Cardiovascular physiology Flashcards
What are the functions of the cardiovascular system?
Delivery of oxygen and other nutrients.
Removal of carbon dioxide and other waste products.
Support thermoregulation and control body fluid balance.
Hormone transport.
Regulation of immune function.
Outline the gross structure of the heart.
Two atria above two ventricles.
Greater muscle mass in left ventricle.
Describe the functions of the right and left heart.
Right heart - Receives deoxygenated blood which it pumps to the lungs.
Left heart - Receives oxygenated blood from the lungs and pumps to all other tissues in the body.
List the four valves in the heart.
Atrioventricular (Tricuspid and bicuspid)
Semilunar (Pulmonary and aortic)
List the order of cardiac conduction
- SA node
- Right atrium
- AV node
- Purkinje fibres
- Left atrium
- Bundle of his
- AV bundle branches
- AV right bundle branches
What do the different waves in the ECG trace represent?
P wave - Atrial depolarisation
QRS - Ventricular depolarisation
T wave - Ventricular repolarisation
What are tachycardia and bradycardia?
Tachycardia > 100bpm
Baradycardia < 60bpm
What is Henry’s law?
When a mixture of gas is in contact with liquid each gas dissolves in the liquid in proportion to it’s partial pressure and solubility until equilibrium is achieved and the gas partial pressure are equal in both locations.
How is oxygen transported in the blood? (2 ways)
Dissolved in plasma, 3mL per L of blood.
Bound to haemoglobin men 150g/L women 130g/L
What is the equilibrium equation for haemogolbin and oxygen binding?
Hb4 + 4O2 <> Hb4O8
How much oxygen does each gram of haemoglobin hold?
1.34mL
How is carbon dioxide transported in the blood? (three ways, include percentages)
Dissolved in blood - 7%
Carbamino compounds - 23%
Bicarbonate ions - 70%
What is the equation for the formation of bicarbonate ions from carbon dioxide and water?
CO2 + H2O <> H2CO3 <> HCO3- + H+
What is blood pressure?
The pressure exerted by blood on vessel walls.
What are the two equations for MABP?
2/3DBP + 1/3SBP
DBP + 0.33(SBP-DBP)
What is cardiac output? What is the equation?
Total volume of blood pumped by the ventricle per minute.
Q = HR x SV
What is stroke volume? What is the equation?
The volume of blood pumped during one beat.
SV = EDV - ESV
What is heart rate variability? Why can it be beneficial?
Variation in time interval between heart beats.
Beneficial in response to stimuli
Outline the autonomic control of heart rate.
Sympathetic - Increase heart rate and ionotropism
Parasympathetic - Decrease heart rate and ionotropism
What benefits have been associated with high heart rate variability?
Good emotional regulation
Well being
Information processing
What negative consequences have been associated with low heart rate variability?
Depression, anxiety, poor emotional regulation
IBS
Ageing
Cardiac mortality
What is VO2?
What is the equation?
What are the determinants?
The difference between the volume of gas inhaled and volume of gas exhaled per unit of time.
VO2 = [(Vi x FiO2)-(Ve x FeO2)]/T
Blood flow and oxygen extraction
What is the fick equation?
VO2 = Q x (Ca02-Cv02)
Define maximal oxygen uptake.
How do you measure it?
What are you looking for?
The maximum ability to take in, transport and utilise oxygen during exercise.
Ramp/Step incremental test.
Looking for: Plateau of oxygen consumption, RER > 1.10, HR within 10 of predicted max, RPE > 17
What is lactate threshold and turnpiont?
Threshold - The first increase above baseline
Turnpoint - Point at which there is a sudden increase in lactate.
Outline the response to increasing exercise intensity.
Increased blood pressure - This rise is larger in the systolic than in the diastolic.
Increase in cardiac output - Increase in HR is linear until exhaustion. Stroke volume increases then levels off.
What is the shape of the oxyhaemoglobin dissociation curve?
Sigmoidal
What factors affect haemoglobin O2 affinity?
Acidity - Increases during exercise. Affinity of Hb decreases. More O2 delivered to acidic sites.
Partial pressure of CO2 - Rises during exercise, affinity of Hb decreases. Harder a tissue is working the more O2 will be unloaded.
2,3 BPG - Formed during glycolysis. Helps unload O2 by binding with Hb.
Temperature - Affinity of Hb decreases. More O2 delivered to warm muscle.
Expain how there is increased oxygen utilisation during exercise?
Increased O2 extraction from blood. Dilation of peripheral vascular beds. Increased Q. Increase in pulmonary blood flow. Increase in ventilation.
