digestive system

What are the four main functions of the digestive system in order?

1. Ingestion

2. Digestion

3. Absorption

4. Defecation

What are the two main groups of digestive system organs?

Alimentary canal (GI tract) and accessory organs

What are the organs of the GI tract in order?

Oral cavity, pharynx, esophagus, stomach, small intestine, large intestine

What is the mucosa?

The inner lining of the oral cavity that is open to the outside and prone to infection.

What is the function of the palate?

Separates the nasal cavity and oral cavity.

What are the main functions of the mouth (oral cavity)?

Mastication (chewing), mixing food with saliva, starting the swallowing process, and tasting food.

In what order does food move posteriorly from the oral cavity?

Oropharynx, laryngopharynx, esophagus

What is peristalsis?

Slow, directional contraction of involuntary, smooth muscles in the walls of hollow GI tract organs that propels food through the GI tract.

What are the four layers of the walls of hollow GI tract organs from inside to outside?

Mucosa, submucosa, muscularis, serosa

What is the mucosa?

Inner lining of the lumen; contains epithelium, lamina propria, and a thin smooth muscle layer.

What is the submucosa?

Soft connective tissue with blood vessels, nerve endings, and lymphoid tissue.

What is the muscularis?

Involuntary, smooth muscles that perform peristalsis; contains an inner circular layer and an outer longitudinal layer.

What is the serosa?

Thin outer covering of simple squamous ET that secretes serous fluid for lubrication; includes the visceral peritoneum.

Why does the stomach have three layers of smooth muscle in the muscularis?

To smash and mash food into bits by peristalsis.

What are the two sphincters that control the entry and exit of food from the stomach?

Cardiac sphincter and pyloric sphincter

What are the main functions of the stomach?

Mechanical digestion of food, beginning chemical digestion of protein, and sending chyme to the small intestine.

What is the function of mucous neck cells in the stomach?

Produce alkaline mucus.

What is the function of enteroendocrine cells in the stomach?

Produce gastrin (hormone).

What is the function of parietal cells in the stomach?

Produce HCl.

What is the function of chief cells in the stomach?

Produce pepsinogen.

What is the primary function of the small intestine?

Most nutrient absorption.

What three structures increase the surface area for absorption in the small intestine?

Circular folds, villi, and microvilli

What are the subdivisions of the large intestine?

Cecum, colon, rectum, anal canal

What are the four regions of the colon?

Ascending colon, transverse colon, descending colon, sigmoid colon

What type of muscle is the external anal sphincter and is it under voluntary or involuntary control?

Skeletal muscle, voluntary control.

What are the two types of propulsion of food in the digestive system?

Peristalsis and mixing

What structures perform mechanical digestion?

Teeth, tongue, and stomach muscles

What breaks down large molecules into their components by breaking chemical bonds in chemical digestion?

Enzymes

What are the accessory digestive organs?

Teeth, tongue, salivary glands, pancreas, liver, gallbladder

What are the types of teeth (anterior to posterior) in each quadrant of the mouth?

2 incisors, 1 canine, 2 premolars, 3 molars

What are the two main regions of a tooth?

Crown and root

What are the three layers of the crown of a tooth?

Enamel, dentin, and pulp

What is the function of saliva?

Moistens and binds food into a bolus, and begins starch digestion.

Salivary glands produce & secrete _ thru ducts (exocrine)

Saliva

What are the three pairs of salivary glands?

Parotid glands, submandibular glands, sublingual glands

What are functions of the pancreas?

Produces digestive enzymes and hormones.

What hormones does the pancreas produce?

Insulin and glucagon

What and where is the liver?

Largest gland in the body, located on the right side, inferior to the diaphragm.

Name one of the lobes that the Liver consists of.

R lobe and L lobe

What is bile?

Produced by the liver, stored in the gallbladder, emulsifies fats.

What is the function of the gallbladder?

Stores bile and secretes it into the duodenum to aid in fat digestion.

What are the three phases of swallowing?

Voluntary, pharyngeal (involuntary), esophageal (involuntary)

Describe the voluntary phase of swallowing.

In the oral cavity; tongue shapes food into bolus.

Describe the pharyngeal phase of swallowing.

Bolus of food moves into oropharynx; uvula blocks entry to nasopharynx and epiglottis blocks entry to larynx/trachea.

Describe the esophageal phase of swallowing.

Larynx, epiglottis, and uvula return to pre-swallowing positions; peristalsis pushes bolus down esophagus to stomach.

What does the stomach secrete?

Gastrin, pepsinogen, HCl

What hormones does the small intestine secrete that causes the pancreas & gallbladder to secrete enzymes & bile thru ducts to duodenum?

Cholecystokinin (CCK) and secretin

What does intestinal flora do?

Digest remaining nutrients, produce vitamins K & B12, release gas, & absorb water.