Human Digestion and Absorption

Flashcards about the human digestion system including the organs, each organ's roles, and potential diseases.

Ingestion

The process of taking food in

Digestion

The process of changing food into simple components which the body can absorb

Egestion

Ridding the body of solid waste

Mouth

Food enters; mechanical digestion (mastication) occurs with teeth breaking up food; bolus of food forms; chemical digestion occurs with saliva, enzymes, amylase, mucin, buffers, and anti-bacterial chemicals

Amylase

Enzyme that digests starch

Mucin

Slippery protein (mucus); protects soft lining of digestive system; lubricates food for easier swallowing

Buffers

Neutralizes acid to prevent tooth decay

Anti-bacterial chemicals

Protect and kill bacteria that enter mouth with food, using lysosomes and immunoglobulins to kill viruses and bacteria

Pharynx

The back of the throat; contains the larynx which is the passage for air and closes when we swallow

Esophagus

Connects mouth to stomach; epiglottis closes airway; bolus moved along by peristalsis; cardiac sphincter keeps food from backing up into esophagus

Epiglottis

Closes airway

Cardiac sphincter

Keeps food from backing up into esophagus

Stomach

Collecting & churning (mechanical and chemical digestion); gastric glands secrete gastric juice (water, enzymes, hydrochloric acid) that kills most bacteria and begins protein digestion and mucus to protect lining; chyme is the semi-liquid mass of partially digested food; Pyloric sphincter regulates passage of chyme into small intestine

Gastric glands

Gastric juice (water, enzymes, hydrochloric acid) that kills most bacteria and begins protein digestion and mucus to protect lining

Chyme

Semi-liquid mass of partially digested food

Pyloric sphincter

Regulates passage of chyme into small intestine

Bile

Emulsifies lipids

Duodenum

Opening from common bile duct; secretes fluids from liver & gallbladder and pancreas; amylase breaks down carbohydrate, sodium bicarbonate neutralizes the acidic chyme and lipase

Amylase

Breaks down carbohydrate

Sodium bicarbonate

Neutralizes the acidic chyme

Ileocecal valve

Sphincter that regulates passage of chyme into large intestine

Large intestine (colon)

Reabsorbing & eliminating; fermentation of undigested residues by bacteria occurs (e.coli); terminates at rectum, where water some minerals are absorbed; anus controls defecation

Anus

Sphincter that controls defecation (excretion of fiber residue, wastes and some water)

Peristalsis

Muscular contractions that push contents forward

Segmentation

Inward squeezing for greater mixing of secretions

Pepsin

An enzyme that breaks down large proteins into amino acids

Digestive Glands

Groups of specialized secretory cells found in the lining of the alimentary canal or accessory organs

Gall bladder

Pouch structure located near the liver which concentrates and stores bile

Bile duct

A long tube that carries bile

Bile

A bitter, greenish-yellow alkaline fluid, stored in the gallbladder between meals and upon eating is discharged into the duodenum where it aids the process of digestion

Pancreas

An organ which secretes both digestive enzymes (exocrine) and hormones (endocrine)

Trypsin, chymotrypsin

Digestive enzymes – digest proteins

Liver

Produces bile stored in gallbladder until needed; breaks up fats

Small Intestine

Most chemical digestion takes place here; simple sugars and proteins are absorbed into the inner lining; Fatty acids and glycerol go to lymphatic system; Lined with villi, which increase surface area for absorption, one cell thick

Villi

Increase the surface area of the small intestines, thus providing better absorption of materials

End-products of digestion:

CHO >>> Monosaccharides

End-products of digestion:

Fats >>> Glycerol + fatty acids

End-products of digestion:

Proteins >>> Amino acids

Vascular system

Water-soluble nutrients (monosaccharides, amino acids, water-soluble vitamins, minerals, water) enter the blood via the portal vein for transport to the liver

Lymph system

Fat-soluble nutrients (lipids, fat-soluble vitamins) enter here, eventually entering the blood near the heart

Chylomicrons

Very, very low density (85% triglyceride); absorbed from small intestine into lymph & circulated to cells where some of lipid material is picked off & remnants return to liver

VLDL

Very low density lipoprotein (50% triglyceride); made by liver & travels to cells

LDL

Low density lipoprotein (50% cholesterol); remains of VLDL; high levels increase risk of heart attack

HDL

High density lipoprotein (50% protein); removes cholesterol from blood for return to liver; high levels decrease risk of heart attack

Large intestines (colon):

Re-absorb water; use ~9 liters of water every day in digestive juices; > 90% of water reabsorbed

Rectum

Eliminate feces, undigested materials, extracellular waste, mainly cellulose from plants

ULCERS

Erosion of the surface of the alimentary canal generally associated with some kind of irritant

CONSTIPATION

A condition in which the large intestine is emptied with difficulty; too much water is reabsorbed and the solid waste hardens

DIARRHEA

A gastrointestinal disturbance characterized by decreased water absorption and increased peristaltic activity of the large intestine; results in increased, multiple, watery feces

APPENDICITIS

An inflammation of the appendix due to infection

Dysphagia

Difficulty swallowing with tendency to choke/aspirate

Upper GI Problems

Reflux esophagitis (“heartburn”) which often occurs due to a hiatal hernia and Gastritis (inflammation of stomach lining) and Peptic Ulcers (erosions of the lining of stomach or duodenum)

GALLSTONES

An accumulation of hardened cholesterol and/or calcium deposits in the gallbladder

ANOREXIA NERVOSA

A psychological condition where an individual thinks they appear overweight and refuses to eat

HEART BURN

Acid from the stomach backs up into the esophagus