Humans as Organisms

1. Humans as Organisms

2. Contents • Nutrition • Digestive System • Circulatory System • Breathing • Respiratory System • Aerobic Respiration • Anaerobic Respiration • Nervous System • Hormones • Homeostasis • Disease • Drugs

3. Nutrition The main food types are: Carbohydrates (sometimes referred to as Starch) are required by our bodies as a source of energy. Example of food which carbohydrates can be found in are pasta, potatoes and rice. Fats are needed to insulate our bodies and to make cell membranes. They also contain fat-soluble vitamins. Example of food which fats can be found in are cheese, butter, oils and margarine. Protein are required for growth and repair. Examples of food which contain protein are meat, fish, eggs and cheese. Fibre is important because it allows the muscles in our intestines to move the material along (called peristalsis). Fibre is not digested in our diet. Examples of food which contain fibre are wholemeal products e.g. bread, fruit and vegetables.

4. Digestive System The food we eat needs to be broken down into small pieces which we chew up into even smaller ones before swallowing them. Once the food gets to the stomach the food is broken down further by the stomach's muscular walls. This is known as physical digestion. Substances which our body needs cannot be absorbed into our blood until they have been broken down further and converted into small soluble chemicals. Enzymes are responsible for this process. This process is called chemical digestion. Peristalsis is the movement of food through the digestive system by the contractions of two sets of muscles in the walls of the gut. The two sets of muscles produce wave-like contractions enabling food to move down the gut. Carbohydrate is turned into glucose, which our bodies need to make energy. Protein is turned into amino acids, required for cell growth and repair. Fats and oils are turned into fatty acids and glycerol, needed to insulate our bodies and make cell membranes. Vitamins and minerals do not have to be digested because they are already small enough to get into our blood.

5. Digestive System 1. Chemical Digestion starts in the mouth through enzymes and saliva. The food is then moved to the stomach 2. The Small Intestine receives the food next and produces protease and lipase, food is absorbed into blood, large surface area by villi 3. Large Intestine (Colon) is where indigestible food is passed to. Any excess water is absorbed before it is excreted from the anus. The Stomach produces protease, HCl and pummels food with muscular walls The Pancreas produces enzymes: carbohydrase, lipase, protease The Gall Bladder stores bile after its been made by the liver

6. Villi Villi are small projections covering the inside walls of the small instestine. Food products pass into the blood stream through the villi. Villi are located in the small intestine, and absorb very small molecules into the blood stream All other molecules (indigestible) are passed into the large intestine

7. Circulatory System The heart is a four-chambered muscular pump which pumps blood round the circulatory system. The right side of the heart pumps de-oxygenated blood to the lungs to pick up oxygen. The left side of the heart pumps the oxygenated blood from the lungs around the rest of the body. 1. Deoxygenated blood enters through the vena cava into the right atrium 2. It’s then pumped through a valve into the right ventricle chamber 3. And then up through the pulmonary valve into the pulmonary artery towards the lungs 4. Oxygenated blood enters through the pulmonary veins into the left atrium 5. It’s then pumped through a valve into the left ventricle 6. And then through the aortic valve and out of the aorta to the rest of the body

8. How the Blood is Transported Arteries (thick walled muscular tubes) carry blood away from the heart at high pressurein thick walled lumen Capillaries (very narrow tubes) have thin walls to allow glucose and oxygen to diffuse through Veins (thin walled tubes) carry low pressure blood back to the heart. Veins have thinner walls and valves to prevent backflow of blood

9. Breathing When we breathe in and out we suck air into them then expel it again. Oxygen is absorbed from the lungs into the blood, and carbon dioxide is removed from the blood and breathed out from the lungs. This exchange is vital

10. Alveoli • Alveoli are the final branchings of the respiratory tree and act as the primary gas exchange units of the lung • Used for exchanging gases: • Deoxygenated enters lungs from body, oxygenated enters capillaries from lungs • Advantages of alveoli: • Moist • Large surface area • Good blood supply

11. Respiratory System Respiration is the release of energy from glucose or other organic substances. Energy is required for growth, repair, movement and other metabolic activities. There are two main types of respiration, aerobic and anaerobic.

12. Aerobic Respiration Aerobic respiration takes place in the presence of oxygen. Glucose molecules react with oxygen molecules to form carbon dioxide and water molecules, with energy being released by the breaking of bonds in the glucose molecules. • Our bodies require energy for the seven life processes • This energy is obtained from respiration glucose + oxygen  water + carbon dioxide + energy • Glucose comes from our food, oxygen from breathing • Water and carbon dioxide are exhaled

13. Anaerobic Respiration • Anaerobic respiration occurs when oxygen is not available. Glucose is only partially broken down, and lactic acid is produced - together with a much smaller amount of energy. • Energy can still be produced without oxygen • Only a little bit of energy is obtained from respiration glucose  lactic acid + energy • Anaerobic respiration occurs in humans when oxygen is not obtained quick enough (e.g. running fast) • Only 1/20th energy amount is produced compared to aerobic • Lactic acid builds up, which causes muscle fatigue due to oxygen debt • This is overcome by deep breathing to oxidise the acid

14. Nervous System The nervous system is a means of gathering information about, and responding to, changes in the environment either inside or outside the body. The nervous system is made up of receptors which respond to stimuli and pass on information about them. The central nervous system co-ordinates the information and responds by sending signals to the effectors, which bring about a response. • e.g. you walk into a bright room • Stimulus  receptor  CNS  effector  response So… Light intensity  eye  brain  eye muscles receive information  eye muscles make pupil smaller Electrical signals are carried around the body along neurones

15. Neurones • There are 3 neurones: • Sensory – carry signals from sense organs to brain • Relay – carry messages from one part of CNS to another • Motor – carry signals from CNS to muscles

16. Reflex Arc • The subconscious movement from a stimulus that can cause harm e.g. a bee sting • The reflex arc does not require a conscious action, which might be too slow • So… the brain is bypassed… • Stimulus  receptor  effector  response

17. Hormones • Hormones help to regulate metabolic processes in the body • Hormones are secreted into the blood through endocrine glands • They travel in the blood to organs where they take effect The endocrine system

18. Hormone Gland Action Anti-diuretic hormone (ADH) Pituitary gland Controls blood water level by triggering uptake of water in kidneys Follicle stimulating hormone (FSH) Pituitary gland Triggers egg ripening and oestrogen production in ovaries Luteinising hormone (LH) Pituitary gland Triggers egg release and progesterone production in ovaries Thyroxine Thyroid gland Controls metabolic rate Adrenaline Adrenal gland Prepares body for action (fight or flight) Insulin Pancreas Controls blood sugar levels by increasing uptake of glucose Glucagon Pancreas Controls blood sugar levels by decreasing uptake of glucose Oestrogen Ovaries Controls puberty and the menstrual cycle in females; stimulates production of LH and suppresses production of FSH in pituitary Progesterone Ovaries Maintains womb-lining; suppresses FSH production in pituitary Testosterone Testes Controls puberty in males

19. The Menstrual Cycle The Key stages are 1. The egg ripens in the ovaries - stimulated FSH 2. Womb lining build-ups - stimulated by Oestrogen 3. Egg is releases - stimulated by the LH (about day 14) 4. Maintenance of uterus lining - stimulated by progesterone 5. Uterus lining breaks down - caused by low levels of oestrogen and progesterone 6. Blood and tissue loss (menstruation) • Four hormones are involved: • Oestrogen • Progesterone • FSH (Follicle stimulating hormone ) • LH (Luteinising hormone )

20. Homeostasis • Homeostasis is the body’s method of controlling the internal conditions • Controlling Temperature • Too hot? • 1. Our hairs lie flat so we let more body heat out • 2. We sweat and the evaporation of this cools us down • 3. Increased blood flow occurs through the skin to radiate out heat • Too cold? • 1.Our hairs stand up trapping a layer of air which acts like an insulator • 2. We stop sweating stopping the heat loss by evaporation • 3. Decreased blood flow occurs through the skin

21. Homeostasis • Controlling Blood Sugar Level • Blood Glucose level too high? • 1. Insulin injected by pancreas • 2. Glucose absorbed by tissues • 3. Glucose absorbed by liver • 4. Blood glucose reduced • Blood Glucose level too low? • 1. Insulin not injected by pancreas • 2. Less glucose absorbed by tissues • 3. Less glucose absorbed by liver • 4. Blood glucose increased • Diabetes – This is a condition where people who suffer from this do not make insulin so it needs to be injected

22. Homeostasis • Controlling Body Water • Too much water? • 1. Hypothalamus (part of brain) detects too much water in blood • 2. Pituitary gland releases less ADH • 3. Kidneys absorb more water from blood • 4. More water reaches bladder and is lost through urine • 5. Blood water level returns to normal • Too little water? • 1. Hypothalamus (part of brain) detects too little water in blood • 2. Pituitary gland releases more ADH • 3. Kidneys absorb less water from blood • 4. Less water reaches bladder and is lost through urine • 5. Blood water level returns to normal

23. Fighting Infection • Microbes (an organism too small to be seen by the naked eye) can enter the body through the mouth, nose and cuts or bites in the skin • Microbes (bacteria and viruses) can cause diseases • Two types of white blood cell: • Lymphocytes – engulf pathogens • Phagocytes – contain antibodies • White blood cells do 3 things: • Engulf the microbe • Produce antibodies to neutralise the microbe • Produce antitoxins to neutralise the toxins released by the microbe

24. Tobacco & Smoking • Cigarettes are harmful in three ways: • Nicotine – addictive drug that leads to heart disease. Nicotine raises blood pressure and narrows arteries • Tar – coats the lining of the lungs  less O2 is absorbed. Tar contains carcinogens which cause cancers • Carbon monoxide – poisonous gas which joins onto red blood cells making them incapable of transporting oxygen around the body

25. Drugs Drug type Example Effect Stimulants Caffeine, nicotine Increased alertness Sedatives Alcohol, tranquilisers CNS slowed Painkillers Aspirin, morphine Suppress pain receptors & neurones in CNS Hallucinogens LSD, cannabis Feeling of enormous energy, hallucinations Alcohol Alcoholic drinks Lowers inhibitions, slowed CNS and reaction times Solvents Glue, paint, fuel Distorted perception, hallucinations

26. Summary • Food is digested  v small molecules are absorbed into blood • The heart pumps oxygenated blood to the body, and deoxygenated blood to the lungs • Organisms inhale oxygen and exhale CO2 • Organisms respire to produce energy required to survive Glucose + oxygen  water + carbon dioxide + energy • Anaerobic respiration produces energy without oxygen Glucose  lactic acid + small amounts of energy • Stimulus  receptor  CNS  effector  response • Hormones help regulate the body’s metabolic rate • The body controls: water, temperature, glucose content by homeostasis • The body’s white blood cells fight disease • The body is affected in different ways by many types of drug