Download - The Digestive System
The Digestive SystemFunction: 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
Small intestine: Absorption
• Duodenum, jejunum, ileum (together= 6 m)
• More enzymes
• Absorption occurs on the villi, which are lined with capillaries
Large Intestinea.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.
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.