Anatomy

The process of breaking down food groups into molecules that are small enough to be utilized by the cells of the body

Overview of GI tract Functions:
Mouth---bite, chew, swallow

Overview of GI tract Functions:
Pharynx and esophagus

Overview of GI tract Functions:
Stomach

Overview of GI tract Functions:
absorbs electrolytes & vitamins (B and K)

Overview of GI tract Function
--defecation

Where is the peritoneum serous membrane found?

Covers organs

Lines the walls of body cavity

Potential space containing a bit of serous fluid

What are the 4 layers of the GI Tract?

Contains buccinator muscle that keeps food between upper & lower teeth

Area between cheeks and teeth

-the roof = hard, soft palate and uvula
-the floor= the tongue

Pharyngeal Arches consists of __ muscles

– extends from palate to tongue
– forms the first arch
– posterior limit of the mouth

– extends from palate to pharyngeal wall
– forms the second arch
– between: palatine tonsil

• Parotid below your ear and over the masseter
• Submandibular is under lower edge of mandible
• Sublingual is deep to the tongue in floor of mouth
• All have ducts that empty into the oral cavity

•Wet food for easier swallowing
• Dissolves food for activation of taste receptors
• Bicarbonate ions buffer acidic foods

Chemical digestion of starch begins with _______ (salivary amylase) and _____ (lingual lipase)

Composition & Functions of Saliva:
Helps destroy bacteria

Protects mouth from infection with its rinsing action---1 to 1.5 l/day

What are the 5 structures of a tooth?

Composition of Teeth:
– hardest substance in body
– rich in calcium salts (calcium phosphate and carbonate)

Composition of Teeth:
– calcified connective tissue (harder than bone-more calcium salts)

Composition of Teeth:
– bone-like
– periodontal ligament (fibrous connective tissue) connects cementum to bone socket

Dentition:
– 20 teeth that start erupting at 6 months
– 1 new pair of teeth per month

Dentition:
– 32 teeth that erupt between 6 and 12 years of age
– differing structures indicate function

What teeth for:
for biting

What teeth for:
Tearing

What teeth for:
Crushing & grinding food

What teeth:
Third set of molars may impact (no room)

-Funnel-shaped tube extending from internal nares to the esophagus (posteriorly) and larynx (anteriorly)
-Skeletal muscle lined by mucous membran

Deglutition or swallowing is facilitated by _____ and ______

Physiology of the Esophagus - Swallowing
--tongue pushes food to back of oral cavity

Physiology of the Esophagus - Swallowing
---pharyngeal stage

– breathing stops & airways are closed
– soft palate & uvula are lifted to close off nasopharynx
– vocal cords close
– epiglottis is bent over airway as larynx is lifte

• Collapsed muscular tube
• In front of vertebrae
• Posterior to trachea
• Posterior to the heart
• Pierces the diaphragm at hiatus

Histology of the Esophagus
Mucosa is composed of which type of tissue?

Histology of the Esophagus
large mucous glands

Histology of the Esophagus
Upper 1/3 is skeletal, middle is mixed, lower 1/3 is smooth

Upper esophageal sphincter prominent circular muscle, lower sphincter is narrowing of lumen, physiological

Histology of the Esophagus:
connective tissue blending with surrounding connective tissue--no peritoneum

Size of the stomach when empty

Stomach stretches due to _______

What are the 3 parts of the stomach?

Which part of the stomach starts to narrow as approaches pyloric sphincter

Empties as small squirts of ________leave the stomach through the pyloric valv

Secrete pepsinogen and gastric lipase (fat digestion)

Secrete HCL –converts pepsinogen to pepsin (protein digestion) and intrinsic factor- absorption of vitamin B12 for RBC production

Secrete Gastrin hormone (g cell)- release more gastric juice, increase gastric motility, relax pyloric sphincter, constrict esophageal sphincter preventing entry

Three layers of smooth muscle--outer longitudinal, middle circular & inner oblique

Permits greater churning & mixing of food with gastric juice

Chemical Digestion:
– HCl denatures (unfolds) protein molecules
– HCl transforms pepsinogen into pepsin that breaks peptides bonds between certain amino acid

Chemical Digestion:
– gastric lipase splits the triglycerides in milk fat

Chemical Digestion:
Kills microbes in food

Protect stomach walls from being digested with 1-3mm thick layer of mucous (aspirin inhibits mucous formation)

What is absorbed by the stomach?

3 meters long----2.5cm in diameter
Large surface area for majority of absorption

What are the 3 parts of the small intestine?