DigestiveAnd

ExcretorySystems

Digestive System

Functions of the Digestive System

• Digestion• Waste Removal (solid)• Conversion of food energy to

energy usable by the body• Absorption of nutrients.

Organs of the Digestive System

• Mouth• Salivary glands• Esophagus• Stomach• Small Intestine• Large Intestine• Liver• Pancreas

Digestive Process

In the mouth•Food is chewed and swallowed•Enzymes are added to food in

this process.•Once swallowed, it moves

down the esophagus to the stomach

Enzymes•Proteins that catalyze, or

increase the rates of chemical reactions.

Peristalsis

•Process where food is moved through the digestive system by waves of rhythmic muscular contractions.

In the stomach•Strong acid and powerful

enzymes mix with the food and break down the food into chyme.

•It is then moved to the small intestine.

In the Small Intestine

•Secretions from the small intestine, liver, and pancreas finish breaking down the proteins, carbohydrates, and fats

•Most of the absorption of nutrients takes place in the small intestine

In the Large Intestine

•Vitamins, Minerals, and Water are absorbed.

Role of the Liver in digestion

•Secretes chemicals that help digest fats in the small intestine.

•Stores energy reserves.

Role of the Pancreas in digestion

•Secretes enzymes that break down carbohydrates and proteins in the small intestine.

Excretory System

Functions of the Excretory System

•Removes waste made by cells

•Maintains – salt content– water content– blood pressure– acid-base balance

Organs of the Excretory System

•Kidneys•Lungs•Skin

Kidneys

•Filter blood about 10 times a day. (about 1 liter per hour)

Nephrons• Blood filtering units in the kidney.• Each kidney has millions of them.• They remove salts, water, and cell

waste from the blood.• 99% of the water removed by the

nephrons is reclaimed by the capillaries.

• Liquid waste is called urine.

Urinary Tract• Ureter – tube that carries urine

from the kidney to the urinary bladder.

• Urinary Bladder – stores urine.

• Urethra – tube that runs from the urinary bladder to the outside of the body.

Lungs

•Remove carbon dioxide (CO2) from the blood and expels it from the body

Skin•Excretes water, salts, small amounts of hydrogen wastes, and other substances such as toxins in sweat