Chapter 24 Digestive and Urinary Systems

Section 1: Objectives Compare mechanical digestion with chemical digestion. Describe the parts and functions of the digestive system.

The Digestive System Your digestive system is a group of organs that break down food so that it can be used by the body. Food passes through the digestive tract. The digestive tract includes your mouth, pharynx, esophagus, stomach, small intestine, large intestine, rectum, and anus. The liver, gallbladder, pancreas, and salivary glands are also part of the digestive system.

The Digestive System

The breaking, crushing, and mashing of food is called mechanical digestion. In chemical digestion, large molecules are broken down into nutrients with the aid of enzymes.

The Digestive System

Teeth With the help of strong jaw muscles, teeth break and grind food.

The Digestive System Saliva contains an enzyme that begins the chemical digestion of carbohydrates. Leaving the Mouth Once the food has been reduced to a soft mush, the tongue pushes it into the throat, which leads to a long, straight tube called the esophagus.

The Digestive System The stomach is a muscular, saclike, digestive organ attached to the lower end of the esophagus. Tiny glands in the stomach produce enzymes and acid to break food down into nutrients. After a few hours of combined mechanical and chemical digestion, food leaves your stomach as a soupy mixture called chyme.

The Digestive System The Pancreas is an organ located between the stomach and small intestine. The pancreas makes fluids that protect the small intestine from the acid in chyme. The Small Intestine is a muscular tube that is about 2.5 cm in diameter. In the small intestine, nutrients are absorbed into the bloodstream through fingerlike projections called villi.

The Digestive System

The liver is a large, reddish brown organ that helps with digestion by making bile to break up fat. Bile is stored in a saclike organ called the gallbladder, which squeezes the bile into the small intestine. The liver also stores excess nutrients until the body is ready to absorb them into the bloodstream.

The Digestive System

Material that can’t be absorbed into the blood is pushed into the large intestine. The large intestine absorbs most of the water in undigested material and changes the liquid into semisolid waste material.

The Digestive System It has taken each of your meals about 24 hours to make this journey through your digestive system.

Chapter 24 Sec. 1 Recap 1) List all of the parts of the digestive system. 2) What is the difference between mechanical and chemical digestion? 3) What does the enzyme found in saliva responsible for? 4) What is the function of the pancreas? 5) What is the function of the liver?

Section 2: Objectives Describe the parts and functions of the urinary system. Explain how the kidneys filter blood. Describe three disorders of the urinary system.

The Urinary System The urinary system contains the organs that remove waste products from your blood. The kidneys act as filters for the blood. The kidneys are a pair of organs in the urinary system that clean the blood and excrete products as urine. Inside each kidney are more than 1 million microscopic filters called nephrons.

The Urinary System

The evaporation of water in sweat cools you down. As the water content of the blood drops, the salivary glands produce less saliva, resulting in thirst. When you get thirsty, antidiuretic hormone is released. ADH hormone signals the kidneys to take water from the nephrons and return it to the body.

The Urinary System Some beverages contain caffeine, which is a diuretic. Diuretics cause the kidneys to make more urine. Diuretics decrease the amount of water in blood.

The Urinary System Three Kidney Injuries/Diseases: Bacterial Infections Bacteria can get into the bladder and ureters through the urethra and cause painful infections. Kidney Stones Salts and other wastes can collect inside the kidneys and form kidney stones. Kidney Disease Damage to nephrons can prevent normal kidney functioning and can lead to kidney disease.

Chapter 24 Sec. 2 Pop Quiz 1) What is the function of the kidneys? 2) What does ADH signal to the body? 3) What is the effect of diuretics to the body? 4) List 1 common diuretic. 5) List 3 common kidney injuries/diseases.