EXCRETORY SYSTEM

By: Domingo A. Victoria

FUNCTION

1.Collection and elimination of metabolic waste products 2.Maintain homeostasis.

METABOLIC WASTES

•heat •carbon dioxide from respiration •water derived from the oxidation of carbonates and fats •bile salts and pigments from the breakdown of other worn-out tissues and from excess dietary intake •urea from protein metabolism

HUMAN EXCRETORY SYSTEM

•located in the lower abdomen •excretory structures include the kidneys,urinary bladder, ureters, and urethra •the main wastes collected is called urine •other organs for excretory include the liver, lung and skin

KIDNEY

•paired, bean shaped organs located on both sides of the spinal column •around 5 in along 3 in wide and 1 in thick •composed of over one million nephrons

•organs for homeostasis for they regulate the composition of the blood Blood Supply of the Kidney

1.renal artery - carry blood with dissolved cellular wastes into the kidney 2.renal vein - carry filtered blood out from the kidney

Internal Parts of Kidney

1.cortex - outer granulated layer 2.medulla - radially striated or lined layer 3.renal pelvis – inner space or cavity conyinous with the ureter

Structure of the Nephron Renal corpuscle or corpuscles of

malphigii.

1.glomerulus - composed of several looped capillary vessels which connect afferent arteriole (entry of blood) with the efferent arteriole (exit of blood). 2.Bowman’s capsule – enclosed the glomerulu.

Renal tubules

1.capsule– expanded as Bowman’s capsule enclosing the glomerulus

1.Tubular secretion- molecules (uric acid, creatinine, ammonia) from the blood moved into the distal convoluted tubule through active transport.

2.Reabsorption of water - returns by osmosis following active reabsorption of salts along the length of the nephron and notably at the loop of Henle and collecting duct. 3.Excretion - urines formed and goes out of the kidney through the pelvis and ureter going into the urinary blader for tempory storage.

Rx COMMON KIDNEY DISORDERS •Acute real failure, which occurs suddenly, may be caused by bacterial infection, injury, shock, congestive heart failure, drug poisoning, or severe bleeding following surgery. Treatment may include drugs to address the underlying cause or to stimulate proper kidney function, blood transfusion, surgery or in some cases, kidney dialysis in which the blood is mechanically filtered

•Chronic renal failure is a progressive deterioration of the kidney function over a long period of time. It can be caused by disease such as hypertension, diabetes, lupus erythematosus, acquired immunodeficiency syndrome (AIDS), and a form of cancer called myeloma.

•Urinary calculi, commonly known as kidney stones, result from the gradual buildup of crystallized salts and minerals in the urine. Kidney stonescan cause intense pain if they obstruct a passageway that carries urine. Usually, the stones pass through and out of the urinary tract or their own. If they fail to pass out of the body, they, can be removed surgically or broken up non-surgically by an ultrasound technique called lithotripsy

1. Proximal convoluted portion- connected to the capsule, about 14mm in the length and 60 µmin diameters. 2. Loop of Henle- consisting of two straight (ascending and descending) limbs running parallel to each other 3. Distal convoluted portion- short and much convoluted leading to a short, arched connecting portion, which empties into a straight collecting duct leading to the renal pelvis

Steps of Urine Formation

1. Pressure filtration Small molecules (water, glucose,

amino acids, salts, urea, uric acids) from the glomerulus were forced by the blood into the Bowman’s capsule.

2. Selective Reabsorption Molecules(water, amino acids, salts)

return to the blood at the proximal convoluted tubule through diffusion and transport.