N3.1 Digestion

digestion

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

transport

to carry nutrients around the body to its cells

nutrient

chemical substance that an organism needs to sustain life

digestive system

body system that breaks down food and absorbs nutrients

diaphragm

Large, flat muscle at the bottom of the chest cavity that helps with breathing

gastrointestinal tract

another name for alimentary canal

lumen

space within a tubular part or organ

mechanical digestion

physical breakdown of food

chemical digestion

breaking down food with enzymes

saliva

digestive juice produced by salivary glands

tastant

taste-provoking chemical

umami

savory taste

taste bud

sense receptor in the tongue that responds to sweet, salty, sour, bitter, umami, and perhaps fat

tongue

manipulates food for chewing and swallowing; a taste organ

bolus

A soft mass of chewed food.

pharynx

throat; passageway for food to the esophagus and air to the larynx

epiglottis

a flap of cartilage that covers the windpipe while swallowing

esophagus

A muscular tube that connects the mouth to the stomach.

sphincter

circular ring of muscle that constricts a passage or closes a natural opening

upper esophageal sphincter

the muscular ring located at the top of the esophagus

lower esophageal sphincter

a muscular ring that controls the flow between the esophagus and stomach; aka cardiac sphincter

chyme

mixture of enzymes and partially-digested food

pyloric sphincter

opening from the stomach into the duodenum

amylase

Enzyme in saliva that breaks the chemical bonds in starches

small intestine

Digestive organ where most chemical digestion and absorption of food takes place

duodenum

first part of the small intestine

jejunum

Middle portion of the small intestine

ileum

the last and longest portion of the small intestine

ileocecal valve

Valve at the junction of the small and large intestines

cecum

a pouch connected to the junction of the small and large intestines.

appendix

blind pouch hanging from the cecum

rectum

A short tube at the end of the large intestine where waste material is compressed into a solid form before being eliminated

anus

A muscular opening at the end of the rectum through which waste material is eliminated from the body

motility

ability to move

peristalsis

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

segmentation

contractions of the circular muscles in the digestive tract that mix food

digestive enzymes

proteins found in digestive juices that act on food substances, causing them to break down into simpler compounds

catalyst

substance that speeds up the rate of a chemical reaction

hydrolysis

Breaking down complex molecules by the chemical addition of water

gastric juice

digestive secretions of the stomach glands consisting chiefly of hydrochloric acid

hydrochloric acid

HCl, strong Acid, pH 2

pancreatic juice

the clear alkaline digestive fluid secreted

sodium bicarbonate

NaHCO3, base, pH 8-9

intestinal enzymes

made in intestinal epithelial cells; on their surface and also released into duodenum

bile

A substance produced by the liver that breaks up fat particles.

emulsifier

a compound with both water-soluble and fat-soluble portions that can attract fats and oils into water, combining them.

liver

organ that produces bile

pancreas

An organ in the abdominal cavity with both digestive system and endocrine roles

fiber

A tough complex carbohydrate that the body cannot digest

excretion

Process by which metabolic wastes are eliminated from the body

defecation

elimination of feces