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Biology 2.2.2

AS OCR biology - health and disease

What is health? A state of physical, social and mental wellbeing, not just the absence of disease
What is disease? A departure from good health, caused by malfunction of body or mind, causes physical and mental symptoms
What is a parasite? An organism that lives on a host internally (tapeworm) or externally (head louse). Parasite gains nutrition from hsot, host is harmed and is vulnerable to invasion by other microorgansisms causing secondary infections
What is a pathogen + examples + characteristics? An organism that causes disease. Bacteria- prokaryotae kingdom, divide by binary fission, release toxic waste products and damage cells e.g. cholera, TB. Viruses- invade cells by binding to protein receptors on surface, use genetic machinery to replicate
Continued e.g HIV/AIDS. Fungi live in skin send out reproductive hyphae that release spores from skin surface e.g. athlete's foot, ringworm. Protists - invade cells and feed on contents as they grow e.g. malaria
What do the terms prevalence, morbidity, incidence and mortality mean? Prevalence - the number of people with a disease at one point in time. Morbidity - number of people with disease as a proportion of the population. Incidence - number of new cases of a disease in a year. Mortality -number of deaths from a disease per year
What do the terms pandemic, epidemic, endemic and transmission mean? Pandemic - worldwide epidemic. Epidemic - disease spreading rapidly over large area. Endemic - disease always present in a population. Transmission - the way that a pathogen travels from one host to the next
What is malaria caused by? Eukaryotic protist from genus Plasmodium, e.g. P.Vivax, P. falciparum, P.ovale, P.malariae
How is malaria transmitted? Anopheles mosquito (vector) feeds on haemoglobin and transmits Plasmodium from an infected individual to another person. Unscreened blood transfusions, unsterilised needles, across the placenta
What is the lifecycle/transmission pattern with the anopheles mosquito? If host has malaria, mosquito sucks gametes into stomach fuse to form gametes. Sporozoites in salivary glands. New host: injects saliva as anticoagulant. Sprozoites multiply in liver then enter red blood cells and release gametes
What is the global impact of malaria? 300 million people infected, 90% in sub-Saharan Africa, 3 million deaths per year, limited to tropical regions where anopheles mosquito can survive, endemic, global warming is allowed mosquito to survive further north
What is HIV/AIDS caused by/ how does it affect the body? HIV virus binds to complementary receptors on Th cells, uses cell's genetic machinery to replicate, cell bursts, releasing viruses, when number of Th cells < threshold level =AIDS. HIV/AIDS weakens immune system-> opportunist infections e.g. pneumonia
How is HIV/AIDS transmitted? Exchange of body fluids. Blood-to-blood contact: sharing hypodermic needles, needle-stick, unscreened blood transfusions. Unprotected sex. Mother to baby, across placenta, childbirth and breast milk. Unsterilized medical equipment
What is the global impact of HIV/AIDS Pandemic, prevalence 30 million, 70% in sub-Saharan Africa
What is TB caused by? 2 bacteria strains: Mycobacterium tuberculosis, Mycobacterium bovis. affects the lungs
How is TB transmitted? Droplets released when an infected person talks, laughs, coughs or sneezes. Can be contracted from the milk and meat of cattle. Factors encouraging spread: homelessness, poor ventilation, poor health, poor diet, overcrowding
What is the global impact of TB? Pandemic, 30% of global population currently infected, 1% newly infected per year, common in South-east asia and sub-saharan africa, some strains are becoming resistant to drugs
What are leucocytes, types and properties? White blood cells made in bone marrow.1)phagocytes-engulf+ingest pathogens- 2 types: neutrophils (60%, die after engulfing, lysosomes+lobed nucleus), macrophages (larger, lysosomes, survive after engulfing p). 2)lymphocytes - B(bone marrow), T(thymus g)
What are the features of the non-specific immune response?
Created by: 11043