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123 Cards in this Set
- Front
- Back
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Define homeostasis. |
Controlling the internal environment of the body at stable levels. |
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Define exothermic. |
Something that releases heat e.g. respiration. |
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Define osmoregulation. |
Controlling the amount of water in the body. |
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What is osmoregulation monitored and controlled by? Why? |
Monitored by: Hypothalamus Controlled by: Kidney (too much water - more urine. Not enough water - less urine.) Petuitary gland (controls sweat glands.) Reason: Many of the body's reactions require water/aqueous conditions. Stops dehydration & cells swelling. |
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What is blood glucose regulation monitored and controlled by? Why? |
Monitored by: Pancreas Controlled by: Pancreas and liver Reason: Levels too high: coma/death Levels too low: body tissue fluid too concentrated - dehydration
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Which things does homeostasis maintain? |
- Blood pH - Blood glucose regulation - Thermoregulation - General body pH - Salt concentration - Oxygen levels - Osmoregulation
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Define hypothalamus. |
The part of the brain controlling body temperature. |
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Define denatured. |
When an enzyme has gone past its optimum temperature. |
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Define thermoregulation. |
The maintenance of the body at a constant temperature of 37 degrees Celsius. |
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What part of the brain controls thermoregulation? |
The hympothalamus. |
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How does the hypothalamus receive information about the body's temperature? |
1) From the nerve endings in the dermis of the skin about the temperature outside of the body. 2) From the blood for information about the temperature inside the body. |
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Thermoregulation What happens if the skin's temperature is too high? |
1)The sweat gland secretes sweat 2) The sweat evaporates from the skin 3) This transfers heat to the surroundings, cooling the skin down |
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Thermoregulation What happens if the skin's temperature is too low? - HINT: Hair |
1) The hypothalamus causes the erector muscles in the dermis to contract 2) This causes the body hairs to stand upright 3) This is designed to trap more air next to the skin as insulation |
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Thermoregulation What happens if the skin's temperature is too low? - HINT: Shiver |
1) The hypothalamus causes muscles to shiver 2) This releases heat, warming you up |
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Thermoregulation What happens if the skin's temperature is too low? - HINT: Blood flow |
1) The hypothalamus reduces the blood flow near the skin by using vasoconstriction 2) This keeps the warm blood deeper 3) Heat loss to air is reduced |
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Define vasoconstriction. |
When the hypothalamus reduces blood flow to the skin by narrowing the blood vessels closest to the surface. |
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What is the opposite of vasoconstriction? |
Vasodilation (when the body is too hot and needs to lose heat) |
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Define negative feedback. Why does it happen? Give an example. |
Definition: When a change to the body happens in one direction and body mechanisms work to make it change in the opposite direction. Why: It helps keep body conditions under control. Example: Thermoregulation (control of body temperature) |
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Define stimulus. |
A change in the body's surroundings. |
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Define response. |
A voluntary reaction to a stimulus using conscious thought. |
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Define receptor organ. |
An organ that detects the change in the environment (stimulus). |
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Define effector organ. |
Organs that bring about the response as they produce the effect (e.g. muscle). |
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Define reflex. |
An automatic, involuntary reaction to a stimulus. Reflexes bypass the brain and are a direct link from a sensory neurone to a motor neurone in the spinal cord. |
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Define vesicle. |
Areas containing neurone transmitters. |
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Define synapse. |
The gap between neurones. |
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Define impulse. |
An electrical signal transmitted along a neurone. |
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Define neurotransmitter. |
A substance diffusing across the gap between neurones at a synapse and triggers an impulse to be generated in the neurone on the other side of the synapse. |
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Explain how a neurone carries impulses from receptor cells in the skin (text). |
1) Neurotransmission - Electrical impulses travel along neurones/nerve cells. 2) The neurones carry the nerve impulse. 3) Dendrites at the end of the dendron receive impulses from receptor cells or other neurones. 4) The impulse moves along the dendron, past the cell body to the axon. 5) The impulse passes along the axon, where it passes across to the other neurones. |
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Explain how a neurone carries impulses from receptor cells in the skin (image). |
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What are neurones? |
Elongated cells consisting of a cell body and a long, thin axon. Specialised cells that conduct electrical impulses through the body. |
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What does a motor neurone look like? (Image) |
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What does a sensory neurone look like? (Image) |
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What is the purpose of the myelin sheath? |
It insulates the electrical impulse so it remains in the axon. |
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Which direction does the nerve impulse move when it's in the dendrone? |
Towards the cell body. |
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What do dendrites do? |
Receive electrical impulses from receptor cells. |
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Which directions do axons and dendrons go in relation to the cell body? |
Axon AWAY Dendrone TOWARDS |
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What is the order in which a stimulus reaches the sensory neurone? |
1) Stimulus 2) Receptor 3) Dendrite 4) Sensory neurone |
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Define nerves. |
Nerves are bundles of neurones packed together. |
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Define spinal cord. |
An organ which connects to the brain and contains many nerves packed together. |
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What does CNS stand for? What is it made up of? What does it do? |
1) Central Nervous System 2) The brain and the spinal cord 3) It controls the body |
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True or false - the thicker the neurone, the faster it is. |
True. Thicker neurones mean a faster speed of neurotransmission. |
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What is the order in which a stimulus becomes a response? |
1) Stimulus 2) Receptor 3) Co-ordination 4) Effector 5) Response |
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Why don't relay neurones have a myelin sheath? |
1) It'd take up space in the spinal cord 2) They're short so they need to speed up the impulse |
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Why are synapses useful? |
The chemicals are only released from axon endings, so synapses ensure that the impulse only flows one way. |
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How do vesicles send neurotransmitters to receptors? |
1) The vesicles release the neurotransmitters 2) These neurotransmitters are transmitted to receptors 3) The receptors receive them and therefore trigger a NEW impulse to send IMPORTANT: A NEW impulse is sent - the previous neurotransmitters don't pass through!
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Explain/describe the sequence of the reflex arc. |
1) A stimulus is detected by receptors 2) A signal travels along a sensory neurone 3) A signal passes from a sensory neurone to a relay neurone 4) The signal reaches the muscle or gland 5) The muscle responds / the gland releases chemicals. |
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Define hormones. |
Hormones are "chemical messages" secreted by the endocrine gland. They travel in the blood from organ to organ. Cells in the body respond to hormones by making changes. |
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What does the endocrine gland secrete? |
Hormones. |
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How do hormones travel from organ to organ? |
Via the blood. |
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List the hormone and effect for the thyroid gland. |
Gland: Thyroid Hormone: Thyroid Effect: Regulates metabolism |
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List the hormone and effect for the adrenal glands. |
Gland(s): Adrenal Hormone: Adrenaline Effect: Speeds up heart beat
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List the hormone and effect for the pituitary gland. |
Gland: Pituitary Hormone: Anti-dieuretic Effect: Makes kidneys produce concentrated urine |
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List the hormone and effect for the pancreas gland. |
Gland: Pancreas Hormone: Insulin, glucagon Effect: Insulin - lowers blood glucose levels Glucagon - raises blood glucose levels |
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List the hormone and effect for the ovaries gland. |
Gland: Ovaries Hormone: Oestrogen Effect: Causes development of female reproductive organs
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List the hormone and effect for the testes gland. |
Gland: Testes Hormone: Testosterone Effect: Causes development of male reproductive organs |
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What is glucose and what are its functions? |
- Glucose is a type of sugar - Its functions are 1) To be stored in the liver as glycogen 2) To be used by the body for respiration to give us energy Respiration: C(6)H(12)O(6)+0(2) --> 6H(2)O+6CO(2)+Energy |
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Which two hormones regulate blood glucose levels? |
Insulin and glucagon. |
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Which two organs help regulate blood glucose levels? |
The pancreas and the liver. |
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What happens if your blood glucose/sugar levels are too high? |
1) The pancreas secretes insulin, which lowers BG levels 2) This causes the liver to store excess glucose as glycogen 3) BG levels are back to normal when excess is stored as glycogen |
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What is excess glucose stored as when there's too much? |
Glycogen. |
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What does the pancreas secrete? |
Insulin. |
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What happens if your blood glucose levels are too low? |
1) The pancreas secretes glucagon 2) The glucagon causes the liver to release glucose into the blood by breaking down its glycogen stores (made from when there is excess glucose) 3) BG levels return to normal |
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If there's too much insulin, what is there not enough of? |
Glucagon. |
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What is diabetes? |
When a person's body can't control their blood glucose levels well enough. High blood glucose levels can cause fatigue and damage organs e.g. the eyes |
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What is wrong when someone has Type 1 diabetes? |
No insulin is produced, so when blood glucose levels rise, the body can't bring it back down to the right level. |
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How would someone with Type 1 diabetes treat themselves? |
They'd inject insulin into the subcutaneous fat layer beneath the skin, absorbing the insulin and spreading into the blood vessels. |
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What is wrong when someone has Type 2 diabetes? |
When not enough insulin is produced or cells don't respond well to insulin. |
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How would someone with Type 2 diabetes treat themselves? |
They would have to take on a healthier diet. |
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How do you work out a BMI? |
weight in kilograms kg --------------------------------------- OR --------------- (height in metres)squared m(sq.) |
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Define tropism. |
Growth movement in response to a stimulus. |
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What four things do plants need to grow? |
1) Water 2) Minerals 3) Sunlight 4) Air supply |
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What do plants respond to? |
Water - hydrotropism Light - phototropism Gravity - geotropism/gravitropism |
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What's the difference between positive and negative tropisms? |
Positive tropisms grow towards a stimulus Negative tropisms grow away from a stimulus |
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Define hyperglycemia. |
When blood glucose levels are too high. |
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Define hypoglycemia. |
When blood glucose levels are too low. |
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Define hydrotropism. |
A response to water. |
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Define auxins. |
Plant hormones that affect the growth and elongation of cells in plants. |
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Where are auxins produced? |
In the tip of the shoot of a plant. In root tips. These two have opposite effects. |
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What happens if sunlight is coming from the left of a plant? |
The auxins will move to the opposite/shaded side of the plant, causing the cells to grow and elongate and therefore making the plant lean in the direction of the sunlight. |
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What do auxins in roots do? |
They stop cell elongation, causing positive geotropism. This helps the roots to anchor the plant in place and to reach moisture underground. |
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Define giberellins. |
A set of plant hormones that cause seeds to germinate by causing the starch stored in a seed to be turned into sugars that the seed uses for energy to grow, and flowers and fruit to form. |
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Define germination. |
When a seed starts to grow a shoot and root. |
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Describe the relation of shoots to light, water and gravity in relation to tropisms. |
Light: Positive tropism (+ve) Water: No tropism Gravity: Negative tropism (-ve) |
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Describe the relation of roots to light, water and gravity in relation to tropisms. |
Light: Negative tropism (-ve) Water: Positive tropism (+ve) (stronger than geo.) Gravity: Positive tropism (+ve) |
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Define narcotic. |
A drug that makes you sleepy. |
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What do painkillers do? |
- Block impulses from being sent to the brain - Block transmission of pain responses via neurones to the brain - e.g. Heroin (more addictive derivative of morphine) Morphine (v. strong, extremely addictive) Opiates (from opium poppy) Paracetamol |
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What do hallucinogens do? |
- Make you see things that don't exist - Change perception of time, space, colour - e.g. LSD Cannabis Solvents (e.g. glue) |
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What do stimulants do? |
- Speed up activity of nervous system - Increases release of neurotransmissions - Increases level of alertness - Improved memory - e.g. Caffeine Cocaine Ecstasy |
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What do depressants do? |
- Reduce anxiety - Slows down activity of neurones in the brain - e.g. Alcohol Solvents Heroin |
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How do you know if someone is addicted to a substance? |
If they become dependent on it and cannot function properly without it. |
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What can smoking do to your lungs? |
- Blacken them - Alveoli walls break down & merge, leading to less gas exchange: difficulty breathing, emphysema - Bronchitis - ciliated epithelial cells' cilia stop working, mucus produced by goblet cells can't be swept. Coughing, difficulty breathing, bronchus inflamed -Lung cancer |
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What makes cigarettes addictive? |
Nicotine. It raises your dopamine levels, increasing happiness, enjoyment and motivation.
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What does the tar in cigarettes lead to? |
- Yellow stained nails and teeth - Stops cilia from working
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What is a malignant tumour? |
A tumour that moves around (primary to secondary).
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What is a benign tumour? |
A tumour that stays in one place. |
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What does the carbon monoxide produced by smoking do? |
- Enters the body when breathing in - Enters the blood stream and binds to haemoglobin in red blood cells instead of oxygen - Less oxygen = reduced aerobic respiration |
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What is the structure of the lungs? |
1) Trachea 2) Bronchi 3) Bronchioles 4) Alveoli |
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What are the short term effects of alcohol? |
- Slows down activity in brain and CNS - Slower reaction times - Sometimes breathing stops -Reduces negative feelings - Lowers inhibitions - More likely to take risks - Blurred vision - Bad co-ordination - harder to do simple tasks -Large amounts: unconsciousness - death by choking on vomit |
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What are the long term effects of alcohol? |
- Frequent drinking can damage all organs - Damages liver when taken with blood to be broken down - Cirrhosis of the liver - Normal tissue destroyed, liver can't function - Long period of time: brain damage - Affects learning and memory - Blood clot in the brain - Addiction
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What are the medical criteria for a transplant? |
- Similar tissues - Similar ages - Geographic location - How ill the patient is |
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What are the ethical criteria for a transplant? |
- People's lifestyles - Alcohol abusers - Clinical obesity
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Define pathogen. |
Microorganism that causes disease. |
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Define virus. |
A particle that can infect cells and cause the cells to make copies of the virus. E.g. influenza virus. |
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Define bacteria. |
A simple single-celled organism without a nucleus. E.g. Salmonella. |
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Define fungus. |
An organism that feeds on dead or decaying material. E.g. athlete's foot. |
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Define protozoan. |
A type of single-celled protoctist that requires a source of food (i.e. can't photosynthesise, like some other protoctists can). |
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Define antiseptic. |
A chemical substance that kill microorganisms outside the body. E.g. Savlon. |
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Define antibacterial. |
A chemical substance that prevents pathogens from damaging us. E.g. Penicillin, Witch Hazel. |
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Define antibiotic. |
A chemical substance that kills/prevents bacteria and some fungi from growing. Some people INCORRECTLY use them to treat viruses. |
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Define antifungal. |
Antibiotics that only affect fungi. |
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How can pathogens be spread? |
- Airborne: spread by coughs and sneezes. E.g. Influenza, cold viruses and TB bacteria. - Water: may contain bacteria e.g. those that cause cholera. - Food: may contain food-poisoning bacteria e.g. salmonella - Contact: e.g. athlete's foot is transferred to skin e.g. in shower rooms - Body fluid: Transferal of infected fluids e.g. sexual intercourse and sharing needles. E.g. HIV - Vectors - houseflies: can carry dysentery from human faeces to food - Vectors - mosquitoes: can pass pathogens into blood by biting e.g. malaria
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What are the body's natural non-specific defences? |
- Cilia - Tears - Blood clots: Platelets - Nose hairs - Stomach - Skin |
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What do cilia do to defend the body? |
They move mucus produced by goblet cells that is made to trap dirt, dust and microorganisms. |
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What do tears do to defend the body? |
Tear glands make a liquid containing lysozymes (type of enzyme that kill microorganisms). |
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What do blood clots do to defend the body? |
If the skin is broken, the blood clots to block entry to any pathogens. Platelets are the cells that cause the blood to clot. |
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What do nose hairs do to defend the body? |
They filter out dust that might carry pathogens. Mucus also helps to trap microorganisms. |
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What does the stomach do to defend the body? |
It makes hydrochloric acid to kill harmful microorganisms in food (as well as to help with digestion). |
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What does the skin do to defend the body? |
It forms a protective barrier. Sweat glands in the skin make chemical substances that kill harmful microorganisms. |
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What do pathogen-specific defences involve? |
Antibodies and T-cells and B-cells. |
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What defences to plants have? |
Non Specific: e.g. thorns Specific: Anti-bacterial defences - Natural defences we can use - e.g. witch hazel, tea tree Alkaloids - Used in defence |
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How do bacteria become resistant to antibiotics? |
1) Susceptible bacteria are killed, leaving only the most resistant ones. 2) Resistant bacteria survive and reproduce, producing a new colony of resistant bacteria.
Another way is by not completing the antibiotic term prescribed - 40% of people don't complete it. The strong bacteria survive as a result. |
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What does MRSA stand for? |
Methicillin-resistant Staphylococcus aureus |
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What makes MRSA dangerous? |
It's resistant to many antibiotics and is therefore hard to treat. |
