The Digestive System

Function: Breaks down foods into simpler molecules that can be absorbed and used by the cells of the body.

Structures Organs: mouth, pharynx, esophagus, stomach, small intestine, and large intestine. Accessory glands: salivary glands, pancreas, and liver

Types of Digestion Mechanical- grinding and crushing the food into smaller pieces that are easier to process. (example: teeth & chewing)  Causes a physical change Chemical- enzymes (specialized proteins) breaking to food down into simpler molecules your cells can use.  Causes a chemical change

Mouth The mouth is where the digestive system begins. Mechanical and chemical digestion occur here. -Teeth tear and crush food

Mouth, cont. Salivary glands release saliva into the mouth that contains enzymes like amylase to break down starches into sugars.

Pharynx  Esophagus Bolus (food ball) passes from mouth through the pharynx into the esophagus Peristalsis- smooth muscles contract, pushing food down to the stomach.

Stomach: Structure/Fxn. Continues both mechanical and chemical digestion Smooth muscle churns and mixes food to produce chyme HCl makes it acidic

Chemical Digestion- Enzymes Enzyme Activity #1

Lock and Key With your partner, answer the following on 1 sheet of paper with both names. 1.What molecule did you have in your food? 2.What is the name of the enzyme that breaks down that molecule? 3.How did you know what enzyme would break down that molecule by looking at it? 4.Why is it important for food to be broken down into simpler molecules? 5.Describe how enzymes work to break down food. (you may use your book)

Small intestine: Absorption Duodenum, jejunum, ileum (together= 6 m) More enzymes Absorption occurs on the villi, which are lined with capillaries

Large Intestine a.k.a. colon Absorption of water –If too little is absorbed = diarrhea –If too much is absorbed = constipation Unabsorbed material passes through rectum, then anus

Accessory Digestive Organs Pancreas- VERY important fxns. –Regulate blood sugar (diabetes) –Produces several enzymes –Produces sodium bicarbonate—a base Why is this important? Liver- produces bile which is then stored in the gall bladder

The Excretory System Structures: skin, lungs, kidneys, ureters, urinary bladder, urethra Function: Remove waste products

The Kidneys Primary organs of the excretory system. Remove waste products from the blood Maintain blood pH Regulate water content of the blood Waste is excreted as urine.

The kidneys, cont. Located on either side of the spinal column near the lower back.

Nephron Unit The functional units of the kidney are called nephrons. Each nephron is a small,independent processing unit. Function:As blood enters a nephron through the inpurities are filtered out and emptied into the collecting duct.

Dialysis/Homeostasis by Machine The kidneys are the master chemists of the blood supply.In dialysis,blood is removed from the body through a tube inserted in the arm and pumped through special tubing that acts like nephrons.

The Bladder Urine (waste) flows from the kidneys thru the ureters to the bladder where it is stored. Then, urine passes from bladder thru the urethra to exit the body

Sum it Up! At the bottom of your notes, explain how each of the following serves an excretory function: Skin? Lungs? Kidneys?