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What is the structure of a bacterium?
- Single celled
- Cell membrane, surrounded by cell wall
- Strand of DNA (no nucleus)
What are the four types of pathogens?
- Reproduce by asexual reproduction (binary fission)
- Can damage cells
- Can release toxins
- Every invading cell has antigens
- When foreign antigen is encountered →
- antibodies produced
- After infection, memory cells produced = immunity
- Bacteria can mutate= resistance
- Resistance=natural selection, those that are resistant survive
- Resistant strains can't be treated by antibiotics, e.g. MRSA (causes wound infections), resistant to methicillinOveruse of antibiotics=more resistance.Resistance is becoming more common
What is a catalyst?
A substance that increases the rate of reaction without undergoing any permanent change itself.
What is respiration?
- Involves many reactions, all of which are catalysed by enzymes.
- Process of releasing energy form glucose, which goes on in every cell.
- Aerobic= with oxygen
- Anaerobic=without oxygen
- Respiration used to build larger molecules, to keep body temp steady.
- Anaerobic is incomplete breakdown of glucose
- Produces lactic acid, does not release as much energy
- Glycogen converted back to glucose during exercise
Active transport in gut
- When high conc. of nutrients in gut, they diffuse naturally into blood.
- When low conc. of nutrients in gut but high in blood, active transport is used.
- This stops us from starving.
- Tissues can include more than one type of cell
- Organs can include more than one type of tissue
Enzymes and digestion
- Amylase breaks down starch into maltose (saliva, pancreas, small intestine)
- Protease breaks down proteins into A.A (made in stomach -pepsin-, pancreas, small intestine)
- Lipase breaks down lipids into fatty acids and glycerol (made in pancreas and small intestine)
- Stomach: breaks down food
- Liver: produces bile (neutralises acidic stomach acid and emulsifies fats)
- Gall bladder: stores bile
- Small intestine: Where nutrients are absorbed
- Large intestine: water is absorbed
- rectum: stores faeces
- Breathing in: Diaphragm and intercostal muscles contract, ribs move up and out, pressure decreases
- Breathing out: Diaphragm and intercostal muscles relax, ribs move down and in, pressure increases
- Ventilators: help people to breathe, work by pumping air into lungs, can destroy alveoli.
- Too much clotting can cause stroke and deep vein thrombosis.
- Haemophilia is a genetic disease where blood doesnt clot because clotting factor is missing. This can be injected.
- You need to match the blood groups to transfuse.
- A, B, AB, O - refer to antigens on surface of RBC's.
- RBC's have A or B antigens (or neither, or both)
- If anti-A/B antibody meets A/B antigen, agglutination occurs.
- O has no antigens - can donate to anyone.
- Adrenaline affects heart rate (fight or flight mode)
- A group of cells called pacemakers produce small electric currents, which cause heart to contract.
- Sino atrial node stimulates the atria
- Atrio ventricular node stimulates ventricles
- SAN stimulates AVN.
- Artificial pacemakers used if cells don't work.
- Electrocardiograms (ECG) used to show electrical activity of heart.
- Echocardiogram are ultrasounds of heart.
Sense organs and receptors
- Eyes (SO): Light receptors
- Ears: sound receptors
- Nose: smell receptors
- Tongue: taste receptors
- Skin: touch receptors
- Messages from CNS (brain and spinal chord) are sent to effectors (muscles)
- Sensory neurons: send signals from receptors to CNS
- Relay neurons: carry signals from sensory neutrons to motor neurone
- Motor neurons: carry signal from CNS to effector
- Pain receptors are stimulated
- Impulses travel along sensory neutron
- Impulses pass through relay neutron via synapse
- Impulse travels through motor neuron via synapse.
- When impulse reaches muscle, it contracts.
- Reflexes improve chance of survival.
- Drugs (like ecstasy) block serotonin receptors.
- Serotonin conc increases - mood enhancer.
Hormones vs nerves
- Hormones travel in blood stream
- Hormones are slow nerves are fast
- Hormones have long lasting effects, nervous do not
- Nerves act on specific area, hormones more general
- Homeostasis is about maintaining a constant internal environment
- Negative feedback is used to bring levels back to normal e.g. water.
- Adrenaline: released from adrenal glands. Responsible for fight or flight mode. Triggers glycolysis in liver and muscles.
- Insulin: Released from beta cells in pancreas. Reduces glucose levels.
- Glucagon: Increases blood glucose, released from alpha cells.
- ADH: released from pituitary gland. Inhibits loss of water. Acs on lower parts of nephron.
- Testosterone: growth, puberty, hair growth.
Menstrual cycle hormones
- Oestrogen: Produced in ovaries. Inhibits FHS, overrides progesterone at the end of pregnancy. Buildup of uterus.
- Progesterone: maintains the lining of the uterus. Inhibits FSH and LH. Causes breast development
- FSH: Released by pituitary gland at start of menstrual cycle. Stimulates development of primary follicles which secrete oestrogen.
- LH: Produced by pituitary gland at around day 12 of cycle. Causes release of egg cell.