nutrition

What are the four major absorptive processes that nutrient absorbtion relies on?

1) passive diffusion: diffusion of nutrients across the absorptive cell membranes 2) facilitated diffusion: uses a carrier protein to to move nutrients down a concentration gradient 3) Active absorbtion: Involves a carrier protein as well as energy to move nutrients against a concentration gradient into absorptive cells. 4) Endocytosis (Phagocytosis and pinocytosis): forms of active transport in which the absorbtive cell membrane forms an invagination that engulfs a nutrient to bring it into the cell

2 main causes of peptic ulcers

1- infection with bacteria helicobacter pylori (weakens mucus coating that protects the tummy and the duodenum) 2- heavy use of NSAID meds like asprin (supresses the synthesis of prostaglandins compounds that promote the formation of the protective mucus

the gi tract recieves a total of how much water per day

10

the large intestine holds more than how many species of bacteria

400

What is bile ?

A cholesterol-containing yellow green fluid that aids in fat digestion and absorption produced by the liver. It breaks down large fat globules into micelles (tiny fat droplets) that are suspended into the watery chyme. The liver secretes 2-4 cups of this per day.

What is pancreatic juice/ what is its purpose/ how many cups of it is produced per day

Pancreatic juice is an alkaline mixture of sodium bicarbonate and enzymes...the sodium bicarbonate neutralizes the acidic chyme arriving from the tummy and thereby protects the small intestine from damage by acid.

What are glycocalyx

Projections of proteins on microvilli. They contain enzymes to digest protein and carbs.

major site of digestion and absorption. coiled below the stomach in the abdomen. divided into three sections...duodenum, jejunum, and ileum. It is considered small because of its narrow diameter not its length.

SMALL INTESTINE

The small intestine secretes secretin and CCK which do what?

Secretin and CCK (cholecytokinin) are both hormones that trigger the release of enzyme and bicarbonate-containing pancreatic juices that digest carbs fat protein and reduce the acidity of the intestinal contents. CCK also slows GI motility to give digestive enzymes from the small intestine and the pancreas enough time to do their work.

what is inulin

a carb known as a fructan bc it is made of several units of the sugar fructose...prebiotic

what is an ulcer

a very small erosion of the top layer of cells in the stomach or duodenum..in younger people these tend to develop in the small intestine whereas in older people they occur in the stomach

The three main functions of the large intestine

houses bacterial flora that keep GI tract healthy, absorbs water and electrolytes, and forms and expels feces

Where does most nutrient absoprtion occur?

in the small intestine...about 95 percent of it

what supresses gluconeogenesis while what increases glycogen

insulin supresses gluconeogenesis while glucagon increases glycogen

the main site where electrolytes are absorbed

large intestine

condensation reaction

linking of two monosaccharides...one molecule of water is formed

the simpler forms of carbs

monosaccharides and disaccharides

The three secretions of the small intestine

mucus, enzyme, and hormone containing fluid

difference between phagocytosis and pinocytosis

phagocytosis--absorptive cells engulf compounds pinocytosis--absorptive cells engulf liquids

the more complex forms of carbs

polysaccharides

non nutritive sweetners

saccharin, cyclamate, aspartame, neotame, sucralose, acesulfame-k, tagatose, and stevia

what are lacteals

special lymphatic vessels in the villi that transport nutrients to larger lymphatic vessels that connect to the thoracic duct. Thoracic duct extends from the abdomen to the neck where it connects to the blood stream and a very large vain called the left subclavian vein.

The three main parts of the large intestine

the colon, rectum, and the anus

Why is having a large surface area important in the small intestine

the large surface area increases the thoroughness and efficiency of digestion and absorption

What are probiotics

the live microorganisms that when consumed in sufficient amounts colonize the large intestine and provide health benefits

amylose and amylopectin

the two types of plant starch

what is the bodys only way to excrete chloresterol?

through the feces

t/f the body's entire supply of absorbative cells is replaced every 2-5 days

true

t/f we need 130 g of carbs a day

true

the finger-like projections on the interior of the small intestine that increase its surface area 600 times over that of a smooth tube

villi and microvilli

cause of heartburn

when stomach acid backs up into the the esophagus

what is the ileocecal valve

It is the sphincter between the ileum and the colon and is where the small intestine empties

How is lymph different than blood

Lymph is not pumped through the vessels like blood is...instead it slowly flows as muscles squeeze and contract the lymphatic vessels

Gastin: produced by? Function?

Gastrin is produced by the cells in the stomach. It signals other stomach cells to release HCL and pepsinogen (for protein digestion).

In the cardiovascular system, where are the nutrients directly absorbed

In the bloodstream in the capillary beds inside the villi...blood then flows into the hepatic portal vein system and collects in the large hepatic portal vein which then leads to the liver. The liver then metabolizes or stores a portion of these absorbed nutrients. Nurtients not absorbed go into the general circulation where nutrients are delivered to all cells where they are used for energy, growth, development, maintenance, and regulation. Waste products are then excreted by the lungs and kidneys

Where does most digestion occur in the small intestine? What does it require?

In the duodenum and upper part of the jejunum. Digestion requires many secretions from the small intestine itself as well as secretions from the liver, gallbladder, and pancreas

oligosaccharides

complex carbs that contain 3-10 single sugar units

what does fermentation do?

creates short-chain fatty acids that can be absorbed and used as an energy source in the colon

the storage form of carbohydrate in humans and other animals

glycogen

t/f bile is stored the small intestine

false gall bladder

What is transported in the lymphatic system?

fat soluble nutrients like vitamins a, d, e, and k and some proteins are transported in the lymph

functional fiber

fiber added to food to provide health benefits

dietary fiber

fiber naturally in food

insoluble fiber

fibers that are not easily dissolved in water or metabolized by bacteria in the large intestine. included cellulose, some hemicelluloses, and lignins

soluble fiber

fibers that dissolve in water and can be metabolized (fermented) by bacteria in the large intestine; including pectin, gums, and mucilages; also called viscous fibers

what are prebiotics

food ingredients that promote the growth of beneficial bacteria in the large intestine

The four hormones that are part of the endocrine system and that play key roles in the regulation of digestion and absoprtion

gastrin, secretin, cholecystokinin, and gastric inhibitory peptide.

GERD

gastroesophageal reflex disease: occurs when the lower esophageal sphincter relaxes and lets stomach contents backflow into the esophagus

the most abundant monosaccharide

glucose

the common monosaccharides

glucose, fructose, and galactose

Which type of absorption requires energy?

Active absorption requires energy...active absorption allows the cell to concentrate nutrients on either side of the cell membrane. Examples include amino acids and some sugars such as glucose which are actively absorbed.

What are brush-border enzymes and what are they responsible for?

Brush-border enzymes are enzymes produced in the small intestine and are responsible for the chemical digestion of the macronutrients. They usually complete the last steps of digestion resulting in compounds that are now small enough to be absorbed.

What are enterocytes

Cells that produce digestive enzymes and absorb nutrients. Each enterocyte has a brush border made up of microvilli that are covered with the digestive enzyme containing glycocalyx

What does the cardiovascular system consist of?

Consists of the heart, blood vessels (arteries, capillaries, veins), and blood.

THE THREE SECTIONS OF THE SMALL INTESTINE

The Duodenum (10 inches) The jejunum (4 feet) The ileum (5 feet)

What is the purpose of the circular folds in the small intestine?

The circular folds make the chyme flow slowly following a spiral path as it travels through the small intestine. The slow spiraling process mixes the chyme with digestive juices and brings it into contact with the villi where nutrients can then be absorbed.

5 sections of the colon

The colon is the largest portion of the large intestine...the five sections are the cecum, ascending colon, transverse colon, descending colon, and sigmoid colon

What is the enterohepatic circulation?

The continual recycling of compounds between the small intestine and the liver.

As something becomes progressively digested and absorbed, the small intestine releases gastric inhibitory peptide to do what?

The gastric inhibitory peptide signals the stomach to slow motility and decrease the release of gastric juice

The accessory organs of the digestive system that work with the small intestine but are not actually part of it physically.

The liver, gallbladder, and pancreas

What is the role of the pancreas in digestion?

The pancreas provides digestive enzymes to break down large macronutrient molecules into smaller subunits

After nutrients are absorbed in the small intestine, where are they delivered?

They are delivered to either the cardiovascular (blood system) or the lymphatic system...choice of system depends on whether the nutrient is fat or water soluble.

How do the secretions from the accessory organs (liver, gallbladder, and pancreas) come together and where do they empty into?

They come together at the sphincter of Oddi aka hepatopancreatic sphincter and empty into the duodenum

What are villi lined with?

Villi are lined with goblet cells that make mucus, endocrine cells that produce hormones and hormone-like substances and cells that produce digestive enzymes and absorb nutrients known as enterocytes.

What is transported by the cardiovascular system?

Water-soluble nutrients (proteins, carbs, b-vitamins, and vit-c) and short and medium chain fatty acids are transported by the cardiovascular system

gallstones

affect 10-20 percent of US adults Occurs when substances in the bile (mainly cholesterol and bile pigments form crystal-like particles.

beta bonds

cannot be easily broken down by digestive enzymes for absorption in the small intestine

what is bolus

chewed food mixed with saliva

total fiber

dietary and functional fiber