3.3: homeostasis

homeostasis

homeostasis

maintenance of stable internal environment in body despite fluctuations in internal and external functions

conditions which need to be controlled

temperature, water levels, blood glucose concentration

reason for temp to be controlled

to provide suitable environment for enzymes so they can work fastest at optimum temperature

2 processes involving skin which colls body

sweating, vasodilation

sweating

water evaporates from skin surface resulting in increased energy transfer away from body

vasodilation

allows blood to flow closer to surface of skin allowing more heat to be released from body

process of vasodilation

body detects rise in temperature, blood vessels supplying cappilaries at skin surface dilate, more blood flows closer to skin surface where more heat energy released

3 processes to keep body warm

vasoconstriction, shivering, erection of hairs on skin

process of vasoconstriction

body detects drop in temperature, blood vessels supplying capillaries at skin surface constrict, less blood flows closer to skin surface so less heat lost to surroundings

2 effects caused by insulin secretion

more glucose taken up by cells and glucose converts into glycogen for storage causing decrease in blood glucose levels

effect of glucagon secretion

causes glycogen to be broken into glucose to raise blood glucose levels

difference between type 1 and type 2 diabetes

type 1 is where body doesn’t produce enough insulin whereas type 2 is where body no longer responds to insulin

type 1 treatment

insulin injections

type 2 treatment

reducing intake of simple carbohydrates, losing weight, increasing exercise. there are some drugs to make insulin more effective in body by helping pancreas make more insulin or reduce amount of glucose absorbed by gut

what happens if animal cell placed in soultion of lower water potential

cell shrinks or crenates

what happens if animal cell placed in soultion of higher water potential

cell bursts or lyses as water moves into cell

what happens if animal cell placed in soultion of equal water potential

no net movement of water in or out of cell

function of kidneys

maintains balance of water and other substances in body through urine production. filters out waste products such as water, ions, urea from body. selectively reabsorbs useful substances such as glucose, ions and water into body

general structure of kidney

cortex, medulla. renal artery carries blood to kidney. each kidney contains many nephrons. ureter carries fluid from kidneys to bladder

ADH

secreted into bloodstream, increases permeability of kidney tubules to water. increases reabsorption of water, where more water leaves tubule to move into bloodstream

negative feedback loop when dehydration detected

thirst signals activated, more ADH released

negative feedback loop when overhydration detected

less ADH released, dilute urine produced, salts retained