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78 terms

nutrition and digestion

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BMI
Body Mass Index is used to assess healthy body weight. A person's weight in kilograms divided by the square of height in meters.
macronutrients
A chemical substance that an organism must obtain in relatively large amounts. For example carbohydrates, fats & proteins.
micronutrients
Nutrients required in small or trace amounts. Some examples are vitamins and minerals.
carbohydrates
molecules made of C, H, and O in a 1:2:1 ratio; a source of energy for the body.
monosaccharide
single sugar (ex. glucose)
disaccharide
double sugar (ex. sucrose)
polysaccharide
a complex molecule composed of three or more monosaccharides (ex. starch)
dehydration synthesis
A chemical reaction in which two molecules covalently bond to each other with the removal of a water molecule.
hydrolysis
a chemical reaction in which water reacts with a compound to produce other compounds
glycogen
An extensively branched glucose storage polysaccharide found in the liver and muscle of animals.
cellulose
polysaccharide consisting of glucose monomers that reinforces plant-cell walls; indigestable by humans
fat
molecules made of C, H, and O in no set ratio; a source of energy for the body;building materials for cell membranes & hormones, insulate from cold, protect vital organs from injury
saturated fats
solid at room temperature; all bonding sites on the carbon atom are occupied by hydrogen ("bad" fat)
unsaturated fats
have double bonds; "good" fats; poly unsaturated fats (many double bonds); mono unsaturated fats (1 double bond)
cholesterol
A steroid that forms an essential component of animal cell membranes and acts as a precursor molecule for the synthesis of other biologically important steroids. Too much can lead to life threatening problems.
proteins
contains carbon, hydrogen, oxygen, and nitrogen; are a source of energy; needed by tissue for repair and growth; can be enzymes, antibodies, hormones
amino acid
organic compounds containing an amino group and a carboxylic acid group; are the basic building block of proteins; twenty different types, eight of which the body cannot make and we must get from the diet
peptides
chain of amino acids held together by peptide bonds
minerals
inorganic cpds. needed in small amounts for some chemical reactions, building of bones, hemoglobin, hormines, enzymes & vitamins
vitamins
compounds that help regulate many vital body processes, including the digestion, absorption, and metabolism of other nutrients. Required in small amounts. Some are fat soluble and some are water soluble.
anorexia nervosa
an eating disorder in which a normal-weight person diets and becomes significantly underweight, yet, still feeling fat, continues to starve
bulimia
eating disorder characterized by excessive eating followed by purging
mechanical digestion
The process through which your food is physical broken down into smaller, more manageable pieces. The result is a physical change.
papillae
small rough elevations on tongue containing taste buds
uvula
structure hanging from the middle of the back edge of the soft palate prevents food from entering the pharynx when we swallow.
salivary glands
three pairs of exocrine glands in the mouth that secrete saliva; involved in chemical digestion and lubricates food
parotid gland
largest salivary gland, found below & in front of each ear
sublingual gland
smallest salivary gland, found beneath the floor of the mouth, behind the incisor
submaxillary gland
found below & behind the sublinguals
bolus
ball of food formed by the tongue, for ease of movement through the esophagus
pharynx
throat; passageway for food to the esophagus and air to the larynx
epiglottis
flap of tissue that covers the trachea when you swallow to prevent food from entering the lungs
esophagus
a muscular tube that connects the mouth to the stomach
peristalsis
wave-like muscle contractions of the alimentary tract that moves food along
serosa
the delicate outer layer of tissue of most organs, that holds esophagus in place
stomach
large, J-shaped, muscular sac that continues the mechanical and chemical digestion of food
gastric glands
found in the stomach and secrete gastric juices
gastric juice
digestive secretions of the stomach glands consisting chiefly of hydrochloric acid and mucin and the enzymes pepsin and rennin and lipase
cardiac sphincter
the ring-like muscle between the esophagus and stomach that controls food flow; will prevent flow of food and acids back into the esophagus
pyloric sphincter
ring of muscle that controls the opening between the stomach and the duodenum;
rugae
folds in the lining of the stomach that expands surface area
pepsin
enzyme that breaks down proteins in the stomach
pepsinogen
released in stomach, reacts with HCl to create pepsin
rennin
chemical found in baby's stomach and is used to slow down the movement of milk through the digestive system to give time for absorption of nutrients
ulcers
open sores in the lining of the stomach or the small intestine generally associated with some kind of irritant or bacterial infection which results in the loss of the mucus laryer. Allows HCl to create a hole in the stomach.
villi
Small fingerlike projections on the walls of the small intestines that increase surface area
microvilli
Tiny hair-like projections of the cytoplasmic membrane located only in the small intestine to facilitate absorption by increasing surface area.
lacteal
a small vessel in the center of the villi that transports the products of fat digestion to the circulatory system
duodenum
first part of the sm. intestine; .5 m long; involved in chemical digestion
jejunem
second part of the sm. intestine; 2.5 m long; continues some chemical digestion but mostly involved in absorption of nutrients
ileum
third part of the sm. intestine; 3 m long; contains fewer & smaller villi for the continuation of absorption of nutrients
large intestine
1.5 m long & greater diameter than the sm. intestine; involved in water (& some mineral) reabsorption; forms and stores feces for elimination; vit. B-12 & K are produced here
ileocaecal valve
A sphincter muscle situated at the junction of the small intestine (ileum) and the large intestine
caecum
sac located near the junction of the ileum and lg. intestine
appendix
a vestigial process that extends from the lower end of the cecum and that resembles a small pouch; no role in digestion but might help to fight infections
rectum
A short tube at the end of the large intestine where waste material is compressed into a solid form before being eliminated
anus
opening of the rectum to the outside of the body control the timing of elimination (to some extent) by anal sphincters
ulcerative colitis
inflammation of the lining of the rectum & large intestine
Crohn's disease
inflammation can be any where in the G. I. tract, but is mostly in the small intestine
constipation
irregular and infrequent or difficult evacuation of the bowels; can have many causes, but often not enough fiber in the diet.
liver
divided into 2 large lobes; produces bile, breaks down old red bl. cells and a.a., stores excess chemicals, detoxifies various poisons
bile
A substance produced by the liver that breaks up fat particles and is stored in the gallbladder.
cirrhosis
chronic disease characterized by scarring of liver tissue, most often caused by alcoholism or a nutritional deficiency.
alcoholic hepatitis
inflammations of the liver leading to decreased ability to break down toxins. Some symptoms are nausea, vomiting, abdominal pain, jaundice.
gallbladder
a muscular sac attached to the liver that secretes bile and stores it until needed for digestion
cholecystokinin
hormone the small intestine secretes to stimulate release of pancreatic juice from pancreas and bile from gallbladder
gallstones
small hard particles made of cholesterol which form and collect in the gall bladder --may block the bile duct causing pain and discomfort, may treated by surgical removal of the gall bladder
pancreas
located partially behind the stomach in the abdomen, and it functions as both an endocrine and exocrine gland. It produces digestive enzymes as well as insulin and glucagon.
secretin
A hormone secreted by the small intestine in response to low pH (e.g., from stomach acid). It promotes the release of bicarbonate from the pancreas to act as a buffer.
cellulase
made by microbes in intestine to break down cellulose in GI tract
ruminants
An animal, such as a cow or sheep, with an elaborate, multicompartmentalized stomach specialized for an herbivorous diet.
crop
a pouch in many birds and some lower animals that resembles a stomach for storage and preliminary maceration of food
gizzard
thick-walled muscular pouch below the crop in many birds and other organisms, containing gravel to mechanically grind food
prostomium
liplike covering over mouth; pushes soil into mouth
intracellular digestion
process in which food is digested inside cells
extracellular digestion
digestion occurs outside the cells; eg. in alimentary canals
xylem
the vascular tissue through which water and nutrients move upward in some plants
phloem
vascular tissue responsible for the transport of nutrients and the carbohydrates produced by photosynthesis