Digestive and Excretory Systems

What is “digestion” Process of breaking down food into simpler molecules that can be absorbed by the body  Break up food into smaller pieces (mechanical)  Chemically break down food (chemical)  Absorb nutrients

I. Mouth Mechanical digestion Chemical digestion Amylase in saliva breaks down starch. II Pharynx  Epiglottis covers trachea so you don’t choke 

III. Esophagus ~ 25 cm long Connects pharynx to stomach Smooth muscles use peristalsis to move the food (wave contractions)

IV. Stomach Chemical and mechanical digestion  Produces mucus  Hydrochloric acid  Pepsin to break down protein  Food here 2-3 hours…called chyme

Ulcer (stomach): This sharply punched out gastric ulcer has been present for some time as judged by the amount of puckering of the surrounding mucosa and by the undermining and depth of the ulcer. Frequently, vessels in the base of the ulcers will ulcerate and the patient will bleed profusely, if not fatally.

V. Small intestine ~ 7 meters long 3 parts  Duodenum Chyme flooded with enzymes and digestive fluids from intestine, pancreas, liver Pancreas digests carbs, fats, proteins, makes sodium bicarbonate to neutralize the acid Liver secretes bile to break up fat

Liver Gallbladder Duodenum Bile duct Pancreas Pancreatic duct To small intestine The Liver and the Pancreas

Pancreas

V. Small intestine  Jejunum  Ilium (Ileum) Both absorb nutrients Villi in small intestine increase surface area for better absorption Food is now nutrient free

Small Intestine Villus Circular folds Villi Epithelial cells Capillaries Lacteal Vein Artery The Small Intestine

Villi

VI. Large intestine (colon) ~1.5 meters long Remove water from material  Too much…constipation  Not enough…diarrhea Food here hours Feces stored in rectum, out through anus

Excretory system Maintaining Homeostasis by ridding the body of waste products Excretion:  Process of getting rid of waste  Water, urea, salt, carbon dioxide Skin: water and salt Lungs: water and carbon dioxide Kidneys: water and urea

Kidneys (Renal) Kidneys: water and urea (salts) Filtration, reabsorption, secretion Acts as a filter system Gets rid of waste products Balances the body's fluid content Produces hormones that control blood pressurehormonesblood pressure Produces the hormone Erythropoietin to help make red blood cellsErythropoietinblood cells Activates vitamin D to maintain healthy bones

Kidney (Cross Section) Cortex Medulla Vein Artery Kidney Ureter Urinary bladder Urethra The Urinary System Section 38-3

Kidney Nephron Cortex Medulla Renal artery Renal vein Ureter To the bladder Bowman’s capsule Glomerulus Capillaries Collecting duct To the ureter Loop of Henle Artery Vein Structure of the Kidneys Section 38-3

Filtration Most filtration occurs in the glomerulus. Blood pressure forces water, salt, glucose, amino acids, and urea into Bowman’s capsule. Proteins and blood cells are too large to cross the membrane; they remain in the blood. The fluid that enters the renal tubules is called the filtrate. Reabsorption As the filtrate flows through the renal tubule, most of the water and nutrients are reabsorbed into the blood. The concentrated fluid that remains is called urine. Secretion Substances such as hydrogen ions are transferred from the blood to the filtrate. The Nephron

Human Kidney

Blood Vessels in the Kidney

Liver (Hepatic) Filters harmful chemicals out of blood Breaks down amino acid into urea Bile Production Heaviest organ (iron)

Skin (Dermal) Largest surface area (Largest organ) Perspiration gets rid of wastes (urea, water, salt) and regulates body temp