The Excretory System a general overview Excretory Organs

The Excretory System …a general overview

Excretory Organs Inferior vena cava Kidney Dorsal aorta Ureter Urinary bladder * Renal arteries carry blood TOWARDS each kidney & renal veins carry blood low in oxygen AWAY from each kidney

A Closer Look Inside the Kidney Renal cortex region Glomeruli (location of microscopic NEPHRONS) Medulla region Renal vein Renal artery Renal pelvis Ureter

Organs of Excretion SKIN - sweat glands excrete perspiration (H 2 O, salt, some urea) - cools body - more urea excreted through skin if kidneys fail Ø LIVER - produces “urochrome” (yellow pigment in urine; from breakdown of heme) - deposited in blood excreted by kidneys Ø

…more organs… - remove CO 2 - removes some H 2 O Ø INTESTINES - iron & calcium excreted into intestinal cavity - salt leaves body in feces; Na+ & K+ through skin Ø KIDNEYS - excrete urine containing end products of metabolism Ø LUNGS

What are some of our wastes? ? Ø Ammonia (NH 3) from amino acid breakdown Ø Urea (from breakdown of ammonia) 2 NH 3 + CO 2 NH 2 – C – NH 2 + H 2 O O * Some ammonia eliminated as uric acid

Ø Creatinine by-product of muscle contraction Ø Bile pigments Ø CO 2 Ø Ions Ca+2 & Fe+2 (in blood) Na+ & K+ (from nerves) Ø H 2 O

Reabsorbing things at the Kidneys - high blood pressure if too much water retained - dehydration if too much water released Ø Glucose - low energy (ATP) production - cell metabolism Ø Amino Acids - protein synthesis disrupted - body can’t produce structural parts * Results if these substances AREN’T reabsorbed back into the blood at the kidneys Ø H 2 O

A close up look at a NEPHRON (where removal of materials & reabsorption occurs in the kidneys)

Kidneys: Supplemental Questions (Answers) Regulatory Function 1. Posterior pituitary gland 2. Blood volume increases (H 2 O reabsorbed from kidneys into blood) 3. More urine 4. Inhibits secretion of ADH 5. Buffering in urine (NH 3 + H+ NH 4+); H+ ions are excreted into urine

Kidney Disorders 1. (a) urethra (b) bladder (c) nephron 2. Waste substances & urea build up in blood (imbalance of ions, high [NH 3]) 3. Immunosuppressive drug (prevents body from rejecting new organ) 4. Artificial kidney machine blood pumped through dialysis tubing & exposed to dialysis solution (wastes move into dialysis solution)