Water and Waste Animal Survival Pages 130 – 137 Torrance

Water Balance We gain water from food, drink and chemical reactions We gain water from food, drink and chemical reactions We lose water from sweating, breathing, passing urine and passing faeces. We lose water from sweating, breathing, passing urine and passing faeces. Water gain must equal water loss Water gain must equal water loss See fig 14.6 p131 See fig 14.6 p131

Kidney Structure and Function Our two kidneys are attached to our blood supply by the renal artery and renal vein. Our two kidneys are attached to our blood supply by the renal artery and renal vein. The renal artery carries “dirty” blood to the kidneys The renal artery carries “dirty” blood to the kidneys The renal vein carries “clean” blood away from the kidneys The renal vein carries “clean” blood away from the kidneys A ureter carries urine from the kidneys to the bladder A ureter carries urine from the kidneys to the bladder

The kidneys The kidneys are the main organs for regulating the water content in a mammal The kidneys are the main organs for regulating the water content in a mammal The kidneys work by filtration of blood and The kidneys work by filtration of blood and re absorption of useful materials such as glucose re absorption of useful materials such as glucose Urea is a waste product removed in the urine Urea is a waste product removed in the urine CREDIT CREDIT Urea is formed in the liver from the breakdown of surplus amino acids. Urea is formed in the liver from the breakdown of surplus amino acids. It passes into the blood and is carried round the body until it reaches the kidneys where it is removed It passes into the blood and is carried round the body until it reaches the kidneys where it is removed

Urinary System Diagram Renal artery – transports blood to the kidney Kidney – filters blood Renal vein – transports blood from the kidney Urethra – transports urine to outside of body Ureter – transports urine to bladder Bladder – stores urine

The Structure of a Kidney CREDIT Each kidney is made up of tiny filtration units called nephrons A nephron is made up of a Bowman`s capsule, a glomerulus and a tubule. Two main processes occur here : Filtration and Reabsorption

Nephron Diagram CREDIT Glomerulus - filters blood Bowman’s Capsule – collects filtrate Blood capillaries – reabsorbs useful substances Collecting duct – collects urine

Nephron function CREDIT StructureFunctionDecription Glomerulus Bowman`s capsule Blood capillaries Collecting duct Filtration of blood Proteins and cells stay in blood. Water, glucose and urea forced out Collects glomerular filtrate Contains water, glucose and urea Useful materials (water and glucose) leave tubule and enter blood Carries urine to the ureter Urine contains water and urea only Reabsorb and transport useful materials

Water Balance The kidneys control the water balance of the body in a mammal The kidneys control the water balance of the body in a mammal 70% of the body is water 70% of the body is water We produce different volumes of urine to regulate our water needs. We produce different volumes of urine to regulate our water needs. The kidneys are controlled by a hormone called ADH (anti diuretic hormone) The kidneys are controlled by a hormone called ADH (anti diuretic hormone) ADH is released by the pituitary gland in the brain. ADH is released by the pituitary gland in the brain.

Pituitary and ADH

How ADH regulates the kidneys CREDIT ADH is produced by the pituitary gland in the brain ADH is produced by the pituitary gland in the brain If the water content of our blood is too high - Less ADH is produced and the kidneys make lots of watery urine. If the water content of our blood is too high - Less ADH is produced and the kidneys make lots of watery urine. If the water content of the blood is too low we produce more ADH and the kidneys make small volumes of concentrated urine If the water content of the blood is too low we produce more ADH and the kidneys make small volumes of concentrated urine See p132 fig 14.7 for details See p132 fig 14.7 for details

Role of ADH CREDIT Role of ADH CREDIT

sweating High ADH Small volume of Concentrated urine High water in blood little water reabsorbed low water back into blood

Low water in blood Lot of water reabsorbed Lot of water back into blood Drinking lots of water Low ADH Large volume of dilute urine

Too much water drunk High water level in blood Pituitary releases less ADH Kidney reabsorbs less water High volume of dilute urine produced ADH and too much water CREDIT 1 2 3

ADH and too little water CREDIT Too little water drunk Low water level in blood Pituitary releases more ADH Kidney reabsorbs more water Low volume of concentrated urine

Kidney failure treatments Since the kidney is responsible for the removal of wastes from the blood, any damage, either from accidents or disease, can lead to a build up of poisonous wastes in the body. Since the kidney is responsible for the removal of wastes from the blood, any damage, either from accidents or disease, can lead to a build up of poisonous wastes in the body. Kidney Machine Kidney transplant Benefits Limitations Purifies the blood No rejection Can live a more normal life if it is successful Expensive dialysis takes 12 hours twice a week Rejection of kidney Anti rejection drugs reduce bodies ability to fight disease

Kidney DIALYSIS Involves being connected to a machine for long periods of time Involves being connected to a machine for long periods of time