Chapter 17

Lesson 1: The Digestive SystemLesson 2: Caring for the Digestive

SystemLesson 3: The Urinary System

The Digestive System

Lesson 1

The functions of the digestive system can be

divided into these three main processes: Digestion- the mechanical and chemical

breakdown of foods for use by the body’s cells.

Absorption- the passage of digested food from the digestive tract into the cardiovascular system.

Elimination- the expulsion of undigested food or body wastes.

Functions of the Digestive System

The nervous system and the cardiovascular

system also play a role in digestion.

The nervous system triggers the digestive process to begin at the sight or smell of food and controls muscles that move through the digestive system.

After food is broken down, the nutrients are absorbed into the blood and the cardiovascular system delivers the nutrients to all cells in the body.

Functions Continued

The digestive process begins in the mouth.

Your teeth break the food into smaller pieces.

Your salivary glands produce saliva- the first digestive juices used in the digestive process.

Your tongue forms chewed food into a size and shape that can be swallowed.

Structures of the Digestive System

Structures Continued

• Swallowed food enters the esophagus- the muscle tube that connects the pharynx with the stomach.

• Peristalsis- a series of involuntary muscle contractions that move the food through the digestive tract.

The stomach is a hollow, saclike organ

enclosed in a muscular wall. It has three tasks in digestion.

The stomach mixes food with gastric juices- secretions that contain hydrochloric acid and pepsin.

The stomach stores swallowed food and liquid.

The stomach moves food into the small intestine.

Structures Continued

Structures Continued

• The pancreas produces enzymes that break down the carbohydrates, fats, and proteins in food.

• The liver produces bile- a fluid important in the breakdown and absorptions of fats.

• The gallbladder stores bile between meals.

From the stomach, food enters the small

intestine, which is 20-23 feet long and 1 inch in diameter.

Digestive juices from glands in the lining of the small intestines, as well as from the pancreas and liver, are mixed with digesting food.

Nutrients are absorbed from the wall of the small intestine and carried through the body by the cardiovascular system.

Structures Continued

Undigested parts of food pass into the colon,

or large intestine, which is 5-6 feet long and 2 ½ inches in diameter.

The large intestine absorbs water, vitamins, and salts.

Solid wastes are eliminated through the large intestine. They are formed into feces- wastes excreted through the anus during a bowl movement.

Structures Continued

Caring for the Digestive System

Lesson 2

These health behaviors will help keep your

digestive system healthy:

1. Follow a well-balanced diet including a variety of foods that are low in fat and high in fiber.

2. Wash your hands before preparing a meal and before eating.

3. Eat slowly and chew your food thoroughly.4. Drink at least eight, 8-ounce glasses of water

each day.5. Avoid using food as a way of dealing with your

emotions.

Health Behaviors and the Digestive System

Health Behaviors Continued

The reward for maintaining good eating habits could be a lifetime free of digestive problems or habits that could

lead to disease.

Problems of the Digestive System

There are several functional problems of the digestive system.

Indigestion is a feeling of discomfort in the

upper abdomen. It can be caused by eating too much, eating to quickly, or eating foods that are spicy or high in fat.

Heartburn is a burning sensation in the center of the chest that may rise from the bottom, or tip, of the breastbone up in the throat. Frequent or prolonged heartburn can be an indication of more serious digestive disorders.

Problems Continued

Excessive gas can result in cramps or an

uncomfortable feeling of fullness in the abdomen. Foods such as beans and cabbage may cause gas.

Constipation is a condition in which feces become dry and hard and bowel movements are difficult. Constipation can be caused by not consuming enough water or fiber.

Problems Continued

Problems Continued

• Nausea is the feeling of discomfort that sometimes precedes vomiting.

• Diarrhea is the frequent passage of watery feces.

Structural problems of the digestive system

usually require medical attention.

Gallstones are formed when cholesterol in bile crystallizes and blocks the bile duct between the small intestine and the gallbladder.

Appendicitis is the inflammation of the appendix- a tube about 3-4 inches long that extends from the beginning portion of the large intestine.

Problems Continued

Gastritis is an inflammation of the mucus

membrane that lines the stomach.

Lactose intolerance involves an inability to digest lactose, which is a type of sugar found in milk and other dairy products.

A peptic ulcer is a sore in the lining of the digestive tract.

Problems Continued

Cirrhosis is scarring of the liver tissue. It is

usually caused by prolonged and heavy alcohol use.

Crohn’s disease causes inflammation of the lining of the digestive tract.

Cancer of the colon and rectum is the second leading cause of cancer deaths in the United States.

Problems Continued

Colitis is an inflammation of the large intestine

or colon.

Hemorrhoids are veins in the rectum and anus that are swollen as a result of increased pressure.

Tooth decay is a problem with the digestive system, because teeth are very important in the digestive process.

Problems Continued

The Urinary Sytem

Lesson 3

Function of the Urinary System

The main function of the urinary system is to filter waste and extra fluid from the blood.

Function Continued

• Urine is liquid waste material excreted from the body through the process of urination.

• Urine consists of water and body wastes that contain nitrogen.

• These body wastes become toxic to cells if they remain in the body for too long.

Kidneys are bean-shaped organs about the

size of a fist.

Kidneys are located near the middle of the back, just below the rib cage

They remove waste products from the blood through tiny filtering units called nephrons.

Function Continued

Ureters are tubes that connect the kidneys to

the bladder.

The bladder is a hollow muscular organ that acts as a reservoir for urine.

The urethra is the tube that leads from the bladder to the outside of the body.

Function Continued

Health Behaviors and the Urinary System

Proper urinary function is important because wastes that are not removed from the body quickly become toxic.

These health behaviors will help you keep

your urinary system healthy:

1. Drink at least eight 8-ounce glasses of water each day, and limit your intake of caffeine and soft drinks.

2. Eat a well-balanced diet.3. Practice good hygiene and personal care.4. Have regular medical checkups.

Health Behaviors Continued

Problems of the Urinary System

Kidney disorders should be monitored by a health professional.

Nephritis is the inflammation of the nephrons.

Kidney stones form when salts in the urine crystallize into solid stone.

Uremia is a serious condition associated with a decrease in blood filtration by the kidneys.

Problems Continued

Kidney failure can be:

acute- having a sudden onset.

chronic- involving a progressive los of kidney function.

Problems Continued

Kidney damage may require one of these forms of

treatment:

1. Hemodialysis is a technique in which an artificial kidney machine removes waste products from the blood.

2. Peritoneal dialysis uses peritoneum- a thin membrane that surrounds the digestive organs, to filter blood.

3. Kidney transplant involves the replacement of a nonfunctional kidney with a healthy kidney from a donor.

Problems Continued