Term
| What are the major biological functions of glucose (6) |
|
Definition
1. Metabolic fuel for ATP production, especially important for brain & RBCs!
2. Substrate for biosynthesis: AA's, fat, cholesterol, ribose/deoxyribose, Vit C
3. Glycogen (storage form of glucose)
4. Lactose (milk sugar essential for neonatal mammals)
5. Glycogonjugates e.g. glycans and oligosaccharides secreted in milk (immune function) and mmb proteins (signal transduction)
6.Signaling nutrient (gut hormones, insulin) |
|
|
Term
| What do brain cells use as energy substrates? Discuss the use of glucose as the main source of ATP under normal or fed conditions |
|
Definition
Glucose under normal nutrition, ketone bodies in a state of starvation
-brain cells cannot store glucose, rely on a constant supply of energy source from the blood
-glycolysis & TCA generate ATP to supply neurons with energy
-blood brain barrier will allow some molecules to pass while others cannot |
|
|
Term
| Discuss species-specific biological strategies or mechanisms for maintaining blood levels of D-glucose in adult bovine species |
|
Definition
Dry cows
-gluconeogenesis using short chain VFAs e.g. propionate from microbial fermentation of hay
Lactating cows:
-digest grain starch to absorb glucose, and also gluconeogenesis using propionate produced by microbial fermentation & blood circulating AA's
Beef steer/replacement heifers
-cereal grains as a source of starch -> sugar, maintain sugar via gluconeogenesis using propionate produced by microbial fermentation of fibre, and blood circulating AA's |
|
|
Term
| Discuss species-specific biological strategies or mechanisms for maintaining blood levels of D-glucose in monogastric species |
|
Definition
-fresh grass or poor quality hay is enough to maintain blood sugar levels using propionate produced by microbial fermentation of fibre & starch and using blood circulating AAs
Can supplement cereal grains to maintain sugar levels for animals in work or reproducing |
|
|
Term
| Discuss species-specific biological strategies or mechanisms for maintaining blood levels of D-glucose in monogastric avian species |
|
Definition
| cereal grains maintain sugar levels in blood by digesting cereal starch, and carrying out gluconeogenesis |
|
|
Term
| Discuss species-specific biological strategies or mechanisms for maintaining blood levels of D-glucose in adult swine |
|
Definition
Reproducing swine/lactating/growing finishing pigs
-digestion of grain starch as well as gluconeogenesis |
|
|
Term
| What will be the alternative energy substrate for brains when lactating sows or cows undergo a prolonged fasting? |
|
Definition
-fatty acids will be mobilized from adipose tissue and carried to muscle & liver via bloodstream to provide ATP
-fatty acids converted to volatile short-chain ketone bodies in the liver, released into bloodstream and carried to the brain where they are used as alternative energy substrates
-starved lactating animals may use blood glucose to maintain lactose levels in their milk, dangerous because the blood glucose levels are already very low! |
|
|
Term
| What organs carry out gluconeogenesis in animals? |
|
Definition
primary organ: liver
secondary organs: kidneys & SI mucosa |
|
|
Term
| What energy substrates are used for gluconeogenesis in animals? |
|
Definition
glycerol
amino acids
VFAs e.g. propionate |
|
|
