nutrition: gastrointestinal system

Gastrointestinal System

Nursing Assessment

Function of the G.I. System

IngestionDigestionAbsorptionElimination

G.I. Tract

MouthPharynx EsophagusStomachSmall Intestine (duodenum, jejunum, ileum)Large IntestineRectumAnus

G.I. Associated Organs

LiverPancreasGallbladder

Factors that influence G.I. functioning

PsychologicalEmotionalStressDietAlcoholCaffeineNicotineOrganic diseases fatigue

Structures and Functions of the G.I. Tract

Composition

The G.I. Tract is a tube approximately 30 ft. (9m) extending from mouth to anus.

It is composed of four layersMucosaSubmucosaMuscleSerosa

Neuro Intervention

Autonomic nervous system Parasympathetic Excitatory :Increase of peristalsis Sympathetic Inhibatory : Decrease of peristalsis Sensory information is relayed via both

parasympathetic and sympathetic afferent fibers.

Enteric Nervous System

Composed of two layers Lie between the mucosa and the circular muscle

layer and the circular and longitudinal muscle layers

Neurons contribute to the coordination of the G.I. Motor and sensory activities

“Gut Brain”Contains numerous neuronsAbility to control movement and secretion of the

G.I. Tract

C.V. Intervention

G. I. Tract and the accessory organs get 25-30% of the cardiac output

Venous blood draining the GI tract organs empties in the portal vein, which then perfuses the liver

Splanchnic artery innervates the upper GI tractHepatic and superior mesenteric artery branches

innervate the small intestine

C.V. (cont)

Superior and inferior mesenteric arteries supply blood to the large intestines

Because such a large % of the cardiac output perfuses these organs, the GI tract is a major source from which blood flow can be diverted during exercise and stress.

G.I. Movement

Segmentation (mixing)Peristalsis (propulsion)

G.I. Secretions

Enzymes and hormones for digestion Mucus to provide protection and

lubricationWaterElectrolytes

Peritomeum

Covers the abdominal organsParietal layer lines the abdominal cavity

wallVisceral layer covers the abdominal organsPeritoneal cavity is the potential space

between the parietal and visceral layersTwo folds of the peritoneum are called the

mesentery and the omentum

Mesentery

Attaches to the small intestine and part of the large intestine to the posterior abdominal wall

Contains blood and lymph vessels

Omentum

The lesser omentum goes from the lesser curvature of the stomach to the upper duodenum to the liver

The greater omentum hangs from from the stomach over the intestines like an apron

Contains fat and lymph nodes

Ingestion

The mouth is the entrance of the GI tract.The food is moved on to the stomach and

other organs for digestion and absorbtion.

Ingestion

Intake of foodHypothalamus “appetite center”Directly of indirection stimulated by

hypoglycemia, empty stomach, decrease of body temp

Input from higher brain centersAppetite stimulated by taste, smell and

sight

Ingestion (cont)

Appetite decreased by stomach distention, illness, hyperglycemia, N&V, and certain drugs

Deglutition, swallowing, mechanical component of ingestion involving the mouth, pharynx, and esophagus

Digestion

Releases nutrients from foodSeparation of other nutrients from food

componentsTakes place in the small intestine

Absorbtion

Delivers nutrients into the blood.Absorbing structures (microvilli) located in

the small intestine transfer the nutrients into the portal blood and lymph.

Water is absorbed in colon later.

Elimination

Excretes nondigestible wasteThe fecal mass moves from the colon to

the rectum, where it is stored and excreted.

Before the mouth

Smell and vision and hunger

Smell

Vision

Mouth

Lips and oral (buccal) cavityHard and soft palateTeeth TongueTaste budsSalivary glands

What happens in the mouth?

Teeth?Tongue?Salivary glands?

Extra Credit

What type of pathophysiology or conditions can cause problems while eating?

Pharynx

Muscleomembranous tube that may be divided into the nasopharynx, oropharynx, and the laryngealpharynx. The mucus membrane of the pharynx is continuous with the nasal cavity, mouth, auditory tubes and larynx.

Functions

Oropharynx secretes mucusEpiglottis closes over the larynx during

swallowingOropharynx moves the food downReceptors in the oropharynx are stimulated

by food and liquids which initiates swallowing

Any Problems?

Esophagus

Hollow , muscular tubing that receives food from the pharynx and moves it to the stomach by peristaltic contractions. Located in the thoracic cavity and starts behind the trachea and the lower end of the pharynx and extends to the stomach. The upper third is composed of striated skeletal muscle and the distal two thirds is composed of smooth muscle.

Functions

Upper esophageal sphincter (criphapharyngeal) relaxes and the peristaltic wave moves the bolus into the esophagus. The muscular layers contract and propels the food in the stomach. The lower esophageal sphincter (LES) at the distal end of the esophagus remains contracted except during swallowing, belching, or vomiting.

LES

Important barrier that prevents reflux of acidic gastric contents into the esophagus

Name That Pathophysiology

Stomach

Stores food, mix food with gastric secretions and empties into the small intestine. Very little water, alcohol, electrolytes, or drugs are absorbed

Back to digestion

MuscularChemical

Muscular

Mixing and propulsive movementsControlled by the nervous system

Longitudinal Muscle

Long smooth muscles arranged in fiber bundles that extend lengthwise along the GI tract help propel the food mass downward.

Circular contractile muscles

Smooth muscle fibers that extend around the hallow tube forming the alimentary canal.

These rhythmic contractile rings cause sweeping waves along the digestive tract pushing food forward.

This movement is called peristalsis

Sphincter muscles

More defined circular muscles at strategic points form muscle sphinters that act as valves--pyloric, ileocecal, and anal—to prevent reflux and backflow and keep the food mass moving in a forward direction.

Mucosal muscles

Thin embedded layer of smooth muscle produces local constrictive contractions every few centimeters.

They contact mix and chop, the food mass, effectively churning and mixing it with secretions to form a semiliquid called chyme that is ready for digestion and absorption.

Gastrointestinal Secretions

EnzymesHCl acid and buffer ionsMucusWater and electrolytes

Enzymes

Specific enzymes attack designated chemical bonds within the structure of nutrient compounds freeing their component parts.

Enzymes

The major enzyme of the stomach is pepsin, which begins the breakdown of protein.

Pepsin is secreted in the form of pepsinogen and is activated by HCl acid.

Small amount of gastric lipase (tributyrase) that acts only on butter fat

Enzymes

Children have a gastric enzyme called renin (don’t confuse it with renal renin) that aids in the coagulation of milk. It coagulates the protein of milk from liquid to solid which slows the emptying of the stomach, ensuring a gradual passage to the small intestine.

Hydrochloric acid and buffer ions

The agents produce the pH necessary for the activity of certain enzymes

ACID!!!!!!

HCl acid creates the acidic environment necessary for certain enzymes to work.

A pH of 1.8-3.5 is needed for pepsin to work . A pH of 5 or above there will be little or no pepsin activity

Mucus

This sticky, slippery fluid lubricates and protects the lining of the inside wall of the gastrointestional tract and eases the passage of the food mass.

Water and electrolytes

These agents provide an appropriate solution in the amounts needed to circulate the substances released in the digestive process.

Small Intestine

Digestion and absorptionDuodenum, jejunum, and ileumIleocecal valve

Duodenum

Mixes the chyme from the stomach and the digestive secretions from the pancreas and the liver from the common bile duct

Enzymes

Specific enzymes act on specific macronutrients to bring out their final breakdown to form the body can absorb and use.

Mucus

Glands located at the entrance to the duodenum secrete large amounts of mucus to decrease the acidity of the chyme

Other mucus lubricates and protects the mucosal lining in the duodenum

Hormones

Secretin: stimulates the pancreas to send alkaline pancreatic juices into the duodenum

Bile

Emulsifies the fats and facilitates digestion

Composition

The serous coat is formed by the peritoneum. The mucosa is thick, vascular, and glandular. Circular folds in the mucous and submucous layers provide greater surface for digestion and absorption.

Villi

Finger like projections in the mucous membrane. They also increase surface area for digestion and absorption.

Duodenum absorbs:

IronCalciumMagnesium

Jejunum

Nutrients area absorbed in the blood stream

Simple sugarsWater soluble vitamins (C and all B’s

except B-12

Ileum absorbs:

Amino Acid (the end product of protein digestion)

Fat soluble vitamins (A,D,E, and K)Fatty acids and cholestrolVitamin B-12Sodium, potassium, and alcohol

Large Intestine

Absorbs fluids and electrolytesGarbage compactor Secretes mucus

Garbage

Feces consist of water, bacteria, unabsorbed minerals, undigested food stuffs, bile pigment, and desquamated epithelial cells

Large Intestine

Manufactures Vitamin B-12Produce Vitamin KBreak down of amino acids and produce

nitrogenMoves and breaks down indigestible

complex carbohydrates (Methane)

Liver

Largest solid organ in the bodyStores, manufactures, transforms and

excretes a number of substances involved in metabolism.

Functions

Carbohydrate metabolismProtein metabolismFat metabolismSteroid metabolismBile production and secretionStorageMononuclear phagocyte system

Gallbladder

Pear shaped sac located below the liverConcentrates and stores bileBile is produced by hepatic cells and

secreted into the bile ducts by hepatic cells and secreted into the biliary canaliculi of the lobes

Common Bile Duct

The hepatic duct merges with the cystic duct from the gallbladder and form the common bile duct

Back to the GB

Most bile is stored and concentrated in the gall bladder

It is released into the cystic duct and moves down the common bile duct to enter the duodeum at the ampulla of Vater

In the intestines most of the bilirubin os reduced to stercobilinogen and urobilogen by bacterial action

Too much information

Stercobilinogen accounts for the brown color of stool

Pancreas

Exocrine and endocrine glandExocrine gland: enzymes to metabolize

food.

Spleen

Who cares????????

The Effects of Aging on the G.I. Tract

It’s Happening Right Now

Tooth and dentin wear down; cavitiesPeriodontal disease lead to tooth lossTaste buds and sense of smell goEsophageal smooth muscle weakensLES becomes more incompetentDecrease on HCL, delayed gastric

emptying, and constipation

Okay….Spleen

Phagocytosis However it may be removed and the liver

will compensate.

Physical Inspection

MouthAbdomenRectum and anus

Mouth

Lips: color, cracking, ulcers, symmetryMouth: Ulcers, colorTongue: Teeth: dentures, cavitiesPharynx

Abdomen

InspectionAuscultationPercussionPalpation

Inspection

4 QuadrantsColor, texture, scars striae, dilated veins,

rashes, lesionsUmbilicusPulsations

Auscultation

Listen for 5 minutes (yeah, right)Warm it upPresent, absent, increased, decreased, high

pitched, tinkling, gurgling, rushingAortic bruits?

Percussion

TympanyDullness

Palpation

Light palpationDeep palpation

Rectum and anus

InspectionPalpation