Nutrition for a Changing World - Study Guide Chapter 3

The levels of organization within the body

cell, tissue, organs, organ system, body (organism)

Identify the organs of the digestive systems

Mouth, throat (pharynx), esophagus, stomach, small intestine - Doudenum, jejunum, ileum-, large intestine, rectum

Role of mouth in digestion

chews food into smaller particles that become mixed with saliva

role of esophagus

to carry food, liquids, and saliva from the mouth to the stomach

role of stomach

-A muscular organ that moves the food around, mixing it with stomach secretions

-The stomach produces hydrochloric acid which aids digetion by lowering the pH to enable enzymes in gastric juice to break down food.

-The gastric juice (pepsin) begins the digestion of proteins.

-Other cells in the stomach wall secrete mucus, which protects the stomach lining from attack by digestive enzymes.

role of small intestine

-completes digestion and absorbs nutrients into the bloodstream

3 parts of the small intestine

duodenum, jejunum, ileum

role of large intestine

-absorption of water and any remaining nutrients

-storage of indigestible materials before eliminated from body

-synthesis and absorption of vitamins

-transportation of waste products out of alimentary canal

role of rectum

The faeces are stored here before periodically being removed via the anus in a process called egestion.

accessory glands

teeth, salivary glands, liver, gall bladder, pancreas

Ingestion

Intake of food

Mastication

the act of chewing

propulsion

the pushing of food down the GI tract

deglutition

the act of swallowing

Peristalsis

Involuntary waves of muscle contraction that keep food moving along in one direction through the digestive system.

Digestion

Breakdown of food substances into simpler forms that can be absorbed and used

Absorption

The process by which nutrient molecules pass through the wall of the digestive system into the blood

Defication

the discharge of feces from the body.

Chyme

Partially digested, semiliquid food mixed with digestive enzymes and acids in the stomach.

Bile

a digestive juice secreted by the liver and stored in the gallbladder

Probiotics

live microbes applied to or ingested into the body, intended to exert a beneficial effect

Prebiotics

food components (such as fibers) that are not digested by the human body but are used as food by the GI bacteria to promote their growth and activity

amaylase

a digestive enzyme in saliva that breaks down starch and glycogen

Lipase

a digestive enzyme in the mouth, stomach, and pancreas, that breaks down fats

Protease

digestive enzyme which breaks protein down in the stomach and pancreas

circular folds

deep folds of the mucosa and submucosa that extend completely or partially around the circumference of the small intestine that increase the surface area for absorption in the small intestine

Villi

Tiny finger-shaped structures that cover the inner surface of the small intestine and provide a large surface area through which digested food is absorbed

Microvilli

Hair like projections on the surface of the villi that increase surface area.

Ranking of food components that leave the stomach from fastest to slowest

1. Liquids

2. Carbohydrates

3. Proteins

4. Fats

vomiting

expelling matter from the stomach through the mouth

diarrhea

frequent passage of loose, watery stools

constipation

Hard, slow stools that are difficult to eliminate; often a result of too little fiber in the diet

hemorrhoids

painful inflamed veins

acid reflux

a condition where the sphincter seperating the stomach and esphagus is relaxed and causes the chyme to go back into the esophagus, causing a heartburn

heartburn

burning sensation produced by acid reflux into the esophagus

Gastroesophageal reflux disease (GERD)

a more serious form of acid reflux plus inflammation and/or erosion of the esophageal lining along with pain and gastrointestinal issues - not treating can lead to cancer

Gallstones

Small crystals that form from bile in the gallbladder

Diverticular disease

a condition characterized by pouches or pockets in the wall or lining of any portion of the digestive tract

irritable bowel syndrome (IBS)

symptom complex marked by abdominal pain and altered bowel function (typically constipation, diarrhea, or alternating constipation and diarrhea) for which no organic cause can be determined; also called spastic colon

inflammatory bowel disease

a broad term that describes serious chronic conditions that are caused by abnormal responses by the body's immune system causing inflammation on the GI tract most common IBDs are ulcerative colitis

ulcerative colitis

mucosa of the intestine becomes irritated and swollen and open wounds (ulcers) and crohn's disease

Ulcers

Open sores in the lining of the digestive system

lumen

the inner space of the GI tract, lined with mucosal cells

Mucosa

tissues that line the GI tract made up of epithelial cells

mechanical digestion

the physical breakdown of food by mastication (chewing) and mixing with digestive fluids

chemical digestion

the chemical breakdown of food using enzymes and other chemical substances released from the salivary glands, stomach, small intestine, liver, gallbladder, and pancreas

Peristalsis

rhythmic, wavelike contractions of the smooth muscles of the GI tract

Segmentation

the contraction of the circular smooth muscles in the small intestine that makes the intestinal contents with digestive fluids and brings the nutrients in the intestinal fluid into contact with the intestines observative surface

Bolus

a masticated round lump of food lubricated in the mouth by mixing with saliva

sphincter

a ring like muscle that relaxes or contracts to open or close a bodily passageway

brush border

name for the microvilli covered surface of the small intestine that functions in the absorption of nutrients

bile

a fluid produced in the liver concentrated and stored in the gallbladder and secreted into the small intestine in response to food present in the stomach bile promotes the digestion of fat by emulsifying it which allows life is easier access

simple Diffusion

movement of a substance across a cell membrane down a concentration gradient

facilitated diffusion

movement of a substance across the cell membrane down a concentration gradient with the assistance of a specific transport protein

celiac disease

an inflammatory response meditated by the immune system that damages the mucosa of the intestines and is triggered by the presence of gluten protein in the diet