Biology Notes PDF

Biology notes C 4. 3 - the heart The heart as a pump Key notes Right atrium ONLY brings and takes blood to and from the lungs. Left atrium takes and brings blood to and from the WHOLE body Left ventricle is stron...

Biology notes C 4. 3 - the heart The heart as a pump Key notes Right atrium ONLY brings and takes blood to and from the lungs. Left atrium takes and brings blood to and from the WHOLE body Left ventricle is stronger as its pumping more blood so needs stronger contractions Coronary heart disease -​ Normally solved using a stent ( metal mesh that’s placed in the artery ) -​ Used to open up blocked arteries -​ They also release drugs to stop blood from clotting Or alternatively can be solved with a statin with is a drug to help cardiovascular disease as it controls blood cholesterol levels - slows down the rate of fatty material deposited in the coronary arteries. b 4.5 - breathing and gas exchange Adaptations of the alveoli -​ Made of clusters of alveoli which create a large surface area -​ Also have a rich supply of blood capillaries ( maintains a concentration gradient ). this means gas exchange occurs on the steepest concentration gradients as the exchange is effective and rapid. -​ B 5.10 - more about plant diseases Aphids - sharp mouthparts Penetrate the phloem vessel in plant cells ​ And they feed on phloem sap (high in sugar/ glucose) ​ They attack in huge numbers - this deprives the plant of being able to complete photosynthesis. ​ This can seriously damage and weaken the plants ​ aphids are also vectors for disease, viruses,bacteria and fungi from diseased plants into the tissues of healthy plants ​ They can be destroyed through chemical pesticides or in enclosed spaces e.g greenhouses. Non communicable diseases - mineral deficiency Comes from the soil where the plant grows as not enough mineral ions are bring able to reach the plant. ​ This cannot be passed from one plant to another. ​ Soil includes a lot of nutrients including ​ Nitrate ions to convert sugars made from photosynthesis into proteins needed for growth and protein synthesis. ​ Nitrate deficiency can lead to growth in the plant being stunted ​ Magnesium ions to make chlorophyll needed for photosynthesis ​ If magnesium is low not enough chlorophyll can be made so in turn not enough photosynthesis can be made. ​ the leaves then become yellow and growth slows down because the plant can’t photosynthesise fully so not enough pigment (chlorophyll) for the plant can be made this is called chlorosis. Detecting disease Symptoms of disease include. Important - ​ Stunted growth (nitrate deficiency) ​ Spots on leaves (black spot fungus on roses) ​ Areas of decay or rotting (black spot on roses) ​ Growths (bacterial infections) ​ Malformed leaves and stems (aphids etc) ​ Discolouration (magnesium deficiency or tobacco mosaic virus) ​ presence of visible pests (aphids, caterpillars) Treatment Can be treated using Pesticides or anti fungal treatment If it has spread too far and cannot be treated the disease should be removed as quick as possible to prevent pathogens spreading. B11 human coordination - 11.1 principles of human control The endocrine system -​ Made up of glands that release chemicals called hormones into the bloodstream 1)​ The blood then is able to carry the hormone to the organ/s that needs it. -​ The target organ has receptors on its cell membranes which pick up hormone molecules which in turn triggers a response in the cell itself. Rapid response hormones: -​ include insulin which controls your blood glucose -​ Adrenaline to prepare your body for fight or flight. Slow acting hormones Include growth and sex hormones -​ Have long term effects instead of immediate effects. The Endocrine Glands Endocrine glands produce the hormones that provide chemical control for the body -​ But most endocrine glands are controlled by one gland in the brain called the pituitary gland Pituitary gland -​ Acts as the master gland -​ Releases multiple different hormones into the blood through response to the body’s change in condition -​ Some hormones have a direct affect on the body e.g ADH ADH (hormone) -​ Affects the amount of urine produced by the kidney -​ Controlling the growth rate in children FSH (follicle stimulating hormone) -​ Stimulates the ovaries to produce oestrogen TSH -​ Stimulates the thyroid gland to produce thyroxine (helps to control the rate of metabolism) Different endocrine glands Pancreas - controls level of glucose in the blood Adrenal - prepares body for fight or flight response in stressful situations Ovaries - controls development of the female sexual characteristics involved in the menstrual cycle Testes - controls development of male sexual characteristics involved in the production of sperm 11.2 - the control of blood glucose levels Insulin and the control of blood glucose levels When eating, blood glucose will vary as the body digests the nutrients in the food as large amounts of glucose will pass into your blood. -​ To stop blood glucose spiking too much insulin is used to stabilise, monitor and control it. -​ When glucose spikes after a meal the pancreas produces insulin which allows glucose to move from the blood into your cells where it's used. Soluble glucose converted to - insoluble glycogen Stored glycogen can be converted back into glucose when it's needed. Glycogen - stored in the liver and the muscles -​ When those stores are full, excess glucose is converted to lipids. Glucagon - control blood glucose levels When blood glucose concentration falls, the pancreas also releases glucagon. Glucagon - makes you liver break down glycogen, to convert it into glucose which means the stored glucose is released back into the blood. Pancreas uses negative feedback control to switch between the two hormones to be able to control blood glucose. What causes Diabetes Type 1 diabetes - when your pancreas doesn't produce enough/any insulin so your blood glucose is not controlled Type 2 diabetes - linked to obesity/ lack of exercise -​ Pancreas still makes insulin but your body stops responding properly to the insulin. Treating diabetes - type 1 -​ You need to have replacement insulin before meals Insulin injection - protein that's digested into your stomach. -​ This injected insulin then allows glucose to be taken in by your cells and then converted into glycogen in the liver so it stops the glucose in your blood from getting too high and when it falls the glycogen is converted back to glucose. But this is ONLY a treatment as it does not permanently cure diabetes. Curing type 1 diabetes 1)​ Transplanting a pancreas -​ But the operation if difficult and risky -​ Not enough donors for the amount of people with type 1 diabetes 2)​ Transplanting pancreatic cells that are bale to make insulin from dead and living donors -​ But there's limited success so far 11.4 The role of negative feedback Most hormones in your body are controlled by negative feedback systems - involve the coordination of changes in the body's internal environment. Negative feedback Used to maintain the body at a steady state Increase - changes take place to decrease it Decrease - changes take place to increase it -​ Whatever the initial change is the negative feedback does the opposite Thyroxine and negative feedback Thyroxine in your neck uses iodine from your diet to produce thyroxine which controls the body's metabolic rate -​ Also plays an important part in growth and development If Thyroxine in the blood starts to fall, sensors pick it up in the pituitary gland and TSH is released which stimulates the production of thyroxine. Adrenaline Adrenal glands located at the top of the kidneys release lots of adrenaline in stressful situations e.g stressed, angry, frightened, excited -​ Adrenaline is then rapidly carried around the body through the blood affecting the organs such as -​ Heart rate and breathing rate increases -​ Stored glycogen in the liver is converted to glucose for respiration -​ Pupils of your eyes dilate to let more light in -​ Mental awareness increases -​ Blood is diverted away form the digestive system and goes to the bigger muscles instead Adrenaline also boosts the production of oxygen and glucose to the brain and muscles which prepares the body for fight or flight. Then after the adrenal glands stop releasing adrenaline and systems return to normal. NO negative feedback loop. Chapter 12 - homeostasis in action 12.1 - controlling body temperature In everything you do your body should remain at 37 degrees -​ Because this is the optimum temperature for your enzymes to work at. -​ Even a few degrees above or below can affect how your enzymes work leading them to -​ not working properly Basic temperature control To control your core temperature it relies on the thermoregulatory centre in the hypothalamus of the brain. Hypothalamus - has receptors that are very sensitive to temperature changes in the blood flowing through the brain. -​ Also temperature receptors on the skin which give information to the centre about the skin's temperature even if its 0.5 degrees difference. Cooling the body down When you heat up receptors track it and energy is transferred to the surroundings to cool the body down. Blood vessels - capillaries on the skin surface dilate (open wider)which lets more blood flow through the capillaries -​ This causes a flush in your skin (redness) which due to radiation from your skin to surroundings eventually cools you down. -​ You produce more sweat from the sweat glands , this extra sweat cools you down as water evaporates from your skin which transfers energy to the environment. Keeping warm When cold - enzyme controlled reactions in your cells fall too low -​ Means you can't carry out enough respiration -​ And then your cells begin to die Blood vessels - capillaries on your skin contract to reduce blood flow which reduces radiation from skin to surroundings. Sweat production - reduced or stopped Skeletal muscles- contract and relax rapidly causing you to shiver. 12.2 Removing waste products -​ As you move you body you respire, warming the body -​ When you respire you produce waste -​ When you digest food you take millions of molecules into your body Cells are always producing waste products -​ The more extreme conditions you put yourself in the more waste products you produce Main poisonous waste products Carbon dioxide These both are dangerous if levels build up Urea Carbon dioxide Co2 produced during respiration must be removed -​ Co2 diffuses out of cells into your blood down a concentration gradient then removed by your lungs when you exhale. Urea Produced through the breakdown of amino acids in the liver -​ Passes from liver cells into the blood -​ Is a poisonous gas and can cause extensive damage to cells. -​ But it's filtered out of your blood through the kidneys along with any excess water and salt. -​ Urea is produced when you eat more protein than you need This extra protein cannot be stored in the body so is converted by amino acids into ammonia which is then converted to urea which is safely removed from the body Maintaining water and mineral ion balance in the body Removal of urea- one of the ways we balance water and mineral ions in body fluids If the cells lose/ gain to much water due to osmosis it means fluids surrounding them dont function properly Water ,mineral ions and urea are lost through No control over -​ Water leaves the lungs every time you exhale -​ Water, mineral ions and urea are lost through sweat Control over -​ Urea, excess water and excess mineral ions are removed from the body via the kidneys the excreted in the urine- this tightly regulated to: -​ Maintaining the water and mineral ion content of the blood -​ Remove urea