Lecture 7 Part 1 Flashcards
functions of CHO
- primary function= energy source
- used in tissue synthesis
- energy reserves
what is CHO not stored as
glycogen
- converted to fats
digestion
preparation for absorption
how are monosaccharides absorbed
only through SI
what are the enzymes useful in digestion of CHO
amylase
sucrose
lactase
maltase
what is absorbed very efficiently
galactose (main source of energy) and glucose (net producer of ATP)
what is not absorbed very efficiently
mannose
how are some monosaccharides absorbed
- absorbed then converted to glucose in intestinal wall
- converted in liver to glucose
what are the typical fasting/normal levels of blood glucose in different animals
cattle and sheep= 40-60
nonruminants= 80-120
humans= 70-90
increase in blood glucose=
diabetes
how are cellulose and hemicellulose digested
- cellulose cleaves bonds
- VFA’s absorbed thru rumen wall and some in colon of nonruminant herbivores
- cellulose/hemicellulose—>glucose—>VFA
fates of glucose
catabolized to release energy
- fuel animals activity
- build new tissue
- surplus energy stored as fat
where is glycogen stored
liver and muscle
what varies in storage of glucose
relative rate of storage vs breakdown
what is the rate of storage driven by
- what animals are being fed
- what they are doing (energy in and energy out)
how is the liver important to glucose
- glucose released from liver
- stores small amounts for quick export
- build glucose from metabolic precursors
- distributer and creator of glucose
what are the three important stages for energy (metabolic pathways)
- glycolysis
- TCA cycle
- electron transport chain
glycolysis
Embden-Myerhoff pathway
glucose–>2 pyruvate—>TCA or Lactate
- 1st metabolic pathway to derive energy from Carbs
what happens to lactate in “Cori Cycle”
converted to glucose in the liver
- lactic acid causes soreness in muscles
TCA cycle
citric acid cycle/krebs cycle
- 8 step reaction
acetyl CoA—>CO2, H2O, ATP, Heat, FADH2
how many acetyl-CoA will fuel how many turns
1
how many glucoses can fuel 2 trips around cycle
1
about how many ATP are produced from TCA cycle
38
- can vary based on gross or net
electron transport chain
- oxidative phosphorylation
- occurs within mitochondria
- energy trapped as ATP
- use NADH and FADH2 to fuel ATP synthase
what are the three G’s of metabolic pathways
- glycogenesis
- glycogenolysis
- gluconeogenesis
glycogenesis
- glucose to glycogen
- liver
- insulin initiates reactions
how does insulin initiate reactions
pull some glucose out of circulatory system and bring glucose levels down
glycogenolysis
glycogen to glucose
- starvation, fasting, prolonged exercise
what two things stimulate glycogenolysis
epinephrine
glucagon
gluconeogenesis
creation of glucose from non CHO source
- most prevalent with hypoglycemia
- occurs in liver, some in kidney
