Maintaining Homeostasis Function of the Digestive System Provide

Maintaining Homeostasis

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

How? �Ingest food �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

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

Relating Structure to Function

Stomach �Rugae • 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

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

Mesentery �Thin tissue �Connects small intestine �Contains capillaries for absorption

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

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

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

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

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

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

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

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

Reabsorption �Needed substances are returned to blood

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

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