Excretion and Homeostasis Flashcards
excretion
the process by which metabolic waste and harmful substances produced by chemical reactions within the body cells are removed from the body
importance of excretion
prevents harmful substances from building up and killing cells
metabolic waste
carbon dioxide, water , urea, bile , heat
excretory organs
kidneys - water , urea and salt
lungs - carbon dioxide
skin- water , urea and salts in the form of sweat
liver- bile and urea
kidneys functions
excrete metabolic waste from the body and to regulate the volume of blood plasma and the bodies fluids by regulating the water concentration in our bodies
Journey through the nephron
ultrafiltration occurs in the glomeruli, pressure in the blood forces substances through the bowmen’s capsule known as filtrate . The filtrate then travels through the 1st convoluted tubule where some useful substances are absorbed by the network of capillaries around the nephron. In the loop of henle some water is reabsorbed and some salts and water is reabsorbed in the 2nd convoluted tubule via selective reabsorption. The filtrate then continues to the collecting duct where it is carried to the bladder to be stored
renal dialysis
this is when the kidney fails so waste is not able to be removed from the body , harmful substances build up and cause the blood to become toxic , during renal dialysis blood from a vein flows through a dialysis machine and the is returned to the body , this separates the blood and waste products via a permeable membrane
the skin
epidermis- protects the layers from sun damage and water loss
sebaceous gland- secrets sebum
nerve ending - detects stimulus
subcutaneous layer- prevents heat loss
hairs- prevents heat loss
capillary network- regulate body temp
sweat glands /pores - evaporates and cools body
homeostasis
maintaining a constant internal environment
negative feedback
this is achieved by the nervous systems and hormones
if this fails levels would continue to increase or decrease and a persons health may be impaired
osmoregulation
osmoregulation- the regulation of water content of blood plasma and body fluids
deals with ADH(antidiuretic hormone)
too little water in the blood- the hypothalamus senses the amount of water and the pituitary gland secrets ADH which travels in the blood to the kidney which causes the collecting duct would become more permeable to allow more water to be reabsorbed which makes less urine to be produced
too much water - hypothalamus detects amount of water in blood and pituitary gland secrets little ADH and the collecting duct and 2nd tubules become less permeable to retain water and a lot of urine is produced
thermoregulation
temp rises - the skin produces sweat to remove heat, vasodilation which is the arterioles dilate increasing blood flow and heat loss , respiration slows , and hair follicle lies flat which allows air flow freely to take away heat
temp drops - Skin stops producing sweat, vasoconstriction which is when the arterioles constrict decreasing blood flow and heat loss , respiration speed up increasing heat loss and hair follicles stands up straight which traps a layer to trap heat and warm the body
regulation of carbon dioxide
if it increases the blood becomes more acidic . Receptors in the medulla detects this change and sends messages to muscles in the diaphragm to adjust the rate of breathing
Regulation of blood glucose levels
the pancreas constantly monitors the level of glucose in the blood
rises- the pancreas secrets insulin which stimulates body cells to absorb glucose for respiration and for the liver to convert excess into glycogen
drops - secrets glycogen which stimulates the liver cells to convert stored glycogen to glucose
Regulation of blood glucose levels
the pancreas constantly monitors the level of glucose in the blood
rises- the pancreas secrets insulin which stimulates body cells to absorb glucose for respiration and for the liver to convert excess into glycogen
drops - secrets glycogen which stimulates the liver cells to convert stored glycogen to glucose
