Digestive System

Gastrointestinal Tract (GI Tract)

a continuous, muscular; hollow tube

GI tract function

chemical/mechanical breakdown and absorption

breaks down food into usable form, absorbing nutrients into the blood stream

Peristalsis

Involuntary waves of contraction (food moving)

Organs of the digestive system

food moves through them

mouth

pharynx

esophagus

stomach

small intestine

large intestine

Accessory organs of the digestive system

contribute but food does not move through

salivary glands

pancreas

liver

gallbladder

Mouth

Mechanical and chemical digestion occurs here

3 pairs of salivary glands

parotid glands, submandibular, sublingual

Parotid glands

anterior to ears

Submandibular glands

under mandible

Sublingual glands

under the tongue

Carbohydrate digestion begins in

the mouth

Pharynx

part of both the respiratory and digestive system

Esophagus

in the thoracic (mostly),

posterior to trachea,

passes diaphragm then connects with the stomach (in the abdominal cavity) at the lower esophageal sphincter

Lower esophageal sphincter

ring of muscle

prevents contents (food) of the stomach from moving into the esophagus

Stomach

hollow organ, can contract

no absorption in stomach except alcohol

food enters, the stomach stretches, stimulates secretion of gastrin, causes secretion of gastrin juices, 3 juices

pepsin, HCl, mucus

Pepsin

enzyme that breaks down protein

HCL (hydrochloric acid)

strong acid, makes stomach very acidic, ph of 2, once it leaves the stomach you can feel it, helps sterilize food

Low HCL can lead to bacteria in stomach (food poisoning)

• because food becomes sterilized

Mucus

protects stomach from HCl

There is very little

chemical digestion (HCL does that)

Digestion in stomach is mostly

mechanical because the stomach churns

pyloric sphincter

between stomach and small intestine, keeps food in stomach

Malnourishment cause

protein is not being digested

chronic low stomach acid

low HCl and pepsin

person cannot break down protein so they cannot use it

Epigastric pain (heart burn)

lower esophageal sphincter opens

HCl goes back up

after someone eats

Ulcer

crater/pothole in stomach

caused by strain of bacteria called H. Pylori

If an ulcer gets bad it could erode…

through stomach lining and into the blood vessels

Ulcer treatment

Take out the stressors

No spicy food or alcohol

Ulcer s/s

epigastric pain 1-3 hrs after eating

blood in stool if it gets bad

Small intestine

largest part of the GI tract

chemical digestion and absorption happen

inside there are hair like projections called villi and microvilli to max surface area

Has three sections:

1. duodenum

2. jejunum

3. Ileum

Why is the small intestine the largest part of the GI tract

nutrient absorption

duodenum

after pyloric sphincter

At the end, all nutrient absorption has happened all thats left is…

fiber and water

at the end there is a valved called the

ileocecal valve

in between small and large intestines

Large intestine

large in diameter but shorter

no digestion

absorbs excess water

Why does the large intestine absorb water

if a person eats something bad the water rushes into the large intestine to flush it out

Sections of the large intestine

Cecum

colon

ascending colon

transverse colon

descending colon

sigmoid colon

rectum

anus

Cecum

appendix hangs off

sigmoid colon

in pelvic cavity

anus

contains two anal sphincters

internal anal sphincter

external anal sphincter

internal anal sphincter

made up of smooth muscle

external anal sphincter

made up of skeletal muscle

Diverticulitis

small pouches that develop in the lining of the large intestine and become infected

Diverticulitis s/s

pain in lower left quadrant

fever

nausea

bloating

Diverticulitis risk factors

obesity

low fiber diet

Diverticulitis tx.

liquid diet until it heals

Antibiotics

Liver

located in the right upper quadrant

fx. breaks down toxins in the blood

breaks down old red blood cells and makes bile

root word for liver

hepat

hepatitis

inflammation of the liver

What damages the liver

alcohol

Gallbladder

connected to the liver, stories bile and releases it into the bile duct

bile

green watery substance that emulsifies fat

Why bile is green

when the liver breaks down old red blood cells and a pigment called bilirubin is produced the bile becomes green

Jaundice

if liver is damaged the bile accumulates in the liver instead of where its supposed to go, it over flows and goes into the blood stream

Also occurs if a bile duct is blocked

turns the body tissue yellow

Pancreas

exocrine and endocrine functions

pancreatic lipase

pancreatic amylase

Exocrine function of the pancreas

the pancreas secrets pancreatic enzymes that are released through a pancreatic duct to the first part of the small intestine (duodenum)

pancreatic lipase

breaks down lipids

pancreatic amylase

breaks down carbohydrates (further)

Involuntary muscle

smooth muscle

Voluntary muscle

skeletal muscle