- Allows blood to bypass pulmonary filter
- blood flows from right atrium to left atrium
- gives risk to VGE becoming arterial gas embolism (AGE)
- fatal sequelae: myocardial infarction, stroke, pulmonary embolism
what are the effects of valve disease?
hardening of valve reduces ventricular filling (AV) or ejection (Semilunar)
what is the effect of IHD?
narrowing of coronary arteries cause ischaemia in heart muscle
what are the effects of myocardial infarction?
significant occlusion leads to death of heart muscle
what are the effects of hypertension on heart muscle?
hypertension increases afterload which means the ventricle must work harder
what is the effect of dilated cardiomyopathy on heart muscle?
dilated LV reduces generatable pressures which reduces ejection
what is the effect of hypertrophic cardiomyopathy on heart muscle?
increased LV thickness reduces internal ventricular volume & impedes filing
