Heart, Blood Vessels, and Diseases

• The following are study notes on the topics of heart and blood vessels, blood, coronary heart disease, health issues, lifestyle and non-communicable diseases, cancer, communicable diseases, human defense systems, vaccination, and response to exercise.

The Heart and Blood Vessels

• Students should understand the structure and function of the heart and lungs and how the lungs are adapted for gaseous exchange.
• The heart is an organ that pumps blood around the body using a double circulatory system.
• The right ventricle pumps blood to the lungs for gas exchange.
• The left ventricle pumps blood throughout the rest of the body.
• Knowledge of the blood vessels is associated with the heart, which is limited to the aorta, vena cava, pulmonary artery, pulmonary vein, and coronary arteries
• Knowledge of the lungs is restricted to the trachea, bronchi, alveoli, and the capillary network surrounding the alveoli.
• The natural resting heart rate is controlled by a group of cells in the right atrium, acting as a pacemaker.
• Artificial pacemakers are electrical devices used to correct irregularities in the heart rate.
• The body contains three types of blood vessels: arteries, veins, and capillaries.
• Students should be able to explain how the structure of blood vessels relates to their functions.
• Students should be able to use simple compound measures, such as rate, and perform calculations for blood flow.

Blood

• Blood is a tissue consisting of plasma in which red blood cells, white blood cells, and platelets are suspended.
• Students should know the functions of each of these blood components.
• Students should identify different types of blood cells in a photograph or diagram and explain how they are adapted to their functions.

Coronary Heart Disease: A Non-Communicable Disease

• Students should be able to evaluate the advantages and disadvantages of treating cardiovascular diseases with drugs, mechanical devices, or transplants.
• In coronary heart disease, fatty material builds up inside the coronary arteries, narrowing them. this reduces blood flow to the heart muscle.
• Stents are used to keep the coronary arteries open.
• Statins are used to reduce blood cholesterol levels, which slows down the rate of fatty material deposit.
• Faulty heart valves can be replaced using biological or mechanical valves.
• A donor heart, or heart and lungs, can be transplanted in cases of heart failure.
• Artificial hearts are used temporarily while waiting for a transplant or to allow the heart to rest.

Health Issues

• Students should be able to describe the relationship between health and disease and the interactions between different types of disease.
• Health is defined as a state of physical and mental well-being.
• Diseases, both communicable and non-communicable, are major causes of ill health.
• Other factors, including diet, stress, and life situations, can significantly affect physical and mental health.
• Different types of diseases can interact with each other.
• Defects in the immune system increase the likelihood of infectious diseases.
• Viruses living in cells can trigger certain cancers.
• Immune reactions to pathogens can trigger allergies.
• Severe physical ill health can lead to depression and other mental illnesses.
• Translate disease incidence information between graphical and numerical forms.
• Construct and interpret frequency tables, diagrams, bar charts, and histograms.
• Use a scatter diagram to identify a correlation between two variables.
• Understand the principles of sampling as applied to scientific data, including epidemiological data.

The Effect of Lifestyle on Some Non-Communicable Diseases

• Students should be able to discuss the human and financial costs of non-communicable diseases at various levels, including local, national, individual, and global.
• Students should be able to explain the effects of lifestyle factors, such as diet, alcohol, and smoking, on the incidence of non-communicable diseases.
• Risk factors are linked to an increased rate of disease and can include a person's lifestyle or substances in the body or environment.
• The effects of diet, smoking, and exercise on cardiovascular disease.
• Obesity is a risk factor for Type 2 diabetes.
• Alcohol affects liver and brain function.
• Smoking affects lung disease and lung cancer.
• Smoking and alcohol affect unborn babies.
• Carcinogens, including ionizing radiation, are risk factors in cancer.
• Many diseases are caused by the interaction of a number of factors.
• Understand the principles of sampling as applied to scientific data in terms of risk factors.
• Translate information between graphical and numerical forms.
• Extract and interpret information from charts, graphs, and tables in terms of risk factors.
• Use a scatter diagram to identify a correlation between two variables in terms of risk factors.

Cancer

• Cancer results from changes in cells that lead to uncontrolled growth and division.
• Benign tumors are growths of abnormal cells contained in one area, usually within a membrane, without invading other parts of the body.
• Malignant tumor cells are cancers, invading neighboring tissues and spreading to different parts of the body, forming secondary tumors.
• Scientists have identified lifestyle and genetic risk factors for cancer.

Communicable (Infectious) Diseases

• Students should be able to explain how diseases caused by viruses, bacteria, protists, and fungi are spread in animals and plants.
• Explain how the spread of diseases can be reduced or prevented.
• Pathogens are microorganisms that cause infectious diseases.
• Pathogens may be viruses, bacteria, protists, or fungi.
• They may infect plants or animals and can be spread by direct contact, water, or air.
• Bacteria and viruses may reproduce rapidly inside the body.
• Bacteria may produce toxins that damage tissues and cause illness.
• Viruses live and reproduce inside cells, causing cell damage.

Viral Diseases

• Measles is a viral disease with symptoms of fever and a red skin rash, which can be fatal if complications arise.
• Most young children are vaccinated against measles.
• The measles virus is spread by inhaling droplets from sneezes and coughs.

Human Defence Systems

• Students should describe the non-specific defense systems of the human body against pathogens, including the skin, nose, trachea, bronchi, and stomach.
• Understand the role of the immune system in defending against disease.
• If a pathogen enters the body, the immune system tries to destroy it.
• White blood cells defend against pathogens through phagocytosis, antibody production, and antitoxin production.

Vaccination

• Vaccination prevents illness in an individual and reduces the spread of pathogens by immunizing a large proportion of the population.
• Vaccination involves introducing small, dead, or inactive quantities of a pathogen to stimulate white blood cells to produce antibodies.
• If the same pathogen re-enters the body, white blood cells respond quickly to produce the correct antibodies, preventing infection.

Response to Excercise

• During exercise, the human body reacts to the increased demand for energy.
• The heart rate, breathing rate, and breath volume increase to supply muscles with more oxygenated blood.
• If insufficient oxygen is supplied, anaerobic respiration takes place in muscles.
• Incomplete glucose oxidation leads to lactic acid buildup, creating an oxygen debt.
• Muscles become fatigued and stop contracting efficiently during prolonged activity.
• (HT only) Blood carries lactic acid to the liver, where it is converted back into glucose, the amount of extra oxygen neede after exercise to react with the acid and remove cells.