The Digestive System Human Anatomy and Physiology Per 2 & 3

Miss Tavitian

Main functions

- Ingest food

- Break down food small enough to cross cell membrane

- Absorb nutrients

- Eliminate what cannot be digested

Digestion begins when you begin to salivate

Long hours of school “taking notes”

Alimentary Canal = tubular passage starting with mouth and ending with anus

Mouth

Teeth

• Mechanically break down food

Saliva• chemically break down

food

• Salivary amylase digestion of starch to maltose

https://www.youtube.com/watch?v=DKeEbVLZNWc

https://www.youtube.com/watch?v=4Ed57ZCoXjg

Chewed Food + Saliva = bolus

• Tongue pushes food toward the soft palate which triggers a swallowing reflex

Salivary Glands produce saliva which travels through ducts

Medical Conditions

Parotid TumorSwollen Submandibular gland

Pharynx = common passageway for food & air

• soft palate pulled up to block nasopharynx

• Tongue also prevents food from coming back to oral cavity

During swallowing:

During swallowing, the Larynx is pulled up and the Epiglottis closes off the glottis

When Food Does Go Down The Wrong Pipe it can lead to major problems

Pulmonary Aspiration

Pulmonary – relating to lungs

Aspiration – breathing in a foreign object

Problems associated with food going down the wrong pipe

Aspiration Pneumonia

-Pneumonia- infection or swelling of lungs

-Aspiration pneumonia can be caused by inhalation of food or drink, vomit, oil, bacterial ingestion

Choking – airway is obstructed by object

Once the bolus enters the Esophagus, it makes its way to the stomach through peristalsis

Once the food enters the Stomach, the esophageal sphincter will close to ensure food stays in stomach (2-3seconds)

When The Esophageal sphincter fails to close completely, and gastric acids come up the esophagus, Acid Reflux occurs

“Heartburn”

-“Heartburn” is the symptom associated with the stomach acid traveling up the esophagus

- The esophagus is posterior to the heart

Upon entry into the stomach

-Three important jobs of the stomach:

> store food

> break down food into liquefied mixture

> slowly empty food into small intestine*nutrients do not get absorbed in stomach

In the Stomach

Chief Cells produce pepsinogen and chymosin

> protein digestion begins in stomach

Parietal Cells produce ->Hydrochloric Acid (HCl)

>Intrinsic Factor binds to B12 so it doesn’t get broken down

Pylorus associated with pyloric sphincter & hold food until ready to be passed on

Food will stay in stomach for 6-8 hours

A Couple more cells of the stomach

-Chief Cells

-Parietal Cells

- Mucous CellsSecrete mucous to protect

epithelium from HCl acid

-G Cells

secrete Gastrin hormone which helps stimulate HCl

https://www.youtube.com/watch?v=mw8ptO3Ty6A

Mucous protects stomach from HCl,

Peptic Ulcer -> Barium X-ray highlights organs

Parts of Stomach

Cardiac Region part of the stomach closest to the heart

Fundic Region holds food temporarily

Body of stomach main part of stomach

Pyloric region leads to pylorus which empties into small intestine

Stomach

Layers of StomachRugae- folds of the stomach

Overview of Stomach

Gastric Bypass Surgery

https://www.youtube.com/watch?v=WN6pECaL3Fw

https://www.youtube.com/watch?v=X0ObD-6aRlI

Upon Leaving the Stomach food + gastric juices (chyme) travels through pylorus to small intestine

Parts of small intestine

Three Parts to the small intestine:

-Duodenum

-Jejunum

-Ileum

What Happens in the small intestine?

• Ducts from Liver, Gallbladder, and Pancreas join to form one duct that enters Duodenum

• Proteins, Lipids, and Carbohydrates will finish undergoing digestion

Food will pass from small intestine to large intestine through Ileocecal valve

Large Intestine

Parts of Colon (aka Large Intestine)

Large Intestine has four parts:- Ascending Colon- Transverse Colon- Descending Colon- Sigmoid Colon

Haustra- pouches in large intestine that expand to store material

https://www.youtube.com/watch?v=Ujr0UAbyPS4

Taenia coli- Muscle along the surface that help with peristalsis (green arrow)