2.77b thermoregulation

• negative feedback look - method of control/ mantaining constant conditions

in humans = body temp is constantly 37/8 degrees
• body temperature is feeds into the brain (hypothalamus) and is compared to the theoretical optimum body temp
• if the body temp needs to be changed then this is done by the effector, skin.
• the response will either be a decrease or a increase and feeds this information once again to the brain (hypothalamus)

components that control body temp in skin are sweat glands and the capillary network [which allows blood to move closer or further away from the surface of the skin].

if your body temperature gets too high your hypothalamus regulates to your skin which bring around cooling, like sweating, hairs being flat and blood flow to the surface of the skin increases as blood vessels dilate (get bigger, also called vasodilation) which increases the exchange of heat to the outside of the body e.g. evaporation of sweat and radiation

if your body temperature gets too low your hypothalamus sends messaged to your skin which causes shivering, vasoconstriction and raised hairs. vasoconstriction reduces heat exchange and forces blood to travel further down the tissues

the efficiency of both of these regulations increases the further away your body temperature gets from your optimum temperature

2.77a thermoregulation

• homeostasis - that the conditions are kept constant
• homeothermic temperature is kept constant
• some organisms (mammals) who's body temperature remains the same and carry out a process called thermoregulation
• other organisms body temperature varies on the environment
• the optimum temperature for max rate of reaction for enzyme reactions is approximately the same as the temp as mammals body temeperature

2.76 sensitivity

• sensitivity is what organisms use to respond to changes in the environment
• changes in the environment (stimuli) include changes in:
-light
-temperature
-pressure
-chemical
• in order to be able to detect these changes organisms require to have receptors
• in order to respond to changes in the environment organisms require effectors e.g. muscles, glands
• the response ensures that the organism can survive the changes of the environment

2.75 Urine

• urine conatins: salts, water, urea
• salt and water affects the composition of tissue fluid called osmoregulation
• the removal of urea is part of the process of the excretion of metabolic waste.
• the composition of urine varies on the conditions in which a person is operating

2.74 ADH

• ADH - Anti-dirretic hormone
• it is produced in the hypothalamus region of the brain
• it flows through the blood as the kidney as it's target
• ADH has the ability to make the blood more or less concentrated
• ADH targets the collecting duct, and makes it possible for more water to be absorbed through the collecting duct (2.72)
• it makes the walls more pours, allowing more water to pass
• the consequence of this would be that the urine would have a smaller volume and a higher concentration

How does ADH react with:
a hot day -


a cold day -



dehydration -

2.73 glucose reabsorbtion

• selective reabsorbtion - the molecule is selected (glucose) and put back into the blood
• filtration occurs in bowman's capsule
• Gluscose was one of the filtrates taken out of the blood.
• Urine does not usually contain glucose (urine containing glucose is usually diagnosed as diabetes)
• But the reason why glucose is present in the urine after being filtrated out of the blood is because in the proximal convoluted tubule section glucose is removed and taken back into blood
• so glucose is reabsorbed into the blood in the PCT

2.71 Ultrafiltration

• The nephron carries of the filtration of blood which results in filtered blood (clean) as well as waste represented by urine.
•The urine will emerge from the end of the Medulla and carry on into the pelvic region.
• urine contains water, salts and (urea)
• The filtration begins in the bowman's capsule.
• First the blood arrives in the kidneys through the afferent arteriole with HIGH pressure.
• It continues into a twisted part in the arteriole called the glomerulus (inside the capsule)
• Then the blood exits the capsule out of a smaller arteriole than the Afferent called the Efferent
• The blood pressure increases in the glomerulus
• The high pressure forces plasma (water, salts, amino acids, glucose and urea) out inside the blood.
• These are forced into the inside of the bowman's capsule
• When the plasma is forced into the capsule we change the name of it to glomerula filtrate
• so the blood has been filtered by pressure due to the smaller blood vessel generating a high pressure forcing the liquid into the tube