The heart and blood Flashcards
Name six substances that are transported in the blood.
- Oxygen
- Carbon dioxide
- Glucose
- Urea
- Hormones
- Antibodies
What is the function (job) of the vena cava?
A vein that carries deoxygenated blood to the heart from the body’s systems
How does blood enter the heart?
Through veins
How does blood leave the heart?
Through arteries
What is the function (job) of the pulmonary vein?
Carries oxygenated blood from the lungs to the heart
What is the function (job) of the aorta?
An artery that carries oxygenated blood from the heart to the body
What is the function (job) of the pulmonary artery?
Carries deoxygenated blood from the heart to the lungs
Where does blood from the vena cava enter the heart?
Through the right atrium
Where does blood from the pulmonary vein enter the heart?
Through the left atrium
What is the function (job) of the heart valves between the atria and ventricles?
Prevents blood from flowing back into the atria
Humans have a double circulatory system. What are the two circuits?
- Pulmonary circulation (lungs)
- Systemic circulation (rest of the body)
Why is the pulmonary circulation under low pressure?
Because the lungs are close to the heart
What are two ways that faulty heart valves can be replaced?
- with a biological valve from a human donor or made from animal tissue from a pig or cow
- with a mechanical valve made from strong, durable materials
How does the heart beat independently from the nervous system?
Specialised cells in the right atrium generate electrical signals that make the heart contract, and act as a natural pacemaker
What is an artificial pacemaker?
A medical device that uses electrical impulses to regulate heart beats
Describe the structure of the arteries.
- Thick and elasticated walls
- Lots of connective tissue to provide strength
- Narrow lumen (channel that carries blood)
Describe the structure of the veins.
- Thin walls
- Much less muscular tissue than arteries
- Less connective tissue than arteries
- Wide lumen (channel that carries blood)
What is plasma?
A straw-coloured liquid that makes up just over half the volume of blood.
What are some useful things contained in the blood plasma?
- Glucose
- Amino acids
- Vitamins and minerals
- Hormones
- Waste products, e.g. urea
What are three types of blood cell and cell fragments?
- Red blood cells
- White blood cells
- Platelets
What is the function (job) of the red blood cells?
Transporting oxygen
What is the function (job) of the white blood cells?
Ingesting pathogens and producing antibodies
What is the function (job) of platelets?
Involved in blood clotting
What is the function (job) of the pigment haemoglobin in red blood cells?
Haemoglobin can combine reversibly with oxygen (creating oxyhaemoglobin)
Describe FOUR ways that red blood cells are adapted for the transport of oxygen.
- No nucleus, so more room for haemoglobin
- Small and flexible, so they can fit through narrow capillaries
- Biconcave shape, to maximise their surface area for absorbing oxygen
- Thin, creating a short diffusion distance for oxygen
What is the function (job) of phagocytes?
Phagocytes engulf and destroy unwanted microorganisms by phagocytosis
What is the function (job) of lymphocytes?
Lymphocytes produce soluble proteins called antibodies when a foreign body such as a microorganism enters the body
What are the two ways that platelets stop bleeding?
- they have proteins on their surface that enable them to stick to breaks in a blood vessel and clump together
- they secrete proteins that result in a series of chemical reactions that make blood clot, which plugs a wound.
When people donate blood, it must first be screened before it is used in blood transfusions.
What three things might blood be screened for?
- infectious agents such as HIV
- their blood group
- the presence of certain antibodies
When blood is examined under the microscope, cells must first be stained.
Giemsa stain is commonly used.
What colour does Giemsa stain red blood cells, white blood cells and platelets?
Giemsa stains:
- red blood cells pink
- platelets pale pink
- white blood cell cytoplasm pale blue
- white blood cell nuclei magenta
What substance can block coronary arteries, leading to a heart attack?
Cholesterol
What is the function (job) of statins? How do they do this?
Statins are drugs that help to lower cholesterol in the blood.
They do this by lowering its production in the liver.
What is a stent?
A device used to keep a narrow or blocked coronary artery open
What are stents made from? Why?
Stents are made from metal alloys, and do not lead to an immune response in the patient
Why will someone have to take immunosuppresant drugs following a heart transplant?
This prevents the person’s immune system from rejecting the donor heart
What are some disadvantages of using statins to treat heart disease?
- Not suitable for people with liver disease.
- Some side effects.
- Must be taken for life.
What are some disadvantages of using heart transplants to treat coronary heart disease?
- Few donor hearts are available
- Recovery time is long
- Risk of infection
What are some disadvantages of using replacement heart valves to treat coronary heart disease?
- Biological valves may wear out
- Blood clots may stick to mechanical valves, so anti-blood clotting drugs need to be taken
What is the equation for calculating cardiac output?
Cardiac output = heart rate x stroke volume
What is cardiac output?
The amount of blood pumped by the heart in one minute.
Where in the heart are pacemaker cells found?
In the right atrium
Digitalis is a drug that slows the heart rate.
Where does digitalis originate from?
Foxgloves
