Flashcards in Cardiovascular System Deck (325)
What are the two circuits of the cardiovascular system?
Pulmonary and systemic
What are the differences in resistance and pressure between the pulmonary and systemic circuit?
Pulmonary: Medium resistance and medium pressure
Systemic: High resistance and high pressure
What is special about the the liver?
It has a dual supply of blood. One supply is from the gut via the hepatic portal vein. One supply is from the systemic arteries.
What percentage of blood volume is in each of the pulmonary circuit, heart and systemic circuit?
Where does most blood sit?
In the systemic veins
Why is an outlet valve essential for a ventricle?
When the ventricle is filling, it prevents arterial blood from returning to the pump.
Why is an inlet valve necessary?
To prevent high-pressure blood in the pumping chamber from returning to the veins.
What are the two phases that ventricles undergo?
What is an atrium? What is its purpose?
A reservoir upstream of the pump. During the ejection phase, it accumulates venous blood which can enter the ventricle quickly during the filling phase.
Why is it advantageous for the inlet and outlet of the ventricle lie close together?
The walls of the pumping chamber can shorten in length as well as in width.
How does an appendage (auricle) improve the heart?
Increases the capacity of the atrium.
How are the two ventricles separated?
Anterior and posterior interventricular sulcus
What is the heart's job?
To repressurise blood.
What are the peak pressures of the left and right atrium and ventricle?
Right atrium: 5 mmHg
Left atrium: 8 mmHg
Right ventricle: 27 mmHg
Left ventricle: 120 mmHg
What are the names of the valves between the left atrium and ventricle and the right atrium and ventricle?
Left atrium and ventricle: Mitral/bicuspid valve
Right atrium and ventricle: Tricuspid valve
What is below each valve to hold it in place?
Are atria effective pumps?
What type of tissue are valves made from?
Fibrous connective tissue
What are the Chordae tendineae?
Tendinous cords which tether the atrioventricular valves, thus preventing them from bursting upwards into the atrium during systole.
What is another name for atrioventricular valves?
Ventricular inlet valves
What forms the core of the heart?
The left ventricle
What are the open ends of the ventricles each subdivided into?
An inlet and outlet.
What must be the diameter of the inlets? Why is this?
Must be of a large diameter in order to admit blood at low pressure
Why do the outlets have a small diameter?
Blood leaves the ventricles at high pressure
What are the names of the inlet and outlet valves?
Inlet: triscuspid (right) and mitral/bicuspid (left)
Outlet: pulmonary (right) and aortic (left)
What shape is the pathway taken by blood through the ventricles?
What is the ratio of the peak pressure of the LV:RV? Compare this to the ratio of the wall thickness.
How many cusps does the pulmonary valve have?
How are outlet valves sometimes described?