heart blood and communicable disease

What is the double circulatory system and why is it important?

Blood passes through the heart twice for every complete circuit of the body (Right ventricle -> Lungs -> Left atrium; Left ventricle -> Body -> Right atrium). It allows blood to be pumped to the body under much higher pressure.

Trace the flow of blood through the heart?

Vena cava -> Right atrium -> Right ventricle -> Pulmonary artery -> Lungs -> Pulmonary vein -> Left atrium -> Left ventricle -> Aorta -> Body.

Why is the wall of the left ventricle thicker than the right ventricle?

The left ventricle needs to generate higher pressure to pump blood all around the body, whereas the right ventricle only pumps blood to the lungs.

What is the pacemaker of the heart?

A group of specialised cells located in the right atrium wall that control the natural resting heart rate by sending electrical impulses.

How is an irregular heart rate treated?

With an artificial pacemaker—an electronic device implanted under the skin connected to the heart via wires that sends regular electrical signals.

How are arteries adapted to their function?

1. Carry blood away from heart under high pressure. 2. Thick muscular walls with elastic fibres to stretch and recoil. 3. Narrow lumen to maintain high pressure.

How are veins adapted to their function?

1. Carry blood towards heart under low pressure. 2. Thin walls and wide lumen to reduce resistance. 3. Contain valves to prevent backflow of blood.

How are capillaries adapted to their function?

1. Thin walls (one cell thick) for a very short diffusion pathway. 2. Permeable walls allowing exchange of oxygen, glucose, and waste.

What are the main structures of the human respiratory system?

Air passes through Trachea -> Splits into two Bronchi -> Branches into smaller Bronchioles -> Ends in tiny air sacs called Alveoli, surrounded by capillaries where gas exchange occurs.

What are the four components of blood and their functions?

1. Red blood cells: Transport oxygen using haemoglobin. 2. White blood cells: Defend against pathogens. 3. Platelets: Fragmented cells that help blood clot. 4. Plasma: Liquid carrying dissolved nutrients, CO2, urea, and hormones.

How are red blood cells adapted for oxygen transport?

1. Biconcave disc shape increases surface area to volume ratio. 2. Contain haemoglobin which binds to oxygen. 3. No nucleus to maximise space for haemoglobin.

What is Coronary Heart Disease (CHD)?

A non-communicable disease where fatty material builds up inside coronary arteries, narrowing them, reducing blood flow, and limiting oxygen supply to cardiac muscle cells.

What is a stent and what are its pros and cons?

A metal mesh tube inserted into a coronary artery to keep it open. Pros: Immediate effect, long-lasting. Cons: Risk of surgery complications/infection, risk of blood clot (thrombosis).

What are statins and what are their pros and cons?

Drugs that lower 'bad' LDL cholesterol levels in blood, slowing down fatty deposit buildup. Pros: Reduce risk of strokes/heart attacks. Cons: Must be taken daily, potential side effects (e.g., liver damage).

What are the pros and cons of mechanical vs biological heart valves?

Mechanical: Durable, last a lifetime; requires lifelong blood-thinning medication. Biological (pork/beef/donor): No blood-thinning drugs needed; wear out and need replacing after 10-15 years.

What is health?

A state of physical and mental well-being.

What is the difference between communicable and non-communicable diseases?

Communicable: Caused by pathogens, can be transmitted between organisms. Non-communicable: Cannot spread between organisms; caused by genetic or lifestyle factors.

Give three examples of interactions between different types of diseases?

1. Immune system defects make a person more susceptible to infectious diseases. 2. Viruses in cells can trigger cancer (e.g., HPV -> cervical cancer). 3. Immune reactions triggered by pathogens can provoke allergies like asthma.

Define risk factor?

An aspect of a person's lifestyle, environment, or genetic makeup that increases the probability of developing a disease.

What are the main risk factors for cardiovascular disease and cancer?

1. Cardiovascular disease: Diet high in saturated fat, lack of exercise, smoking, high blood pressure. 2. Cancer: Smoking (lung), UV exposure (skin), alcohol consumption, genetic mutations (BRCA genes).

Why does correlation between a risk factor and a disease not prove causation?

A correlation shows a statistical relationship between two variables, but does not prove one causes the other unless a biological mechanism is proven through experimental testing.

What are carcinogens and ionising radiation, and how do they cause cancer?

Carcinogens are chemicals (e.g., in tobacco smoke) that can cause cancer. Ionising radiation (UV, X-rays, gamma rays) damages DNA. Both can cause mutations that lead to uncontrolled cell division.

What is cancer?

Uncontrolled cell division and growth resulting from changes in DNA (mutations), forming a mass of cells called a tumour.

What is a benign tumour?

A mass of abnormal cells contained in one local area (usually within a membrane) that does not invade other tissues or spread.

What is a malignant tumour?

A cancerous growth that invades neighbouring tissues and splits off into the bloodstream to form secondary tumours elsewhere in the body.

What are the human and financial costs of non-communicable diseases?

Human: reduced quality of life, early death, family members caring for patients. Financial: cost of treatment to health services, lost working days and lower income.

How can heart failure be treated?

A donor heart, or heart and lungs, can be transplanted. Artificial hearts are occasionally used to keep patients alive while waiting for a heart transplant, or to allow the heart to rest as an aid to recovery.

What is the effect of alcohol on the body?

Alcohol damages the liver (e.g., cirrhosis) and affects brain function (e.g., slower reactions, poor judgement).

What is the effect of smoking on the lungs?

Smoking damages the lungs and increases the risk of lung disease and lung cancer.

What are the effects of smoking and alcohol on unborn babies?

Smoking and alcohol during pregnancy can harm the unborn baby (e.g., smoking can cause low birth weight and premature birth; alcohol can damage the baby's development).

What causes many diseases?

Many diseases are caused by the interaction of a number of factors. Other factors including diet, stress and life situations can also have a profound effect on both physical and mental health.