NUTR 240 Exam 1

Macronutrient

energy-yielding nutrients

Micronutrients

non-energy yielding nutrients; needed in small amounts to regulate body processes (bone/tissue growth, blood clotting, vision, etc.)

Dietary Reference Intake (DRI) makes 2 types of energy intake recommendations:

1. Estimated Energy Requirements (EERs)

2. Acceptable Macronutrient Distribution Ranges (AMDRs)

Estimated Average Requirements (EARs)

used to evaluate the nutrient intake of populations; the amount of a nutrient that is estimated to meet the needs of 50% of people in the same gender and life-stage group

Recommended Dietary Allowances (RDAs)

calculated to meet the needs of nearly all healthy individuals in each gender and life-stage group; serves as a target for individual intake

Adequate Intakes (AIs)

estimates used when there is insufficient scientific evidence to set an EAR and calculate an RDA; based on observed or experimentally determined approximations of the average nutrient intake by a healthy population

Tolerable Upper Intake Levels (ULs)

maximum level of daily intake of a nutrient that is unlikely to pose a risk of adverse health effects to almost all individuals in the specified group; used as a guide for limiting intake when planning diets and evaluating the possibility of overconsumption

Estimated Energy Requirements (EERs)

provides an estimate of the number of calories needed to keep weight stable in a healthy person; variables include age, gender, weight, height, and level of physical activity

Acceptable Macronutrient Distribution Ranges (AMDRs)

recommendations for proportions of each of the energy-yielding nutrients (carbohydrate, fat, and protein) that make up a healthy diet

10-35% of calories from protein, 45-65% of calories from carbs, 20-35% of calories from fat

Functions of digestive system

digestion and absorption

Amylase

enzyme in saliva that begins breakdown of carbs

Accessory Organs of the Digestive System

Salivary glands, liver, pancreas, gallbladder

Pharynx Function

keeps food (bolus) out of airways

Esophagus Function

Moves bolus from mouth to stomach with peristaltic contractions

Peristaltic contractions

involuntary wave-like muscle movement that occurs in the digestive system to move food along

Stomach Function

temporary storage container for food; mechanical and chemical digestion; muscle contractions mix boli with gastric juice to further digest food into chyme

Chyme

semi-liquid food form

Small Intestine

main site of digestion and absorption

3 segments of small intestine

duodenum

jejunum

ileum

Lumen

opening in the middle of the intestinal tract

Mucosa (enterocyte)

layer of epithelial cells lining the lumen; responsible for some digestion and for the absorption of the end products of digestion

Anatomical features to increase absorption

1. Large circular folds

2. Villi

3. Mucosal cells on surface of each villi are covered with microvilli

Microvilli (brush border)

finger-like projections that increase the surface area for diffusion; the absorptive cell

Peptidases

Small intestine brush border enzyme (comes from pancreas)

breaks polypeptides into shorter polypeptides and amino acids

Sucrase

(enzyme) breaks sucrose into glucose and fructose

Lactase

(enzyme) breaks lactose into glucose and galactose

Maltase

(enzyme) breaks maltose into glucose

Bicarbonate Ions

neutralizes acidic chyme

pancreatic amylase

(enzyme) breaks starch into shorter glucose chains and maltose

Pancreatic Lipase

Breaks triglycerides into monoglycerides, fatty acids, and glycerol

Trypsin/Chymotrypsin

(enzyme) breaks proteins into shorter polypeptides

created in pancreas, works in small intestine

Pepsin

(enzyme) breaks proteins into shorter polypeptides

created in stomach, works in stomach

Gastric lipase

breaks triglycerides into monoglycerides, fatty acids, and glycerol

created in stomach, works in stomach

Lingual Lipase

(enzyme) breaks triglycerides into monoglycerides, fatty acids, and glycerol

made in lingual glands of tongue, works in mouth

Large Intestine Function

absorption of water, electrolytes, vitamins, and minerals

Chemical Digestion pathway of carbs

sugars, starches —> double sugars and short glucose chains —> single sugars —> blood vessel—> liver

Chemical digestion pathway of proteins

long amino acid chain—> amino acids —> blood vessel—> liver

Chemical digestion of lipids

large lipid droplets—>short chain fatty acids—>blood vessel—>liver

large lipid droplets—> long chain fatty acids—>lymph—>blood stream

What type of transport do amino acids use for absorption?

active transport (transporter uses ATP to carry substance across a cell membrane against the concentration gradient)

How do amino acids travel to the liver?

hepatic portal vein

What process is used to absorb glucose and galactose?

active transport

What process is used to absorb fructose

facilitated diffusion

Soluble fiber

can be digested by bacteria in the colon

Insoluble fiber

minimal digestion

Health benefits of fiber

lowers blood glucose post meal (soluble)

moves contents through the GI tract to prevent constipation (insoluble)

Pathway of lipids

fat (tricylglycerol) —>fatty acids —>enterocyte—>re-synthesis into chylomicrons—>lymph—>blood—>ALL ORGANS

Bile is produced by _______ and secreted into the ______

liver, gallbladder

Bile contains

bile salts, bilirubin, cholesterol, fatty acids, lecethin

Bile function

emulsifies lipids; disperses dietary fats into micelles- allows pancreatic lipase to reach tricaylglycerol to break down into 2 fatty acids and one monacylglycerol

What hormones control bile release?

secretin, cholecystokinin (CCK), somatostatin

Ghrelin

(hormone) hunger, growth hormone release; increases gastric emptying

Secreted in stomach

Gastrin

(hormone) acid secretion

Insulin

(hormone) lowers blood glucose; increases glucose transport to muscles and adipose for use

Glucagon

(hormone) stimulates the liver cells to convert glycogen into glucose for energy production; raises the blood sugar level

Glycogen

storage form of glucose in animals; stored in muscles and liver and can be broken down into glucose for energy

Gluconeogenesis

the synthesis of glucose from simple noncarbohydrate molecules. Amino acids from protein are the primary source of carbons for glucose synthesis; occurs in liver

Cholecytokinin

(hormone) stimulates gall bladder contraction to expel bile, gastrointestinal motility, slows stomach emptying and contributes to satiety; increases pancreatic juice secretion

Works in small intestine

GLP-1 and GLP-2

(hormone) incretin activity, satiation

gastrointestinal motility and growth

works in colon

oxyntomodulin

(hormone) satiation and acid secretion

works in colon

Secretin

(hormone) inhibits gastric secretion and motility; increases output of water and bicarbonate from the pancreas; increases bile output from the liver

Pancreatic exocrine secretion

Leptin

(hormone) inhibits hunger; produced in adipose tissue

Micelles

the products triglyceride digestion and fat soluble vitamins mix with bile to form smaller droplets; help the body absorb essential lipids and vitamins from the liver and gallbladder

How do fatty acids and monoglycerides enter enterocytes?

simple diffusion

What happens after fatty acids enter enterocytes?

they are resynthesized into triglyceride, packaged into chylomicrons and travel through the lymphatic system to the blood

small fatty acids diffuse directly into intestinal capillaries

Liver function

gatekeeper between the body and substances absorbed from the intestine; important for storage of nutrients, in the synthesis and breakdown of amino acids, proteins, and lipids

Maltose structure

glucose + glucose

Sucrose structure

glucose + fructose

Lactose structure

glucose + galactose

Starch originates from _____ sources and glycogen originates from ____ sources

plant, animal

What are the reactants and ATP input of glycolysis?

glucose. 2 NAD+

2 ATP

What are the products of glycolysis?

2 pyruvate, 2 NADH

2 ATP

What are the reactants of Acetyl Co-A Formation?

2 pyruvate. 2 CoA, 2 NAD

What are the products of Acetyl Co-A formation?

2 acetyl CoA, 2 CO2, 2 NADH

Krebs cycle reactants and ATP input

2 acetyl coA, 6 NAD+, 2 FAD

No ATP

Products of krebs cycle

6 NADH, 2 FADH2, 4 CO2

2 ATP

Reactants of electron transport chain

NADH and FADH2

Products of Krebs cycle

2 NADH from #1, 2 NADH from #2, 6 NADH from #3, 2 FADH from #3

10 NADH x 2.5 = 25 ATP

2 FADH x 1.5 =3 ATP

How much ATP does one cycle of cellular respiration make?

32 ATP

Glycolysis

6-carbon sugar is broken down into two 3 carbon molecules called pyruvate to generate 2 ATP

Acetyl-CoA formation

one carbon is removed from pyruvate and released as CO2, the remaining 2 carbon compound combines with a molecule of coenzyme A (CoA) to form acetyl CoA; high energy electrons are released and passed to NAD to carry to ETC

Citric Acid Cycle

Acetyl coA combines with oxaloacetate (4 carbon molecule derived from carbohydrates) to form a 6 carbon molecule called citric acid

Cycle removes one carbon at a time to produce CO2, after 2 carbons are removed, a 4 carbon oxaloacetate is reformed and the cycle can begin again

Oxidative Phosphorylation

Electron transport chain and chemiosmosis

Electron transport chain

series of protein complexes (4) and organic molecules associated with the mitochondrial inner membrane

Protein complexes accept electrons from the shuttling molecules (NADH and FADH2) and pass them from one to another down the chain until they are finally combined with oxygen to form water

Chemiosmosis

as electrons are passed along the protein complexes, they used the released energy to pump H+ from the matrix to the intermembrane space, forming an electrochemical gradient; the energy stored in the gradient is used to make ATP by the ATP synthase

How much ATP per NADH

2.5

How much ATP per FADH2

1.5

_____ increases serum glucose concentration; _____ decreases serum glucose concentration

glucagon, insulin

How does insulin decrease glucose levels?

promotes the storage of glucose as glycogen in liver, stimulates muscle uptake of glucose and storage as glycogen; stimulates protein synthesis and stimulates uptake of glucose into adipocytes for storage as fat

Which processes are promoted by glucagon?

stimulates gluconeogenesis in the liver, signals liver to break down glycogen into glucose

Glycogenesis

process of forming glycogen from glucose; occurs with an excess of carbohydrate not needed immediately for energy production

Glycogenolysis

pathway in which glycogen breaks down into glucose-1-phosphate and glucose

Gluconeogenic amino acids

intermediates of the Krebs cycle that are used to synthesize glucose

Ketogenic amino acids

primarily involved in the production of acetyl-CoA

Under what conditions are ketone bodies used as energy sources?

low carbohydrate conditions, or fasting

How are amino acids used when glucose is limiting?

used to make glucose and ketones

Ketone Bodies

occurs when oxaloacetate is limited so acetyl CoA cannot be broken down

Liver converts acetyl Co-A to ketones to be released into the blood

Excess excreted by urine

Ketosis

if fluid intake is low and ketone production is high

_____ stimulates glycogen production

insulin

______ inhibits glycogen production

epinephrine