hnf 171 exam 2 wvu

Digestion

larger food molecules are broken down to smaller molecules, mechanically and chemically

Absorption

•process of taking these products through the intestinal wall

What happens in the mouth?

Saliva is mixed with food particles to create bolus. Food is mixed with digestive secretions

What separates the mouth from the esophagus?

The epiglottis

The lower esophageal sphincter

•This sphincter prevents backflow of the acidic stomach contents into the esophagus

Pyloric sphincter

Controls flow of chyme into small intestine and backflow of bile into stomach

What are the muscular actions of digestion?

Peristalsis

Stomach secretes \______________ to aid in the digestive process

gastric juice

Gastric juices contain

•Hydrochloric acid (HCl)
•Pepsinogen
•Gastric lipase
•Gastrin,

What is secreted in the stomach and what does it do?

Chyme- churns food.

the major site of digestion and absorption.

small intestine

three segments of the small intestine

duodenum, jejunum, ileum

The small intestine collects from the

stomach

•Contains cholesterol
•Emulsifies fats

Bile

•Sodium bicarbonate

neutralizes acidic chyme

5 hormones play roles in the regulation:

•Gastrin
•Secretin
•Cholecystokinin (C C K)
•Somatostatin
•Glucose-dependent insulinotropic peptide (G I P)

Gastrin-

Triggers the stomach to release HCl and pepsinogen; stimulates gastric and intestinal motility

CCK

Stimulates release of pancreatic enzymes and bile from the gallbladder

Secretin

Stimulates release of pancreatic bicarbonate

Gallbladder stores and concentrates what?

bile

The livers function is:

Produces bile: Contains cholesterol and emulsifies fats

The pancreas function:

produces pancreatic juices:

3 main functions of the large intestine

1.Houses microbiota

2.Absorbs water and electrolytes:

3.Forms and expels feces

Interior of small intestine has circular folds and fingerlike projections

villi and microvilli

Villi are lined with

enterocytes

Nutrients absorbed in the small intestine are delivered to 1 of the 2 circulatory systems:

•Cardiovascular system
•Lymphatic system

What is the determining factor in absorption of nutrients?

•Water soluble
•Fat soluble

Water soluble nutrients are transported by what system?

Cardiovascular

Includes sugar, starch, and fiber

carbohydrates

Main source of carbohydrates

plants

Monosaccharides

•Single sugars

Disaccharides

•Monosaccharides and disaccharides are simple sugars

Polysaccharides

many glucose molecules linked together

Monosaccharides types

glucose, fructose, and galactose

Glucose

•Most abundant monosaccharide
•Linked together with other sugars in our diets
"Blood sugar"

Fructose

•Found in fruits, vegetables, honey, and high-fructose corn syrup

Galactose

•Most in our diets is combined with glucose to form lactose (milk sugar)

complex carbohydrates

Starch
•Digestible polysaccharide

Fiber
•Indigestible polysaccharide

Glycogen
•Storage form of carbohydrate in humans and animals

Insoluble fibers

•Do not dissolve in water
•Form structural part of the plant cell
•Cellulose, hemicellulose, lignins
•Seeds, whole grains

Soluble fibers

-Dissolve in water
•Found inside and around plant cells
•Pectins, gums, mucilages, and some hemicelluloses
•Oat bran, fruits, legumes, and psyllium

Digestible carbohydrates are broken down to \_______________.

glucose / primary source of energy.

Carb digestion: Begins in the mouth with \___________ \___________ in saliva

salivary amylase

Carb digestion in stomach: \__________________ inactivated in the stomach.

Salivary amylase

Carb digestion in the small intestine: \_______________ are digested by enzymes in the absorptive cells of the small intestine.

Disaccharides

Most carbohydrate digestion and absorption take place in the

small intestine

\__________ \__________ and \______________ are secreted into the small intestine to break polysaccharides from starch into disaccharides.

Pancreatic amylase and dextrinase

Primary lactose intolerance

•Insufficiency of lactase production

Secondary lactose intolerance

•Conditions of the small intestine damage the lactase producing cells

Primary lactose intolerance symptoms

•Symptoms include abdominal pain, bloating, gas, diarrhea

Secondary lactose intolerance symptoms

•Crohn's disease, diarrhea

Carbohydrate Absorption

1) Mouth- starch broken down to polysaccharide/disaccharide by amylase
2)Stomach- Salivary amylase is inactivated by the acidity
3) Pancreas- Pancreatic amylase and dextrinase break polysaccharides from starch into disaccharides
4) Small Intestine- Enzymes break down the disaccharides into monosaccharides.
5) Liver- absorbed monosaccharides are sent to the liver
6) Large Intestine- soluble fiber is metabolized into acids and gases by bacteria
7) Rectum- Insoluble fiber escapes digestion and is excreted in feces

What organ stores extra glycogen?

Liver

If glycogen storage capacity is exceeded, glucose is converted \________.

fat

Hormones involved in blood glucose homeostasis

Insulin-Released after eating, when blood glucose levels are high

Glucagon- Released if no dietary carbohydrates are present, blood glucose levels have fallen

Ratio of blood glucose response of a food compared with a standard

Glycemic index

Fiber DRI

14 grams per 1000 kcalories

type 1 diabetes mellitus

diabetes in which there is no beta cell production of insulin--the patient is dependent on insulin for survival

type 2 diabetes

progressive disorder in which body cells become less responsive to insulin

nutritive sweeteners

sweeteners that yield energy, including both sugars and sugar alcohols

non-nutritive sweeteners

manufactured sweeteners that provide little or no energy; also called alternative sweeteners

sugar alcohols

sweeteners that are structurally related to sugars but provide less energy than monosaccharides and disaccharides because they are not well absorbed

moderate alcohol intake

-1 drink per day for females
-2 drinks per day for males

12 oz beer, 9 oz liquor, 5 oz wine, 1.5 oz spiritz

Where is alcohol absorbed?

Stomach absorbs 20%, Remainder absorbed in small intestine

factors that impact alcohol metabolism

The ability to produce enzymes is key to alcohol metabolism.
Ethnicity, gender, age

Benefits of moderate alcohol consumption

•Reduce stress and anxiety
•Stimulate appetite and increase dietary intake in elderly
•Lower the risk of cardiovascular disease

risks of excessive moderate alcohol intake

•High blood pressure and stroke
•Osteoporosis
•Brain damage and cognitive impairment
•Inflammation of stomach lining
•Intestinal bleeding
•Pancreatitis
•Suppression of immune system
•Sleep disturbances
•Impotence
•Hypo- or hyperglycemia
•Abdominal obesity
•High triglycerides
Nutritional deficiencies

effects of alcohol abuse on nutrition status

Alcohol abuse can lead to poor nutritional status and development of nutrient deficiencies.
•Deficiencies of vitamins and minerals can also occur

major types of lipids

fats (triglycerides), phospholipids, steroids

In what form are most dietary lipids found?

triglycerides

basic structure of triglycerides, fatty acids, and phospholipids?

•Long chains of carbon atoms linked together
•Surrounded by hydrogen atoms

Free fatty acid structure

•Carboxyl end (COOH): α-carbon
•Methyl end (CH3): ω-carbon

How do we classify fatty acids?

•Number of carbons (Short, medium, or long chain fatty acids)
•Extent of saturation with hydrogen
Shape (straight or bent

What makes a fatty acid saturated or unsaturated?

Fatty acid chains with no double bonds are referred to as saturated

an unsaturated fatty acid will contain one or more double bonds

What makes a fatty acid mono-saturated?

•One double bond
•Missing 2 hydrogens in the chain

What makes a fatty acid poly unsaturated?

•At least 2 double bonds
•Hydrogens missing at double bonds

Primary Triglycerides

•Animal fat and vegetable fat are primarily triglycerides

Dietary examples containing saturated, monounsaturated, and polyunsaturated fatty acids

Olive oils

What is an essential fatty acid?

fatty acids that the body needs but cannot make

What are the two essential fatty acids?

alpha-linolenic acid and linoleic acid

fat digestion

mouth, stomach, small intestine

What does the small intestine do for fat digestion?

-Fat triggers release of cholecystokinin
•Bile released from gallbladder
-•lipase and colipase released from pancreas

Four main types of lipoproteins:

chylomicrons, VLDL, LDL, HDL

What do chylomicrons do?

•Largest and least dense
•Transport dietary lipids
•Liver removes remnants from blood

End product of triglyceride digestion

•Cardiovascular system:
•Short-chain and medium-chain fatty acids
•Portal vein à Liver
•Lymphatic system:
•Long-chain fatty acids
•Re-esterified into triglycerides

LDL

low-density lipoprotein/ aka "bad cholesterol"

HDL

high-density lipoprotein/ aka good cholesterol

VLDL

very low density lipoprotein

Where is excess fat stored?

adipose tissue

Which blood lipid is most associated with heart disease?

Diets high in trans fats increase risks of CVD

Protein structure

Made of the elements carbon, hydrogen, oxygen, and nitrogen

What makes each amino acid different?

R group/chain

Essential vs. non-essential amino acids

9 Essential: Must be obtained by food
11 Non- essential: Can be created by body

What are dipeptides?

2 amino acids

What are polypeptides?

Long strands of amino acids. (10 or more)

protein synthesis

Forming proteins based on information in DNA and carried out by RNA

Transcription of proteins

messenger RNA copies the genetic information from DNA

Translation (protein synthesis)

reading the mRNA codons to make proteins; occurs on the ribosomes (TRNA)

What is protein denaturation?

unfolding of a protein

What can denature a protein?

temperature and pH

protein digestion

begins in the stomach