Homeostatis

Homeostatis = The processes in the body that help maintain a constant internal environment

Conditions that must be kept constant = salt, blood sugar levels, temp, water

Carbon Dioxide is a waste product of respiration, screted by the lungs

Amino acids that we don't use are converted into urea by the liver, excreted by the kidneys in the urine, urine is stored in the bladder

Water and ion content of cells are carefully controlled - if not too much or too little water may move in and out of cells by osmosis

Maitaining a constant internal temperature

Receptors in skin and brain detect body temperature = thermoregulatory centre

We need to regulate temperature so enzymes can work at their best - if not enzymes can denature

Normal internal nody temp. = 37 degrees

Above = Enzymes denature and block metabolic pathways,

Below = Slow down metabolism and effect the brain

Body temp. can increase because: being ill, excersise: reactions release heat, being in a hot climate

Body temp. can decrease because: may be in a cold climate, being wet

If core temperature rises:

- Blood vessels dilate nearer to the surface of skin to allow more clood flow through capillaries - heat is released through radiation

- Sweat glands produce more sweat. The sweat evaporates from skin's surface. Energy used for sweat to evaporate comes from the skin's surface = we cool down

If core temperature falls:

- Blood vessels nea surface of the skin constrict and less blood flows through capillaries = less heat is radiated

- We shiver - muscles contract quickly and this requires respiration and some energy produced is released as heat

Pancreas monitors and controls the level of sugar in the blood

Too much sugar --> pancreas produces insulin --> sugar stored in liver,glycogen

If insulin is not produced or respond to insulin = blood sugar level = fatally high = diabetes

Symptoms: going to toilet constantly, feeling tired, feeling ill

Treatment: frequent checking of blood glucose levels, injecting insulin, maintaining/controlling diet

Increases risk: heredity, advancing age, overwieght, poor diet, inactivity