Presentation on theme: "EXCRETORY SYSTEM (urinary)"— Presentation transcript:
1EXCRETORY SYSTEM (urinary) I INTRODUCTIONExcretion rids body waste substances, particularly end products of metabolism.Several organs assist in the excretory process but the kidneys which are a part of the urinary systemare the primry organs of excretion.
2EXCRETORY SYSTEM contd. Urine is formed by more than one million nephrons in each kidney which not only serves to rid the body of nitrogenous wastes, but also to regulate the water content, the salt levels, and the pH of the blood.USE pp. 243 & 244 of the lab manual.
3EXCRETORY SYSTEM CONTD. I EXCRETORY PROCESS IN HUMAN BODY1. Lungs--carbon dioxide2. Sweat-Glands--urea (in small quantities.3. Digestive Tract-excess Calcium,andiron from the small intestine.4. Kidneys--Nitrogenous wastes , (urea)5. Liver--Bile pigments
4EXCRETORY SYSTEM contd. Proteins are broken down into amino acids.They may be used to produce new protein or they may be deaminated in the liver to form ammonia.Ammonia is toxic and is converted in the liver to urea. This is delivered to the kidneys by the blood. (ON BOARD)
5EXCRETORY SYSTEM contd. FUNCTIONS OF EXCRETORY SYSTEM1. Excretion of nitrogenous products of metabolism in urine.2. Maintenance of the proper water balance in the body.3. Maintenance of the proper conc. Of salts.4. Regulation of pH in the blood.
6EXCRETORY SYSTEM contd. URINARY SYSTSEM1. Kidneys--(bean shaped organs about 4”X2”. They are reddish brown in color.2. URETERS--(tubes which convey the urineto the bladder.)3. URINARY BLADDER--(hollow muscular organ that can hold up to 600 mls. Of urine.4. URETHRA--(tube that runs from bladder to body surface. Drains the bladder.)
7EXCRETORY SYSTEM contd. ANATOMY & FUNCTION OF THE KIDNEY1. CORTEX--Layer that lies next to outside of kidney. Contains the nephrons, the filtering units of the kidneys.2. MEDULLA--The inner layer of the kidney.It consists of thousands of collecting tubules. Forms pyramids & calyx PELVIS--Hollow collecting chamber.
8EXCRETORY SYSTEM contd. The formation of urine by the nephron results from 3 physiological activities that occur in different regions of the nephron:I F I L T R A T I O N1. Blood pressure forces small moleculesfrom the glomerulus into Bowman’scapsule.The glomerular filtrate (20 percent of
9EXCRETORY SYSTSEM contd. 3. This glomerular filtrate , collected in Bowman’s capsule is carried to the renal tubule .per cent of the blood (serum protein & blood cells) is carried by the efferent vessel to the network of veins sorounding the renal tubule.This is accomplished by blood pressure.
10EXCRETORY SYSTEM contd. II. SELECTIVE REABSORPTION1. Cells in the walls of the proximal convoluted tubule reabsorb whatever substances are needed and pass them out into the venous capillaries sorrounding the tubule.2. The tubule is able to select for reabsorption just the amount of any one substance needed by the blood.
12EXCRETORY SYSTEM contd. III. SECRETIONIn the distal convoluted tubule substances not needed in the blood, are transferred out of the blood from the venous capillaries into the the tubule. The tubule then secretes these into the filtrate.Substances excreted are: (1) water (2salts (3) urea (4) Uric ascid (5) creatinineAll are excreted from the body in the urine.