Homeostasis and Response

Core questions – Unit 5 Biology – Homeostasis and response No. Question 1 What is homeostasis? 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Why is homeostasis important for enzyme function? Give 2 examples of automatic control systems? What is the nervous system? What parts make up the nervous system? What is a receptor? What is a sensory neurone? What is the central nervous system (CNS)? What is a motor neurone? What is an effector? What does a muscle do when stimulated? What does a gland do when stimulated? What is a reflex action? What is a reflex arc (list the order)? What is a synapse? How is a nerve signal transferred across a synapse? What can be used to measure human reaction time? Why is it better to use a computer programme to measure human reaction time? What is the brain made of? (Triple only) What are the different regions of the brain? (Triple only) What is the function of the cerebral cortex? (Triple only) What is the function of the medulla? (Triple only) What is the function of the cerebellum? (Triple only) What range of methods do scientists use to investigate the brain? (Triple only) Why is it difficult to investigate brain function? (Triple only) What is the eye? (Triple only) Answer The regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes It maintains optimum conditions for enzyme action Nervous response or chemical response A system that enables humans to react to their surroundings and to coordinate their behaviour Receptors, neurones, spinal cord/brain, effectors Cells that detect a stimuli Neurones that carry electrical impulses from the receptors to the central nervous system The brain and the spinal cord Neurones that carry electrical impulses from the CNS to effectors Muscles or glands, which bring about responses Contract Secretes a hormone Automatic and rapid response to a stimuli that does not involve the conscious part of the brain Stimulus  receptor  coordinator  effector  response The connection between two neurones Chemicals diffuse across the gap The ruler drop test It removes human error making it more accurate and precise Billions of interconnected neurones and has different regions that carry out different functions Cerebral cortex, cerebellum, medulla Controls consciousness, intelligence, memory & language Controls unconscious activities like breathing and your heartbeat Controls muscle coordination Study patients with brain damage already; electrically stimulate parts of the brain; use MRI scans It is complex and delicate meaning it can be easily damaged, leading to problems with brain function A sense organ containing receptors sensitive to light intensity and colour 27 Label this picture of the (Triple only) 28 29 What is accommodation? (Triple only) Describe the process of focussing on a near object? (Triple only) 30 Describe the process of focussing on a distant object? (Triple only) 31 32 33 34 35 36 What is myopia? (Triple only) What is hyperopia? (Triple only) How are vision defects corrected? (Triple only) How does the iris react to bright light? (Triple only) How does the iris react to dim light? (Triple only) How is body temperature monitored and controlled? (Triple only) How are temperature changes detected in the body? (Triple only) How does the body respond when temperature is too high? (Triple only) How does the body respond when temperature is too low? (Triple only) 37 38 39 40 41 42 43 44 45 46 47 Why does shivering warm us up? (Triple only) What is the endocrine system? How are hormones transported in the body? What is a hormone? What are the main glands in the body? What is the function of the pituitary gland? What is the function of the ovaries? What is the function of the testes? eye The process of changing the shape of the lens to focus on near or distant objects  The ciliary muscles contract  The suspensory ligaments loosen  The lens is then thicker and refracts light rays strongly  The ciliary muscles relax  The suspensory ligaments are pulled tight  The lens is then pulled thin and only slightly refracts light rays Short sightedness Long sightedness Spectacle lenses which refract the light rays so that they do focus on the retina; laser eye surgery Circular muscles in the iris contract and radial muscles relax, making the pupil smaller Radial muscles in the iris contract and circular muscles relax, making the pupil larger By the thermoregulatory centre in the brain Receptors in the thermoregulatory centre detect changes in blood temperature; Temperature receptors in the skin send electrical impulses to the thermoregulatory centre Blood vessels supplying skin capillaries dilate (vasodilation) Sweat is produced from the sweat glands  Blood vessels supplying skin capillaries constrict (vasoconstriction)  Sweating stops  Skeletal muscles contract rapidly (shivering) When muscles contract, respiration increases, releasing more energy (some as heat) Composed of glands which secrete chemicals called hormones directly into the blood stream In the blood A chemical molecule, released from glands, affecting a target organ Pituitary gland, thyroid, ovaries, testes, pancreas, adrenal gland Produces several hormones (known as the ‘master gland’) Produces oestrogen Produces testosterone 48 49 50 51 What is the function of the thyroid? What is the function of the adrenal gland? What is the function of the pancreas? What are the differences between nerves and hormones? 52 53 How is blood glucose levels monitored and controlled? Describe what happens when the blood glucose level is too high? 54 Describe what happens when the blood glucose level is too low? (HT only) 55 56 57 58 59 60 61 What is Type 1 diabetes? What are the symptoms of Type 1 diabetes? How is Type 1 diabetes treated? What is Type 2 diabetes? How is Type 2 diabetes treated? What is a major risk factor for Type 2 diabetes? What substances in the body will affect the function of cells through osmotic changes? (Triple only) Why does an imbalance of ions or wa(Triple only)ter in the body negatively affect cells? How do ions and water leave the body? (Triple only) 62 63 64 65 66 67 Produces thyroxine Produces adrenaline Produces insulin  Nerves act fast, hormones act slow  Nerves act for short period of time, hormones can act for long periods of time  Nerves act on a very precise area, hormones act in a more general way Through blood flow in the pancreas  Blood glucose level detected by the pancreas  Pancreas releases insulin into the blood  Glucose is removed from the blood and stored as glycogen in the liver and muscles  Blood glucose level detected by the pancreas  Pancreas releases glucagon into the blood  Glycogen is converted into glucose and released into the blood stream A disorder in which the pancreas fails to produce sufficient insulin Uncontrolled high blood glucose levels Insulin injections When the body cells no longer respond to insulin produced by the pancreas A carbohydrate controlled diet and an exercise regime Obesity Ions and water Too much water can enter or leave the cells through osmosis Water leaves via the lungs through exhalation Water and ions are lost from the skin in sweat What is the job of the kidneys? (Triple only) To remove excess water, ions and urea in the urine How is urea formed in the body? (Triple only) (HT Only)  Protein is broken down into amino acids  Amino acids are deaminated to form ammonia  Ammonia is toxic so is converted to urea Describe how the kidneys work? (Triple only) Kidneys filter the blood (everything is removed, except proteins) Selective reabsorption – useful substances like glucose, ions and some water are absorbed back into the blood Urea is excreted in the urine What is anti-diuretic hormones? (Triple only) (HT only) Controls how much water is reabsorbed back into the blood 68 69 How is the water level in the body monitored and controlled? (Triple only) (HT only) Describe what happens when water content in the body is too low? (Triple only) (HT only) 70 Describe what happens when water content in the body is too high? (Triple only) 71 What treatments can be offered to people with kidney failure? (Triple only) How does a dialysis machine work? (Triple only) 72 73 74 75 76 77 78 79 80 81 82 Why do useful substances not leave the blood through dialysis? (Triple only) How often do dialysis sessions take place? (Triple only) What are the disadvantages of kidney dialysis? (Triple only) What are the disadvantages of a kidney transplant? (Triple only) What are the stages of the menstrual cycle? What is menstruation? What hormones are involved in the menstrual cycle? What reproductive hormones are produced in the ovaries? What productive hormones are produced in the pituitary gland? What is the function of oestrogen? It is monitored in blood flow through the brain and controlled by ADH which is released by the pituitary gland  Receptor in the brain detects that the water content is too low  Pituitary gland releases more ADH  ADH makes the kidney tubules more permeable so more water is reabsorbed back into the blood  Receptor in the brain detects that the water content is too high  Pituitary gland releases less ADH  ADH makes the kidney tubules less permeable so less water is reabsorbed back into the blood Regular dialysis Transplant  Persons blood flows between partially permeable membranes surrounded by dialysis fluid  Dialysis fluid has the same concentration of dissolved ions and glucose as healthy blood  Waste substances like urea leave the persons blood through diffusion into the dialysis fluid The dialysis fluid contains the same concentration of useful substances as human blood Three times a week, 3-4 hours each session  May cause blood clots or infections  Takes a long time  It is expensive  It could be rejected by the recipients body  There are long waiting lists Stage 1 – Menstruation Stage 2 – The uterus lining builds up Stage 3 – The egg is released (ovulation) Stage 4 – The wall is maintained until menstruation The uterus lining breaks down Oestrogen, progesterone, FSH, LH Oestrogen and progesterone FSH & LH    Causes the lining of the uterus to grow Stimulates the release of LH Inhibits the release of FSH 83 What is the function of progesterone? 84 85 What is the function of LH? What is the function of FSH? 86 87 88 89 90 What is hormonal contraception? How can oestrogen be used as a contraceptive? How can progesterone be used as a contraceptive? Describe how an oral contraceptive works? Describe how an injection, implant or skin patch work? 91 92 93 94 95 96 97 What is a barrier method of contraception? Name some barrier methods of contraception? What is an intrauterine device (IUD)? What is a spermicide? What is abstinence? What is sterilisation? How can FSH and LH be used to increase fertility? (HT only) Describe the process of In Vitro Fertilisation (IVF)? (HT only) 98 99 What are the advantages of IVF? (HT only) 100 What are the disadvantages of IVF? (HT only) 101 What is negative feedback? (HT only) 102 103 104 105 What is adrenaline? (HT only) What is the function of adrenaline? (HT only) What is thyroxine? (HT only) What is the basal metabolic rate? (HT only)  Maintains lining of the uterus after an egg is released  When levels of progesterone fall the lining of the uterus breaks down  Inhibits the release of LH and FSH Stimulates the release of an egg  Causes an egg to mature in one of the ovaries  Stimulates the ovaries to produce oestrogen Use of hormones to prevent release of an egg If taken regularly, it inhibits the production of FSH so egg development stops Stimulate the production of a thick mucus which prevents any sperm getting through to the egg Contains hormones to inhibit FSH production Contains slow release progesterone to inhibit the maturation and release of eggs for a number of months or years Prevents the sperm reaching an egg Condom, diaphragm Prevents the implantation of an embryo. They can also release hormones. Something that kills of disables sperm Not having sexual intercourse Cutting or tying the fallopian tubes in females, or the sperm duct in males By encouraging the maturation and release of an egg in females that have low levels of these hormones Give the mother FSH and LH to stimulate the maturation of several eggs Collect the eggs and fertilise them artificially with sperm outside the womb Allow the fertilised egg to develop into embryos Insert one or two embryos back into the mother’s uterus (womb) Allows infertile couples to have a child Multiple births (more likely to have twins/triplets) Success rate is low, making it emotionally stressful It can be physically stressful to the mother if they react to the hormones An automatic control system in the body that brings about changes when a set level (water, glucose) becomes too high or too low A hormone produced by the adrenal glands in times of fear or stress Increases heart rate and boosts the delivery of oxygen and glucose to the brain and muscles A hormones released by the thyroid glands that stimulates the basal metabolic rate The speed at which chemical reactions in the body occur while the body is at rest 106 How are thyroxine levels controlled? (HT only) 107 Describe what happens when levels of thyroxine in the blood are higher than normal? (HT only) 108 Describe what happens when levels of thyroxine in the blood are lower than normal? (HT only) 109 What is auxin? (Triple only) 110 What stimuli do plants respond too? (Triple only) 111 How does auxin respond to light in the shoots? (Triple only) 112 How does auxin respond to gravity in the shoots? (Triple only) 113 How does auxin respond to gravity in the roots? (Triple only) 114 What are Gibberellins? (Triple only) (HT only) 115 What is Ethene? (Triple only) (HT only) 116 How are auxins used in agriculture and horticulture? (Triple only) (HT only) 117 How is Ethene used in the food industry? (Triple only) Thyroxine is released in response to thyroid stimulating hormone (TSH) is released from the pituitary gland TSH release from the pituitary gland in inhibited. This reduces the amount of thyroxine released from the thyroid gland TSH release from the pituitary gland in stimulated This increases the amount of thyroxine released from the thyroid gland A plant hormone that controls growth near the tips of shoots and roots Light (phototropism), gravity (gravitropism or geotropism) More auxin accumulates on the side that’s in the shade The cells in the shade grow faster, so the shoot bends towards the light When shoots grow sideways, auxin accumulates on the lower side of the tip The cells on the lower side to grow faster, so the shoot bends upwards What roots grow sideways, auxin accumulates on the lower side of the root The cells on the lower side grow slower, so the root bends downwards Plant hormones important in initiating seed germination A gas produced by aging parts of plants – it controls cell division and ripening of fruits As weed killers – by disrupting normal growth patterns As rooting powders For promoting growth in tissue culture To control ripening of fruit during storage and transport (HT only) 118 How are Gibberellins used in agriculture and horticulture? (Triple only) (HT only) To end seed dormancy – make seed germinate at times of the year that they wouldn’t usually Promote flowering Increase fruit size