3.2 Circulatory System Flashcards
What organ moves blood around the body?
The heart (made from muscle tissue)
Describe the journey of blood through a heart to the lungs?
Deoxygenated blood enters the right atrium through the vena cava
The right atrium contracts and blood is forced into the right ventricle through atrioventricular valves
The right ventricle contracts and the blood is pumper into the pulmonary artery
The pulmonary artery transports the blood to the lungs where CO2 diffuses out into the lungs and oxygen diffuses into red blood cells and binds to haemoglobin
Describe the journey of blood through the heart from the lungs?
The blood now oxygenated at a lower pressure returns to the heart via the pulmonary vein and enters the left atrium
The left atrium contracts and the blood is forced into the left ventricle through the atrioventricular valves
The left ventricle contracts and the blood is forced under high pressure into the aorta and transported around the rest of the body
Why are valves in the heart?
To prevent the back flow of blood
What are heart strings used for in the heart?
They keep the valves in place
Why is the septum in the heart?
It separates the oxygenated and deoxygenated blood
What are coronary arteries and used for?
They lie on the surface of the heart and the heart immediately needs oxygenated blood to respire for energy to contract
Why does the left ventricle have a thicker muscular heart wall?
It has to contract stronger to pump blood around the entire body
What are the two separate circulatory systems?
One for the lungs and one for the rest of the organs
What do arteries do?
Carries oxygenated blood away from the heart and to the organs (except the pulmonary artery)
Name some properties of an artery?
Carries blood with high pressure
Thick layer of muscular and elastic tissue to with stand high blood pressure
Not permeable
Doesn’t contain valves
What do veins do?
Carries deoxygenated blood from the organs back to the heart (except the pulmonary vein)
Name some properties of a vein?
Carries blood with low pressure
Little muscular and elastic tissue (thinner walls)
Contains valves to prevent back flow of blood
What do capillaries do?
Carry blood through organs allowing exchange of substances with all living cells
Name some properties of capillaries?
Only 1 cell thick - short diffusion distance
Large network of them - large surface area
Only one red blood cell can fit through at one time
Why is a stent used?
If arteries begin to narrow or are blocked blood flow is restricted so organ can become deprived of nutrients and oxygen
What are stents used for?
To keep blood vessels open
What are stents often used in and why?
Coronary arteries
They narrow due to fatty deposits cutting off blood to the heart
What is the surgery called to insert a stent?
Angioplasty
What is a stent made out of?
Metal mesh and it’s non-corrosive
What are two differences between a foetal heart and an adult heart?
The foetal heart has:
The ductus venosus: connecting the pulmonary artery and the aorta
A hole between atriums
How does the foetal heart change when born?
The ductus venosus closes upon the first breath as a result of increase in pressure and never reopens
The hole closes as a result of adrenaline causing high blood pressure when you are born
Why is it important a foetal heart changes?
Oxygenated blood and deoxygenated blood need to be separated
It could cause fatigue if not enough oxygen gets to the muscles
What is blood?
A tissue
What does blood consist of?
Fluid called plasma
Red blood cells
White blood cells
Platelets
What is the function of plasma?
It transports many substances:
CO2 from organs to lungs
Soluble products of digestion from small intestine to other organs (glucose and amino acids)
Urea from liver to kidney
Name some properties of a red blood cell?
It is a biconcave disk (larger surface area)
No nucleus
Contains red pigment haemoglobin
What is the function of a red blood cell?
The haemoglobin combined with the oxygen to form oxyhemoglobin in the lungs
Red blood cells transport this to the organs where the oxyhemoglobin can split back into the two components
What is the reaction in red blood cells?
Oxygen + haemoglobin ⇌ oxyhemoglobin
Describe a white blood cell and what it does?
Contains a nucleus
Part of the bodies defence system against pathogenic microorganisms
They engulf pathogens or produce antibodies and antitoxins
What are platelets and what do they do?
Small fragments of cells
Don’t have a nucleus
They help clot blood at the site of a wound
What does artificial blood not contain that blood from donors contain?
It doesn’t contain cells
What are the advantages of artificial blood?
Doesn’t need refrigerating
Matching blood isn’t necessary
What are the disadvantages of artificial blood?
Expensive
Doesn’t carry as much oxygen
Can be insoluble so doesn’t mix well with blood
Unpleasant side effects
What are the advantages of an artificial heart?
It doesn’t need to match the persons tissue
No immunosuppressant drugs
What are the disadvantages of an artificial heart?
Expensive
Can only be used for a short time
Issues with blood clotting
You have to spend a lot of time in hospital
