Blood circuit and the heart L7 Flashcards
What is the daily output of blood?
7000 litres
How many muscular pumps does the human heart have?
Two
What is the consequence of stoppage of blood pump?
Unconsciousness in 10 seconds and death in 4 minutes.
How heavy is the heart?
300 grams
Structure of the valves
Soft and pilant (flexible) yet tough enough to withstand 100,000 closures per day for 70-80 years.
Which circuit is larger?
Systemic
What is the ratio of blood found in pulmonary and systemic circuit?
9%/84%
What is the resistance of the systemic circuit?
High because it is much larger - has way more volume
What kind of pressure do we need in the systemic circuit and why?
High pressure to drive the blood through the circuit as it has got more volume to move
What about the resistance and pressure of the pulmonary circuit?
Medium resistance
Arteries
High pressure vessels that take blood away from the pumps
Veins
Low pressure vessels that take blood towards the pumps
What is the name for the connecting vessel that goes from the gut to the liver?
The hepatic portal veins - transport nutrients
Is building a ventricular pump active or passive?
Passive
What happens during the filling phase?
Here the ventricle is represented as a box with thick
muscular walls. There is a venous inlet on the left side
and an arterial outlet on the right. While the ventricle is
filling (from the venous end) an outlet valve is essential
to prevent arterial blood from returning to the pump.
Ejection phase
An inlet valve is necessary to prevent high-pressure
blood in the pumping chamber from returning to the veins.
What is an improvement that can be done to the ventricular pump?
An atrium is a reservoir upstream of the pump. During
the ejection phase (when the inlet valve is closed) the
atrium accumulates venous blood. This blood can enter
the ventricle quickly during the filling phase.
What is another improvement?
f the inlet and outlet of the pump are moved to lie close
together, then the walls of the pumping chamber can
shorten in length as well as in width.
Adding an ‘appendage’ (also known as the auricle) which increases the
capacity of the atrium.
Structure of the heart
Peak pressures
Left Ventricle: 120mmHg
Right Ventricle: 27mmHg
Left Atrium: 8mmHg
Right Atrium: 5mmHg
Cross sections through the heart walls
Process of oxygenated and deoxygenated blood through the heart
Inlet valves
Semilunar - tricuspid, mitral/bicuspid
Outlet valves
Atrioventricular - pulmonary/aortic
Venous drainage
Process which deoxygenated blood is carried away from an organ and returned to the heart (first delivered to the liver via the heptic portal vein)
Diastole
Phase of the cardiac cycle when the heart relaxes after contraction
Mid-systole
When the heart contracts
What are the free edges of each flap tethered by?
Tendinous cords - which help prevent it from bursting upwards into the atrium during systole (contraction of heart)
Is the valve opened or closed?
Opened
Is the valve opened or closed?
Closed
Wall thickness
Left Ventricle: Thick
Right Ventricle: Medium
Left Atrium: Thin
Right Atrium: Thin
Ox/Deox blood?
Left Ventricle: Ox
Right Ventricle: Deox
Left Atrium: Ox
Right Atrium: Deox
What happens to the outlet (pulmonary/aortic) valves during ventricular filling?
The outlet valves are closed as the pressure in the arteries is higher than that of the ventricles. Once the pressure in the ventricle chambers is greater than the pressure in the arteries, these valves are forced open, and ejection of blood occurs.
Structure of the heart (use the diagram on medsci manual)
