nutrition: gastrointestinal system
DESCRIPTION
TRANSCRIPT
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