WEEK 3 Flashcards
describe the CHO metabolic pathway?
CHO - monosaccarides transported into S.I then into blood
Liver - hepatocytes pass glucose into circulating system.
Remaining glucose transported round body
Glucose taken up by cells in response to insulin and glycolysis
describe Fatty Acid Metabolism?
matrix or mitochondria, free ferrety acids used when glucose is low.
RBCs cannot use FA, cannot cross blood/brain barrier.
what do fatty acids undertake when in mitochondria?
oxidation - transformed into Acetyl CoA and oxidised for energy.
what is the carnitine shuttle?
long chain of FA into cytoplasm of mitochondria.
where is the CoA and ATP converted into Acetyl CoA synthase?
cytoplasm of cell
how are Ketone made form FAs?
3 molecules bodies produced in liver with fatty acid broken down in excess.
depends on the levels of available CHO that occur in striving/fasting CHO restrictions.
what is ketongenesis?
prodution of ketones form fatty acids.
how are fatty acids converted into TCA cycle?
FA - Acetyl CoA - citrate - TCA cycle
name the state when excess ketone bodies accumulate?
ketosis
what is ketoacidosis?
absence of insulin induces liver to produce glucose at high rate.
Fatty acid oxidation results in acetyl CoA
Acetyl CoA converted to ketone bodies
ketone bodies cause ketoacidosis
amino acid catabolism?
1- removal of amine group
transfer of amine group from amino acid to receptor.
2- breakdown of carbon skeletal
Glutamate - NH3 - urea cycle
what is the equation for the Urea cycle?
NH3 ➡️ carbonyl phosphate
NH3 + CO2 + 2ATP ➡️ carbonyl phosphate + 2ADP + PI
what is the role of the urea cycle?
carbonyl group is transferred to ornithine forming citullive. carbonyl reacts with asparate.
cleavage of argininosuccinate to release arginine
arginine is hydrolysed to urea
summarise the steps involved in ruminant digestion?
food mixes with saliva - passed into rumen - passed into reticulum, broken down into cuds - partially digested food - regurgitated into animals mouth and re-chewed/re-swallowed back into rumen(chewing the cud) - cellulose breakdown occurs in rumen - moves into omasum - water and vitamins are absorbed into body, pH decreases, enzymes released to breakdown before entering abomasum - further breakdown, passed to small + large intestines, nutrients absorbed before extrection.
describe the structure of Cellulose?
Beta 1,4- glycolic bonds, non ruminants cannot digest Beta only alpha bonds. Ruminants can hydrolyse bonds called microbial fermentation.
what is the role of rumen microbes in digestion>
rumen provides an anaerobic environment.
Cellulocytic bacteria - provided cellulose eneymze with cleavage
Amylolytic bacteria - produce amylase enzyme which cleaves A-1,4 bonds in starch and sugars.
how do microbes function in the rumen? and how VFAs are synthesised?
secrete enzymes that digest to yield simple sugars. produce Glucose - converted into - volatile fatty acids (VFAs) by microbial fermentation. VFAs short fatty acids, provide energy fr ruminants.
give some empales of VFAs?
Butryate, Propinate, Acetate.
describe how VFAs are absorbed?
rumen squamous epithelium (functions similarly to small intestine epithelium of non-ruminants), papillae increase SA on rumen so continuous removal of VFA from rumen drops the pH of rumen fluid.
More papillae = greater uptake of VFAs.
describe how VFA are used for energy provision?
proponiate - glucose synthesis
acetate - milk fat synthesis
butyrate - derived form acetate and used for ketone body synthesis.
describe how VFA are used in the rumen for energy provision?
proponiate converted into GNG which is converted into glucose
Butyrate converted into B-hydroxybutyrate which is converted into acetyl CoA - TCA or Triacyglycerol (TAG)
Acetate converted into acetyl CoA - TCA or Triacyglycerol (TAG) (Fatty acid synthesis)
how the lipid equations that are metabolised in ruminants?
triglycerols ➡️(microbial lipase) fatty acids and glycerol
polyunsaturated fatty acids ➡️(shift of the double bond by rumen bacteria) saturated fatty acids
describe the formations of micelles in SI?
single layer phospholipid + cholertsol outer shell
non polar lipids in core. hydrophilic head and hydrophobic body.
how are triglucerols transformed into chylomicrons?
they are resynthesised in enterocyte and packaged with cholesterol + phospholipids into chylomicrons.
Chylomicrons enter into lymphatics and ultimately emptying into veins.
how do chylomicrons leave the enterocyte intestinal cell?
exocytosis into the lymph vessels.
describe how fatty acids are used for energy?
fatty acids taken up by LIVER for energy via b-oxidation to form acetyl CoA, enters TCA cycle for ATP synthesis.
OR
FA are converted into ketones bodies in LIVER, ketone bodies then transited into tissue.
As rate of fat metabolism ⬆️, circulating fee FA levels ⬆️.
what is required for the metabolism of fat?
glucose
what is ketosis?
occurs in dairy cattle in early lactation, high glucose levels demand + intense adipose utilisation.
it occurs when animal feed intake is NOT sufficient for the animal. it burns fat and makes things called ketones, which it can use for fuel
describe how ketosis causes ketone bodies in milk and urine?
not enough glucose intake- metalosation of FA and G, FA and G oxidised to acetyl CoA, excess acetyl CoA is convertedto ketone bodies acetotacetae and B-hydroxybutyrate.
ketosis occurs, ketone bodies build up in urine and milk supplies.
describe protein microbal digestion in ruminanats?
uses hydrolysis - cleave peptides bonds
and deamination. - removal of AA groups releasing NH3 and C isolation.
NH3 detoxified by urea cycle to form urea
microbes can therefore synthesise ALL amino acids .
how is pepsinogen to pepsin conversion stimulated?
in abomasum, chemical breakdown of protein occurs, preside of food stimulates HCL secretion, causing stimulation of pepsinogen to pepsin.
describe how the ruminant milk synethsis is actiavted?
Food is broken down into cellulose into VFAs (propionate, butyrate, acetate) in rumen leads to glucose in liver from GNG being produced and leading to lactose being produced.
Milk fat produced from acetate and butyrate via FA synthesis and protein made form microbial digestion.
describe the stomach in ruminants?
Rumen, reticulum, omasum and abomasum.
Forestomach - non-glandular. not produce digestive enzymes. able to house food for later, store energy
describe the reticulum?
reticular papillae, HONEYCOMB pattern, grazing animals have larger papillae, contains 3 layers; gas layer (methane + CO2) solid layer(fresh forage), liquid layer(fluoride present)
describe the reticulum motility in ruminant?
mixing of food with rumen microorganism, prevent accuminaltion of VFAs, mixing the cud with saliva
describe the 3 contraction patterns in reticulum of ruminants?
mixing (primary) contractions - dorsal ruminal sac contraction
eructing (secondary) contritions - gas bubbles move crainally, cause-dorsal sac contracts
Rumination - thorax expands epigoliattis closes yje larynx, antiperstailic oesophageal wave starts and move the bolus chewing the cud in the mouth.
what control the reticulrumen rumination?
central NS innvertaion of reticulum, vagus nerve branches
explain the modulation of motility of reticulumreumen rumination?
external stimuli
response - excitatory
inter stimuli