The search for better health
Discuss the difficulties of defining the terms ‘health’ and ‘disease’ - Disease is any condition that impairs normal living processes and is recognised by the presence of specific symptoms - Many diseases are best understood as a disturbance of homeostasis - Health is a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity - ‘Health’ and ‘disease’ are not always easy terms to define - For example, someone with HIV may be ‘healthy’ if symptoms of disease AIDS have not appeared Outline how the function of genes, mitosis, cell differentiation and specialisation assist in the maintenance of health - Degree to which an organism is healthy depends on whether or not its cells are functioning properly and how well the body can repair of a malfunction/imbalance - Growth of tissue and healing of tissues are dependent on protein metabolism - Protein metabolism is controlled by genes - Important chat genes causing this metabolism have not been altered by mutations - Mitosis is cell division that will allow normal growth and repair - If processes controlling mitosis go wrong, cancer may occur - Cancer occurs when cells divide rapidly and do not carry out cell differentiation and specialisation properly - Cell specialisation allows cells to develop the structure to best perform specific functions - Cell differentiation is the normal process by which a less specialised cell develops or matures to possess a more distinct form and function Distinguish between infectious and non-infectious disease - Infectious diseases can be caused by prions, bacteria, viruses, protozoans, fungi or macroscopic parasitic animals - Infectious diseases can be spread from one organism to another by direct or indirect transmission - Non-infectious diseases cannot be spread rom one organism to another - Non-infectious disease can be caused by genetic factors, environmental factors, diet or physiological malfunction Explain why cleanliness in food, water and personal hygiene practices assist in control of disease - Control of disease caused by organisms include: - ways of preventing contamination of food and water through: - proper sanitation - proper food handling - personal hygiene - water treatment processes - ways to prevent decomposition and spoilage of food - ways to prevent transmission of disease and infection by using: - disinfectants - sterilisations and antiseptics - minimising contact with food and water - crowded conditions, poor sanitation and untreated sewage increase the spread of disease
Identify the conditions under which an organism is described as a pathogen - A pathogen is any organism living in or on another organism that is capable of causing disease - If a pathogen is to cause a disease, it must: - have enough virulence (number of particular pathogen needed to cause disease). A virulent pathogen will only need to be present in small numbers to cause the disease - enter the host through a certain part of the body or survive on the body without being destroyed by the body’s natural acidity and mucus - escape from one host to another - survive transmission from one host to another. Some pathogens can only be transmitted by direct contact because they cannot survive long outside the host - Pathogens cause disease symptoms in a number of ways: - large numbers of pathogens present are too many for the host tissue to function normally - the pathogens actually destroy cells or tissues - bacteria produce poisons called toxins - the pathogen may not directly harm the host but an excessive immune response by the host may damage tissue Describe the contribution of Pasteur and Koch to our understanding of infectious disease Pasteur - Pasteur and Koch stimulated the search for microbes as causes of disease - Among other things, Pasteur discovered that microbes such as bacteria can cause disease - With his famous swan-neck flask experiment, he...
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