Chapter 7- Circultory System Flashcards
What are the functions of the circulatory system?
- transports oxygen and nutrients to cells
- transports carbon dioxide and other wastes away from the cells
- transports hormones to the cells
- maintains the pH of body fluids
- distributes heat and maintains body temperature
- maintains water content and ion concentration in body fluids
- protects against disease-causing micro-organisms
- clots when vessels are damaged
What are the components of the circulatory system?
- heart
- blood
- blood vessels
What is diastole?
The phase when the heart muscle is relaxed during the cardiac cycle.
What is systole?
The phase of the cardiac cycle in which contraction of the atrium and/of ventricles occurs.
What is an artery?
A blood vessel that carries blood away from the heart.
What is a vein?
A blood vessel that carries blood from body tissue to the heart.
What is the double circulation system?
The circulation system in which blood flows from the heart to the lungs and back to the heart (pulmonary circulation), then from the heart to the other body tissues and back to the heart (systemic circulation).
What are the features of an artery?
Thick wall, small lumen diameter, no valves and very elastic.
What are the feature of a vein?
Thin walls, large lumen diameter, valves prevent back flow, less elastic.
Where does blood become deoxygenated?
Near the body cells and organs.
Where does blood become oxygenated?
The alveoli of the lungs.
Which artery carries deoxygenated blood?
Pulmonary artery.
Which vein carries oxygenated blood?
Pulmonary vein.
What is blood made of?
55% plasma
45% cells + cell fragments
What are the functions of blood?
- delivers oxygen from lungs to cells
- delivers nutrients to cells
- transports hormones from endocrine glands to target tissue
- distributes heat evenly
- carries antibodies and white blood cells which provide protection
What is pulmonary circulation?
When blood flows from the heart, to the lungs and back to the heart.
What is systemic circulation?
When blood flows from the heart, to the body cells and back to the heart.
What percent of oxygen is carried in the plasma?
3%
What molecule does oxygen combine with in the blood? What molecule does this create?
Oxygen combines with haemoglobin to create oxyhemoglobin.
What are the different ways that carbon dioxide is transported in the blood?
8% dissolved in plasma
22% as carbaminohaemoglobin
70% as bicarbonate ions
How does carbon dioxide form bicarbonate ions?
The carbon dioxide reacts with water to form carbonic acid (H2CO3). The carbonic acid then disassociates into hydrogen and carbonate ions.
What are red blood cells known as?
Erythrocytes
What are white blood cells known as?
Leucocytes
What are platelets known as?
Thrombocytes
What encloses the heart?
The pericardium
How can blood flow to an organ be increased?
- increase in heart rate
- vasodialation
What is vasodilation?
The relaxing of the artery wall muscles which increases the diameter of the artery.
What is vasoconstriction?
The contraction of the artery wall muscles which decreases the diameter of the artery.
How long are the atria in systole for?
0.1 sec
How long are the atria in diastole for?
0.7 sec
How long are the ventricles in diastole for?
0.5 sec
How long are the ventricles in systole for?
0.3 sec
Where is blood flow the slowest?
The capillaries
What is blood flow in the capillaries the slowest?
As it allows time for diffusion to occur.
What is the function of erythrocytes?
Oxygen combines with haemoglobin of the surface so that it can be transported around the body via the blood vessels.
What is the function of leucocytes?
Destroys/removes dead cells and invading micro-organisms.
What is the function of thrombocytes?
Necessary for blood clotting.
What is the function of plasma proteins?
Acts as an immune response.
What occurs when simple injury to blood vessels is caused?
- the walls of the blood vessels constrict which reduces the blood flow
- the platelets stock to the rough surface caused by the injury
- other platelets are attracted to the site and a plug is formed
- the plug helps reduce blood flow
- platelets release vasoconstrictors
What occurs when there is serious injury to blood vessels?
Blot clotting or coagulation
What are the steps of coagulation?
- there are a number of clotting actors present in the plasma
- a complex series of reactions results in the formation of threads of an insolvable protein called fibrin
- the fibrin threads form a mesh (clot) that traps blood cells, platelets and plasma
- The threads stick to the damaged blood vessel to hold the clot in position
- clot retraction occurs: network or threads contract, become closer, denser and stronger
- the edges of the damaged blood vessel are pulled together
- serum is squeezed out and the clot dries to form a scab to prevent entry of infection micro-organisms
