chapter 24 the digestive and urinary systems. section 1 the digestive system objectives: compare...

Chapter 24

The Digestive and Urinary Systems

Section 1 The Digestive SystemObjectives:•Compare mechanical digestion with chemical digestion.•Describe the parts and functions of the digestive system.

Major Functions of the Digestive System

• Break down ingested food• Put nutrients into the bloodstream• Remove waste from the body

Organs of the Digestive System• Mouth- teeth, salivary glands, tongue• Esophagus• Stomach• Small Intestine• Large Intestine• Pancreas• Liver• Gall bladder

Accessory Organs

Mouth• Digestion begins here!• Teeth and tongue are used in mechanical

digestion- physical breakdown of food• Saliva and enzymes begin chemical

digestion- chemical breakdown of food

Esophagus• Muscular tube that connects mouth to stomach• Moves food downward by peristalsis, or

muscular contractions• Epiglottis seals off windpipe during swallowing

to prevent choking

Stomach- Mechanical and Chemical Digestion

• Muscular pouch that expands to hold your food

• Hydrochloric acid (HCl) and the enzyme pepsin combine to form gastric juice

• A gummy coating of mucus protects the stomach lining from the strong chemicals

• Chyme, a thick liquid containing partially digested food, is produced here

Pancreas• Makes digestive enzymes• Makes hormones that regulate sugar levels

Small Intestine• Most chemical digestion occurs here!• Inner surface is covered in villi and microvilli,

millions of tiny finger-like projections that absorb nutrient molecules from the chyme

• The villi create a large surface area so as many nutrients as possible can be absorbed

• Longest portion of the digestive tract

Liver• Makes bile to break up fat• Stores nutrients• Breaks down toxins

Gallbladder• Temporarily stores bile and releases it into

the small intestines

Large Intestine• No digestion occurs here• Water is absorbed from remaining food• Waste material, feces, is prepared for

elimination from the body

Rectum• Stores feces until they can be expelled

through the anus.

Section 2 The Urinary SystemObjectives:•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• Excretion is the process of removing waste

products from the body.• The urinary system removes waste products

like carbon dioxide from the body.

The Kidneys as Filters• The kidneys are a pair of organs that

constantly clean the blood.• Your blood cycles through your kidneys

about 350 times a day.• Inside each kidney are nephrons,

microscopic filters that remove waste from the blood. (especially urea)

Water In, Water Out• The balance of fluids in the body is

controlled by chemical messengers called hormones.• Sweat and thirst• Antidiuretic hormone (ADH)-signals the kidneys

to make less urine• Diuretics-cause the kidneys to make more urine

Urinary System Problems• Bacterial infections-bacteria in the bladder; if

spreads to kidneys, then permanent damage can be caused to nephrons

• Kidney stones-when salts and other wastes collect inside the kidneys and form stones; can interfere with urine flow

• Kidney disease-can be caused by damage to nephrons; dialysis used as treatment to filter blood