Chapter 3 The Human Body: Are We Really What We Eat

hunger

a physiologic sensation that prompts us to eat

appetite

a psychological desire to consume specific foods

anorexia

an absence of appetite

hypothalamus

a region of forebrain above the pituitary gland where visceral sensations such as hunger and thirst are regulated

hormone

a chemical messenger secreted into the bloodstream by one of the many glands of the boys which acts as a regulator of physiologic processes at a site remote from the gland that secreted it

cell

the smallest unit of matter that exhibits the properties of living things such as growth, reproduction, and metabolism

cell membrane

the boundary of an animal cell that separates its internal cytoplasm and organelles from the external environment

cytoplasm

the interior of an animal cell, not including its nucleus

organelle

a tiny organ within a cell that performs a discrete function necessary to the cell

tissue

a group of like cells that performs a function for example muscle tissue

organ

a body structure composed of two or more tissues and performing a specific function for examples the esophagus

system

a group of organs that work together to perform a unique function for example the gastrointestinal system

digestion

the process by which foods are broken down into their component molecules either mechanically or chemically

absorption

the physiologic process by which molecules of food are taken from the gastrointestinal tract into the circulation

elimination

the process by which undigested portions of food and waste products are removed from the body

gastrointestinal (gi) tract

a long muscular tube consisting of several organs the mouth, esophagus, stomach, small intestine, and large intestine

sphincter

a tight ring of muscle separating some of the organs of the GI tract and opening in response to nerve signals indicating that food is ready to pass into the next section

cephalic phase

the earliest phase of digestion in which the brain thinks about and prepares the digestive organs for the consumption of food

saliva

a mixture of water mucus enzymes and other chemicals that moistens the mouth and food binds food particles together and begins the digestion of carbohydrates

salivary glands

a group of glands found under and behind the tongue and beneath the jaw that release saliva continually as well as in response to the thought, sight, smell, or presence of food

enzymes

small chemicals usually proteins act on other chemicals to speed up body processes but are not changed during those processes

bolus

a mass of food that has been chewed and moisten in the mouth

esophagus

a muscular tube of the GI tract connecting the back of the mouth of the stomach

peristalsis

waves of squeezing and pushing contractions that move food in one direction through the length of the GI tract

stomach

a j-shaped organ where food is partially digested, churned, and stored until it is released into the small intestine

gastic juice

acidic liquid secreted within the stomach it contains hydrochloric acid pepsin and other compounds

denature

the action of the unfolding of proteins in the stomach, proteins must be denatured before they can be digested

chyme

a semifluid mass consisting of partially digested food, water, and gastric juices

small intestine

the longest portion of the GI tract where most digestion and absorption takes place

gallbaladder

a tissue sac beneath the liver that stores bile and secretes it into the small intestine

bile

fluid produced by the liver and stored in the gallbladder it emulsifies fats in the small intestine

pancreas

a gland located behind the stomach that secretes digestive enzymes

lacteal

a small lymph vessel located inside the villi of the small intestine

brush border

the microvilli covered lining cells of the small intestine’s villi. These microvilli tremendously increase the small intestines absorptive capacity

liver

the largest auxiliary organ of the GI tract and one of the most important organs of the body its functions include the production of bile and processing of nutrient-rich blood from the small intestine

large intestine

the final organ of the GI tract, consisting of the cecum, colon, rectum, and anal canal and in which most water is absorbed and feces are formed

enteric nervous system

the nerves of the GI tract

heartburn (gastroesophageal reflux)

a painful sensation that occurs over the sternum when hydrochloric acid backs up into the lower esophagus

gastroesophageal reflux disease

a more painful type of GER that occurs more than twice a week

peptic ulcer

an area of the GI tract that has been eroded away by the acidic gastric juice of the stomach

diarrhea

a condition characterized by the frequent passage of loose, watery stools

constipation

a condition characterized by the absence of bowel movements for a period of time that is significantly longer than normal for the individual. When a bowel movement does occur, stools are usually small, hard, and difficult to pass

irritable bowel syndrome

a bowel disorder that interferes with normal functions of the colon