Homeostasis is the way the body keeps a constant internal environment so that the reactions within the body can happen at optimal capacity. The following need to be kept at a constant level so that the cells can work properly:
1. Sugar content
3. Ion Content
4. Water content
Active Transport = is when gas particles or particles dissolved in a solution travel from a low concentration to a high concentration
Blood Sugar = the amount of sugar there is in a given amount of blood.
Capillary = The smallest type of blood vessel that carries blood directly to the cells.
Concentration = the amount of something there is in a given space.
Contract = A muscle contraction is when they tighten.
Dilate = get bigger/wider.
Endurance = How long you can exercise for.
Enzyme = Something that speeds biological reactions.
Evaporate = a liquid that turns into a gas.
Excess = more than needed.
Foreign Body = something from outside your human body.
Glucose = a type of sugar.
Homeostasis = the process of keeping internal conditions the same.
Hormone = chemicals that are secreted by glands around the body
Immune system = The system inside you that fights foreign bodies.
Impulse = an electrical impulse that is sent along the central nervous system when there is a change in environment.
Internal Environment = the conditions inside you.
Ion = A positively or negatively charges atom .
Molecule = A group of atoms bonded together.
Organ Donor Card = A card that some people carry that means when they die their organs can be donated to other who need them.
Osmosis = is a special kind of diffusion and is when water molecules travel from a high concentration to a low concentration.
Permeable barrier = a barrier with holes that allow certain substance to pass through.
Respiration = the process in cells that produces energy.
Transplant = when an organ is lifted from one person into another.
Somethings need to be kept at the same level as too much or too little can have a negative effect on the body, these are:
Temperature - which needs to be kept at 37 degrees with 1 one degree each side margin.
Ion Content - Too much or too little ion content can alter the amount of water that is brought in through osmosis.
Water Content - Water levels need to be kept at about the right level as too much water or too little water coming in and out of cells can damage them.
Blood sugar - High blood sugar can cause heart attacks and low blood sugar can cause your body to shut down.
The body also needs to dispose of certain produces such as Carbon Dioxide which is removed through respiration and urea which comes out in urine.
Controlling Body Temperature
Enzymes in the human body work best at 37 degrees and so the body needs to be kept at around this temperature. The body is kept at this temperature by the thermoregulatory centre inside the brain which receives impulses from the skin about the temperature of the environment around. The body reacts in different ways dependant on whether its too hot or too cold:
- The hairs on the skin lie flat
- Sweat is produced which traps in heat and takes the heat i when the sweat evaporates.
- The vessels near the skin dilate meaning the blood runs closer to the skin making heat loss quicker.
- The blood vessels near the skin contract so the blood flows further inside the body so there is less heat loss.
- The hairs on the skin stand up to trap and insulating layer around the body.
- No sweat is produced.
- The muscles contract causing shivering releasing energy to heat the body.
Controlling Blood Sugar
Glucose is a sugar needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin, a hormone given by the pancreas, controls blood sugar levels in the body. It travels from the pancreas to the liver in the bloodstream. For people without diabetes the blood sugar level should be between 4 -8 mmol/l. However when you have a full packet of tangfastics for example blood sugar is raised to around 25. This is ok in once in a while treat but if this is happening regularly then this can seriously damage your health. The body controls blood sugar through the production of Glucagon and insulin.
Eating foods containing carbohydrates puts glucose into the blood from the gut. The blood glucose concentration of the body is monitored and controlled by the pancreas. The pancreas produces the hormone insulin, which allows the glucose to go from the blood into the cells. A second hormone (Glucagon) which is produced in the pancreas when blood sugar levels fall. This causes Glucagon to be converted into glucose and be released into the body. When the glucose levels increase the pancreas stops producing insulin.
Controlling Water Levels
Water is taken in through food and drink and lost through urine, sweat and when you breathe out. The kidneys will send excess water into the bladder which will excrete it out as urine. On a day when you drink a lot but don't sweat you will have a light coloured urine. On a day when you take in the same amount of water but sweat more you will have a darker coloured urine.
The Kidneys and Homeostasis
The kidneys are adapted to for fill 3 main roles:
1. Removal of urea - Proteins can't be stored by the body so any excess if converted into fates and carbohydrates. Urea is a waste product of this this reaction which takes place in the liver. Urea is poisonous and so is filtered from the blood in the kidneys and sent to the bladder to be disposed of as urine.
2. Adjustment of ion content - Ions such as sodium are into the body as food but an imbalance in ion content can effect the rate of osmosis in and out of the cells. Excess ions are removed from the blood stream by the kidneys. However some ions are lost through sweat, which is why sweat tastes salty.
3. Adjustment of water content - Water is taken in through food and drink and lost through urine, sweat and when you breathe out. The kidneys will send excess water into the bladder which will excrete it out as urine. On a day when you drink a lot but don't sweat you will have a light coloured urine. On a day when you take in the same amount of water but sweat more you will have a darker coloured urine.
The function of the Kidney is to filter the blood so that the body gets the nutrients it needs in the right quantities. Filtration is undertaken in the nephron which is placed under extreme pressure. There is a capillary network that weaves around the spaghetti like nephron which at one end has a bowman's capsule that looks like a big C. At the other end is the renal vein that heads towards the bladder. The blood is pushed through the bowman's capsule which acts as a filter so big molecules are not squeezed out and stay in the blood. As the liquid flows through the nephron useful substance are reabsorbed back into the blood stream via active transport. All the waste products are sent to the renal vein which is connected to all the nephrons within the kidney and the waste products are sent to the bladder.
Dialysis is the process where a machine takes over the function of your kidney as it isn't properly working. In a dialysis machine the persons blood flows alongside a permeable barrier surrounded by dialysis fluid. The barrier acts like the bowman's arc as it doesn't allow the bigger molecules to pass through. The dialysis fluid has the same concentration of ions and glucose as healthy blood which means that useful ions and glucose aren't lost. Only the excess will be passed through the barrier. A person who is on dialysis will have to go in 3 times a week at 3-4 hours a time but dialysis can cause blood clots or infections.
The Function of sport drinks
Sports drinks are designed to replace lost Ions, Water and Sugar which can be lost during exercise through sweat and the nutrients being used up by the muscles. Some advertise that they can hydrate faster than ordinary water or improve endurance but it might be worth taking both just in case.
Diabetes is the condition when the body produces to much or too little insulin. There are two types:
1. Early Onset (Type 1)
2. Developmental (Type 2)
Type 1 is the type of diabetes you are born with and you will normally develop this one in the first few years of life. Type 2 can be developed by poor diet or when there is not enough insulin so glucose builds up in the blood. Diabetes can be prevented using the following 3 methods:
1. Limiting the intake of foods rich in carbohydrates.
2. Regular exercise!
3. Insulin therapy (Basically injecting insulin into the blood stream)
The amount of insulin that needs to be injected is dependant on their diet and activity, those with Type 1 diabetes will probably inject themselves several times a day. Diabetics can have a pancreas transplant, which when successful means they won't need to inject themselves with insulin again. They are still trying to develop an artificial pancreas which removes the chance of needing an organ donor but this research is still a little way off yet.
Sometimes you may need a transplanted organ as the current one doesn't work properly or is diseased. For example if the kidneys are transplanted as the ones they currently have don't work don't filter urine properly. The organ will come from somebody who dies suddenly, in a car accident for example, and have a organ donor card. This organ is taken and transplanted into the patient. Easy enough. However the organ may be rejected as the immune system will see this as a foreign body and try fight against it. There are two ways that doctors are trying to prevent this, the first is to use a donor organ that is very similarly matched with that of the patient. The patient will also be treated with drugs that supress the immune system meaning that the transplanted organs won't be attacked by the immune system.
This topic is covered by the Code Bi.12. and there are resources available in the THS store for this topic. Student worksheets are free and we have a range of quality lessons available for purchase, these include lesson plans, activity's and presentations for each lesson.