NUTR 202 Exam 1 PART 2

Digestive process

a multistep process of breaking down foods into absorbable components using mechanical and chemical means in the gastrointestinal (GI) tract

lumen

interior of the intestinal tract

Gastrointestinal tract consists of:

– Mouth

– Esophagus

– Stomach

– Small and large intestines

– Accessory organs: pancreas, liver, gallbladder

-rectum

What are the accessory organs

pancreas, liver, gallbladder

Mechanical digestion

chewing, grinding food, and moving it through the GI trac

Chemical digestion

digestive juices and enzymes break down food into absorbable nutrients

Segmentation

(sloshing) mixes chyme with chemical secretions; increases time food comes into contact with intestinal walls

Pendular movement

(constrictive wave) enhances

nutrient absorption in small intestine

bolus

mixture of food and digestive secretions

Peristalsis

the forward, rhythmic motion that helps mix

food with digestive secretions and propels the mixture,

called a bolus, from the esophagus through the large

intestine. It is a form of mechanical digestion.

peristalsis is a form of what kind of digestion

mechanical

Chyme

semi-liquid food mass

Main roles of the GI tract are to

– Break down food into smallest components

– Absorb nutrients

– Prevent microorganisms or other harmful compounds

in food from entering tissues of the body

– Maintain the gut microbiome

you swallow what after chewing?

bolus

Mouth (GI woman)

ingestion: food enters the GI tract through the mouth

Mechanical Digestion: chewing tears and shreds food and mixes it with saliva, forming bolus

Chemical Digestion: carbohydrate enzymes secreted by the salivary glands begin carbohydrate breakdown

Pharynx and esophagus (GI woman)

propulsion: swallowing and peristalsis move the bolus from mouth to stomach

Stomach (GI woman)

mechanical digestion: movements mix and churn the bolus with acid enzymes and gastric fluid to form chyme

chemical digestion: stomach enzymes begin the digestion of proteins

absorption: a few fat soluble substances are absorbed through the stomach wall

Both mechanical and chemical digestion begin in the

mouth

Saliva

contains water, electrolytes, mucus, and a few enzymes

what is the job of saliva

Softens, lubricates, dissolves food particles

Bolus

food mass) moves into pharynx, is swallowed,

and enters the esophagus

Epiglottis

closes off trachea during swallowing to

prevent food from lodging in the windpipe and lungs

Once swallowed, a bolus is pushed down your

esophagus by

peristalsis into the stomach

Gastroesophageal sphincter (lower esophageal

sphincter (LES))

bottom of esophagus narrows and

relaxes to allow food into stomach

The gastroesophageal sphincter then closes to prevent

backflow of

hydrochloric acid (HCl) from stomach

Gastroesophageal reflux disease (GERD) is

“reflux"

of stomach acid that causes "heartburn" (irritation of

esophagus lining)

what is the name of the lipoprotein that transports soluble nutrients from the small intestine

chyloproteins

carbohydrates are primarily found in?

plant-based foods

Glucose is the most abundant

carbohydrate in nature

Glucose (chem)

C6H12O6

monosaccharides

contain one sugar

disaccharides

two sugars

The stomach is a muscular organ that continues

mechanical digestions by

churning and contracting to mix

food with digestive juices for several hours

Stomach produces powerful digestive secretions such as

HCl which activates enzyme pepsin, enhances absorption of minerals, and destroys some ingested microorganisms

Gastrin

Pepsin is secreted by

the stomach

what is gastrin (found in the stomach)

hormone stimulates digestive activities and

increases gastric motility and emptying

Pyloric sphincter

located between the stomach and small intestine; allows about 1 teaspoon of chyme to enter the small intestine every 30 seconds

– Prevents backflow of intestinal contents

Small intestine (three segments)

long, narrow, coiled

▪ Duodenum (shortest segment)

▪ Jejunum

▪ Ileum (longest segment)

small intestine accounts for about _______ of the GI tract

20 feet

The small intestine increases surface area by

villi (finger like)

microvilli (hair like)

circular folds

Ileocecal sphincter

prevents backflow of fecal matter into ileum as chyme enters the large intestine

where is majority of the nutrients absorbed? (mainly water and electrolytes)

large intestine

the large intestine has how many sections?

3:

cecum

colon

rectum

how big is the large intestine

5 feet long, 2.5 inches in diameter

Larrge intestine is also known as

the colon

what is stored in the rectum?

stool or feces

Anus (anal sphincter)

connected to the rectum and controlled by two sphincters: internal and external

what is the largest internal organ of the body where BILE is produced

the liver

bile is needed for what?

fat digestion

Gallbladder stores what

stores bile

Gastrin stimulates stomach to release

HCl and enzyme gastric lipase

What stimulates hunger

ghrelin

Secretin causes

pancreas to release bicarbonate to

neutralize HCl

Cholecystokinin stimulates

pancreas to secrete

digestive enzymes, controls pace of digestion

Amylase

digests carbohydrate

Lipase

digests fats

Trypsin, chymotrypsin, and carboxypeptidase

digests protein

bile helps digest what

fat

Bile is recycled back to the liver from the large intestine through

enterohepatic (entero =intestine, hapatic = liver) circulation