9.1 Digestion 1 Flashcards
What is the difference between malabsorption and malnutrition?
malabsorption: inability to transport nutrients or fluids from the GI tract to the blood
malnutrition: inability to obtain necessary nutrients; lack of supply, poor diet, lack of nutrient processing
What are segmentation and mass movement?
Segmentation- small intestine only: chunks up food, mostly circular muscles- increases enzymatic contact and more mechanical breakdown
Mass movements- large intestine/bowel; all coordinate to squeeze/move large amounts of material out for elimination
How are carbs digested and absorbed?
Digestive enzymes: salivary amylase, pancreatic amylase, brush border enzymes
Absorption: small intestine transport is across villi into blood via secondary active transporters
How are proteins digested and absorbed?
Digestion: pepsin, trypsin, chymotrypsin, carboxypeptidase, brush border enzymes
Absorption: small intestine transport is across villi into blood via secondary active transporters
How are fats digested and absorbed?
Emulsified by bile salts
Fat globules-> micelles -> vesicle-like system -> chylomicrons -> lacteal
What are the digestive organs?
Oral cavity Pharynx Esophagus Stomach Small Intestine Large intestine
What are the accessory digestive organs?
Salivary glands
Liver
Pancreas
Gallbladder
What are the linings within the abd/pelvic cavity?
Parietal peritoneum – serous membrane, lines wall of the abdominal cavity
Visceral peritoneum –serous membrane, lines abdominal organs
Peritoneal cavity – contains serous fluid
What is the structure and function of mesentery?
a double-layered sheet of peritoneum surrounding some digestive organs
holds digestive organs to the body wall
contains blood vessels, lymph, and nerves
stores fat
What divides the liver, attaches to body wall?
Falciform ligament
What are the greater/lesser omentum?
Lesser Omentum: ventral, liver to lesser curvature (top) stomach
Greater Omentum: ventral, greater curvature (lower) stomach to transverse colon, also covers small intestine
What is the mesentery proper?
dorsal, connects small intestine to back body wall
What is the mesocolon?
mesentery that connects colon to back body wall
transverse mesocolon
sigmoid mesocolon
What are common causes of peritonitis?
bacterial infection leakage of intestinal or other organ contents into peritoneal cavity bacteria bile stomach acid traumatic injury
What are complications of peritonitis?
peritoneal fluid shift, excess fluid causes peritoneal edema, decreased blood volume, electrolyte imbalance
secondary complications: abdominal abscess paralytic ileus – lack of intestinal motility cardiac arrythmia intestinal perforation septicemia hypovolemic shock
What is the blood supply of the mesenteries?
The Splanchnic Circulation: branches of arteries from abdominal aorta to digestive organs
Hepatic Portal Circulation: blood draining from abdominal organ veins to liver before returning to inferior vena cava
What is the enteric nervous system? What are it’s nerve plexuses? Where are they located?
The “gut brain” semi-autonomous network of neurons within the digestive system with pacemaker cells and local reflex arcs
Submucosal Plexus: beneath, within epithelial, glandular layers
Myenteric Nerve Plexus: between smooth muscle layers
What are the PNS/SNS innervations of the gut?
Parasympathetic input: Vagus Nerve (CN X) Pelvic Splanchnic Nerves Sympathetic input: Thoracic Splanchnic Nerves Sacral Splanchnic Nerves
What are the 4 layers of gut wall?
Mucosa
Submucosa
Muscularis
Serosa- serous covering in peritoneum; Adventitia if retroperitoneal
What are the 2 sphincters in the esophagus? Where are they? Open/closed?
pharyngoesophageal (upper) sphincter prevents aspiration, directs food away from airways (contracted at rest
gastroesophageal (cardiac, lower) sphincter (contracted at rest)
What ate the 2 stages of deglutition?
Voluntary: Oropharyngeal Phase (skeletal muscle)
Tongue propels the food bolus into the pharynx
Respiratory passages are closed off by uvula, upper esophageal sphincter and epiglottis
Bolus moves from pharynx to esophagus
Involuntary: Pharyngoesophageal Phase (smooth muscle)
Bolus moves from esophagus to stomach through cardiac sphincter via peristalsis waves
Respiratory passages can re-open
How can neuromuscular dysfunction cause dysphagia?
lack of gag reflex due to cranial nerve dysfunction, stroke, degenerative neurological conditions, spinal cord injury, trauma
How can structural abnormalities cause dysphagia?
tumors
congenital diverticulum – outpouching of wall
congenital or acquired connective tissue rings around esophagus
congenital or acquired stricture – thinning or narrowing
What is achalasia?
cardiac spasm, surgery may be needed to prevent dysphagia from progressing to aspiration
decreased peristalsis, increased tone, contracted cardiac sphincter
