Final Flashcards
Functions of LI
absorbs remaining water and water soluble vitamins
compaction of feces
how is water absorbed by LI
establish ion gradient using Na and then water moves by osmosis
what is the main component of feces?
indigestible starch components, we don’t have the enzymes to break down cellulose–fiber. Also some metabolic waste
role of bacteria in LI
LI is colonized by bacteria.
some breakdown of starch
produce vitamin K
produce gas through cellular respiration
defacation
2 anal sphincter. 1 smooth internal, one skeletal external
conscious urge is triggered by stretch of rectum
contract ab muscles to change pressure
valsalva maneuver
contraction of ab muscles and increased pressure in thorax assists in defecation. By holding breath you can create a change in pressure to help with defecation
But your heart rate will slow down
absorptive state
ingested nutrients are entering the vbloo from the GI tract (in the 4 hours after a meal)
-body wants to absorb more calores thana re required immediatle
some go to blood stream, the remainder are stored.
-total body storage is adequate for the average person to go weekks without food
post-absorptive state
GI tract is empt of nutrients fro stored nutrients must be used(in between meals)
the role of the liver
most ingested nutrients are carbs and proteins which are absorbed immediately into the blood and transported to the liver in hepatic portal vein
liver can filter/alter nutrients before then tracel to the heart and throughout the body
inactivates and removes toxins using liver enzymes
glucose is taken up
absorptive state events carbs
blood glucose levels rise.
is taken up by liver and skeletal muscle which stores it as glycogen
any excess is take up by the liver and converted to fatty acids and triglycerides for storage
gucose stoarge as lipids
synthesized lipids in liver are released into the bloodstream bound to protein transport molcules called lipoproteins: FDL, LDL and VLDL
What do newly made lipids from glucose travel on?
in blood on VLDLs. These are too big to cross out of capillart. gets to areas of adipose tissue which secrete lipoprotein lipase which seperates the lipid from the liporpotein allowing it to move into the adipose tissue.
fate of absorbed carbohydrates
- directly into blood to boost blood sugar levels
- stored as glycogen in liver or muscle
- stored as fat in adipose tissue
absorptive state events of lipids
go directly into lymph, then added to the blood in the vena cava.
Travel in aggregates
lipoprotein lipase breaks up aggregates and allows monomers to diffuse out of the bloodstrem to the adipose tissue
how are lipids stored?
as triglycerides
formation of triglycerides
glycerol head synthesized by glucose in the adipocyte: can be made by 3 sources, glucose from blood thats stored in adipocytes as fatty acids, glucoe from blood can be converted to stored fatty acids in the liver. ingested fatty acids from the blood
cholesterol
a type of lipid necessary for plasma membranes, bile salts, hormones.
can’t be used to cellular respiration
too much in circulation can contribute to atherosclerosis
changes in cholesterol levels
liver can make it
SI can transport some into blood
some passes as feces
liver can also remove colesterol from blood to make bile salts
cholesterol set point
liver is primary control
works by negative feedback (if blood cholesterol is to high, the liver cholesterol production will be inhibited and more will be transported to digestive system
set point can change based on diet etc
HDLs
remove cholesterol from blood and deliver it to liver or endocrine glands
LDLs
supply all cells with cholesterol for membranes
What non-diet factors impact HDLs?
smoking decreases HDLs
Exercise increases HDLs
circulating estrogen increases HDLs
absorptive state events of proteins
absorbed as AA, which are absorbed by cells for production of new proteins.
If needed for energy some amino acids can be converted to metabolic precursors in the liver– but the N group must be removed as urea–makes urine
Fate of ingested amino acids
- converted to metabolic precursors for energy
each cell stores the AA for protein synthesis
excess is converted to glycofen or lipids for protein storage