Digestive System Flashcards
afferent response
somatic and receptor
efferent response
somatic
autonomic –> sympathetic and parasympathetic make up enteric system (digestive) and can be stimulated by the brain or independently from the brain
digestion
breaking nutrients (not already in your body) down to simplest unit (that can then be absorbed)
absorption
occurs with enzymes after digestion
simple units of carbohydrates
glucose, fructose, galactose
esophagus
carries food from mouth to stomach
carbohydrate digestion
mouth
mechanical digestion - teeth breaking down food into smaller pieces
chemical digestion - salivary amylase breaks bonds of carbohydrates
saliva lubricates food to make it easier to pass through the esophagus
carbohydrate digestion
stomach
chemical digestion stops here
HCl denatures the enzyme by changing its shape and protects us from pathogens that we may eat
carbohydrate digestion
small intestine and pancreas
pancreas is an endocrine gland that secretes pancreatic amalyase into the small intestine
small intestine is a 19-20ft long and releases glucose insulin etropic polypeptide (gpi) when it starts to release glucose
brush borders on the small intestine have pores that break bonds to create simplest units
carbohydrate digestion
large intestine
packages undigested food
glucose paradox
lets glucose pass but expect liver to store it all because glu goes there first but it doesn’t because glucokinase is slow
kidneys and liver make new glucose through gluvoneogeneisis
triglyceride
fatty acid chain and a glycerol
lipase
enzyme responsible for breaking off fatty acids, polar
triglyceride digestion
mouth
mechanical digestion breaks down food into smaller pieces
chemical digestion - lingual lipase breaks up triglycerides but not effective at reaching the ones inside
lubricates food for easy passage to esophagus
triglyceride digestion
stomach
gastric lipase doesn’t get denatured
chemical digestion continues because enzyme not denatured
triglyceride digestion
small intestine and pancreas
pancreas releases pancreatic lipase in duodenum and breaks off fatty acid chains
enteric lipase in small intestine stimulates CCK –> bile secreted into duodenum and emulsifiers fat to get the polar and nonmolecules to mix
circulates in the blood and stimulates the ventromedial hypothalamus which creates a satiety sensation (feel full)
lateral hypothalamus is he hunger senstation
triglyceride digestion
large intestine
fat that does not get absorbed
LDL and HDL
fatty acid pathway
fatty acids form a micelle (simplest unit)
enterocyte absorbs it
triglyceride formed
creates a chylomicron
dumped into lymphatic system in thoracic duct
thoracic duct dumps contents in lymph into the heart
heart distributes fat everywhere
fat in blood
endothelial cells have protein lipase
fatty acids go through adipose
tricylceride
proteins
amino acid is the simplist unit
1/2 amino acids are essential and are obtained through food
1/2 amino acids are nonessential and body makes it
protein digestion
mouth
mechanical digestion
lubricates food
no chemical digestion
protein digestion
stomach
secretes pepsinogen (inactive)
releases HCl which converts pepsinogen into pepsin, breaks peptide bonds and denatures the protein, and protects against pathogens
protein digestion
small intestine and pancreas
enterokinase converts trypsinogen into trypsin
trypsin converts chymotrypsinogen into chymotrypsin
enterokinase is on the brush boarders of the small intestine
inactive enzymes are converted into active
small intestine contains peptidase that breaks peptide bonds
exocytosis releases enterocytes where the food is for packaging
in the small intestine, water follows chlorine and sodium follows chlorine
protein digestion
large intestine
food that doesn’t get broken down is excreted
can package any digested food for subsequent secretion
mix enzymes with water so can get water back
water follows sodium and chloride follows sodium
diahrrea
lactose intolerant causes too much solutes and water goes in the opp direction
bilirubin from the breakdown of RBCs can enter the small intestine and gets converted into sterobin which is brown
celiac disease
gluten is a protein found in flower converted into gliaden
enterocytes get destroyed by gliadin and there are less cells in the small intestine
stay away from gluten products
immunoglobulins
can be passed down in mother’s milk and babies get passive immunity
phases of digestion
cephalic phase
gastric phase
intestinal phase
cephalic phase
promoted by thinking or smelling of food
increase gastrin (releases it)
peristaltic motion, stomach growling
gastric phase
Food enters the stomach —> increase gastrin secretion
Peripheral nervous system activated —> parasympathetic want to store food activates peristalsis (push food)
Intestinal phase
Pancreas secretes bicarbonate ions into duodenum to neutralize the enzymes once they leave the stomach without enzyme activity being affected
Small intestine releases secretion that causes pancreas to release enzymes (pancreatic amylase, pancreatic lipase, trypsinogen, chymotrypsinogen)
Parietal cells
Respond to increase in gastrin and increase release of HCl
Camp moves to the hydrogen pump from inside the cell to the cell membrane
HCl produced in the stomach
Acid reflex
Acid going in wrong direction
Inhibit proton pumps to make less acid in the stomach
Chyme
Food particles, acid, enzymes, and small amount of water
Neutralize the acid with bicarbonate ion in pancreatic duct and duodenum
Add more water to mix enzymes with food more effectively and easier to transport
CFTR (cystic fibrosis transmembrane conductance regulator) found on crypts of lieburkutin that helps add water
Gastrin pathway
Gastrin binds to receptor ATP —> CAMP
CAMP opens up Cl- channel
Cl- from NKCC channel leaks out of Cl- channel
This Cl- is exchanged for bicarbonate
Cl- leaves, Na+ follows and then H2O follows
Peristalsis
Stimulus is the vagus nerve and parasympathetic activation that stimulates the mesenteric plexus
Cells of cajal (peacemaker cell)
Always stimulate smooth muscles for peristalsis but is not string enough to reach threshold
Threshold is reached when you eat food and when mesenteric plexus is stimulated
Smooth muscle cells are unitary
Create segments that maximize digestion and absorption called segmentation
Perestolic rush
Protects mechanism against pathogens
Perestolic motion should be slow to maximize digestion
Body defects pathogen and Perestolic motion speeds up to reduce amount of pathogen absorbed
More solutes and water large intstine
Absorption of nutrients
Secondary active transport
Glucose, amino acid, galactose
Absorption of nutrients
Diffusion
Fructose
Fatty acids
Absorption of nutrients characteristics
Active transport is more efficient because of energy
Too much fructose, stored in the large intestine so more water and diarrhea
Calcium important for muscle contraction but Vitamin D can affect absorption of calcium duodenum
