nutrition: unit 1 test!

digestion

the process by which food is broken down into absorbable units

digestion

the body's ingenious way of breaking down foods into nutrients in preparation for absorption

absorption

the passage of nutrients from the GI tract into either the blood or the lymph

enzyme

• facilitate the making and breaking of bonds in chemical runs

• all are proteins

• ase

ase

a word ending denoting an enzyme

digestive enzymes

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

hydrolysis

a chemical reaction in which a major reactant is split into 2 products

• carbohydrate, lipase, protease

carbohydrates

enzyme that hydrolyzes CHO

lipase

enzyme that hydrolyzes lipids

protease

enzyme that hydrolyzes proteins

gastrointestinal (GI) tract

a flexible muscular tube that extends from the mouth, through the esophagus, stomach, small intestine, large intestine, and rectum to anus

lumen

the inner space within the GI tract

stomach

gastro

intestine

intestinal

spinchter

a circular muscle surrounding, and able to close, a body opening

• found at specific points along the GI tract and regulate the flow of the intestinal contents

mouth

• place where digestion begins

• teeth crush large pieces of food into smaller ones

• salivary glands secrete saliva

saliva

• blends with food particles to ease swallowing

• aids in activation of taste buds

• protects teeth and the linings of the mouth, esophagus, and stomach from attack by foreign substances

salivary amylase

principle enzyme of saliva

• begins CHO digestion

pharynx

a short tube shared by both digestive and respiratory systems

epiglottis

closes off air passages

GI tract

mouth -> pharynx (epiglottis) -> esophagus (bolus) -> stomach

bolus

the amount of food swallowed at one time

esophageal spinchter

• both ends of esophagus

• upper esophageal sphincter opens to allow food to slide into esophagus

• lower esophageal sphincter closes to prevent back flow of food from stomach back into the esophagus

heartburn

reflux of food back into esophagus

esophagus to stomach

• food is transferred to lower portion of stomach

• holding tank (app. 4 cups or 1 liter)

• food remains 2-4 hours

• chemical digestion of proteins begins

• principle secretions: pepsin, gastric juice, hydrochloric acid

• chyme released through pyloric sphincter into small intestine

principles secretions (pepsin, gastric juice, hydrochloric acid)

• grind food into a semiliquid mass known as chyme

• extremely ACIDIC

• strong acidity kills most bacteria and prevents bacterial growth

• stomach protected from acidity of gastric juices by the goblet cells, which secrete mucus that coats and protects stomach cells

small intestine

• 3 parts: duodenum, jejunum, ileum

• food remains 3-10 hours

• chemical digestion of CHO, PRO, and FAT

• primary site of absorption

absorption

• 95% of CHO, PRO, FAT, and vitamins

• 80-95% of water

• some minerals

enzymes

pancreatic and intestinal juices

• contain sodium bicarbonate

• basic or alkaline, thus neutralizes the acidic chyme arriving from stomach

bile

secreted from liver and stored in gallbladder; released into duodenum

• emulsifies fat: brings fat into suspension in water so that enzymes can break it down into their components

large intestine (colon)

• chyme enters large intestine through ileocecal valve

• food remains 24-72 hours

• reabsorption of water and minerals

• waste (fiber, bacteria, & unabsorbed nutrients) with water passes to rectum two sphincters of anus

bacteria

both the small & large intestine permit the growth of ______ (neutral in pH):

• known as intestinal flora

• provide protection against infectious bacteria

• produce a couple of vitamins, including a significant amount of Vitamin K -- consider significance of meds that destroy intestinal flora: i.e. Neomycin - results in an increased prothrombin time- must supplement vitamin K

secretions from the GI tract

saliva, mucus, gastric acids, digestive enzymes

• help protect against foreign invaders

saliva

• organ/gland: salivary glands

• target organ: mouth

• action: fluid eases swallowing; salivary enzyme breaks down CHO

stomach

• organ/gland: gastric glands

• target organ: stomach

• action: fluid mixes with bolus; HCI acid uncoils proteins; enzymes break down proteins; mucus protects stomach cells

small intestine

• organ/gland: pancreas

• target organ: pancreatic juice

• action: bicarbonate neutralizes acidic gastric juices; pancreatic enzymes break down CHO, FAT, and PRO

gallbladder

• organ/gland: liver

• target organ: bile

• action: bile stored until needed

small intestine

• organ/gland: gallbladder/intestinal glands

• target organ: bile/intestinal juice

• action: bile emulsifies fat so that enzymes can attack/intestinal enzymes break down CHO & PRO fragments; mucus protects the intestinal wall

GI tract

ringed with circular & longitudinal muscles that contract and relax

peristalsis

wavelike muscular contractions of the GI tract that push its contents along

• snake swallowing its prey

stomach

consists of circular, longitudinal, & diagonal muscles that work to force the chyme downward

upper esophageal sphincter

opens in response to swallowing; allows bolus to move into esophagus

lower esophageal sphincter (aka Cardiac sphincter)

prevents reflux of acidic gastric juices back into esophagus

pyloric sphincter

holds chyme in the stomach long enough to mix with gastric juice; prevents intestinal contents from entering back into stomach

ileocecal valve

empties the contents of small intestine into large intestine; prevents back flow

two sphincters of anus

prevents involuntary elimination of wastes

homeostasis

the maintenance of constant internal conditions by the body's control systems

hormones

• chemical messengers

• secreted by a variety of glands in response to altered conditions in the body

• each hormone travels to one or more specific target tissues or organs, where it elicits a specific response to maintain homeostasis

gastrin

• place of production: stomach wall

• target organ: glands of stomach

• response: secretion of gastric acid

secretin

• place of production: duodenum wall

• target organ: pancreas

• response: secretion of bicarbonate-rich pancreatic juice

cholecystokinin

• place of production: intestinal wall

• target organ: gallbladder

• response: release of bile and slowing of GI motility

gastric-inhibitory peptide

• place of production: intestine

• target organ: stomach

• response: slowing of secretion of gastric juices & GI motility

small intestine

where does most absorption occur?

villi

fingerlike projections from the folds of the small intestine

microvilli

tiny, hairlike projections on each cell of every villus that can trap nutrient particles and transport them into the cells

crypts

tubular glands that lie between the intestinal villi and secrete intestinal juices into the small intestine

increase

many folds of villi _______ surface area, which increases nutrient absorption

villi

nutrients pass through ________ by:

• simple diffusion

• facilitated diffusion

• active transport

bloodstream

water-soluble nutrients enter _________

lymph

fat-soluble nutrients (insoluble in water, & blood is mostly water) enter ______ & are released into bloodstream at a point closer to heart

diffusion; transport

absorption of nutrients into intestinal cells typically occurs by simple _______ or active _______

vascular system

closed system of vessels through which blood flows continuously in a figure eight, with the heart serving as a pump at the crossover point: heart -> arteries -> capillaries -> veins -> heart

vascular system

• in the digestive system, blood leaving goes by vein to another organ (the liver), and then branches into capillaries in the liver before collecting again into a vein and returning to the heart -- heart -> arteries -> capillaries -> veins -> heart

• purpose: liver prepares the absorbed nutrients for use by the body and defends against harmful substances --- liver quite often suffers damage from ingesting toxins/poisons

lymphatic system

nutrients entering here bypass the liver before eventually entering the vascular system

• heart -> arteries -> capillaries (intestines) -> lymph -> veins -> heart

lymph

a clear yellowish fluid that is almost identical to blood except that it contains no red blood cells or platelets

• transports fat & fat soluble vitamins to the blood stream via lymphatic vessels

choking

heimlich maneuver

• if all else fails, open mouth by grasping both the tongue and lower jaw and lifting. if you can see object, use finger to sweep it and begin rescue breath

diverticula

in the colon

• may develop anywhere along the GI tract, but most common in the colon

choking

• take small bites of food

• chew thoroughly before swallowing

• don't talk or laugh w/food in your mouth

• don't eat when breathing hard

diarrhea

• rest

• drink fluids to replace water

constipation

• eat a high-fiber diet

• drink plenty of fluids

• exercise regularly

• respond promptly to urge to defecate

ulcer

• take medicine as prescribed by physician

• avoid coffee & caffeine & alchohol containing beverages

• avoid food that aggravate your ulcer

• minimize aspirin use

• refrain from smoking cigarettes

belching

• eat slowly

• chew thoroughly

• relax while eating

intestinal gas

• eat bothersome foods in moderation

heartburn

• eat small meals

• drink liquids between meals

• sit up while eating

• wait 1 hour after eating before lying down

• wait 2 hours after eating to exercise

• refrain from wearing tight fitting clothing

• avoid foods, beverages, & meds that aggravate heartburn

• refrain from smoking cigarettes

• lose weight if overweight

pH

the lower, the stronger the acid

• a pH below 7 is acidic; above 7 is alkaline, or basic; 7 = neutral

Mouth

The process of digestion begins in the ________, where large pieces of food are broken down into smaller ones

Saliva; salivary amylase

_______ is secreted, & an enzyme known as _____________ ___________ begins carbohydrate digestion

Pharynx; esophagus

The _________, a short tube shared by both the digestive & respiratory systems, directs the food from the mouth into the __________

Upper esophageal sphincter

A sphincter known as the _____________ opens in response to swallowing

Lower esophageal sphincter (cardiac)

As food enters the stomach, a sphincter known as the ____________ closes to prevent reflux of acidic gastric juices

Heartburn

When the reflux does occur in the stomach, this is known as ___________

Gastrin

A hormone that stimulates the release of gastric acid from the gastric glands of the stomach

Chyme

Pepsin, gastric juice & hydrochloride acid grind food into a semiliquid mass known as ________, which is extremely acidic

Protein; pyloric

Chemical digestion of the nutrient, __________, begins. Food is transferred to the lower portion of the stomach, & the __________ sphincter opens to allow food to move into the small intestine

Stomach

In the ___________, chemical digestion & absorption of carbohydrates, protein, fat, vitamins, water & some minerals occurs

Secretin; sodium bicarbonate

The hormone, ___________, causes the release of pancreatic juice from the pancreas, which is rich in ________________, which neutralizes the acidic substances arriving from the stomach

Bile

The hormone, cholecystokinin, stimulates the release of ________ from its storage place in the gallbladder, which emulsifies fat so that it can be broken down into smaller components

ileocecal valve; large intestine (colon)

At the end of the small intestine, the __________ opens to allow the contents of the small intestine to flow into the ______________

Water; minerals

In the large intestine (colon), the reabsorption of __________ and ________ occurs

Rectum

Waste (fiber, bacteria & unabsorbed nutrients) with water passes to the _________. Wastes are elimated from the body, as the two sphincters of the anus open to allow movement through the anus & outside the body

eating pattern

customary quantities, proportions, and frequencies of consuming various foods and beverages over time

• the combination of many different foods & beverages at numerous meals over days, months, & years

adequacy

providing all the essential nutrients, fiber, & energy in amounts sufficient to maintain health

balance

providing foods in proportion to one another and in proportion to the body's needs

kcalorie control

management of food energy intake

nutrient density

a measure of the nutrients a food provides relative to the energy it provides. The more nutrients and the fewer kcalories, the higher the nutrient density.

empty-kcalorie foods

a popular term used to denote foods that contribute energy but lack protein, vitamins, and minerals

nutrient profiling

ranking foods based on their nutrient composition

moderation

providing enough but not too much of a substance

solid fats

fats that are not usually liquid at room temperature; commonly found in most foods derived from animals and vegetable oils that have been hydrogenated. Solid fats typically contain more saturated and trans fats than most oils.

added sugars

sugars and other kcalorie sweeteners that are added to foods during processing, preparation, or at the table. added sugars do not include the naturally occurring sugars found in fruits and milk products