The Circulatory System Flashcards
What are the components of the circulatory system?
- blood
- blood vessels
- heart
What is the role of red blood cells?
To carry oxygen around the body
What shape are red blood cells? Why?
- biconcave
- to provide a large surface area for diffusion of oxygen
What are the two purposes of the circulatory system?
- transportation of substances
- protection against diseases
Why do red blood cells have no nucleus?
Increases space (or volume) for haemoglobin and oxygen
What are the main components of the blood? (4)
- red blood cells
- white blood cells (Lymphocytes and Phagocytes)
- platelets
- plasma
What is the purpose of the two forms of white blood cell?
- Lymphocytes produce antibodies
- phagocytes engulf and digest microorganisms in phagocytosis
What are the three types of blood vessels?
- Veins
- arteries
- capillaries
In which direction does blood flow through each blood vessel?
- artery - away from the heart
- vein - to the heart
- capillary - from arteries to veins
What is the thickness of the wall of each blood vessel?
- artery - thick
- vein - relatively thin
- capillary - one cell thick (smallest)
What is the blood pressure in each blood vessel?
- artery - high
- vein - low
- capillary - low
Which blood vessel always contains valves?
Which blood vessel is the only exception to this?
- Veins
- The aorta (artery)
What is haemoglobin?
An iron rich substance which carries oxygen in red blood cells
What do white blood cells do broadly speaking?
Protect against disease
What is the broad purpose of platelets? (2)
- To aid blood clotting
- to form scabs
How do platelets work?
- They convert the soluble protein fibrinogen to the insoluble fibrin
- this fibrin forms a mesh network that traps other blood components
What is the purpose of plasma?
It is responsible for the transport of:
- blood cells
- absorbed food molecules
- carbon dioxide
- hormones
- urea
Etc.
What is a lumen
The cavity (space) within a tubular structure
What is the function of the pulmonary vein?
Carries oxygenated blood from the lungs to the heart
What is the function of the aorta?
Carries oxygenated blood from the heart around the body
What is the function of the vena cava?
Carries deoxygenated blood from the body back to the heart
What is the function of the pulmonary artery?
Carries deoxygenated blood from the heart to the lungs
What is the function of the hepatic artery?
Carries oxygen and glucose to the liver
What is the function of the hepatic portal vein?
Carries digested food from the small intestine to the liver
What is the function of the hepatic vein?
Carries glucose and amino acids from the liver around the body
As well as carbon dioxide (from respiration) back to the heart and lungs
What is the function of the renal artery?
Carries blood rich in urea to the kidneys for excretion
What is the function of the renal vein?
Carries purified blood (low in urea) from the kidney to the vena cava
As well as carbon dioxide (from respiration) back to the heart and lungs
What is unique about the human and mammal circulatory system?
They are double circulatory systems
What is meant by a ‘double circulatory system’?
A system of blood flow where:
- blood enters the heart twice
- during a single circulation
What blood vessel does the actual heart muscle receive blood from?
The coronary arteries (which are extensions from the aorta)
What differences are there between the pulse rate of a fit person and an unfit person during exercise?
(3)
A fitter person will have:
- a lower resting heart rate
- a lower maximum heart rate
- a shorter recovery time
What are the two main benefits of regular exercise for the heart?
- it strengthens the heart’s muscle
- it increases cardiac output (more blood/min)
Why does pulse rate increase during exercise? (3)
- muscle cells require more glucose and oxygen
- for respiration
- to produce energy for movement of the muscles
How does increased cardiac output influence the movement of blood to muscles?
(2)
- increases blood pressure
- causing increased blood flow to muscles
What is the purpose of valves?
To prevent back flow of blood
