Digestive system Flashcards
Functions of the Digestive System
Ingestion
Secretion
Mixing and propulsion
Digestion
Absorption
Defecation
eating
Ingestion
release of water, enzymes,
buffers
Secretion
movement along GI tract
Mixing and propulsion
breakdown of foods
Digestion
Digestion:
by movements of digestive organs
Mechanically
digestion:
by enzymes
Chemically
moving products of digestion into the body
Absorption
dumping waste products
Defecation
-A tube through which foods pass and where digestion and absorption occur.
- Includes: mouth, pharynx, esophagus, stomach, small intestine, large intestine
Gastrointestinal (GI) tract
Organs of the Digestive System
Gastrointestinal (GI) tract
Accessory organs
- Organs that help in digestion but through which
food never passes. - Includes: teeth, tongue, salivary glands, liver, gallbladder, and pancreas
Accessory organs
is an inflammation and enlargement of the parotid glands accompanied by moderate fever, malaise (general discomfort), and extreme pain in the throat, especially when swallowing sour foods or acidic juices.
Mumps
mumps virus that typically attacks the parotid glands.
paramyxo virus
a “3- in-1” vaccine that protects against measles, mumps, and rubella.
Prophylaxis - MMR vaccine
- Chewing mixes food with saliva
- Rounds up food into a soft bolus for swallowing
Mechanical digestion
- Salivary amylase (enzyme) breaks down
polysaccharides (starch) à maltose - Continues in the stomach for about an hour until acid inactivates amylase
Chemical digestion
- the stomach contents can reflux (back up) into the inferior portion of the esophagus.
Gastroesophageal reflux disease (GERD)
Location: behind stomach
- Produces pancreatic juice in acinar cells
- Passes into duodenum via pancreatic duct
Pancreas
Secretions that help digestion
Sodium bicarbonate (NaHCO3): pH 7.1-8.2
fat-digesting
Pancreatic lipase
starch-digesting
Pancreatic amylase
made in inactivated form
Proteases
- Polysaccharide stored in liver as glycogen
- Converts glycogen, fructose, galactose, lactic acid, amino acids à glucose to ↑ blood glucose
Carbohydrate metabolism
-Produces cholesterol, triglycerides; makes bile
-Makes lipoproteins for lipid transport
Lipid metabolism
Remove NH2 from amino acids à ammonia
(NH3) à urea à to kidneys (urine)
- Synthesize most plasma proteins: albumin
Protein metabolism
Liver Functions
Carbohydrate metabolism
Lipid metabolism
Protein metabolism
Removes many harmful substances from blood
Excretion of bilirubin
Stores fat-soluble vitamins (ADEK) and minerals (Fe, Cu)
Activates vitamin D
- Stretch of rectum wall > neural reflex > contraction of longitudinal muscle
- Combined pressure + parasympathetic activity > relaxes internal anal sphincter
- External anal sphincter is voluntary
- Contraction of diaphragm and abdominal muscles aid defecation
Defecation reflex
Phases of Digestion
cephalic,
gastric,
intestinal
smell, sight, thought of food
Cephalic
stretching, pH of stomach
Gastric
intestinal hormones play key roles
Intestinal phase
two major hormones secreted by the small intestine:
cholecystokinin
secretin
- Decreased GI secretion, motility, strength of responses
- Loss of taste, increased risk for periodontal disease, difficulty swallowing, hiatal hernia, gastritis, peptic ulcer disease
- Increased risk for gallbladder problems, cirrhosis of liver, pancreatitis, constipation, hemorrhoids, diverticulitis
Aging
