Health And Disease Flashcards
Define disease
A departure from good health caused by a malfunction of the mind or body
Define parasite
An organism that lives in or on another living thing, taking nutrition from their host. They do not always cause disease.
Define pathogen
An organism that causes disease that takes over the host cell’s DNA
Causes, means of transmission and global impact of malaria
Eukaryotic parasite from genus Plasmodium (most widespread is a Plasmodium falciparum)
Spread by unsterilised needles, placenta and a vector, the female Anopheles mosquito, proboscis penetrates blood vessel, saliva contains parasite in infective stage, parasite invades liver to multiply then passes into blood, enter erythrocytes and feeds on haemoglobin
Kills 3m people each year. Mainly tropical regions. Most sub-Saharan Africa.
Causes, means of transport and global impact of AIDS/HIV
Human immunodeficiency virus. Once active, attacks and destroys T helper cells in immune system, ability to resist infection is reduced, can contract a range of opportunistic infections. AIDS stands for acquired immune deficiency syndrome
Transmitted by body fluid exchanged: unprotected sex, sharing needles, across placenta or during child birth, breast feeding.
30m died by end of 2005. 2006 spread in China and Russia. Spread is pandemic. Most infected in sub-Saharan Africa.
Causes, means of transmission and global impact of tuberculosis
Bacteria, Mycobacterium tuberculosis and M. bovis. Usually found in the lungs, can affect many body parts though.
Transmitted by droplet infection, talking, laughing, coughing, sneezing. Mainly when overcrowded, poor ventilation, poor health or diet, homelessness. Also in milk/ meat of cattle in some places.
30% of world’s population may be infected, but in many it’s controlled by immune system. 1.6m died in 2005. Most common in sub-Saharan Africa and South-East Asia. Rising in Eastern Europe. Some strains are resistant to drugs.
Define immune response
response to an antigen, involving lymphocytes and the production of antibodies
Define antigen
Molecules that stimulate an immune response
Define antibody
Protein molecules that can bind to antigens (leading to agglutination or neutralisation)
Describe the primary defences against pathogens and parasites
Skin
dead cells slough off, taking bacteria with it.
Physical barrier, prevents entry
Chemical barrier, antimocrobial, and can lower pH
Keratin in cells can’t be easily digested by pathogens
Sebum lowers pH and inhibits pathogen growth
Sweat contains lysozymes, digest bacterial cell walls
Mucous membranes
So, the airways, lungs and digestive systems are protected by mucous membranes. goblet cells, mucous traps pathogens, cilia waft mucus to top of trachea to be swallowed, pathogens killed by acidity of stomach acid.
The eyes are protected by antibodies in the tear fluid The wax in the ear canal traps pathogens
The conditions around the vagina are relatively acidic
Structure and mode of action of phagocytes
Multilobed nucleus (neutrophils), allows flexibility, passage through capillary endothelium. Many lysosomes, many mitochondria. Macrophages larger, made in bone marrow and settle in organs eg lymph nodes.
Phagocyte recognises antigens on pathogen
Pathogen attachs to phagocyte by antibody and surface receptor
Pathogen engulfed by infolding of phagocyte membrane
Lysosomes release lysins into the phagosome (a vacuole with the pathogen trapped inside)
Harmless products of digestion are absorbed
Pathogen antigen presentation on cell surface membrane
The structure of antibodies
Four polypeptide chains held together by disulfide bridges
Y-shaped
A constant region, which is the same in all antibodies. This enables the antibody to attach to the phagocytic cells and helps the process of phagocytosis
A variable region which has a specific shape and differs from one type of antibody to the next. It ensures that the antigen can attach only to the correct antigen complementary shape to antigen shape.
Hinge regions, which allow a certain degree of flexibility. They allow the branches to move further apart to allow attachment to more than one antigen
Mode of action of antibodies
Neutralisation
Antibodies cover binding sites on pathogen
Prevent binding/ entry to host cell
Can bind to toxins (antitoxin)
Agglutination
Bind together many pathogens
Too large to enter host cell
Increase likelihood of being consumed by macrophages/monocyte/neutrophils (phagocytes)
Mode of action of T-lymphocytes
Phagocytes activate T-lymphocytes
Receptors on T cell bind with antigen presented on macrophage
Clonal selection- activates
Clonal expansion- divides to produce clones, which differentiate
Cytotoxic killer T cells, attaches to infected cells, secrete toxic substances (hydrogen peroxide) into cell, kill pathogens inside.
Helper T cells stimulate activity of killer T cells and B cells by releasing interleukins
Suppressor T cells switch off lymphocyte response when infection clears
Memory T cells remain in circulation and can respond quickly if same pathogen enters body again
Mode of action of B lymphocytes
Activated by helper T cells cytokines, and pathogen antibody binding
Colonial expansion, then clones differentiate into
Plasma cells -flow around blood, making and releasing antibodies
B memory cells- remain in body for many years, act as immunological memory
What cells manufacture antibodies?
Plasma cells (from the clonal expansion of B lymphocytes)
Compare and contrast the primary and secondary responses
Primary response When the infecting agent is first detected, the immune system starts to produce antibodies, but it takes a few days before the number of antibodies in the blood rises to a level that can fight the infection Pathogen enters for first time Slow speed of response B and T cells activated Symptoms Secondary immune response The immune system recognises the pathogen if the body is infected again, so the immune system can swing into action more quickly. The production of antibodies rises sooner and reaches a higher concentration. Pathogen enters for second time Fast speed of response Memory cells activated No symptoms
Compare and contrast active, passive, natural and artificial immunity
Active-immune system makes its own antibodies, exposed to antigen, takes a while for protection, long term protection, memory cells produced
Passive- given antibodies made by another organism, no exposure to antigen, immediate protection, short term protection, memory cells aren’t produced
Natural- catching the disease or receiving antibodies from mother through placenta and breast milk
Artificial- vaccination with antigens/ injection of antibodies
Explain how vaccination can control disease
Provide immunity to all those at risk
Herd vaccination- provide immunity for most of population at risk, once enough immune disease can’t spread.
Ring vaccination- vaccinate those in immediate vicinity of new case, villages towns etc.
Can inject/ give orally…live microorganism, harmless version of pathogenic organism, dead pathogen, antigens, harmless toxin.
Discuss responses of governments an other organisations to the threats of new strains of influenza
Vaccinate those at risk to prevent pandemics, the elderly, AIDS sufferers, others at risk.
Strains of flu change each year, researchers estimate the strain that’s most likely to spread.
Outline possible new sources of medicines
Natural compounds found in plants, animals, produced by microorganisms.
Traditional medicines
Self medicating animals (birds line nest with medicinal leaves protect chicks from mites).
A small proportion of organisms have been investigated so far. Lots of potential sources.
Need to maintain biodiversity so species don’t die out before we have a chance to study them.
Describe the effects of smoking on the mammalian gas exchange system
Chronic bronchitis
Inflammation of lungs, smoke damages cilia so goblet cells produce more mucus, which accumulates, so more coughing. Microorganisms multiply in mucus, cause infections leading to inflammation (decreases gas exchange)
Emphysema
Smoke trapped in alveoli, causes inflammation, more phagocytes which produce enzymes that break down elastin in alveoli, alveolar walls destroyed, reduced surface area (decreases gas exchange rate) so wheezing, shortness of breath, faster breathing rate. (Chronic obstructive pulmonary disease, permanent airflow reduction)
Lung cancer
Smoke contains carcinogens, DNA mutations of lung cells, uncontrolled cell growth, malignant tumour formation, blocking air flow, shortness of breath, uses lots of nutrients to grow causing weight loss.
Define health
A state of mental, physical and social wellbeing
Describe the effects of nicotine in tobacco smoke on the cardiovascular system
Causes release of adrenaline, can cause constriction of arteriole and raise blood pressure
Makes platelets sticky, increasing risk of blood clots, if in coronary arteries it could cause a heart attack
