BIOLOGICAL SCIENCE

“DIGESTIVE

SYSTEM”

Prepared by: Ms. Jonna Karla C. Bien, RN

• Gastrointestinal System

• Function-physical and chemical breakdown of food

• Includes alimentary canal and accessory organs

• Accessory organs: Salivary glands, tongue, teeth, liver, gallbladder, and pancreas

Alimentary canal

• Mouth- physical and

chemical breakdown.

• Mastication-the act of

chewing

• Saliva contains

enzyme amylase to

break down

carbohydrates

• Pharynx- contains opening to trachea as well. Epiglottis covers opening of trachea.

• Esophagus-muscular tube dorsal to trachea

• Relies on a rhythmic wave-like motion called peristalsis

Esophagus- transverse view

• Sphincter-a circular

muscle that constricts

a passage or closes a

natural orifice

(opening)

• Cardiac sphincter

• Pyloric sphincter

• Food sits in stomach

for 1-4 hours. Gastric

juices contain

hydrochloric acid-

activates pepsin, kills

bacteria.

• Small intestine: not so

small! 20ft x 1’’

• Duodenum- 1st 10

inches. Bile and

pancreatic juice enter

here

• Jejunum- next 8 ft.

• Ileum- final 12 ft.

When food leaves

small intestine,

digestion is complete

• Small intestine has

lots of enzymes:

peptidases

• maltase, sucrase,

lactase, amylase.

• Lipase

• Bile

Digested food is

absorbed into the

bloodstream.

• Large intestine- 5 ft x

2’’. Separated from

small intestine by

ileocecal valve

• Final absorption of

water, storage of

indigestible material,

absorption of vitamins

B and K by bacteria.

• Colon connects to

rectum- anal canal

opens to the anus

(final opening). Fecal

material is expelled.

What about the accessory organs:

Liver, gall bladder and pancreas • Liver- largest gland in

your body

• Secretes bile-

emulsifies fat, makes

them water soluble.

• Stores glucose in the

form of glycogen

• Makes clotting

proteins

• Detoxifies blood

• Gall bladder- stores

and concentrates bile

• Pancreas- produces

insulin, pancreatic

juices amylase and

lipase. Insulin

regulates the uptake

of glucose by the cells

Diseases • Appendicitis

• Cholecystitis- gall bladder

• Cirrhosis- destruction of liver cells

• Diarrhea

• Diverticulitis

• Gasteroenteritis

• Hernia

• Pancreatitis

• Liver transplant

• Ulcer

• Colitis

• Bariatric surgery