Digestive System

Organs of the alimentary canal

S- stomach

A-anus

M-mouth

P-pharynx

L-large intestine

E-esophagus

S-small intestine

Hard palate

forms the anterior roof

Soft palate

forms the posterior roof

Where is the tongue attached?

attached at the hyoid bone and styloid process of the skull by the ^^**lingual frenulum**^^ to the floor of the mouth

Where is the laryngopharynx?

below the oropharynx and connect the the ^^**esophagus**^^

What role does the esophagus have in the digestive system?

It has no digestive function

Mucosa

innermost membrane (it is moist consisting of surface epithelium, connective tissue, and small smooth muscle layer)

Submucosa

just beneath the mucosa, soft tissue with blood vessels, nerve endings, and lymphatics

Muscularis externa

smooth muscle layer, inner circular layer, outer longitudinal layer

Serosa

outermost layer of the wall contains fluid producing cells

What covers the peritoneal cavity?

Visceral peritoneum (the outermost layer)

What lines the abdominopelvic cavity?

parietal peritoneum (innermost layer)

Where does food enter?

The cardioesophageal sphincter

Where does food empty?

In the small intestine at the pyloric sphincter

Small intestine

The body’s *major digestive* organ, site of nutrient absorption into blood

Where does the small intestine extend?

From the pyloric sphincter to ileocecal valve

Subdivisions of the small intestine

Duodenum- attached to the stomach, curves around the head of the pancreas, enzymes are carries into the duodenum by the bile duct and pancreatic duct.

Jejunum- attaches anteriorly to the duodenum, middle section.

Ileum- extends from the jejunum to large intestine

What are three small intestine structural modifications that increase surface area?

Microvilli- tiny projections of the plasma membrane (create a brush border appearance)

Villi- fingerlike structures formed by the mucosa, contains rich capillary bed and a modified lymphatic capillary called a *lacteal*

Circular folds- deep folds of mucosa and submucosa

Describe the Large intestine

Large in diameter, but shorter in length the small intestine, frames the internal abdomen

Anus

opening of the large intestine

Saliva

mixture of mucus and serous fluids, helps to form a food bolus, contains salivary amylase to begin starch digestion, dissolves chemicals so they can be tasted.

Describe Bile (where its produced and stored)

produced by the cells in the liver and stored in the gall bladder

Where does bile enter?

From the duodenum

What does the buildup of bile result in?

Tissue turning yellow causing a condition called jaudice

How do nutrients detour through the liver?

Via the hepatic portal circulation

Peristalsis

alternating waves of contraction and relaxation the squeezes food along the GI tract

Food breakdown as chemical digestion

Carbs are broken down into simple sugars

Proteins are broken into amino acids

Fats are broken down into fatty acids and glycerol

Absorption

\-End of products digestion are absorbed in the blood or lymph

\-Food must enter mucosal cells and then into blood or lymph capillaries

Where does carb digestion begin?

In the mouth

How is starch broken down?

Into maltose by salivary amylase

List the actives of the pharynx and larynx

They have no digestive function

What does the rooting reflex do?

Help the infant find the nipple

What does the sucking reflex do?

Help an infant hold onto the nipple and swallow

Phenylketonuria

a genetic disorder, inability of tissue cells to metabolize phenylalanine which can result in brain damage and retardation

Anabolism

larger molecules are built from smaller ones

Acidosis

results from incomplete fat oxidation in which acetoacetic accumulates in the blood

What does acidosis breath smell like?

Has a fruity odor

When is acidosis common?

In “no carb” diets, diabetes mellitus, starvation

Role of the liver in metabolism

manufactures bile, detoxifies drugs and alcohol, degrades hormones, produces cholesterol, blood proteins, plays a central role in metabolism.

What is absorbed in the large intestine?

Water, ions, and vitamin K and B are absorbed

How is the release of pancreatic juice into the duodenum stimulated?

Vagus nerve & local hormone secretin and cholecystokinin

Pancreatic enzymes play the major digestive function, what is it?

Helps to complete digestion of starch

What does the presence of food and rising PH cause?

Release of the hormone gastrin; causes stomach to produce protein-digesting enzymes, mucus, hydrochloric acid (makes the stomach acidic)

What does acidic PH do?

Activates pepsinogen to pepsin for protein digestion (provides a hostile environment to microorganisms)

Need to know

What is the function of the large intestine?

To dry out leftover food and produce feces.