Changing the way you learn

Homeostasis

Keeping your internal environment constant including monitering and controlling waste mateials... body temperature...water and ion content..... blood glucose levels
1. Waste products
  1. carbon dioxide - produced by respiration and removed via the lungs when we breathe out
  2. urea produced in the liver by the breakdown of amino acids and removed by the kidneys in urine ...urrea is temporarily stored in bladder and then excreted as urine
Body temperature control
1. inside the brain ---- thermoregulatory centre
  1. monitors and controls body temp ......has receptors that monitor the temp of the blood flowing through the brain and recieves information (impluses) from temp receptors in the skin
2. sweating --- cools the body ----but water is lost so then we need to drink fluid or eat to replace the water and could also less urine
3. core body temp
  1. too hot ----- blood vessels supplying the skin capillaries dilate (widen)...... more blood flows through the capillaries meaning more heat lost by radiation and so the skin appears red when a person is hot due to increased blood flow beneath surface
    1. sweat glands relase more sweat so water in sweat evaporates and carries heat energy away thus cooling the skin surface/body
  2. too cold ---- blood vessels supplying skin capillaries constrict ( narrow ) .... less blood flow through the capillaries and so less radiation of heat energy
    1. muscles start to shiver causing heat energy to be released by respiration in cells
4. body temp 37
Kidneys (dialysis and transplants)
1. kidneys remove urea and excess ions and water from the body
2. dialysis
  1. advantage---- more available than kidney donors and no drugs involved everyday
  2. disadvantages------ long and regular sessions as well as less freedom eg holidays/trips... diet control
  3. as blood flows through dialysis machine -----1) blood is separated from dialysis fluid by partially permeable membranes ----2) the membranes allow urea and excess substances to pass tfrom the blood into the dialysis fluid....3) concentrations of dissolved substances in the blood arerestored to their normal levels
    1. dialysis fluid contains smae concentration of useful substances as blood to ensure glucose and mineral ions arent lost through diffusion
3. transplants
  1. advantages----- no more dialysis....no need to contol diet and frredom
  2. disadvantage----finding donor ...rejection of kidney and need for drugs (immunosupressants)....lead to prone of other illnesses as immune system has been weakened
  3. prevention of rejection ---- donor with similar tissue type mostly close relatives and treated with drugs that suppress the immune system
Kidneys
1. blood vessels carry blood through kidney ( 3 processes)
  1. ultra filtration --- lots of water and all small molecules are squeezed out of the blood under pressure into tubules in the kidney
    1. selective reabsoption---all sugars and any ions and water needed by the body are reabsorbed back into the bloood from the tubuls
      1. exceretion of waste----excess water and ions and all urea pass into the bladder in the form of urine where its stored before being released from the body
Blood sugar concentration
1. type 1 diabetes---pancreas makes no or little insulin ...glucose cannot enter cells then glucose cant convert to glycogen in the liver for storage
  1. controlled by insulin injections ....careful control of diet and exercise
  2. insulin converts glucose to glycogen stored in the liver.... a hormone called glycugon made in the pancreas when blood level too low... this causes glycogen to convert to glucose an be released into the blood
2. pancreas monitors and controls blood sugar levels and secretes hormone insulin...insulin allows glucose to move from the blood into the cells
3. frequent injection---controllable and choose correct concentration of insulin but have to carry it all the time and insulin has to be refridgerated
4. insulin oump ----dont have to remember to inject yourself, dont have to think about it all the time and more freedom with diet and exercise however you have to carry it around ,cant choose hwo much you get and have to eat more regularly

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Homeostasis

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	Created by dpatel383 over 12 years ago