The Digestive and Excretory Systems

The Digestive System

The functionof the digestive system is to convert food into simpler substances (molecules) that can be absorbed and used by cells in the body

The Digestive System

1. Path of food through the digestive tract.a. mouthb. Esophogusc. Stomachd. Small intestinee. Large intestine

The Digestive System

a. Mouth – mechanical breakdown of food with physical and chemical breakdown via saliva. Food is broken down into a thick pasty substance called bolus.

The Digestive System

b. Esophogus – The bolus is transported from the mouth to the stomach via the esophogus. To do this, the esophogus contracts rythmically. These contractions are called peristalis.

The Digestive System

c. Stomach – combination of mechanical digestion by grinding and chemical digestion. The stomach has a ribbed inner lining to grind the food. Chemicals such as hydrochloric acid help break down the food.

The Digestive System

d. Small intestine – the most digestion and nutrient absorption occurs here.i. pancreas – produces digestive enzymesii. Liver – produces bile to break down fatiii. Gall bladder – stores bile

The Digestive System

e. Large Intestine – removes water from undigested material.

The Excretory System

The function of the excretory system is to maintain homeostasis by maintaining water balance.

The Excretory System

1. Excretory Organsa. Lungs – excrete carbon

dioxide and water.b. Skin – excretes excess

salt and water

The Excretory System

2. Kidneys are the main organs of the excretory system.a. Remove waste products from blood.b. Maintain blood pH.c. Regulate water content of the blood.

The Excretory Systemd. Kidneys are on the dorsal

side of the body.i. it takes approximately 45 minutes for the kidney to filter the body’s blood supply.ii. The filtered waste travels through the ureter.iii. The filtered waste is stored in the urinary bladder.