Macronutrients (exam 1)

Secretin

- Produced by S cells in proximal small intestine

- Responds to presence of acidic chyme

Cholecystokinin

- Secreted by I cells of proximal small intestine and enteric nerves

- Responds to presence of fat and partially digested proteins in the duodenum

Pancreatitis

- Zymogens become activated and digest pancreatic tissue

- Condition can occur with:

- Excessive alcohol consumption, Hypertriglyceridemia, Duct blockage, Viral infections, Or injury

- Patient often requires partially hydrolyzed nutrients or lipase

The portal vein brings blood rich in nutrients from the digestive tract to the

Sinusoids (blood vessels in liver)

BILE

- Composed mainly of bile acids and salts

- Acts like a detergent to emulsify fat

THE GALLBLADDER

• 40–50 mL Concentrates and stores bile CCK stimulates it to contract and the sphincter of Oddi to relax

• release of bile

• closing of sphincter oddi

Gallstones

• cholesterol based

• Irritate the organ, causing cholecystitis

• Block the flow of bile (choledocholithiasis)

• Block the flow of pancreatic juice, causing pancreatitis

One mechanism involved in nutrient absorption is ___

diffusion

Absorption of most of the digested food takes place in the stomach.

a. true

b. false

false

COLON

• Contracts to mix materials

• Proximal colonic mucosal cells absorb sodium, chloride, and water

• Influenced by hormones

• Materials dehydrated

produced during fermentation of carbohydrate

Lactic acid and three short- chain fatty acids

BENEFITS OF SHORT CHAIN FATTY ACIDS (SCFAS)

• Acidify the luminal environment

• Serve as signaling molecules

• Exhibit trophic effects

• Improve colonic/splanchnic blood flow

• Increase water and sodium absorption

• Provide energy and serve as substrates for use within cells

• Inhibit tumors and stimulate immune system

BENEFITS OF BACTERIA

• Enhance host’s immune system

• Displace, exclude, or antagonize pathogenic bacteria from colonizing

• Scavenge, sequester, transform, and/or promote excretion of harmful substances

• Enhance fecal bulk and dilute fecal contents

• Role in energy metabolism

PREBIOTICS

• “A selectively fermented ingredient that results in specific changes in the composition and/or activity of the gastrointestinal microbiota, thus conferring benefit(s) upon host health”

• When probiotics break down prebiotics in the colon, they produce butyric acid,

Types of prebiotics

- Fructans

- Galacto- oligosaccharides (GOS),

- Starch and Glucose- Derived Oligosaccharides

- Other Oligosaccharides

- Non-Carbohydrate Oligosaccharides

PROBIOTICS

are live microorganisms, which when administered in adequate amounts confer a

health benefit on the host

Types of probiotics

• Lactobacillus and Bifidobacterium

• Lactococcus spp.,

• Streptococcus thermophilus,

• E. coli Nissle 1917

• The yeast Saccharomyces boulardi

Probiotic sources

• Fermented foods ( e.g. yogurt and pickles) and drinks (e.g. kombucha or kefir)

• Foods supplemented with Probiotics

• Cosmetic products

Lean twin microbiota (Ln)

• Greater capacity to breakdown and ferment polysaccharides

• Associated with ↓ BW

Obese twin microbiota (Ob)

• Higher expression of microbial genes involved

• BCAAs increase

Bacterial fermentation of carbohydrates in the colon produces ____________.

lactic acid

Somatic Division

Efferent neurons to the skeletal muscles

Autonomic division

- Efferent neurons to the internal organs

- Sympathetic

- Parasympathetic

Sympathetic system

slows down GI motility and secretions

Parasympathetic

stimulates motility (peristalsis) GI reflexes and secretion of hormones and

enzymes

ENTERIC NERVOUS SYSTEM

• intrinsic nerve plexuses

• GI tract’s local nervous system

Myenteric plexus

peristalsis, motlilty

Submucosal plexus

secretions, local blood flow

Mechanoreceptors

detect distention (enlargement)

Chemoreceptors

changes in chemical composition

Osmoreceptors

detect changes in osmolarity (concentration)

What is your digestive system’s local nervous system called?

enteric nervous system

Gastrin

• Stomach and small intestine

• Stimulates gastric acid secretion

  Stimulates pepsinogen secretion

Cholecystokinin

• Small intestine and enteric nerves

• Stimulates gallbladder contraction

• Stimulates sphincter of Oddi relaxation

• Stimulates pancreatic enzyme secretion

Secretin

• Small intestine

• Stimulates pancreas juice secretion

• Diminishes gastric emptying

• Diminishes gastric acid secretion

Motilin

• Stomach and intestines

• Stimulates gastric and intestinal motility between meals

Glucose-dependent insulinotropic peptide

• Small intestine Stimulates insulin secretion

• May diminish gastric acid secretion

Peptide YY

Small and large intestines Diminishes gastric acid secretion

Diminishes gastric emptying

Somatostatin

Pancreas, stomach, and small intestine

Diminishes gastric acid secretion

Diminishes gastric emptying

Diminishes pancreatic enzyme secretions Inhibits gallbladder contraction

Glucagon-like peptides

Small and large intestines

Stimulates insulin secretion

Reduces digestive tract motility

Reduces gastric secretions

Pancreatic polypeptide

Pancreas

Decreases gastric emptying

Reduces pancreatic exocrine secretions

RYGB

most common bariatric surgery

• Macronutrient and micronutrient deficiencies

• fat maoabsorption

NUTRIENT DEFICIENCIES IN RYGB PATIENTS

iron, zinc, copper

In sugars that contain many chiral centers,

only the one that is most distant from the carbonyl carbon is designated as D (right) or

L (left)

D and L isomers of a sugar are

enantiomers

Disaccharides

• two monosaccharides attached via a glycosidic bond

• Major energy supplying nutrients

Maltose

Found in beer and malt liquors

Lactose

Milk and milk products

sucrose

Composed of glucose and fructose

Trehalose (in fungi, plants)

Digests slowly, low glycemic response

Oligosaccharides

Contain from 3 to 10 monosaccharide units.

Food Oligosaccharides

maltodextrins

Polysaccharides Function

storage, structure, recognition

Starch and glycogen are

storage molecules

Chitin and cellulose

structural molecules

Cell surface polysaccharides are

recognition molecules

Starch is made of

amylose and amylopectin

glycogen

liver and skeletal muscle

cellolose

A dietary fiber and not an energy source

Mouth

•Secretion/Enzyme – salivary amylase

•Substrate – starch

•Product – oligosaccharides, maltose

•CHO bond cleaved - α(1→4)

Stomach

Secretion/Enzyme - acid

•Substrate – amylase

•Product – inactivated amylase

Duodenum

•Secretion/Enzyme – pancreatic amylase*

•Substrate – starch

•Product – maltose

•CHO bond cleaved - α(1→4)

Circulatory Route

Portal vein → Liver → Heart → Muscles & other tissues

glycaemic

glucose, fructose, galactose, sucrose, lactose, maltose, trehalose, maltodextrins, starch

non- glucaemic

polyols, oligosaccharides, resistant and modified starches, NSP

Digestion primarily in _____ of enterocytes

microvilli

Mucosa

Made of mucosal membrane lamina propria, and muscularis mucosa

Submucosa

Made of connective tissue, blood and lymphatic vessels, lymphoid tissue, and submucosal plexus

Salivary α- amylase

Site of Secretion: Mouth

Preferred Substrate(s) : α (1-4) bonds in starch, dextrins

Primary Site of Action: Mouth, stomach

lingual lipase

site of Secretion : Mouth

preferred substrates: Triacylglycerol

primary site of action : mouth, stomach

pepsinogen/ pepsin

scretion : stomach

substrates: Carboxyl end of phe, tyr, typ.met, leu, glu, asp*

sight of action : stomach

gastric lipase

secretion: stomach

substrates: triacylglycerol

site of action: sromach

Trypsinogen/trypsin

secretion : pancreas

substrates : Carboxyl end of lys, arg*

site of action : small intestine

____________ converts pepsinogen to pepsin

Hcl

Absorption of most of the digested food takes place in the stomach.

a. true

b. false

false

Salvia contains:

• Salivary a-amylase (main enzyme)

• Lingual lipase

Stomach muscles mix food with gastric juices to form

chyme

Gastric glands

• Cardiac glands

• Oxyntic glands

• Pyloric glands

Cells in a gastric oxyntic gland

• Neck (mucus) cells

• Parietal (oxyntic) cells

• Chief (peptic or zymogenic) cells

• Enteroendocrine G- cells

gastric juice enzymes

pepsin, amylase, lipase

cephalic

• before food reaches stomach

• promotes acetylcholine (Ach) secretion and gastrin release

gastric

• once food is in the stomach

• Enhanced gastric secretions caused by:

❑ Distension of the stomach

❑ Presence of protein and some other consumed substances in the stomach

intrinsic

• after food has left the stomach

• Release of somatostatin

• release of CCK

Peptic ulcer disease

• Ulcerations or erosions in mucosa and submucosa layers of the stomach, duodenum, or lower esophagus

• Common cause: Helicobacter (H.) pylori

• Other causes: Chronic alcohol ingestion, Use of NSAIDs

• H2 receptor blockers used to treat

Dipeptidase

• digest on the microvilli of the small intestine cells called enterocytes

Sucrase

• digests sucrose, also on microvilli of small intestine cells

Leptin(controls food intake) is secreted by the

adipose tissue

T/F - Nutrigenomics studies how genetic polymorphisms influence the individual response to nutrient :

false

Medication for bile acids

target bile and enhance fecal secretion, plant sterols added to foods reduces blood cholesterol levels

Which digestive fluid contains bilirubin

bile

Which hormone stimulates hunger

ghrelin

When probiotics break down prebiotics in the colon they produce

butryic acid

Which short chain fatty acid is used by the cells in large intestine as an energy source 

• butyric acid

T/F - necrosis is programmed cell death

false - Necrosis is death of body tissue. It occurs when too little blood flows to the tissue. This can be from injury, radiation, or chemicals. Cannot be reversed.

Research questions

Essential characteristics : Feasibility, interesting, novel, ethical, relevant or worth doing

Hypothesis

Essential characteristics : Measurable, specifies population, identifies time frame, indicates type of relationship, includes variables, defines level of statistical significance