Homeostasis and Response

Alternative transcript:

to the effector ▼ effector produces response What is the function of the nervous system? to send electrical messages via neurons through the brain and spinal cord What is the nervous system made up of? brain, spinal cord and nerve cells Unit 5 - Homeostasis And Response 2 ▾ Diagram of Neurone/ Nerve Cell. ▼ 1 dendrite ▼ 2 cell membrane ▼4 nerve ending ▼5 nucleus 6 axon ▼7 sheath ▼ What is the reflex arc? the passage of information in a reflex from the receptor to the effector (involuntary response) ▾ What is a synapse? Numbers go across from 1-8 - 3 not included Unit 5 - Homeostasis And Response 3 the gap between two neurones ▾ Describe how chemical messages are transferred through the synapse. 1. an electrical impulse travels towards the end of a neurone 2. nerve ending of the neurone releases neurotransmitters 3. chemicals diffuse across the synapse and bind with receptor molecules on the membrane of the next neurone 4. stimulates second neurone to stimulate response Thermoregulation ▾ What is thermoregulation? control of one's internal body temperature ▼ What temperature should the human body be kept at? 37 °C ▼ Where does it occur? thermoregulatory centre in the brain ▼ Where are the two main temperature receptors found in the body? skin and blood vessels ▼ What responses occur when the body is too warm? hairs lie flat vasodilation sweating ▼ What responses occur when the body is too cold? hairs stand on end shivering vasoconstriction ▼ Why do our hairs lie flat when we are hot and stand on end when we are cold? ▼ hot erector muscles on skin surface relax Unit 5 - Homeostasis And Response 4 ▼ cold erector muscles on skin surface contract ▾ Why do vasodilation and vasoconstriction occur? vasodilation blood vessels closest to skin surface dilate. more blood flow to skin surface. more heat energy is radiated/lost. ▼ vasoconstriction blood vessels closest to skin surface constrict. less blood flow to skin surface. less heat energy is lost/radiated. ▾ Why do we shiver and sweat? ▼ shiver skeletal muscles contract to respire more. energy is released in respiration and is released as heat energy. sweat sweat glands produce sweat beads that secrete out of skin and evaporate- taking heat with it. The Brain ▾ Label this image and describe its functions. Unit 5 - Homeostasis And Response 5 ▼ 1 cerebral cortex- controls language, memory, intelligence, consciousness ▼ 2 medulla- controls unconscious actions eg breathing, digestion etc ▼ 3 cerebellum- controls balance, muscles coordination ▼4 spinal cord ▾ How can scientists investigate the brain? MRI - see which parts of the brain are active when doing different tasks Electrically stimulating the brain - to see how the body reacts when different parts are stimulated testing patients with brain damage - to see how the damage has affected the patient Unit 5 - Homeostasis And Response 6 ▾ How do we know what different parts of the brain do? (5) pathological specimens examining damaged areas animal studies studying during surgery non-invasive techniques ▾ Why is treating the brain so difficult? things can go wrong during surgery Brain is enclosed within skull complicated- hard to target with meds The Eye ▾ Label this image and describe its functions. D ▼ A с E A B F 'I' not included for GCSE ▼ Suspensory Ligament connects the ciliary muscle and the lens Unit 5 Homeostasis And Response G H I J 7 ▼ B ▼ C ▼ D VE ▼ F ▾ Pupil allows light to reach receptor cells changes size depending on light intensity ▼ J Cornea ▼G ▼ H A transparent layer that focuses light onto the eye. Refracts light onto the retina Iris ring of muscle which contracts / relaxes to control the amount of light entering the eye (effector) ▼lens ▼ Ciliary Muscle contract / relax to change the shape of the lens transparent disc that changes shape to refract light onto the retina ▼ Sclera protects the eye Retina contains light receptors that detect light intensity and colour ▾ Optic Nerve carries impulse to the brain (sensory neurone) What is 'accommodation'? the process of changing the shape of the lens to focus on near or distant object Unit 5 - Homeostasis And Response 8 ▾ What changes happen to the eye in dim/bright light? ▾ Dim Light radial muscles contract circular muscles - relax pupil dilates ▾ Bright Light radial muscles - relax circular muscles - contract pupil constricts ▾ What changes happen to the eye when focusing on near or distant objects? ▾ Near objects ciliary muscles contract suspensory ligaments loosen (low muscle tension) lens shape thickens So light is refracted stronger ▾ Distant objects ciliary muscles relax suspensory ligaments tighten (high muscle tension) lens shape thins So light is refracted slightly ▼ Myopia ▾ How is myopia caused? when the eyeball is too long when the lens is too thick ▾ Where is the light focused? in front of the retina How can this be corrected? concave lens Unit 5 - Homeostasis And Response 9 ▾ Hyperopia How is this caused? When the eyeball is too short when the lens is too thin ▾ Where is the light focused? behind the retina How can this be corrected? convex lens ▼ What are some treatments for vision defects and how do they work? ▼ Contact Lens float on the surface of the cornea. focus and refract light (like regular glasses) ▾ Laser Eye Surgery surgically reshape the cornea (common for myopia) ▼ Replacement Lens Surgery artificial lens is planted in front of original lens (through a small cut in the cornea) The Endocrine System ▾ What is the function of the endocrine system? in charge of releasing hormones into the bloodstream What are hormones? chemical messengers ▾ How do hormones travel to their target organ? gland secretes hormone into blood hormone travels through bloodstream to reach target organ hormones bind to receptor molecules on target organ ▼ What happens when a hormone is used up? it travels to the liver to be destroyed Unit 5 - Homeostasis And Response 10 Where are hormones produced (in cells)? in the mitochondria- they are proteins ▼ Glands ▾ Pituitary Gland ▾ Hormone Produced ADH, FSH, LH ▼ Role of Hormone Produced ADH- controls water content level at kidneys. FSH + LH- help regulate reproduction ▾ Thyroid Gland ▼ Hormone Produced thyroxine Role of Hormone Produced stimulates metabolic rate ▾ Pancreas ▾ Hormone Produced insulin, glucagon Role of Hormone Produced controls blood glucose concentration (blood sugar levels) ▾ Adrenal Gland Hormone Produced adrenaline ▾ Role of Hormone Produced initiates fight or flight response ▼ Ovary Hormone Produced oestrogen, progesterone ▼ Role of Hormone Produced Unit 5 - Homeostasis And Response 11 triggers ovulation and menstruation ▼ Testes ▼ Hormone Produced testosterone ▼ Role of Hormone Produced regulates sperm production Comparing the Nervous System and Endocrine System ▾ Type of Signal ▾ Nervous System electrical ▼ Endocrine System chemical Transmission of Signal ▾ Nervous System nerve cells/ neurones ▼ Endocrine System bloodstream ▼ Effectors ▾ Nervous System muscles/glands ▼ Endocrine System target cells in particular tissues Type of Response ▾ Nervous System muscle contraction ▾ Endocrine System Unit 5 Homeostasis And Response 12 chemical change ▾ Speed of response ▾ Nervous System rapid ▼ Endocrine System slower ▾ Direction of response ▾ Nervous System short ▼ Endocrine System long Controlling Blood Glucose ▼ What is blood glucose and how is it used? the amount of glucose in our blood, and is used for energy in respiration ▼ What affects the levels of blood glucose in our bodies? diet and exercise ▼ Key Vocabulary and Definitions ▼ Glucose a suger used in respiration for energy ▾ Glycogen a storage substance made of glucose, stored in the liver ▼ Insulin a hormone that tells your liver to change glucose to glycogen (pancreas) ▾ Glucagon a hormone that tells your liver to change glycogen back to glucose (pancreas) ▾ What is the normal blood sugar level (mmol/L) in: Unit 5 - Homeostasis And Response 13 ▼ A fasting person 4.0-5.6 mmol/L ▼ 2 hours after eating anything below 7.8 mmol/L ▼ Explain the stages of blood glucose control. 1. glucose is released into the blood 2. blood sugar rises 3. pancreas is stimulated to release insulin 4. liver removes unneeded glucose from the blood 5. soluble glucose is converted to an insoluble carbohydrate called glycogen 6. glycogen is stored in the liver 7. blood sugar falls 8. glucagon is released 9. glucagon breaks down glycogen converting it back into glucose ▾ Diabetes ▾ Who does it affect? ▼ Type 1 children and young adults ▾ Type 2 people aged 40 and older What is the cause? Type 1 body produces too little insulin ▼ Type 2 cells don't respond to insulin ▾ What are the symptoms? ▼ Type 1 thirst, hunger, weight changes, blurred vision Unit 5 - Homeostasis And Response 14 Type 2 thirst, hunger, weight changes, blurred vision ▼ How is it controlled? Type 1 injecting insulin Type 2 medication, changing diet and lifestyle The Kidneys ▾ What happens if the body cells have too much water? osmotic potential of cells are damaged ▼ What happens if the body cells don't have enough water? dehydration which could result in death ▾ What is osmoregulation? the control of water levels and mineral salts in the blood How does the body take in water? through food and drink ▾ How is water lost from the body? ▼ lungs from exhaling body cannot control this ▼ Sweating sweat contains ions + urea but the body cannot control how much is lost ▼ through kidneys in urine body can control this Blood Concentration ▾ What happens if the blood is dilute? there is too much water in cells - kidneys remove excess water ▼ What happens if the blood is concentrated? Unit 5 - Homeostasis And Response 15 not enough water in cells - kidneys reabsorb water back into blood (urine is more concentrated) ▼ Urea ▼ What is it? excess amino acids (from breakdown of protein in our diet) that need to be excreted safely ▾ How is it excreted? the liver deaminates the amino acids to form ammonia. this is toxic so is converted to urea ▾ Describe the process of removing waste products from the blood. blood (which contains urea) enters kidney through the renal artery kidneys remove urea, excess water and excess ions these leave the kidneys as urine through the bladder blood leaves kidney through the renal vein blood contains no urea ▾ Function of Kidney structures. ▼ Renal Artery carries to blood containing waste products to the kidney ▼ Renal Vein carries clean blood away from the kidneys ▼ Bladder where the waste is stored What is selective reabsorption? when useful substances (glucose, water, ions) are absorbed back into the blood ▼ How is urine formation controlled? water levels are too low ADH is released by the pituitary gland kidney tubules become more permeable to water more water is reabsorbed back into the blood Unit 5 - Homeostasis And Response 16 water levels rise kidney tubules become less permeable to water less water reabsorbed back into blood water levels become too low ▾ How does our body break down excess proteins? excess amino acids need to be excreted they travel to the liver the liver deaminates them to form ammonia ammonia is toxic so it converted to urea for excretion Kidney Failure ▾ What are the four consequences of kidney failure? build-up of urea in the blood unregulated water levels unregulated ion levels death ▼ What are the treatments for kidney failure? dialysis transplant ▾ How does dialysis work? blood is extracted thinned via an anticoagulant (to prevent blood clots) pumped into a dialysis machine where blood and dialysis fluid are separated by a partially permeable membrane (so they flow in opposite directions) air trap removes any air bubbles clean blood enters the body ▼ What is the function of the dialysis fluid? it contains a glucose concentration similar to the blood Unit 5 - Homeostasis And Response 17 an ion concentration similar to the blood and no urea this creates a concentration gradient for the substances to diffuse across the membrane of the blood to the dialysis fluid Kidney Transplant ▾ Advantages cheaper overall patient can lead a more normal life ▼ Disadvantages lasts only 8-9 years shortage of donors must take drugs to avoid infection ▾ Dialysis ▾ Advantages reduces urea and ion levels no overall change in blood glucose concentration water levels are restored ▾ Disadvantages expensive time-consuming patient must follow a strict diet only works for a limited time Reproduction ▾ Definitions of keywords ▼ fertility the ability to reproduce ▾ hormones Unit 5 - Homeostasis And Response 18 chemical messengers produced by glands that are carried by blood to reach its target organ contraception any form of birth control used to prevent pregnancy ▼ oestrogen a female sex hormone (ovaries) regulates menstrual cycle responsible for puberty in girls ▾ progesterone sex hormone produced by ovaries and placenta ▼ FSH stimulates oestrogen production triggers egg to mature in overy ▼ LH triggers egg to be released - ovulation What is an SSC? a secondary sexual characteristic - features that appear during puberty Which hormones are the menstrual cycle regulated by? FSH + LH - in pituitary gland in the brain Oestrogen + Progesterone - in ovaries Stage 1 of the menstrual cycle FSH is released - causes egg to mature lining of uterus breaks down - menstruation begins FSH stimulates the release of oestrogen Stage 2 of the menstraul cycle oestrogen is relased so uterus lining builds up again stimulates release of LH and stops FSH ▾ Stage 3 of the menstrual cycle uterus lining maintained for fertilisation - LH stimulates egg release Unit 5 - Homeostasis And Response 19 ▾ Stage 4 of the menstrual cycle progesterone stops release of LH and FSH is fertilisation does not occur, lining breaks down and cycle restarts - progesterone levels fall ▾ What happens if the woman becomes pregnant? uterus lining remains thick as egg is fertilised Plant Hormones ▾ What is phototropism? the idea that plants grow towards the light ▾ Why does this happen? auxin is produced at the tip of the shoots light causes auxin to concentrate on the darker side of the shoots darker side grows faster, so the plant grows towards the light ▼ What is the function of auxin in shoots of plants? triggers cell growth ▼ Experiment ▾ What happens when you cut the tip of a shoot? the plant stops growing as there is no auxin to trigger growth ▾ What happens when you block light from the tips of shoots? the plant would not grow towards the light so the tip is light-sensitive ▾ What happens when you block light from the lower part of the shoots? no effect- the lower part is not light-senstive ▼ What is the function of auxin in roots? prevents cell growth ▾ What is gravitropism/ geotropism? the idea that roots of plants grow towards gravity ▼ Why does this happen? auxin moves to the lower side of root due to gravity Unit 5 - Homeostasis And Response 20 lower side grows slower - plant grows downwards ▼ Other hormones + functions ▾ Gibberellins initiates seed germination ▼ Ethene controls cell division and ripening of fruits ▼ Commerical Uses of Plant Hormones ▼ Commercial Uses Auxins Killing Weeds weeds take up land, nutrients etc selective weedkillers - kill weeds without damaging the growth of crops Growing Cells in Tissue Culture can be used to grow clones of a plant ▾ Growing using Rooting Powder allows plant cuttings to grow adn develop roots useful for making clones of a plant Commercial Uses Of Gibberellins ▼ Controlling Dormancy farmers can grow plants at all times of the year ▼ Inducing Flowering can flower in any environment ▾ Growing Larger Fruit to make more profit Commercial Uses Of Ethene controls the ripening of fruit during storage and transport to supermarkets Controlling Fertility How can hormones be used to prevent fertility? Unit 5 - Homeostasis And Response 21 ▾ Double Oral Pill ▾ contains progesterone maintains lining of uterus- forms thick mucus to stop sperm reaching the egg ▾ contains oestrogen prevents production of FSH ▾ Advantages and Disadvantages ▾ Advantages 99% effective ▼ Disadvantages side-effects eg nausea, headaches doesn't prevent the spread of STD's ▼ Contraceptive Patch same as the pill but lasts one week ▼ Contraceptive Impact ▼ How it Works inserted under skin of the arm releases continuous amount of progesterone - to stop the ovaries releasing an egg How long it Lasts lasts three years ▼ Contraceptive Injection same as the implant but lasts 2-3 months ▼ IUD ▼ What it is t-shaped device that is inserted into the uterus to kill sperm and prevent the implantation of a fertilised egg ▾ What are some non-hormonal ways of preventing fertility? ▼ Condoms Unit 5 - Homeostasis And Response 22 worn over penis to form a physical barrier only form of contraception that prevents STD's ▼ Diaphram fits over cervix has to be used with spermicide ▾ Spermicide can be used alone not as effective (70-80%) What are some more drastic ways of preventing fertility? Sterilisation cutting or tying of the fallopian tubes/ sperm ducts permenant procedure ▾ Natural methods tracking ovulation and not having sex when the woman is most fertile Not having sexual intercourse ▾ Describe the process of IVF treatment? mother - injected with LH and FSH to trigger the release of a matured egg eggs are drawn in a lab sperm from father is used to fertilise the eggs checked by scientists for any complications healthy embyos are inserted into mothers uterus ▾ Advantages and Disadvantages ▾ Advantages parents can have own biological baby ▾ Disadvantages emotionally stressful physically demanding low success rate Unit 5 - Homeostasis And Response 23 unhealthy embryos are disposed of- unethical can lead to the mother producing multiple babies expensive side-effects eg ovarian cancer Unit 5 - Homeostasis And Response 24