Structure and function of the blood vessels and heart Flashcards
Why is there a need for circulation?
If there is a blockage a heart attack will occur - the circulation to the muscle of the heart will become blocked.
What is ventricular fibrillation?
This is an irregular heartbeat when blood cannot get around the body correctly.
What is an infarct?
Dead or dying heart tissue.
What is ischaema?
When the heart dies due to the lack of oxygen and nutrients.
What is convection?
Ventrical circulation as a result of differences in density, mostly due to varying temperatures.
What is the purpose of the cardiovascular system?
It delivers O2 and nutrients to each cell, removes CO2 and waste from each cell, communicates between organs through the transport of hormones and other extracellular mediators, it is involved in temperature regulation and is a crucial hydrodynamic device in sexual reproduction.
What is blood pressure determined by?
Cardiac output, the blood vessels/vasculature that carries the blood and creates resistance, and the various fluid compartments.
How can cardiovascular circulation be divided?
Into systemic and pulmonary (lung) circuits with the heart as the central pump.
Which side of the heart pumps blood to the lungs?
The right hand side.
What is the composition of the blood?
55% plasma, 45% erythrocytes.
What does plasma contain?
Water, ions, proteins, nutrients, hormones, metabolic wastes, gases etc.
How much blood does a 70kg individual have?
5.5 litres.
Where is most of the blood found at rest?
In the veins and venules - 60%, 9% in heart, 11% in arteries and 7% in the arterioles and capillaries.
What does it mean that it is a parallel circuit?
Most of the organs are supplied separately, so a blockage to one organ will not affect the rest of the organs.
What are the different layers found in blood vessels?
Lumen, endothelial cells, smooth muscle cells and connective tissue.
What makes of the layers of arteries?
A large lumen, a thick layer of smooth muscle and connective tissue.
What is the purpose of the thick elastic smooth muscle in arteries?
The absorb the pressure and pass it on slowly to the rest of the body.
What is the structure of the arterioles?
They have a thin muscular wall and a small lumen.
What is the significance of the arterioles to be able to contract the smooth muscle?
It can regulate the diameter and determine the blood flow to organs and is a major determinant of mean arterial pressure.
What is the structure of capillaries?
They are made up of a single layer of endothelial cells.
What can be exchanged across the capillaries?
Nutrients, oxygen and waste - but not proteins.
Why does bloodflow decrease significantly at the capillaries?
To allow for the exchange of nutrients and oxygen to occur.
What is the structure of veins and venules?
Thin walls, large diameter lumen and valves.
How does blood return to the heart despite the low pressure?
They run close to the skeletal muscle - the contraction allows the blood to return to the heart with the help of valves.
Why is the left side of the heart larger than the right?
It has to pump blood all around the body so needs to be under higher pressure so the muscle is thicker.
What are the three types of muscle in the heart?
Myocardium, epicardium and pericardium.
What is the purpose of the septum of the heart?
It separates the left and right side.
How are valves prevented from flipping inside out?
They are held by tendons.
What are the valves called that go from the ventricle to out of the heart?
Semilunar valves.
What are the valves called that go from the atrium to the ventricle?
Atrioventricular valves.
What is the right atrioventricular valve called?
The tricuspid valve.
What is the left atrioventricular valve called?
The bicuspid valve.
What supplies the heart with blood?
AN extensive network of blood vessels via coronary arteries.
