GCSE Unit 3 Biology- An Overview

• Red blood cells are minute and have a flexible nature that allows them to bend and bounce back to their original shape. This is useful when they have to squeeze through the minute capillary alleyways between cells in the tissues. They contain haemoglobin to carry oxygen to the cells. They have a thin outer membrane to let oxygen diffuse through easily. Shape increases the surface area to allow more oxygen to be absorbed efficiently. They also have no nucleus, so the whole cell is full of haemoglobin. 
• Haemoglobin is found within red blood cells and allows the carry of oxygen around the body. These then travel in the blood and are able to fit through cappillaries and pass oxygen into the body.
• Red Blood Cells transport oxygen from the respiratory surfaces to tissue using the haemoglobin. 
• White blood cells function mainly to protect the body against infection and disease.
• Platelets function to initiate blood clotting for example when we get cut.
• Plasma is mainly there to transport nutrients, waste products, hormones and heat.

• Plasma is mainly there to transport nutrients, waste products, hormones and heat.
• Oxygen and haemoglobin combine in an easily reversible reaction to form oxyhaemoglobin.

• Transpiration is the transport system within plants. Water is pulled up the stem from the roots to the leaves. The water is used for photosynthesis and helps to stop the plant from wilting. Water then evaporates from the leaves into the air.
• http://www.islandnet.com/~see/weather/graphics/photos0910/stomata.jpg           <----Link to an image.
• Transpiration occurs in order to cool the plants and control it's temperature. Xylem are long tubes that sucks water from the leaf all the way to the root hair cells to absorb water. They are able to do this well because they have a large surface area.
• Windy conditions increase the rate of transpiration. Water molecules are blown away from the leaf surface, so more diffuse out of the stomata.
• Humid conditions decrease  to rate of transpiration. The air contains a lot of water already.
• Warm conditions increase the rate of transpiration. The air can hold more water vapour.

• Light causes the stomato to open. This increases the rate of transpiration.
• More transpiration takes place during the day than at night. This is because the stomata are open during the day and closed at night. The stomata may also close in very dry conditions. This is because the water lost in transpiration is not being replaced by water from soil. The stomata close to reduce transpiration.
• The amount of water lost is actually less than the amount of water taken in by the roots. This is because some water is used in photosynthesis.

• Waste chemicals like urea are carried to your kidneys in the blood. The kidneys take these chemicals out of the blood as it flows through them. They are then excreated as urine. So your kidneys 'clean' your blood.
• http://healthmediconline.com/wp-content/uploads/2011/04/kidney.jpg    <---Link to diagram.
• Kidneys: 1. Remove Waste.   2. Control homeostasis.
• Kidneys contain two areas blood vessels and tubule.
• 1. Ultra filtration- lots of water and producs of digestion are squeezed out of the blood and into tubules under pressure.    2. Selective reabsorbtion- The blood takes back the things it wants (e.g. glucose and ions) even though this means going against a concentration gradient blood vessels.  3. Waste- excess water, excess ions and any urea are now removed through the water.                   http://www.pitlochry.pkc.sch.uk/images/Biology/nephron.JPG      <----Link to image.
• Blood is brought to each kidneys via the renal artery. It contains many waste chemicals like urea.

• Useful susbstances are reabsorbed into the blood from the nephron back into the glonearulus against a concentration gradient. This takes place by active transport. Energy from respiration is needed for reabsorption.
• Proteins from the foods we eat are the wate that must be cleaned via our kidneys.

• A kidney transplant is a surgical procedure done in soem patients with kidney disease. It replaces the patients diseased kidneys with a healthy one.
• Kidney transplant surgery takes about three hours. During this surgery the donor kidney will be places in the patients lower abdomen, blood vessels from the donor kidney will be connected to arteries and veins in your body, and the areler from the donor kidney connected to the bladder.
• Risks of having a kidney transplant include: Rejection of the new kidney, severe infection, bleeding, reaction to the anesthesia used and failure of the donor kidney. 
• A transplant rejection is the bodies destruction of a newly introduced organ or tissue. A persons immune system does not recognise the cells of the transplanted tissues.
• Medicines are given to suppress the immune system to stop it from rejecting the kidney. But taking them makes it easy for a person to get sick. Having a suppressed immune system makes it harder for someone to fight off other infection. But they are normally successful. Another way to prevent it is the bone marrow of the patient is treated with radiation to stop white blood cell rejection.

Having a suppressed immune system makes it harder for someone to fight off other infection. But they are normally successful. Another way to prevent it is the bone marrow of the patient is treated with radiation to stop white blood cell rejection.

• Kidney dialysis is a life-support treatment that uses a special machine to filter harmful wastes, salt and excess fluid from your blood. This restores the blood to a normal healthy balance. It replaces many of the kidneys important functions.
• Patients often need dialysis treatments several times a week. How long each session lasts depends on:  -How well your kidneys work. -How much fluid you gained since your last dialysis session. -How much waste has gathered in your blood since your last dialysis session. -Your weight. -The type of machine being used.
• There are two main types of dialysis; Hemodialysis and Peritoneal dialysis.

• http://www.cumberlandcountywoman.com/images/ContentEditor/diagram-breathing-281.JPG   <----Link to a diagram.

• Breathing:

-Ribs; In:They are raised upwards and outwards. Out: They are lowered downwards and inwards.

-Diaphragm; In: The muscles in it contract and your diaphragm flattens. Out: The muscles in it relax and cause your diaphragm to bulge upwards.

-Inter-coastal Muscles; In: Muscles contract. Out: Muscles relax. Both move ribs.

-Lung Volume; In: Air passes into your lungs because the external air pressure is greater. Out: Air is forced out of your lungs because the pressure inside them is greater than external air pressure.

-Thorax; In: Increases its volume, pressure inside decreases. Out: Decreases volume, pressure inside increases.

COPD- Chronic Obstructive Pulmonary Disease.

- This is the co-occurrence of chronic bronchitis and emphysema.

-The diseases of the lungs in which the airways become narrowed. It is not reversible and becomes progressively worse.

• Your trachea branches many times, similar to the roots of a tree. The branches end up at tiny air sacs called aveoli. It is here that has exchange takes place.

• Your gut or digestive system is about 9 meters long. It starts at your mouth and ends at you anus. It bends and twists a lot to fit inside your body. But your gut is not just a simple tube. There are many different parts to it.
• Ingestion is the process of taking food and drink into the body through the mouth. Food enters your mouth in bite-sized chinks. Chew your food well- it's important for digestion. The chewed food is mixed with saliva. Your salivary glands make saliva.
• Saliva contains a carbohydrate enzyme called amylase, this starts to digest starch to sugar.
• Mucus is a slimy substance in saliva. It helps the food slip down your throat. 
• The oesophagus (also known as the gullet) passes the food down to your stomach. It has circular muscles in its wall. These muscles contract and squeeze in behind food to push it along.
• Your stomach is a muscular bag that will hold up to 2 litres of food. Stomach acid also kills germs. After 2-3 hours of churning the food is a runny liquid. A ring of muscle opens to let the food squirt out. It passes into the small intestines a little at a time.

• Small intestines- is not really that small, being about 6 meters long. The liquid food is squeezed gently along. Here three important liquids are added to the food;

-Pancreatic juice; contains carbohydrase proteins and lipases. These enzymes carry on digesting the food.

-Bile sewers; to the small intestine from the bile duct. Bile is made in the liver and is stored in the gall bladder.

-Intestinal juice; is made by glands in the wall of the small intestine. It also has carbohydrase, proteses and lipases in it.

• Absorption- Another important job the small intestine carries out. It has to pass through the wall into the blood. The small intestine was well designed for absorption as it has; A thin lining, a good blood supply, a very large surface area.

• Your large intestine-By the time your food gets here there's not much useful food left. It's mainly fibre, dead cells, bacteria and water. As it passes along the large intestine some of the water is absorbed into the blood. The solid waste or faeces are stored in the rectum. Eventually the faeces are egested through the anus.
• X-Rays; This is how doctors can see inside your gut without opening you up.
• Optical Fibres; Doctors use these to look inside your stomach. Many are held together in a bundle that go down the patients throat.
• The small intesine also has milions of tiny, finger like processes called villi (the singular of villi is villus).
  
• http://media.lanecc.edu/users/rathaketten/225Lectures2011/02B/images/14villi.jpg     <---link to a diagram of a villus.
  

• Micro Organisms are tiny living organisms such as bacteria, viruses and fungi.
• Bacterias are used for making yoghurts and cheese.
• Yeast is a single-celled organism used in making alcoholic drinks and bread.
• The difference between these two processes is whether the yeast respires aerobically or anaerobically.
  • Aerobic respiration: Sugar->Water + Carbon Dioxide
  • Anaerobic respiration: Sugar-> Alcohol + Carbon Dioxide