Week 11: GI Flashcards
DIGESTIVE SYSTEM
_________ ingested food and fluids
- Breaks them down into their units
- Controlled by enzymes
_______ necessary components
- Membrane transport mechanisms
- Mostly in ______________
Processes ingested food and fluids
- Breaks them down into their units
- Controlled by enzymes
Absorbs necessary components
- Membrane transport mechanisms
- Mostly in small intestine
Oral cavity
-Initial phase of ___________ breakdown of food
—Mastication by teeth
-Initial chemical digestion
—_________________________ —starts chemical breakdown of carbohydrates
-Formation of bolus
-Initial phase of mechanical breakdown of food
—Mastication by teeth
-Initial chemical digestion
—Salivary amylase—starts chemical breakdown of carbohydrates
-Formation of bolus
Pharynx
- _____________ (deglutition)
Swallowing
Esophagus
- Closed except during ____________, skeletal muscle at superior end—
followed by smooth muscle
swallowing,
STOMACH
Expansible muscular sac—acts as ____________ for food and fluid
_________ smooth muscle layers
Constant mixing and churning of food
Expansible muscular sac—acts as reservoir for food and fluid
Three smooth muscle layers
Constant mixing and churning of food
STOMACH
Initial digestion of proteins
- By _________
- Formed by combination of pepsinogen and HCl
Production of _________ factor
- Essential for absorption of vitamin B12 in the ileum
Formation of chyme
Absorption of small and lipid-soluble molecules
Initial digestion of proteins
- By pepsin
- Formed by combination of pepsinogen and HCl
Production of intrinsic factor
- Essential for absorption of vitamin B12 in the ileum
Formation of chyme
Absorption of small and lipid-soluble molecules
LIVER
“_________ factory” of the body
Receives blood from hepatic portal vein
- Transport of nutrients from intestine to liver
Hepatocytes store _________
- Play role in carbohydrate, protein, fat metabolism
Production of plasma proteins and clotting factors
Breakdown of old and damaged _________
_______ production
“Metabolic factory” of the body
Receives blood from hepatic portal vein
- Transport of nutrients from intestine to liver
Hepatocytes store nutrients
- Play role in carbohydrate, protein, fat metabolism
Production of plasma proteins and clotting factors
Breakdown of old and damaged erythrocytes
Bile production
PANCREAS
Exocrine pancreas arranged in _________
Secretes digestive _________, electrolytes
- Trypsin, Chymotrypsin, Carboxypeptidase, Ribonuclease, Pancreatic amylase, Bicarbonate ions
Pancreatic duct joins bile duct to enter duodenum
Exocrine pancreas arranged in lobules
Secretes digestive enzymes, electrolytes
- Trypsin, Chymotrypsin, Carboxypeptidase, Ribonuclease, Pancreatic amylase, Bicarbonate ions
Pancreatic duct joins bile duct to enter duodenum
Small intestine
- Duodenum, jejunum, ileum
- Villi (folds of the mucosa) and microvilli (folds of cell membranes)
– Increase surface area for ___________ - Major site for _____________ of nutrients
- Lacteal—lymphatic vessel
- Site of production of:
–_______
– Enterokinase, peptidases, nucleosidases, lipase, sucrase, maltase,
lactase, cholecystokinin (hormone)
- Duodenum, jejunum, ileum
- Villi (folds of the mucosa) and microvilli (folds of cell membranes)
– Increase surface area for absorption - Major site for absorption of nutrients
- Lacteal—lymphatic vessel
- Site of production of:
–Mucus
– Enterokinase, peptidases, nucleosidases, lipase, sucrase, maltase,
lactase, cholecystokinin (hormone)
Large intestine
- ______ patches (lymphatic tissue)
- Resident normal flora
- Breakdown of certain food materials
-Vitamin ___ synthesis by bacteria - Fluid and electrolyte ______________
- Formation of solid feces
- Mass movements
- Peyer patches (lymphatic tissue)
- Resident normal flora
- Breakdown of certain food materials
-Vitamin K synthesis by bacteria - Fluid and electrolyte reabsorption
- Formation of solid feces
- Mass movements
NEURAL AND HORMONAL CONTROLS
Parasympathetic nervous system (PNS)
- Primarily through vagus nerve (cranial nerve [CN] X)
- Increased ______________ and ______________
- Primarily through vagus nerve (cranial nerve [CN] X)
- Increased motility & secretions
NEURAL AND HORMONAL CONTROLS
Sympathetic nervous system (SNS)
-Stimulated by factors such as _______________
- _________ gastrointestinal activity
- Causes vasoconstriction
- _____________ secretions and regeneration of epithelial cells
-Stimulated by factors such as fear, anger
- Inhibits gastrointestinal activity
- Causes vasoconstriction
- Reduced secretions and regeneration of epithelial cells
Facial (CN VII) and glossopharyngeal (CN IX) nerves
- Maintain continuous flow of _______________
saliva in mouth
Stomach empties within _______ hours after meal.
2 to 6
Gastrin
- Secreted by mucosal cells (stomach) in response to ___________ of stomach or partially digested substances
- Increases gastric motility, relaxes pyloric and ileocecal sphincters— promotes _________________________
- Secreted by mucosal cells (stomach) in response to distention of stomach or partially digested substances
- Increases gastric motility, relaxes pyloric and ileocecal sphincters— promotes stomach emptying
Histamine
- Increased secretion of ____________________
hydrochloric acid
Secretin
- Decreases ____________ secretions
gastric
Cholecystokinin
-Inhibits gastric emptying; stimulates contraction of ______________
gallbladder
Carbohydrates
- Digestion starts in ______
- Followed by digestion in the ______ intestine
- Digestion starts in mouth
- Followed by digestion in the small intestine
Proteins
- Digestion starts in _________, continues in small intestine
stomach,
Lipids
- Emulsified by ______ prior to chemical breakdown
-Action of __________ form monoglycerides and free fatty acids
- Formation of chylomicrons
- Emulsified by bile prior to chemical breakdown
-Action of enzymes form monoglycerides and free fatty acids - Formation of chylomicrons
Fat-soluble vitamins
- Vitamins _______________
- Absorbed with fats
A, D, E, K
Water-soluble vitamins
- Vitamins B and C—diffuse into:
blood
Electrolytes
- Absorbed by active transport or ____________
diffusion