cardiac output and lung disease Flashcards
What is the definition of cardiac output?
the volume of blood pumped by one ventricle of the heart in one minute
What are the two factors of cardiac output?
- the heart rate (the rate at which the heart beats)
- the stroke volume (volume of blood pumped out at each beat)
What is the equation for the cardiac output?
heart rate x stroke volume
How do valves prevent the backflow of blood?
- they only open one way
- if there is higher pressure behind a valve, its forced open
- if there is higher pressure in front of the valve its forced shut
What is the role of atria- ventricular valves and when do they open and close?
stops blood flowing back into the atria when the ventricles contract
Open = pressure in atria greater then pressure in ventricles
Closed = pressure in ventricles greater then pressure in atria
What is the role of semi-lunar valves and when do they open and close?
stops blood in the arteries flowing back into the ventricles when the ventricles contract
Open = pressure in ventricles greater then pressure in arteries,
Closed = pressure in arteries greater then pressure in ventricles
What are pocket valves?
valves in the veins
What is the blood supply for the liver called? What is the blood supply for the kidneys called?
liver = hepatic
kidneys =renal
What are bundle of His?
the fibres in the muscle separating the right and left ventricle
label where the atriaventrical node and the sino atrial node are on the heart
Explain this graph for A:
ventricles are contracting (and AV valves are shut because there is a lower pressure in the atrium than the ventricles) forcing blood into the aorta
Explain the graph for C (this includes everything from the huge peak to the end of graph):
pressure rises dramatically as the thick muscular walls of the ventricule contract.
Pressure falls as the ventricles empty and the walls relax
As diastole occurs, blood starts filling the atria, some passively enters the ventricle. The AV valve closes when the light blue line falls below the green (pressure in atria > ventricle)
Why is the pressure for the atrium always low?
Because they have thin walls
Which feature of the aorta allows it to maintain a high pressure?
elasticity of its walls = this creates a recoil action which keeps pressure high
Name the 3 stages of a cardiovascular disease
- Atheroma Formation
- Atheroma = Aneurysm and Thrombosis
- Interrupted Blood Flow to Heart = Myocardial Infarction
Describe how atheroma forms
- Damage to endothelium of artery (e.g. by high blood pressure) = WBCs (mostly macrophages) and lipids from blood clump together under lining = form fatty streaks
- Overtime, WBCs, lipids and connective tissue build up & harden to form fibrous plaque called atheroma
What can the plaque (atheroma) do and cause?
Plaque blocks lumen of artery & restricts blood flow → causes blood pressure to increase
Name the 2 types of disease that affects arteries
- Aneurysm
- Thrombosis
What is aneurysm? Describe how it occurs
Balloon-like swelling of artery
- Atheroma plaques damage and weakens arteries
- Narrow arteries = ↑ blood pressure - ## When blood travels through weakened artery at high pressure = pushes inner layers of artery though outer elastic layer to form balloon-like swelling = aneurysm
What may happen to an aneurysm?
burst and cause haemorrhage (bleeding)
What is thrombosis? Describe how it occurs
Formation of blood clot
- Atheroma plaque can burst through endothelium of artery
- Damages artery wall & leaves rough surface
- ## Platelets and fibrin accumulate at site of damage & form blood clot (thrombus)
What can the blood clot do & what can this lead to?
(thrombosis)
- Blood clot can cause complete blockage of artery or can become dislodged & block blood vessel elsewhere
- Debris from rupture can cause another blood clot to form further down artery
