3.4 Flashcards
what is homeostasis?
homeostasis describes the mechanisms by which a constant internal environment is achieved. the stability attained is actually a dynamic equilibrium, in which continuous charge occurs yet relatively uniform conditions prevail
why is body temperature regulated?
if temperature were allowed to rise out of control, protein and therefore enzyme structure would be affected
why is amount of water regulated?
levels of water affect metabolism and osmosis
why is amount of glucose regulated?
levels can affect osmosis and rate of respiration
why is amount of nitrogenous waste regulated?
it can become toxic in the body so it is important the levels dont get too high
what is negative feedback?
the control system responds when conditions change from the ideal or set point and returns conditions back. there is a continuous cycle of events in negative feedback
what is positive feedback?
when a high level of something triggers the body to increase it even further
describe a negative feedback graph
set point (optimal conditions) in a straight line. curve above and below.
1- deviation from set point
2- corrective action
3- return towards set point
4- moves past set point
5- corrective action
what is a variable?
the thing that the body wants to keep constant
what is a detector?
detects the change (receptor cells)
what is a coordinator?
decides what to do about the change
what is an effector?
produces a response (to the change)
what happens in most biological control systems?
the coordinator is no longer alerted of the deviation
what are the functions of the mammalian kidney?
removal of nitrogenous metabolic waste from the body, control osmoregulation
what is osmoregulation?
mechanism by which the balance of water and dissolved solutes is maintained
how are kidneys supplied with blood?
at arterial pressure by renal artists which branch off the abdominal aorta
how does blood leave the kidneys?
through the venal vein into the inferior vena cava
how many nephrons are in a kidney?
millions of them which act as tiny filtering units
what is the cortex of the kidney?
dark outer layer which has a high density of capillaries as it is the sit of blood filtration
what is the medulla of the kidney?
lighter area inside the cortex which contains nephron tubules which make the kidney pyramids and collecting ducts
what is the pelvis?
innermost part of the kidney which collect urine before it passes to the bladder
what is the ureter?
tube which connects the kidney to the bladder
what is the bladder?
a muscular sac for holding urine
what is the urethra?
a tube which allows for urine in the bladder to be excreted from the body
