Human Anatomy Digestive System

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Functions of Digestive System

1. Ingestion

2. Propulsion

3. Food Breakdown: Mechanical

4. Food Breakdown: Chemical

5. Absorption

6. Defecation

Two main parts of Digestive System

1. Alimentary Canal (ingests, digests, absorbs, excretes)

2. Accessory Digestive Organs (helps with digestion in various ways)

Alimentary Canal AKA…

Gastriontestinal Tract, GI Tract, or Gut

What is the Alimentary Canal

Continuous muscular tube that winds through the ventral body cavity from the Mouth to the Anus

Parts of Alimentary Canal

1. Mouth

2. Pharynx

3. Esophagus

4. Stomach

5. Small Intestine

6. Large Intestine

What type of muscle is used in the Alimentary Canal?

Smooth Muscle (involuntary)

Food enters through the _____ into the ____ Cavity

mouth, Oral

Lips

Protect the anterior opening

Cheeks

Form the lateral walls

Hard Palate

Forms the anterior roof

Soft Palate

Forms the posterior roof

Uvula

A fleshy fingerlike projection of the soft palate, dangles in the back of the oral cavity

Tongue

Floor of the cavity which attaches to the Hyoid Bone and the Styloid Process of the skull

Lingual

Helps to limit movement

Palatine Tonsils

Masses of lymphatic tissue at the posterior end of oral cavity. They are part of the body’s defense system

Lingual Tonsil

Lmphatic tissue that covers the base of the tongue, also part of body’s defense system

Mechanical/physical digestion

Saliva (wet), tongue (mix, move, swallow), teeth (chew)

Chemical digestion

Salivary amylase is made by salivary glands which breaks down startches/carbohydrates in mouth

Stomach

C chapes organ on the left side of the abdominal cavity, nearly hidden by the

Functions of Stomach

1. Storage

2. Moves food along

3. Churns

4. Mixes

5. Pummels

6. Chemically breaks down proteins

Sections of Stomach

1. Cardioesophageal Sphincter

2. Less curvature

3. Great curvature

4. Pyloric Sphincter

Cardioesophageal Sphincter

Muscular opening through which food passes from the esophagus into the stomach

Pyloric Sphincter

Muscular opening that allows food to pass into the small intestine

Compenents of Gastric Juice

1. Intrinsic Factor

2. Pepsinogen

3. Hydrochloric Acid

4. Mucus

Intrinsic Factor

Helps to absorb vitamin B12 in small intestine

Pepsinogen

Activated into pepsin to digest proteins produced by chief cells

Hydrochloric Acid

HCL attrached to the pepsin

Mucus

Protects lining produced by goblet cells

Lipids

Produced in the small intestine to break down fats

Pepsin

In stomach in the presence of HCl

Trypsin

Produced by the pancreas in duodenum of small intestine to break down proteins

Pancreatic Amalyse

Produced by the pancreas in small intestine to break down carbohydrates

Proteins break down into

Amino acids

Small Intestine

Body’s major digestion organ, suspended by Mesentery, helps further digest food coming from the stomach

Villi

Fingerlike projections in the mucosa give the interior lining a velvety appearance

Parts of Small Intestine

1. Duodenum (first)

2. Jejunum (middle)

3. Ileum (last)

Large Intestine

Extends from the Ileocecal Valve to the Anus

Function of Large Intestine

1. To dry out indegestible food residue

2. Absorbs this water back into the body

3. Eliminates remaining residue as Feces

Parts of Large Intestine

1. Cecum

2. Colon

3. Rectum

4. Anal Canal

Cecum

Sac-like beginning of the large intestine. Hanging from the cecum is the worm-like Appendix which can become inflamed by bacteria causing Appendicitis

Colon

1. Ascending Colon

2. Transverse Colon

3. Descending Colon

4. Sigmoid Colon

Rectum

Carries waste from the rectum to the opening called the Anus

Parts of Accessory Digestive Organs

1. Teeth

2. Salivary Glands

3. Pancreas

4. Liver and Gall Bladder

Function of Teeth

Is Mastication, or Chewing. The teeth tear and grind the food, breaking it into smaller fragments

Two sets of Teeth

1. Deciduous Teeth (Baby Teeth)- 20 total

2. Permanant Teeth- 32 total

Classification of Teeth

1. Incisors- chisel shaped for cutting (8)

2. Canines- fang-like eyeteeth for tearing or piercing (4)

3. Premolars- Bicuspids (two cusps) for crushing and gringing (8)

4. Molars- Tricuspids (three cusps) also for crushing and grinding (12)

5. Wisdom

Salivary Glands

Produce Saliva, a mix of mucous and serous fluids and so the food can be tasted

Bolus

A mass of moist food

Three pairs of Salivary Glands

1. Parotid Glands

2. Submandibular Glands

3. Sublingual Glands

Patorid Glands

Lie anterior to the ear

Submandibular Glands

Below Jaw

Sublingual Glands

Below tongue

Pancreas

Soft, pink, triangular gland near the stomach

Function of Pancreas

Produces enzymes to break down all categories of food, also has an endrocine function, producing Insulin for control of sugars in blood

Liver

Largest gland in the body, located more on the right side and under the diaphragm

Functions of Liver

1. Manufacturing Bile

2. Detoxification of drugs and alcohol

3. Degredatoin of hormones

4. Production of cholesterol, albumin, and clotting proteins

Digestive funtion is production of Bile, which…

Is produced by the Liver that goes through the Common Hepatic Duct and enters the Duodenum through the Bile Duct

Bile

Is yellowish-green and contains bile salts, which Emulsifies Fats (physically breaks fats down into smaller fats)

Gall Bladder

Is a green sac that is under the Liver

Function of Gall Bladder

Bile backs up in the cystic duct and is stored in the gall bladder

Saturated Fats

Lipids that come from animals (bad)

Unsaturated Fats

Lipids that come from plants (good)

Carbohydrates

Comes from plants

Fiber

A carbohydrate that can’t be digested but increases the bulk of the stool and aids defecation

Metabolism

All the chemical reactions necessary to maintain life

Two parts of Metabolism

1. Catabolism

2. Anabolism

Catabolism

Enzymes breaking down substances into simpler substances

Anabolism

Building larger molecules from smaller ones

Hyperglycemia

Excessively high levels of glucose in the blood

Hypoglycemia

Blood sugar is too low

Ingestion

Active voluntary process of putting food in your mouth

Propulsion

Food must be propelled from one organ to the next

Food Breakdown: Mechanical

Mechanical digestion, making fragments of food into smaller pieces

Food Breakdown: Chemical

Chemical Digestion, where large food molecules are broken down by Enzymes

Absorptoin

Transport from lumen of the GI Tract to the bloodstream

Defecation

Elimination of indigestible residues and gut bacteria via the anus in the form of feces

Persitalsis

Involuntary waves of contraction and relaxation of the longitudinal muscles in the organ wall