Lecture 19- Post- Absorptive CHO metabolism Flashcards
Catabolism def
Breaking down of a nutrient or tissue
Oxidation def
Utilisation a nutrient to generate ATP, CO2 and H2O
Anabolic def
Creating tissue
Glycolysis def
Breaking down of glucose into pyruvate
Gluconeogenesis def
Making of glucose from non carbohydrate precursor
Glycogen def
Storage form of glucose (Liver and muscle)
* Glycogen synthesis (glycogenesis)
* Glycogenolysis
What do products of glycolysis enter?
What does it generate?
-TCA Cycle
-Citric Acid Cycle
-Krebs Cycle
(All the same thing)
-It generates ATP
Name the primary potential fuel sources: (4)
1-VFA (Volatile Fatty Acids)
2-Non-esterfied Fatty Acids aka free fatty acids
3-Amino Acids
4-Glucose
Where’s the site for CHO digestion in
-Monogastric
-Ruminants
-Small intestine in monogastrics
-Propionate in rumen
Wheres the site for glycogen breakdown?
Liver
Wheres the site of gluconeogenesis?
Liver , kidney
Post absorptive glucose metabolism :
Whats the process for absorbed glucose?
1-Energy/Oxidation (produces CO2 and H2O) Glycolysis and TCA cycle (Produce ATP)
3-Stored as glycogen
4-Stored as fat or made into milk fat
5-Carbons utilized for amino acid synthesis
Name a catabolic process in absorbed glucose:
Energy/Oxidation: produces CO2 and H20
* Glycolysis and TCA cycle
– Produce ATP
Name anabolic processes in absorbed glucose:
-3) Stored as glycogen
– 4) Stored as fat or made into milk fat
– 5) Carbons utilized for amino acid synthesis
Whats the most important metabolic fuel in monogastrics
-Glucose
-Fatty acids.
Whats the most important metabolic fuel for ruminants ?
Acetate
Whats the only fuel that the brain uses?
Glucose
What can the brain use during starvation circumstances as a fuel?
Ketones
How much glucose/day does the adult human brain need?
120g glucose/day
How much glucose/day does the whole body need?
160g/glucose/day
How much glucose is in circulation in the body?
20g
Whats liver glycogen stores of glucose in the body?
150-180g of glucose
Whats the muscle glycogen stores amount in the body?
300-350g of glucose
What is the only organ in the body that can secrete/release glucose?
Liver
(Muscles cannot)
To provide glucose over long periods what does the body transform?
Non-carbohydrate compounds into glucose through gluconeogenesis (Amino acids, Lactate, Glycerol)
What are glucose transporters called?
And how many of them are there?
GLUT
12 GLUT transporter isoforms identified so far
Whats the transporter for GIT and kidney epithelium?
SGLT1
Whats the transporter for brain, placenta and fetal tissue?
GLUT1
Whats the transporter for liver, pancreatic, B-cells, basolateral membranes, intestine/renal tubule (reabsorption)
GLUT2
Whats the transporter for nerve cells, kidney and placenta ?
GLUT3
Whats the transporter for Insluin regulation, muscle, fat, heart?
GLUT4
Whats the transporter for fructose transporter, apical membrane of GIT?
GLUT5
Whats the transporter for intracellular membrane transport , liver?
GLUT7
What does mammalian storage of excess glucose called?
Glycogen
Where does glycogen synthesis occur?
Liver and muscle
What does the synthesis of a branched polysaccharide form glucose resemble?
Amylopectin
What are especially important as an emergency source of blood glucose?
Liver stores
Whats glycogenolysis ?
Breakdown of glycogen into glucose.
The liver secretes the glucose, muscle only oxidises glycogen released
Name precursors for gluconeogenesis :
-Propionate (gut)
-Amino Acids (gut, muscle)
-Glycerol (Fat mobilization)
-Lactic acid (Gut & Cori cycle)
Name glucose requirements:
-Pregnancy (For fetus)
-Lactation (Lactose Synthesis)
-Lipid synthesis (in monogastrics)
Adipose, mammary
What is insulin synthesized by?
By the pancreas
What is insulin stimulation increased by?
Increased glucose concentrations
What does insulin shut down? (2)
-Gluconeogenesis
-Glycogenolysis
What is synthesized by the pancreas?
Glucagon
What is glucagon stimulated by?
the reduction in glucose concentrations
What does glucagon stimulate?
glycogenolysis and gluconeogenesis
What does the adrenal gland synthesize?
Epinephrine
What does epinephrine cause?
Intermediate glycogenolysis
What does epinephrine increase?
Glucose during fight or flight
What are glucose coordinators : (2)
-Insulin
-Glucagon epinephrine cortisol
What is insulin secretion in beta cells triggered by?
rising blood glucose levels
What does insulin binding to the insulin receptor induce?
Signals transduction cascade which allows the glucose transporter (GLUT4) to transport glucose into the cell.
What does insulin also do?
Increases uptake of glucose into cells
What do well fed animals have levels of?
-High insulin levels
-Low glucagon and epinephrine
What do hungry animals have levels of?
-Low insulin levels
-High glucagon and epinephrine
What does lower blood glucose trigger?
Secretion of glucagon
What is glucagon?
A hormone produced by the a cells of the pancreas
Glucagon increases blood glucose in several ways: (3)
- stimulates breakdown of liver glycogen
- inhibits glucose oxidation in liver
- stimulates liver gluconeogenesis
What is epinephrine secreted by?
And why is it stimulated?
Adrenal gland
In response to stressful stimuli
(fear, excitement, haemorrhage, hypoxia, hypoglycaemia, etc..)
What does the hormone epinephrine lead to ?
What does it stimulate?
Leads to glycogen breakdown in the liver and muscle.
Stimulates glucagon secretion and inhibits insulin secretion, reinforcing its effect of mobilizing fuels.
Post absorption of carbohydrate metabolism, monogastric….what occurs?
-Oxidize glucose for energy and energy storage
– Blood glucose averages 80-100 mg/dl
– Gluconeogenesis occurs many hours after a meal
– Much of circulating glucose is diet derived
Post absorption of carbohydrate metabolism, ruminants….what occurs?
-Oxidizes acetate for energy and energy storage
– Gluconeogenesis immediately after meal(100% of circulating glucose is derived from gluconeogenesis)
– Blood glucose averages 40-60 mg/dl
– Circulating glucose is NOT derived from diet
Post absorption of carbohydrate metabolism, most omnivores….what occurs?
-Oxidize glucose for energy and energy storage
– Blood glucose averages 80-100 mg/dl
(Become hypoglycaemic when on a CHO-Free diet)
– Gluconeogenesis occurs many hours after a meal
– Much of circulating glucose is diet derived
Post absorption of carbohydrate metabolism, most omnivores….what occurs?
-Oxidizes glucose for energy and energy storage
– Gluconeogenesis immediately after meal
– Blood glucose content is maintained even on strict
CHO-free diet
– Circulating glucose is NOT derived from diet
– Limited ability to store hepatic glycogen
What is Diabetes Mellitus?
A metabolic disorder in which the body has high sugar levels for prolonged periods of time. (Hyperglycemia)
Due to:
-Insulin deficiency
-Insulin insensitivity
or both
Whats the most frequent diagnosis of endocrine disorders in what animals?
How much has incidences have increased since 1970?
-Diabetes Mellitus
-Companion animals
-Increased 10 fold since 1970
Who was the first human to receive insulin? and what year?
-January 1922
-Leonard Thompson
What are associated factors of diabetes with dogs?
-Increased risk with age
-Certain breed types= more prone.
( Samoyeds, Siberian Huskies, Keeshonds, Finnish Spitz, Miniature Schnauzers and miniature poodles.)
What are dogs with reduces risk of developing DM?
Golden Retriever, Boxer, Papillion and Tibetan Spaniel
What are associated factors with cats and diabetes?
Increased incidence with age
* Certain cat breeds are more prone
– Burmese
* Neutered males have increased risk
What indicates that theres Diabetes mellitus?
GTT
What is GTT unable to determine?
Type 1 or Type 2
How is diabetes determined between type 1 and type 2 ?
-Measure insulin concentrations
–Do an insulin tolerance test
What is obese type 2 diabetes percentage of type two and also what are the factors?
-85%
-Reduced sensitivity to insulin
-Often with hyperplasia of beta cells
-Beta cells insensitive to glucose
-Hyperglycaemia and hyperinsulemia
What is non-obese type 2 diabetes percentage and what are the factors ?
-15%
-Strong genetic trait
-Often associated with mutations in insulin receptors and/or signal transduction molecules.
Type 2 diabetes: what are factors of it?
-High blood glucose
-High blood insulin
-High blood fat levels (NEFA)
-High blood ketones(made from NEFA)
What is insulin deficiency often in conjunction with?
-Glucagon excess
-Glucocorticoid
-Adrenalin
What are clinical signs of type 2 diabetes?
-Weight loss, polyuria, polydipsia
-Weakness and depression
-Bladder Infections
What is the key to controlling type 2 diabetes?
-Exercise
-Diet
What improves insulin sensitivity?
Short term weight loss
What is type 2 treatment and prevention ?
Maintain a healthy body weight
* Maintain blood glucose post-prandially
* Exogenous insulin
* Consistency of diet chemical composition
– Insulin dosage based upon (in part) on dietary CHO
– Use pet foods with guaranteed fixed
formulation
* Minimize dietary simple CHO
