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)
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