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For high school students

Aliya Nabil

on 17 September 2012

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Transcript of Excretion

Excretion Excretion Excretion is the removal of
metabolic waste products
and toxic waste
from the body What is excretion? Anabolism + Catabolism = Metabolism Building complex substances Breaking down complex substances chemical reactions in body Sum total of all Urinary System Kidneys Ureters Urethra Urinary bladder Hilus
connected to renal artery, renal vein and nerves Ureter
carries blood to bladder Bladder
elastic muscular bag that stores urine Urethra
Urine passes through this duct from the bladder to out of the body Sphincter Muscle
when bladder full, it relaxes to allow urine to flow out Structure of a KIDNEY Cortex
-outer dark red region
-protected by fibrous capsule Medulla
-inner thicker pale red region Pyramids
- 12-16 conical structures in the medulla Structure of a kidney tubule (Nephron) Renal Pelvis
-enlarged portion of the ureter inside the kidney There are many nephrons in the pyramids
Urine is formed there
They are surrounded by blood vessels
Each kidney has about 1 million nephrons! Nephrons (Kidney Tubules) by aliya ahmad nabil by Aliya ahmad nabil
Haneem Matali
Hannan Said Mohamud Urine Formation excess mineral salts and nitrogenous wastes are removed by the kidneys in the form of Ultrafiltration
Selective reabsorption How is urine formed?? Ultrafiltration takes place in the mechanical filtration 2 conditions for it to take place: High blood pressure Partially permeable membrane afferent arteriole is wider than efferent arteriole the membrane that wraps around the glomerular blood capillaries have small pores aka BASEMENT MEMBRANE Why are our kidneys important? Kidney Failure why are our kidneys important? 1.The kidneys are excretory organs
They remove mainly nitrogenous waste products (urea) , excess water and mineral salts 2.They are osmoregulators
They regulate the salt and water balance of the body fluid THEY ARE SO IMPORTANT but what if they fail...? What to do when you have kidney failure.. What causes kidney failure? High blood pressure Heavy drinking Diabetes Kidney transplant Dialysis Advantages Disadvantages Fewer diet restrictions No need for dialysis Transplanted kidney works like a normal kidney requires major surgery Need to wait for a donor Body may reject the new kidney How is the blood cleaned in a dialysis machine? Exchange of substances between the blood and the dialysis fluid Exchange of substances 5+7= (cc) image by anemoneprojectors on Flickr NO diffusion out of the blood Diffuses out of the blood DIALYSIS FLUID BLOOD Does not contain metabolic waste products Same concentration of essential substances (glucose,amino acids, essential salts 5+7= Contains metabolic waste products (cc) image by anemoneprojectors on Flickr Same concentration of essential substances (glucose,amino acids, essential salts Increases surface area to volume ratio Speeds up rate of diffusion Spark Tubing is narrow, long and coiled (cc) image by nuonsolarteam on Flickr Direction of blood flow is opposite to the flow of dialysis fluid Maintains concentration gradient Selective reabsorption as the filtrate passes through the tubule useful materials are reabsorbed into the bloodstream If too much filtrate passes out as urine, the body would be dehydrated

the control of water and solute levels in the blood to maintain a constant water potential in the body. OSMOREGULATION Antidiuretic hormone (ADH)
controls amount of water in the blood Pituitary gland releases it In the hypothalamus Loss of water
(SWEATING) Intake of water (DRINKING) Stimulates Hypothalamus More ADH released
by pituitary gland Less ADH released by Pituitary Gland Kidney Tubules reabsorb less water
More urine is produced Kidney Tubules reabsorb
more water
less urine is produced Water potential returns normal
Full transcript