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What does the heart do?
It’s a muscle that pumps blood around the body
What is the double circulatory system?
Right ventricle pumps blood back to the lungs, left ventricle pumps blood to the rest of the body
What does the vena cava do?
It transports deoxygenated blood from the rest of the body to the heart
What does the pulmonary artery do?
It transports deoxygenated blood from the heart to the lungs
What does the pulmonary vein do?
It transports oxygenated blood from the lungs to the heart
What does the aorta do?
It transports oxygenated blood from the heart to the rest of the body
Why are the pulmonary vein and artery different to other veins and arteries?
They have opposite concentrations of oxygen and carbon dioxide to other veins and arteries. (PA = low of oxygen, high of CO2. PV = high of oxygen, low of CO2)
What are pacemaker cells?
Pacemaker cells are cells in the wall of the right atrium which control the heart rate
What is an artificial pacemaker?
An electrical device implanted into the chest which corrects irregularities in the heart rate
What are the coronary arteries?
Arteries on the surface of the heart that provide the heart muscle cells with blood so they can respire
What are arteries?
Blood vessels that carry blood away from the heart and to the rest of the body at high pressure
Features of arteries:
Have a narrow lumen, thick layers of elastic fibres and smooth muscle to withstand high pressure, have no valves
What are veins?
Blood vessels that carry blood from the rest of the body to the heart at low pressure
Features of veins:
Have wide lumen, thin layers of elastic fibre and smooth muscle, have valves to prevent backflow of blood
What are capillaries?
Blood vessels between arteries and veins which allow for diffusion of gases and nutrients at low pressure
Features of capillaries:
Wall is single cell thick (short diffusion distance), narrow lumen to fit between cells, pores between cells so substances can leak out
How do valves work?
The skeletal muscle contracts and squeezes blood to the heart.
What is blood?
A tissue made up of red blood cells, white blood cells, plasma and platelets
What are the functions of blood?
Transport useful substances (e.g oxygen, glucose, amino acids) and waste products (e.g urea, carbon dioxide, lactic acid), regulate body temperature and protect against disease (pathogens)
What do red blood cells do?
Transport oxygen, which attaches to the pigment haemoglobin
What do white blood cells do?
Fight disease - lymphocytes fight bacteria, phagocytes fight pathogens
What does plasma do?
Mostly composed of water, carries red and white blood cells, platelets and other important substances such as hormones and nutrients
What do platelets do?
Clot cuts in the skin and release enzymes to form a scab
What is heart rate?
The number of times the heart beats per minute (BPM)
What is stroke volume?
Volume of blood pumped by heart per beat (cm³)
What is cardiac output?
Volume of blood pumped by heart per minute (cm³/minute)
How do you calculate cardiac output?
Cardiac output = heart rate x stroke volume
How does exercise effect the body?
It increases heart and breathing rate and breath volume
What happens if there is not enough oxygen supplied to the body during exercise?
Anaerobic respiration takes place, and lactic acid builds up in the muscles, creating an oxygen debt
What is an oxygen debt?
The extra oxygen needed to remove the lactic acid build up
How does the body remove lactic acid?
Blood removes it from muscle cells and takes it to the liver, where it is oxidised to form glucose
What is coronary heart disease?
A cardiovascular disease in which the coronary arteries are narrowed and blocked by fatty deposits
What are risk factors for coronary heart disease?
A diet high in salt and saturated fat, old age, hypertension, smoking, obesity
What are the effects of coronary heart disease?
Reduced blood flow through coronary arteries, lower rate of respiration in heart muscle cells, reduced supply of oxygen to heart muscle cells, chest pain, death, increased risk of a heart attack
How is coronary heart disease treated?
Statins, stents and bypass surgery
What is a stent?
A tiny, expandable, cylindrical, metal mesh
How do stents work?
They’re fitted using a catheter, and a balloon inside the stent is inflated, so the stent widens the coronary artery. The balloon is removed and the stent holds the coronary artery open
What are the advantages of stents?
They’re permanent and keep the arteries open, less than 1% have serious complications, only need a local anaesthetic, and many stents release drugs to prevent blood clotting
What are the disadvantages of stents?
Bruising where the catheter was inserted, complex procedure, lots of medication needed afterwards
What are statins?
Drugs that lower a person’s cholesterol
What are the advantages of statins?
Reduce rate of non-fatal heart attacks by 30%, low chance of serious side effects, don’t require surgery
What are the disadvantages of statins?
Can cause serious muscle damage or kidney failure, only available on prescription, expensive, take time to work, could forget to take them
How can heart valves become faulty?
Can become leaky or stiff (stiffness can lower stroke volume)
What are the two types of valves used to replace faulty valves?
Biological and mechanical
What are the advantages of biological valves?
Lower risk of blood clots, don’t need anti-clotting meds, don’t make noise
What are the advantages of mechanical valves?
More readily available, long lasting, no ethical issues, no risk of rejection, low risk of disease transmission
What are the disadvantages of biological valves?
Ethical issues, not as long lasting, wear out and stiffen over time, may need to be replaced, may be rejected, must take immunosuppressant drugs, must wait for suitable donor (if using human valve)
What are the disadvantages of mechanical valves?
May cause blood clots on surface of valve, can be heard opening and closing
What are the 2 types of heart used to replace hearts?
Artificial or transplanted from a donor
What are the advantages of an artificial heart?
More readily available, no risk of rejection, can be used to give diseased hearts a rest
What are the advantages of a transplanted heart?
Most effective at pumping blood, long term treatment, smaller risk of blood clots
What are the disadvantages of an artificial heart?
Risk of blood clots, must take anti-clotting meds, can’t be used long term, expensive
What are the disadvantages of a transplanted heart?
Risk of rejection, must take immunosuppressants, risk of blood clots, must wait for donor
What is health?
The state of physical and mental wellbeing
What is a disease?
A condition that causes ill-health
What are possible causes of a disease?
Genetics, lifestyle choices, pathogens
What is a pathogen?
A pathogen is a disease causing microorganism
What is a communicable disease?
A disease caused by a pathogen which can spread from person to person or organism to person (e.g. influenza, chickenpox, coronavirus, measles)
What is a non-communicable disease?
A disease which cannot spread from organism to organism (e.g. cancer, diabetes, asthma)
Correlation…
Correlation does not mean causation
What does incidence mean?
The number of new cases of a specific disease during a specific time period
What does prevalence mean?
The proportion of a population who have a specific disease during a specific time period
What is sampling?
Taking a small number of observations/measurements from larger populations, is random to avoid bias and uses large samples to get representative data
What can viruses and infections trigger?
Viruses - cancer. Infections - allergies
What is a risk factor?
Something that increases a person’s chance of developing a particular disease
What is a causal mechanism?
The scientific explanation of how a specific risk factor increases the chance of someone getting a specific disease
How does a diet high in cholesterol/saturated fat/salt increase the risk of cardiovascular disease?
Saturated fat increases cholesterol which blocks arteries and increases risk of CHD, hypertension, heart failure and more. Salt increases blood pressure. Can cause build up of fatty deposits in coronary arteries and narrow them, increasing risk of heart disease and CHD.
How does smoking increase the risk of cardiovascular disease?
Smoking narrows blood vessels in the skin, which ages it, nicotine increases heart rate and other chemicals damage arteries’ lining, all of which increase risk of CHD and blood clots. Mixture of chemicals in cigarette increases blood pressure. All of this can increase risk of heart attacks, strokes etc.
How does physical inactivity increase the risk of cardiovascular disease?
Heart muscle weakens due to lack of exercise, so has a worsened blood supply. Exercise lowers cholesterol and reduces risk of heart disease, so a lack of these means there are none of these effects.
How does a diet high in sugar increase the risk of type 2 diabetes (insulin resistance)?
High blood glucose concentration means cells don’t respond to insulin (which lowers blood glucose). Excess food stored as fat, which can build up and cause obesity. Obesity can cause type 2 diabetes.
How does physical inactivity increase the risk of type 2 diabetes (insulin resistance)?
Those who do less exercise have a lower muscle mass percentage and more body fat. Exercise increases metabolic rate, which decreases risk of obesity, which can cause type 2 diabetes.
How does smoking increase the risk of lung cancer?
Tobacco smoke contains tar, a carcinogen, which acts on delicate cells of lungs and increases risk of lung cancer.
How does smoking increase the risk of lung disease?
Some parts of lungs anaesthetised by chemicals in tobacco smoke, and stop working for some time, allowing dirt and pathogens into the lungs. Tar in smoke builds up in lungs, and (along with other chemicals) makes smokers more likely to develop bronchitis, can also cause breakdown in alveoli structure, leading to COPD.
How does exposure to carcinogens increase the risk of cancer?
Ionising radiation - penetrates cells and damages chromosomes, causing mutations in DNA, can be UV light from sun.
How does alcohol affect liver and brain function?
Excessive drinking can lead to cirrhosis of liver, which destroys liver tissue. Active liver cells are replaced with scar tissue that can’t carry out vital functions. Can make brain become so soft and pulpy that structure is lost and can’t function properly (ARBD - alcohol related brain damage)
How does smoking during pregnancy affect unborn babies?
Carbon monoxide enters body and takes up oxygen carrying capacity of blood, possibly leading to the baby not getting enough oxygen to grow. Can cause premature babies, low birthweight babies and stillbirths.
How does drinking alcohol during pregnancy affect unborn babies?
Foetal alcohol syndrome - alcohol passes across placenta. Baby’s developing liver can’t deal with alcohol, so developing brain and body can be badly affected if mother drinks alcohol excessively. Baby could be born with facial deformities, learning disabilities etc. Can cause miscarriages, stillbirths, premature babies.
What is a carcinogen?
Something that causes DNA to mutate and cells to divide and grow uncontrollably and rapidly, causing a tumour.
What is cancer caused by?
A malignant tumour
What causes tumours?
A growth formed by the rapid and uncontrolled growth and division of mutated cells
What is a benign tumour?
A tumour that is non-cancerous, and makes you ill by pressing on other organs and blood vessels. It can grow but not spread
What is a malignant tumour?
A tumour that is cancerous and grows faster than benign tumours. It can spread in the blood to other tissues and organs (metastasis) and form secondary tumours, and makes you ill by pressing on organs and blood vessels.
What are the 5 risk factors for cancer?
Genetics, carcinogens (smoking, alcohol etc), viruses, ionising radiation and older age
How can cancer be treated?
Chemotherapy, radiotherapy and surgery.
What are the 4 types of pathogen?
Bacteria, protist, virus, fungi
How do viruses make you feel ill?
They reproduce inside cells and copies of them burst out, killing cells and destroying tissues.
How does bacteria make you feel ill?
It produces toxins which damage cells and tissues.
How can pathogens be transmitted?
Through direct contact, sexual contact, placental contact, vectors, and they can be airborne or waterborne
What are 3 examples of viruses?
Measles, HIV, and the tobacco mosaic virus (TMV) in plants
What is an example of a protist?
Malaria
What are 2 examples of bacteria?
Salmonella and gonorrhea
What is an example of a fungi?
Rose black spot in plants
How is measles spread?
It is airborne; coughs and sneezes release droplets into the air which are inhaled by other people
What are the symptoms of measles?
Fever, red skin rash. Can be fatal.
How is measles treated and prevented?
No treatment, infected people are isolated. There is an MMR vaccine.
What is a non specific defence?
A defense which destroys any type of pathogen
What is a specific defense?
A defense that is made to only destroy a specific type of pathogen
What are some of the body’s non specific defences?
Skin - impermeable barrier, clots if broken, antimicrobial secretions to destroy bacteria. Nose, trachea and bronchi - mucus traps pathogens, cilia of epithelial cells send this back up the throat. Stomach - hydrochloric acid destroys pathogens.
How do white blood cells fight pathogens?
Lymphocytes produce antibodies which have complementary shapes to a specific pathogen’s antigens. These bind to antigens and alert phagocytes to come and engulf, digest and destroy the pathogen.
How do white blood cells fight bacteria?
Lymphocytes produce antitoxins which bind to and neutralise bacteria’s toxins.
