Digestive System Flashcards
What does the pancreas secrete?
Bicarbonate ions to naturalize stomach acid
Pancreatic amylase
Pancreatic lipase
Trypsin and Chymotrypsin
What is the primary function of bile?
To emulsify fats: breakdown larger fats into smaller droplets to increase the amount of surface area of fats that can react with intestinal lipase and is critical for fats to be fully digested and absorbed
What would happen if an individual could not produce bile?
They would have trouble absorbing fats and most other nutrient processing would be unaffected
Where is glycogen primarily stored in the body?
In the liver
Antibiotics
A group of medications that attack and kill bacterial pathogens
What is an affect of taking antibiotics everyday?
Antibiotics are desired to eliminated pathogens only, but the general mechanism is typically deadly to non-pathogenic bacteria as well—> extended use can result in death of natural, symbiotic bacteria in the digestive gut
The presence of lipids (and proteins) in the small intestine triggers the release of ______________
Cholecystokinin (CCK)
What are the functions of cholecystokinin?
- secreted from the small intestine in response to proteins and fats in the small intestine
- Signals the gallbladder to release bile to the duodenum
- Signals the pancreas to release digestive enzymes to the duodenum (e.g. pancreatic lipase)
- Slows down gastric emptying by decreasing the motility of the stomach so that the duodenum has more time to digest fat
What are the two ways the small intestines protects itself from the acidic chyme?
1) goblet cells: secret mucus to protect the epithelial lining
2) neutralization: the small intestine produces secretin (hormone) in response to entry of chyme from the stomach which stimulates the pancreas to release bicarbonate ions (HCO3-) into the duodenum via the pancreatic duct —> bicarbonate is basic and it neutralizes the acidic gastric juice that just entered the small intestine
Salivary amylase
Breaks down starch into maltose by breaking starch’s alpha-glycosidic bonds
First sight of chemical digestion
What does mastication produce?
Mastication is the physical act of chewing- this creates a bolus which increases the surface area of food and thus exposing it to more enzymes and increasing its moisture in order to facilitate easier swallowing
First site of mechanical digestion
Mesenteries
Network of fat and connective tissue that serves the digestive system through structural support, fat storage and by providing a framework through which blood supply, nerves, and the lymphatics can reach various locations
Where are the gastric glands of the stomach located?
Within the mucous membrane (also known as the gastric mucosa), specifically within the lamina proportional of the gastric mucosa
Mucous cells
- in the stomach
- Secretes mucus that lubricates and protects stomachs epithelial lining from the acidic environment
- mucus is mainly composed of glycoproteins and electrolytes and some cells secrete a small amount of pepsinogen
Parietal cells
- Secrete gastric juice (HCl)
- Release intrinsic factor (a type of glycoprotein) that assist ileum in the absorption of B-12
- Posses many mitochondria for energy to establish proton gradient
digestion: mouth
- salivary amylase breaks down starch into maltose by breaking starch’s a-glycosidic bonds (chemical digestion)
- chewing creates bolus (and saliva which lubricates the bolus), which is swelled, increasing surface area of food and expposing it to more enzymes (mechanical digestion)
digestion: pharynx
- throat
- food (and air) passes through
- contians the epiglottis (flap of tissue) that blocks the trachea so food doesnt enter lungs
digestion: esophagus
- muscular tube leading to stomach
- food travels by peristalses (wave-like motion via smooth muscle)
- lubricated by saliva
stomach: storage
- contains accordion-like folds that allow 2-4 liters of storage
stomach: mixing
- mixes food with water and gastric juice, forming chyme
stomach: physical breakdown
- muscles are activated to breakdown food
stomach: chemical breakdown
- parietal cells secrete HCl
- HCl activates pepsin from pepsinogen (released by chief cells)
- pepsin digests proteins
chief cells
- in the stomach
- secrete pepsinogen (zymogen precursor to pepsin)
- pepsinogen is activated to pepsin by the low pH in stomach and begins protein digestion (protein –> amino acids)
- secretes gastric lipase which breaks down fats to fatty acids and glycerol
G cells
- food entering the stomach causes distention
- distention signals G cells to release gastrin (a large peptide hormone which is absorbed into blood)
- gastrin stimulates parietal cells and chief cells
villi
- finger-like projections of the small intestine that increases the surface area to allow for greater digestion and absoption
- made of enterocytes that are lined by microvilli (increases surface area as well)
- each villi has a lacteal
lacteal
- lymph vessel surrounded by a capillary network that functions for nutrient absoption
- located inside the villus
- nutrients such as glucose and amino acids are absorbed into blood capillaries
- fats such as fatty acids and glycerol are absorbed into lacteals
secretin
- peptide hormone produced by cells lining the duodenum in response to acid in the small intestine (chyme, HCl)
- stimulates the pancreas to release basic bicarbonate ions into the duodenum via the pancreatic duct to neutralize chyme
grehlin
- secreted from stomach wall
- initiates hunger
leptin
- secreted from adipose tissue
- inhibits hunger
peptide YY
- secreted from the small intestine
- concerned with hunger and lack of hunger
insulin in digestion
- secreted from the pancreas
- encourages storage of glucose as glycogen in the liver
epinephrine in digestion
- supresses hunger
