Regulation: is through:
- Sweating when water on the skin evaporates it has a cooling effect
- Radiation of heat the heat is radiated into the air or is conducted (transferred) to any object touching the body. This is done through blood vessels under the skin that either dilate when the body is hot or constrict when the body is cold. Body warm = vasodilatation, body cold = vasoconstriction.
- Convection heat lost due to normal air circulation: wind=cold.
The skin has hairs on it that are controlled by hair erector muscles. When in state of relaxation the hair remain down close to the skin, thus no air is trapped between the body and hair, which then could warm up due to radiation. Cold = goose bumps.
When the body is hot the thyroid gland stops producing thyroxin (a hormone) so that you loose your appetite.
Osmo-regulation: control of the H2O, through ADH. When cells loose water you feel thirsty.
Bi-carbonates: controls the blood pH.
Liver: controls the glucose levels. When glucose rich blood passes through the pancreas, chemoreceptors tell how much glucose there is in the blood, and relative to this info insulin is made. In the pancreas Islets of hangerhams are present:
- Alpha cells: produce glucogen, this transforms glycogen into glucose
- Beta cells: produce insulin, transforms glucose into glycogen.
Insulin and glucogen are antagonistic hormones. If the glucose level in the blood is too high, osmosis occurs and the RBC’s would decrease. Glucose is needed for cell respiration.
Excretion: the removal of waste products produced my metabolism. (Skin-salt, kidney-urea, lungs- O2&CO2, liver-bile).
Surplus amino acids must be degraded to harmless levels. Fresh water fish can get rid of ammonia because the water dilutes it straight away. Bird’s carries as little water as they can so they can fly, only excrete uric acid paste.
The less water is excreted the longer the Loop of Henley.
Human Kidney:
The process of Ultra-filtration: the blood pressure pushes he blood into the glomerus where it only leaves the cells, large proteins and plasma proteins in the capillaries, because it looses the plasma and dissolved substances. The filtrate is called primary urine. This flows into the capsule and it is re-absorbed. In the proximal tubule 80% of the glucose is actively placed back, water passively through osmosis and sodium is pumped out and chloride flows back. The pre-urine remains isotonic (same conc. Level as the blood.)
Loop of Henley: The loop goes down where water is re-absorbed. In the loop going up, NaCl is taken out. This part of the loop is impermeable for water, as the descending part of the loop is impermeable for NaCl.
In the collecting duct water is still taken out, which means the urine is hypertonic compared to the blood. You should still find water in this duct because it is close to the others. The permeability of the duct depends on the ADH levels. (High conc.- more released, low conc.- less released)
Dialysis: a sort of artificial kidney. It works with the process of diffusion. The patient’s blood goes through a machine that cleans it out for them.
