exam 3 review Flashcards
what are the microscopic functional units of the liver composed of?
lobules: hexogonal units of fibrous connective tissue made of hepatocytes to filter blood and surround a cental vein with each of the six points containing a triad
what is a triad?
portal triads are made of a 1. branch oxygenated artery, 2. branch of nutrient rich, deoxygenated portal vien, and 3. the bile duct
what are the main functions of the liver?
- secretes amipathic bile salts to help the digestion of fats (lipids)
- store glucose (as glycogen) / glucose metabolism (in gluconeogenesis)
- make proteins albumins
- detoxify toxic metabolites to excrete feces or urine
what is the bile caniculi?
it is a canal formed to by the bile duct and heptocyte (liver cells)
what is bile?
bile is a yellow-green amipathic fluid made of water, electrolytes, and bulirubin in hepatocyte (liver cells) that help break down fats (lipids) in free fatty acids and monoglcerol to be digested
true or false: you can live without your gallbladder
true! the gallbladder’s primary fnctin is store bile and if removed bile will just be released/ not stored
what is the direction of material from the lumen into the body?
from the lumen, monomers of nutrients are absorbed through the enterocyte cell by the apical mebrane and exit through the basolateral into the intersisital fluid in the blooc, lymh capillaries
differnce between simple and facilitated diffusion
simple: no protein, carrier (transporter), channel help neeeded
facilitated diffusion: uses a protein for bigger, polar, charged moleucules
what are the two forms of active transport?
- primary: directly uses ATP hydrolysis for energy
- secondary: indirectly uses ATP hydrolysis for energy
difference between active and passive transport
passive: is simple or facilitated diffusion that moves down a concentration gradient and does not require energy
active: moves against concentration gradient and requires ATP enegery
what are the types of carrier mediated transports?
there are two broad groups and two embedded in one of the groups
- uniports: one molecule
- coports: two molecules
a. symport: same direction of two molecules
b. antiport: opposite direction of two molecules
where does the majority of digestion occur in the GI tract?
across the apical membrane in the jejunum (second segment) of the small intestine. monomers are absorbed after passing the basolateral membrane into intersistial fluid/ blood and lymph capillaries
what is the type of absorption of amino acids, carbohydrates, fats, and nucliec acids into the enterocyte (SI cell)?
1.** amino acids/ proteins: ** CHECK AA
- monomeric symport co transport with sodium (Na+) by secondary active transport NAAT (indirect ATP hydrolysis) Na ATP pump
- exit: faciliated diffusion across basolateral membrane
2. **carbohydrates/ simple sugars: **
- monomeric symport co transport with sodium (Na+) by secondary active transport SGLT (indirect ATP hydrolysis) Na+-K+ ATP pump
- exit: faciliated diffusion across basolateral membrane
3. **fats/ lipids: **
- apical: monoglyceride and fatty acids by pancreatic lipase enzyme and bile salts into micelles and use simple diffusion into enterocytes
4. **nucleic acids: **sub-monomer absportion
- phosphate group sodium dependent paraceullular absorption
- pentose sugar: simple diffusion, no transporter
- nitrogen base: faciliated diffusion, Na+ dependent
carbohydrate absorption
- Polysaccharides, sugar, and starches are made up of CHO (1:2:1 ratio) where pancreatic amylases break down starch and glycogen into oligosaccarides (2) and disaccharides (2- maltose and sucrose)
- brush boarder enzymes maltase and sucrase further reduce these into monosaccharides (glucose, fructose)
- the monomers are cotransporteed from the lumen across the apical membrane by the SGLT (sodium-glucose symport transporter) using the active transport NA+ K- pump
- monosaccharides exit across basolateral membrane by facilitaed diffustion and enter capillaries
nucleic acid absorption
not considered a macronutrient as the nucleotide tide units are absorbed in the three constituent parts beginning in the stomach and small intestine
1. the pepsinnuclease enzymes cleave polynucleotides into nucleotides
2. nucleosideases: hydrolyze bond between pentose sugar and nitrogenous base
3. phosphateases: hydrolyze bond between phosphate group and pentose sugar
what is absorbed from nucleic acids and what is their methods?
nucleosides:
1. nitrogenbases- by facialitated diffustion and Na+ dependent mechanisms
2. pentose (5 carbon ) sugars: simple diffusion (no GLT or GLUTs needed) across enterocyte apical membrane
3. phosphates (HPO4 2-): Na + dependent and paracellular (between cells) transport
what are the transports of carbohydrates across the apical and basolateral membranes?
apical: active transport of monosaccharides by SGLT transporter using Na+ concentration gradient
basolateral: primary direct ATP hydrolytic facilitated diffusion by GLUT transporter into capillaries
protein absorption
- many small di- and tri- peptides catabolize into monomeric amino acids by low stomach pH
- proteases and trypsin enzymes of enterocyte brush boarder to fragment proteins
- sodium amino acid cotransporter (NAAT) transports amino acids across the apical membrane
- amino acids exist across basolateral membrane by faciliated diffusion and enter capillaries
lipid absorption:
lipids are nonpolar/ insoluble in water
1. bile salts emulsify (extract fat globules) and break down into smaller droplets to allow lipase to access glycerol and fatty acids
2. pancreatic lipases hydrolyze triglycerides to produce monoglycerides and free FAs are released
3. hydrolyzed triglycerides and bile salts form micelles
(lipid monolayer)
– Bring lipids in close contact with enterocyte
4. Fatty acids and monoglycerides diffuse from micelles
into enterocytes and convert into trigylercides packaged in chylomicrones by simple diffusion
digestion and absorption summary
got it, ty
cellular respiration
goal, reactants, products, type of metabolism
aerobic (O2) catabolic metabolism of glucose to produce ATP (36-38)
reactants: glucose and oxygen
products: carbon dioxide and water and ATP
what is the cloaca?
the common opening/ vent in chickens to the reproductive, excretory, and digestive tracts
the bird’s GI tract
- in the mouth: lacks teeth, no mechanical digestion, beak/bill variation
- crop: storage of undigested food between esophagus and proventriculus
- two part stomach: proventriculus and gizzard/ ventriculus
- small and large intestine
cellular respiration
reactants, products, energy used and produced?
oxygen (O2) requiring aerobic reaction using 2 ATP to create 36-38 ATP
reactant: glucose and oxygen
products: carbon dioxide and water
what is cellulose? how does it affect digestion?
hemicellular stucture made of pectin in plant cell walls needs to be broken down by cellusases (endoglucanase and exoglucanase) to get to glucose but animals do not make endogenus cellulases so we rely on the microbiome in the gut
cellulose/ hemicellulose are made of what (monomeric) subunits?
volatile short chain (2-6) carbon fatty acids that break down by microbial fermentation into 2-4 carbon carboxylic acids
what two ways is cellulose released?
foregut fermentation: process of ruminants, cattle where digestion of celluolose/ plant matter occurs in the stomach
hindgut fermentation: monograstic organisms where digestion of celluolose/ plant matter occurs in the small intestine ** two types**
1. colonic (equine): horses, rabbits, hares, some rodents, some reptiles
2. cecal: some rodents, some reptiles, humans
comapring fermenters, what percent of GI volume is most prevelant in ruminant (foregut fermenters) and colonic/ equine (hindgut fermentors)?
foregut ruminant: 70% GI mass in stomach
hindgut colonic/ equine: 45% GI mass in the large intestine
macromolcules absorbed in different digesters
nucleotide
DNA canva absorption
amino acid
Protein canva absorption
fats
Lipid canva absorption
starch, glucose, sugars
Carbohydrate canva absorption
