NTR 401 - Exam 1 - Dr. Allen

Essential Nutrient

A nutrient required for normal physiological function that cannot be synthesized by the body and must be obtained from a dietary source.

9 amino acids

2 fatty acids

13 Vitamins

15 minerals

Conditionally Essential Nutrient

Nutrients not ordinarily required in the diet but which must be supplied exogenously to specific populations that do not synthesize them in adequate amounts.

Estimated Average Requirement (EAR)

The average daily nutrient intake level estimated to meet the requirement of half the healthy individuals in a particular life stage and gender group.

Tolerable Upper Intake Level (UL)

Highest average daily nutrient intake level likely to pose no risk of adverse health effects to most or all individuals in the general population. As one increases to levels above _____ the potential risk of adverse effects may increase

Recommended Dietary Allowance (RDA)

The average daily dietary nutrient intake level sufficient to meat the nutrient requirement of nearly all (97-98%) healthy individuals in a particular life stage and gender group

Acceptable Macronutrient Distribution Range (AMDR)

An intake range for an energy source associated with reduced risk of chronic disease

Reference Height and Weight

Established for each gender population groups. The tables can then be used by consumers or nutrition professionals to determine the EAR

Homeostasis

Property of a system within an organism in which a variable is actively regulated to remain very nearly constant

-pH

-Na, K, and Ca concentration

-Blood Glucose

Gastrin

Produced by the Parietal Cells of the stomach; stimulates gastric acid and pepsinogen secretion and gastric motility and role in the proliferation of gastric mucosal cells

Cholecystokinin (CCK)

Produced by Enteroendocrine Cells of the Duodenum, the first segment of the Small Intestine

Responsible for post-prandial pancreatic enzyme secretion and gall bladder contraction; released in response to presence of fat or protein in small intestine

Ghrelin (Growth Hormone Releasing Peptide)

"Hunger hormone"

Acts on Hypothalamic Cells of the Brain

Regulates appetite and plays a significant role in regulating the distribution and rate of energy use.

When the stomach is empty ________ is secreted

Leptin

"Satiety Hormone"

Hormone secreted by adipose cells to regulate energy balance by inhibiting hunger

Opposed by ghrelin

Appetite

Desire or willingness to eat

Satiety

Physical feeling of fullness that allows us to stop eating for awhile

Decreases as nutrients from meal diminish

Digestion

Chemical breakdown of food by enzymes secreted into the lumen of the GI tract by glandular cells in the mouth, chief cells in the stomach, and exocrine cells of the pancreas, and exocrine cells of the brush border membrane, and mucosal cells of the small intestine.

Gall Bladder

Serves to store and concentrate bile

Bile is an alkaline solution containing electrolytes, pigments, bile salts, and other substances that digest lipids

Exocrine Secretions of the Pancreas

Pancreatic Juice is composed of two secretory products critical to proper digestion: digestive enzymes and bicarbonate. Enzymes are synthesized and secreted from the _______ acinar cells.

Saliva

99.5% Water

Plus: Electrolytes, mucus, epithelial cells, glycoporteins, enzymes (amylase and lipase) and antimicrobial agents

Watery substance formed in the mouths of animals

Gastric Glands

Secrete HCl, Pepsin, and mucins

-Found in Fundus and Body of Stomach

-HCl secretion is coupled to dissociation of water

and carbonic acid

Enterocytes

Simple columnar epithelial cells found in the small intestine

Surface coat contains digestive enzymes

Microvilli on apical surface increase surface area

Have a secretory role

Ileal Brake

Primary negative feedback mechanism that controls the rate at which food moves through the gut. The function of the _______________ is to ensure the rate at which food is transmitted is optimal for digestion and absorption of nutrients.

Portal vein

blood vessel that carries blood from the GI tract, gall bladder, pancreas, and spleen to liver.

This blood is rich in nutrients that have been extracted from food.

Component of Hepatic System

Villi

Small finger like projections extending into the Lumen of the small intestine.

Greatly increase the surface area of the Small intestine

Hepcidin & Ferroportin Connection

________ is a protein that is a key regulator of Iron entry into the circulation of mammals.

When hepcidin level is abnormally low, iron overload occurs due to increased _________ mediated iron efflux from storage and increased gut iron absorption.

Calbindin-D

Calcium binding proteins

Mediate calcium absorption

Synthesis is dependent on Vitamin D

Mellathionein

Synthesized in the Liver and Kidneys.

Have the capacity to bind physiological (zing, copper, selenium) and xenobiotic factors.

Thought to provide protection against metal toxicity

Alpha Amylase

Specific enzyme for alpha-1,4-linked chains

Product of cleavage is maltotriose and maltose.

Salivary Amylase --> Starches

Sucrase

Secreted from the Small intestine

Located in the Brush border

Catalyze the hydrolysis of sucrose to fructose and glucose

Hypolactasia

"Lactose Intolerance"

Inability do digest lactose due a lack of Lactase enzyme

Symptoms include bloating, diarrhea, gas, and nausea.

Active Transport

Movement of molecules across a cell membrane from a region of lower concentration to a region of their high concentration.

Uses cellular energy to move against the gradient (ions, glucose, amino acids)

May use ATP

Plant Sterols

Typical western diet contains 100-400 mg

Shown to inhibit the intestinal absorption of cholesterol

Margarines, Vegetable oil spreads, salad dressings

Tannins

Astringent, polyphenolic biomolecule that binds to and precipitates proteins, amino acids, and alkaloids.

Causes the dry and puckery feeling from unripened fruit, red wine, or tea

Phytate

Saturated cyclic acid

Principal storage form of phosphorus, especially in bran and seeds.

Found in cereals and grains.

Oxalic Acid

Limits Calcium absorption if foods high this are consumed

Dietary Fiber

Soluble: dissolves in water, readily fermented into gases in the colon. Delays gastric emptying and extend "fullness"

Insoluble: Does not dissolve in water, metabolically inert and provides bulking, easing defecation

Chitin

A derivative of glucose, it is the primary component of cell walls.

Exoskeletons of arthropods.

Structure is comparable to cellulose and keratin.

Pectin

A structural heteropolysaccharide contained the primary cell walls of plants.

Mainly extracted from citrus fruits and used as a gelling agent in jams and jellies.

Source of Dietary fiber

Enterohepatic (pancreatic) recirculation

Circulation of biliary acids, bilirubin, and other substances from the liver to the bile, followed by entry into the small intestine, absorption by the enterocyte and transport back to the liver.

Zymogen

Inactive precursor digestive enzymes that are secreted via the stimulation of CCK binding to acinar cells

Ex. Pepsinogen

Adequate Intake (AI)

The recommended average daily nutrient intake level based on observed or experimentally determined approximations or estimates of nutrient intake by groups of healthy people that are assumed to be adequate. Used when an RDA cannot be determined

Hunger

Physiological state that causes food seeking behavior

Satiation

Reduction of hunger and termination of eating: generally marks end of meal

Interplay of psychological, physiological, and metabolic event

Thirst

Homeostasis of body fluid regulation

Control is a combination of plasma sodium concentration and arterial blood pressure

Absorption

Movement of nutrients, including water and electrolytes, across the mucosal cells into the lamina propia, where they enter the blood or lymph

Circulatory System

How all nutrients are carried to all of the cells of the body

GI Tract

Function is to digest complex molecules in foods and to absorb simple nutrients, including monosaccharides, fatty acids, amino acids

Secretin

Produced in the Duodenum.

Stimulates pancreatic bicarbonate secretion, promotes intestinal digestion by pancreatic enzymes, and regulates water homeostasis

Somatostatin

(Growth Hormone-Inhibiting Hormone)

Inhibitory effects on endogenous hormone release and on GI secretion

Inhibits Glucagon and Insulin secretion

Maltase

Located in the Brush border of the small intestine

Breaks down the disaccharide Maltose to 2 Glucose

Lactase

Located in the brush border of the small intestine

Essential to the complete digestion of whole milk

Breaks down lactose