1. Maintaining Homeostasis

2. Function of the Digestive System
Provide the body with nutrients needed to sustain life

3. How? Ingest food Break down food into smaller pieces (monomers)
mouth
Break down food into smaller pieces (monomers)
Mouth (teeth, saliva) mechanical digestion
Stomach, small intestine
Absorb the monomers (nutrients)
Small intestines
Eliminate indigestible remains
Large intestine

4. Interactions Between Digestive And….
Respiratory system provides oxygen
Circulatory system transports nutrients
Nervous system regulates smooth muscles and release of hormones
Muscular system provides power for mechanical digestion
Skeletal system store minerals released from digestion

5. Relating Structure to Function

6. Stomach Rugae Mucous Membrane Sphincter
Deep gastric folds – increase surface area
Disappear as stomach fills
Mucous Membrane
Protects from acid
Secretes gastric fluids and acid
Sphincter
Valve that controls movement of food
Examples: cardiac, pyloric

7. Small Intestine Villi - Fingerlike projections Increase surface area
Thin epithelium, one cell thick, which enables a shorter diffusion path

8. Mesentery Thin tissue Connects small intestine
Contains capillaries for absorption

9. Accessory Organs Liver
Produces bile for digestion of fats in small intestine
Produces glucagon for releasing stored sugar
Produces urea from toxic ammonia
Gall Bladder - stores bile until needed after a high fat meal
Pancreas
Produces pancreatic enzymes needed for digestion (ex: lipase, protease)
Produces insulin - hormone that regulates blood sugar

10. Feedback Loop: High Blood Sugar (glucose)
Pancreas secretes insulin
Insulin triggers cells to store glucose
Liver- glycogen
Muscles -glycogen
Fat
Blood sugar level drops

11. Feedback Loop: Low Blood Sugar (glucose)
Pancreas secretes glucagon
Glucagon triggers release of stored glucose
Blood Sugar rises

12. Diabetes mellitus Type 1 - Pancreas does not produce insulin Type 2
Cells cannot absorb glucose
Cells cannot produce energy
Type 1 - Pancreas does not produce insulin
Type 2
Insulin is produced
Abnormal protein channels
Long Term Consequences
Damage to blood vessels
Kidney failure
Blindness
Heart Attacks

13. Malfunctions Ulcers – lining of stomach is destroyed
Appendicitis—infection of appendix (tiny part of small intestine)
Diarrhea—Large intestine does not reabsorb water
Cancer—abnormal growths
Hepatitis—liver inflammation
Gall stones—crystallized cholesterol in gall bladder
GERD—backup of acid into esophagus

14. Urinary System Regulate Composition of Blood by Removing wastes
Maintaining balance between water and dissolved ions (salts)
Uses over 1 million tiny filtering units – nephron

15. The Kidneys must….. Keep in the blood Remove from the blood Balance
RBC (red blood cells)
WBC (white blood cells)
Proteins
Glucose
Remove from the blood
Toxins and Urea
Balance
Water and salt content

16. How do the kidneys work? Filtration
Blood pressure forces all small molecules into nephron
Salt
Water
Nutrients (glucose, proteins)
Wastes (urea, toxins)

17. Reabsorption
Needed substances are returned to blood

18. Balance Water and salt balance is adjusted
Antidiuretic Hormone (ADH) determines how much water is reabsorbed into blood

19. Feedback Loop 5. Lower salt / more water
1. High Salt / Low water in blood
4. More water is absorbed, less urine is produced
2. Pituitary gland releases more ADH