Digestive SystemEden Area ROPMedical Careers

Functions

• Digestion: Breaking down food mechanically and chemically

• Absorption: passage of substances through walls of digestive system into fluids/tissues

• Elimination: getting rid of waste that is not needed by the body

Alimentary canal

Definition: long muscular tube that begins at the mouth and ends at the anus

The Digestive System

Organs of the Digestive System

• Mouth: chemical and mechanical breakdown of food starts

-Mechanical: chewing and tongue-Chemical: salivary glands

• Pharynx: throat• Epiglottis: flap like structure that covers

trachea and opens and closes to prevent food from entering lungs.

• Esophagus: long tube that connects the mouth to the stomach- uses peristalsis (wavelike muscle movement that pushes food through the digestive system)

• Stomach: muscular sac that receives food/liquid from esophagus – Breaks down food using stomach muscles and

gastric juices– Stores food

Organs of the Digestive System

• Small intestine: long winding tube that digestive matter enters after stomach

3 sections:• Duodenum• Jejunum• Ileum

Organs of the Digestive System

Organs of the Digestive System• Appendix: small sac located at the beginning of

large intestine

• Appendicitis: Obstruction of the opening of the appendix causing digestive matter and mucus to become trapped and bacteria to multiply

Large intestine: receives digestive matter from the small intestine

Sections:– Cecum– Ascending colon– Transverse colon– Descending

colon– Sigmoid colon– Rectum– Anus

Absorption of substances

• 90% of all nutrients are absorbed in the small intestine.

• Liquid is absorbed as the digestive matter passes through the large intestine.

Accessory Organs

• Liver: –Produces bile (digestive juice that absorbs

fat)– Filters out harmful substances– Stores vitamins/minerals–Recycles iron & hemoglobin from worn out

RBCs

Accessory Organs

• Gallbladder: – stores bile and releases it into duodenum as

needed• Pancreas– Secretes insulin– Secretes glucagon– Produces pancreatic juices that help breakdown

food

Conditions of the Digestive System• Hepatitis: inflammation of the liver caused by a

virus or poison– Hepatitis A (HAV): ingestion of fecal matter from

contaminated food or drinks. – Hepatitis B (HBV): Contact with infectious blood,

semen, and other body fluids from having sex with an infected person, sharing contaminated needles, or from an infected mother to her newborn.

– Hepatitis C (HCV): Contact with the blood of an infected person, primarily through sharing contaminated needles to inject drugs. There is no vaccine for Hepatitis C.

Conditions of the Digestive System

• Cirrhosis: a progressive degeneration of the liver –Cirrhosis has various causes but the most

common are heavy alcohol consumption, chronic hepatitis C and obesity

Sphincter: circular muscles that constrict to close off the passageway and relaxes to

allow materials to pass through the opening.

– Cardiac Sphincter, at the top of the stomach– Iliac Sphincter , at the bottom of the stomach– Ileocecal Valve separates the small intestine from

the large intestine– Involuntary Anal Sphincter, which is responsible

for generating the urge to defecate.– Voluntary Anal Sphincter, which allows one to

control defecation.