LO9 Flashcards
functions of the GI
Provides nutrients for the body through absorption
○ Expels waste products as feces
○ Disturbances in normal bowel function can be the first indication that there is a problem with the GI tract or another body system
Anatomy of the GI
The GI tract begins at the mouth and
continues through to the anus.
* The mouth, esophagus, and stomach receive
food where initial digestion occurs.
* The duodenum, jejunum, and ileum are
where most digestion and absorption occurs.
* The cecum, colon, and rectum store and
then eliminate waste.
* Salivary glands, liver, and pancreas are
accessory organs that aid in digestion.
* Also functions as a specialized immune
system.
The mouth
Point of entry into the GI tract.
○ Breaks down nutrients into usable sizes and forms.
○ Saliva dilutes and softens the food for easier swallowing and commences
digestion of carbohydrates.
○ Swallowed food (bolus) enters the esophagus through the relaxed upper
esophageal sphincter
the esophagus
Provides a passage to the stomach.
○ Epiglottis blocks the trachea during swallowing.
○ Smooth muscle layers the esophagus and provides peristaltic contractions to
move food.
○ Mucous membranes secrete mucus that aids in the lubrication of food.
○ Sphincters on either end prevent air from entering and reflux of stomach
contents into the esophagus.
the stomach
Performs several tasks:
○ Storage of swallowed food and liquid
○ Mixing of food with liquid and gastric digestive juices
○ Controlled emptying of contents into the small intestine.
○ Produces two key GI hormones:
○ Gastrin: stimulates gastric acid secretion
○ Ghrelin: has growth hormone releasing activity and stimulates food
intake and digestion.
○ Pepsin breaks down proteins into amino acids.
○ Chyme: dissolved and partially digested bolus.
small intestine
Consists of the duodenum, jejunum, and ileum.
○ Duodenum:
○ Connects the stomach to the jejunum
○ Contains the opening for the common bile duct and main pancreatic duct.
○ Jejunum:
○ Primary function is absorption of carbohydrates & proteins.
○ Ileum:
○ Specializes in the absorption of water, certain vitamins, irons, fats, and bile
salts.
○ Most nutrients and electrolytes are absorbed in the small intestine.
large intestine
The lower GI tract.
○ Primary organ of bowel elimination and is divided into the cecum, colon, and
rectum.
○ Colon is divided into the ascending, transverse, and sigmoid colon.
○ Eliminates large quantities of waste and gas.
○ 3 functions – absorption, secretion, and elimination.
○ Two types of muscular contractions occur in the colon:
○ Slow-mixing contractions – move contents through the colon to the
mucosa where absorptions of sodium and chloride causes water
absorption and develops feces.
○ Mass peristalsis – push the feces toward the rectum
anus and rectum
Feces and flatus are expelled from the rectum through the anal canal and the
anus.
○ Contraction and relaxation of the internal anal sphincter are under autonomic
control.
○ External anal sphincter is under somatic neural control.
factors effecting normal bowel elimination
Diet
○ Fibre provides the bulk of fecal material. High fibre diet is recommended.
○ Fluid Intake
○ Fluid liquefies intestinal contents to ease their passage through the colon.
○ Unless contraindicated, adults should consume 1.5-2 L of fluid/day.
○ Physical Activity
○ Promotes peristalsis.
○ Personal Bowel Elimination Habits
○ Establish a regular and consistent time
○ Privacy
○ Maintain privacy & sensitivity for all patients.
constipation
Causes of constipation:
○ Medications – a major issue for patients taking opioids for pain.
○ Rectal or anal disorders (hemorrhoids)
○ Obstruction
○ Metabolic, neurologic, and neuromuscular conditions
○ Endocrine disorders
○ Dietary habits, lack of exercise, and stress.
○ Diseases of the colon commonly associated with constipation include:
○ IBS
○ Diverticular disease
three classes of constipation
Functional constipation: normal transit mechanism of mucosal transport. Most
common and successfully treated with fibre and fluids.
○ Slow-transit constipation: caused by inherent disorders of the motor function of
the colon. Characterized by infrequent bowel movements.
○ Defecatory disorders: caused by dysfunctional motor coordination between the
pelvic floor and anal sphincter. Can also cause fecal incontinence.
what is diarrhea the result of
- Increased intestinal secretions
○ Decreased mucosal absorption
○ Altered motility
other causes of diarrhea
○ Medications
○ Enteral tube feeds
○ Metabolic & endocrine disorders
○ Viral & bacterial processes
pathophysiology of diarrhea
Secretory – high volume & often associated with bacterial toxins
○ Osmotic – occurs when water is pulled into the intestine by osmotic pressure
of unabsorbed particles
○ Malabsorptive – absorption of nutrients is inhibited due to malnutrition
○ Infectious – infectious agents invading the intestinal mucosa (C.Diff).
○ Exudative – caused by changes in mucosal integrity, epithelial loss or tissue
destruction by radiation or chemotherapy.
○ May also be caused by laxative misuse
Borborygmus
intestinal rumbling
loperamide
to reduce the severity of diarrhea
what is a risk that could occur from diarrhea
potential for cardiac dysrhythmias due to electrolyte and fluid loss especially potassium
pathophysiology of fecal incontinence
- Anal sphincter weakness
○ Neuropathies
○ Disorders of the pelvic floor
○ Inflammation
○ Central nervous system disorders
○ Diarrhea
○ Fecal impaction with overflow
○ Behavioural disorders
○ More common in older age.
factors associated with IBS
○ Heredity
○ Psychological stress
○ Depression/anxiety
○ Diet high in fat and irritating foods
○ Alcohol
○ Smoking
○ Diagnoses is made in the absence of structural or other disorders.
Pathophysiology of IBS
Results from a functional disorder of intestinal motility
○ Changes in motility may be a result of:
○ Neuroendocrine dysregulation
○ Infections or inflammatory disorders
○ Vascular or metabolic disturbances
○ Peristaltic waves are affected at specific segments of the intestine.
○ No evidence of inflammation or tissue changes in the intestinal mucosa.
Fecal specimens
○ Occult blood
○ Cultures
○ Ova and parasites
○ Enteric pathogens (C.Dfficile)
screening tests
Fecal immunochemical test (FIT)
○ Used to detect blood in the stool
○ Used for screening of colorectal cancer
Pico-Salax
it is a bowel prep provided prior to a diagnostic test
gastritis
inflammation of the gastric or stomach mucosa
acute gastritis
○ Often caused by dietary indiscretion
○ Other causes may include – overuse of aspirin (NSAIDS), excessive alcohol intake, bile reflux,
and radiation therapy.
○ Severe case – may cause the mucosa to become gangrenous or to perforate
○ Scaring can occur – resulting in pyloric stenosis or obstruction.
○ May occur with acute illnesses – burns, infection, hepatic/renal/respiratory failure, surgery
○ May be the first sign of systemic infection
chronic gastritis
○ May be caused by benign or malignant ulcers of the stomach.
○ Due to bacteria (helicobacter pylori)
○ Sometimes associated with autoimmune disease
○ Dietary factors (caffeine)
○ Medications
○ Alcohol and/or smoking
○ Chronic reflux of pancreatic secretions
gastritis
○ Gastric mucous membrane
becomes edematous and
hyperemic (congested with
fluid and blood)
○ Superficial erosion occurs.
○ Secretes scant amount of
gastric juice containing very
little acid but ++ mucus.
○ Superficial ulceration can occur
and lead to hemorrhage.
biochemical units of nutrition
Basal metabolic rate (BMR) – the energy requirement of a person at rest. Energy need to
maintain life-sustaining activities.
○ Resting energy expenditure (REE) – BMR + energy to digest meals and perform mild
activity.
○ Nutrients – elements supplied by food that are necessary for body processes and function.
Essential nutrients are those not manufactures by the body
○ Energy needs are met from 3 categories of nutrients:
○ Carbohydrates
○ Proteins
○ fats
carbohydrates
- the main source of fuel (glucose) for the brain, skeletal muscles, red and white cell production and cell function of renal medulla
monosaccharides
Glucose or fructose are the building blocks of all other carbohydrates and cannot be broken down.
disaccharides
Sucrose, lactose, and maltose are composed of two monosaccharides and water.
polysaccharides
Composed of many carbohydrate units
○ Complex carbohydrates
○ Include starch and glycogen.
○ Some can not be digested by humans
what is composed of protein
- collagen, hormones, enzymes, immune cells, DNA and RNA
- Blood clotting, fluid regulation and acid base balances require protein
- these are amino acids
essential amino acids
those that the body cannot synthesize but must have provided in the diet
non- essential amino acids
can be synthesized in the body
explain bonding in amino acids
Amino acids are linked together by peptide bonds to form larger protein molecules – polypeptides
incomplete proteins
Lack a sufficient quantity of one or more essential amino acids
○ Cereals, legumes, and vegetables.
complete proteins
Contains all of the nine essential amino acids in sufficient quantity to support growth
and maintain nitrogen balance.
○ Chicken, soybeans, fish, and cheese.
complementary proteins
Pairs of incomplete proteins that supply the total amount of protein provided by complete protein sources when combined.
nitrogen balence
achieved when the intake and output of nitrogen are equal.
positive and negative balance
positive: required for growth, normal pregnancy, maintenance of lean
muscle, vital organs, and wound healing.
○ Negative nitrogen balance – occurs when the body loses more nitrogen than it gains.
Severe infection, burns, fever, starvation, head injury, and trauma.
fats
most calorically dense nutrient. 9kcal/g
- supplies energy, cushions vital organs, lubricates body tissues, insulates and protects cell membranes
triglycerides
circulate in the blood, and are made up of 3 fatty acids attached to a glycerol
fatty acids
composed of chains of carbon and hydrogen atoms
- they can be saturated or unsaturated
trans fatty acids
raise blood levels of “bad cholesterol” (LDL cholesterol) and lower levels
of “good cholesterol (HDL). Large contributor to coronary artery disease.
fat soluble vitamins
- this would include vitamin A, D, E K
- Can be stored in the body with the exception of vitamin D
Provided through dietary intake
water soluble vitamins
this would include vitamin B and C
- easily destroyed in cooking and must be provided in daily food intake
- not stored in the Body
minerals
- ## inorganic elements essential to the body catalysts in biochemical reactions
macrominerals
calcium, sodium, potassium, phosphorus, magnesium, sulphur and chloride
trace elements
iron, iodine, fluoride, zinc, selenium, chromium, magnesium and copper
