Physiology Flashcards
What is the pulmonary circulation circuit?
% of blood volume?
Oxygen depleted blood leaves the ventricle to the lung and comes back to the left atrium
20% of blood volume
What is the systemic circulation circuit?
% of blood volume?
Arterial blood leaves left ventricle and supplies the whole body including the heart and returns to the right atrium
80% of blood volume
What are the 4 chambers of the heart?
Right atrium
Right ventricle
Left atrium
Left ventricle
What are the 4 main valves of the heart?
Triscuspid
-between right atrium and right ventricle
Pulmonary
-between right ventricle and pulmonary circulation
Mitral
-Between left atrium and left ventricle
Aortic
-Between the left ventricle and systemic circulation
What is the P-wave on an ECG?
atrial depolarisation (ventricular diastole)
What is the QRS wave on an ECG?
Ventricular depolarisation (ventricular systole)
What is the T wave on an ECG?
Ventricular repolarisation
What is cardiac output?
How much blood the heart pumps into circulatory system over time
Cardiac Output= Stroke Volume x Heart Rate
What is stroke volume?
What is it dependent on?
Blood ejected from ventricle on every beat
Depends on
–how much blood is filling the ventricle
–venous return
–heart rate
–how hard this blood fights to leave chamber (total peripheral resistance)
What is heart rate dependent on?
SA node
What are the benefits of placing a cannula in the dorsum of the hand?
Access
No nearby arteries
No nearby nerves
No joints
What are the disadvantages of placing a cannula in the dorsum of the hand?
Small veins
Susceptible to cold/anxiety
Mobile veins
More painful
What are the benefits of placing a cannula in the cubital fossa of the forearm?
Big, well tethered veins
Less painful
Less vasoconstriction
What are the disadvantages of placing a cannula in the cubital fossa of the forearm?
Access is harder
Potential nerve damage
Potential intra-arterial injection
Joint immobilisation
What is air flow driven by?
Pressure gradients
Whenever the alveolar pressure is less than the atmospheric pressure we have inspiration
When the alveolar pressure is greater than the atmospheric pressure we have expiration
What volumes are included in the total lung capacity?
Sum of vital capacity with residual volume (volume of air left in the lung after maximum expiration)
What volumes are included in vital capacity?
Tidal volume (TV) - represents air moving in and out of the lung during quiet breathing
Inspiratory reverse volume(IRV) - take air in to its max
Expiratory reserve volume (ERV)- push air out
VITAL CAPACITY= TV+IRV+ERV
What is pulmonary gas exchange?
Gas exchange occurs between the alveolar air and the pulmonary capillary blood
Gases move across alveolar wall by diffusion
Diffusion is determined by partial pressure gradients
What RBC does nitrous oxide not bind to?
Haemoglobin
Nitrous oxide is carried in simple solution in blood
What is the structure of haemoglobin?
Globular protein
2 alpha and 2 beta chains
4 haem groups
–porphyrin ring
–iron atom
Iron atom reversibly binds to oxygen
What is hypoxia?
Decreased oxygen delivery to tissues
What is hypoxic hypoxia?
Decreased oxygen reaching alveoli
Decreased oxygen diffusion into blood
What is anaemic hypoxia?
Decreased oxygen transport in blood (low haemoglobin)
What is ischaemic hypoxia?
Decreased oxygen transport in blood (low blood cells)
