Carbohydrate Flashcards
History of carbohydrate and exercise? (Levine et al. 1924)
Low blood glucose at the end of a marathon was associated with fatigue and an inability to concentrate
History of carbohydrate and exercise? (Gordon et al. 1925)
Exhaustion, weakness, shock, and other symptoms of hypoglycemia following prolonged effort may be prevented by adequate and timely ingestion of CHO
History of carbohydrate and exercise? (Christensen & Hansen 1939)
A high-CHO diet for 3-7days enabled subjects to exercise for 210min, whereas a high-fat diet reduced performance to 88min
Name different sources of substrate?
CHO
Fat
Amino acids
How to get energy for muscular effort?
Substates are feed into oxidative metabolism to produce ATP
Define glycolysis?
Generation of ATP from glucose to produce pyruvate
What substrate is the most efficient way to produce ATP from the Krebs cycle?
CHO
Why is carbohydrate the most efficient way to produce ATP from the Krebs cycle?
Requires less oxygen to form the same amount of ATP
Effect of exercise on muscle glycogen concentration and stores? (Areta & Hopkines 2018)
Increase in muscle glycogen stores
Exercise might be linked to muscle glycogen stores
Exercise might enable the process of taking in glucose from muscle glycogen storage to be more developed
Name the three processes carbohydrates undergo in the body?
Ingestion
Absorption
Utilisation
How is glucose absorbed?
Na-glucose linked transported 1 (SGLT1) - intestinal lumen to cell microvilli (rate-limited step)
GLUT2 - cell -> capillaries
What rate is glucose absorbed?
60g/hr
What rate is fructose absorbed?
30g/hr
How is fructose absorbed?
GLUT5 -> intenstinal lumen to cell
GLUT2 -> cell to capillaries
Glucose metabolism in the fasted state?
The liver produces glucose through glycogenolysis
Small uptake of glucose through GLUT2 in the liver
Glucose is transferred into circulation where it is delivered to other tissues
Glucose is transferred from the circulation into the muscle, adipose tissue, and the brain
Define glycogenolysis?
The process of producing glucose from liver glycogen
Which transporter transfers glucose and fructose from the cell into the capillaries?
GLUT2
Which transporter transfers glucose from the intestinal lumen to the cell?
Na-glucose linked transported 1 (SGLT1)
Which transporter transfers fructose from the intestinal lumen to the cell?
GLUT5
Which transporter transfers glucose from the circulation into muscle and adipose tissue?
GLUT4
Which transporter transfers glucose from the circulation into the brain?
GLUT2
Name types of monosaccharides?
Glucose
Fructose
Galactose
Name types of disaccharides?
Sucrose
Maltose
Lactose
What makes up sucrose?
Glucose and fructose
What makes up maltose?
Glucose and glucose
What makes up lactose?
Galactose and lactose
Name types of oligosaccharides?
Maltodextrin
Name types of polysaccharides?
Amylopectin
Amylose
Glucose metabolism in the fed state?
Contribution of CHO from the small intestine
Increases glucose concentration in circulation
Pancreas increases insulin concentration on circulation
Reduced glucose production in the liver
Increased uptake in the liver
Increased uptake in the muscle
Increased uptake in the adipose tissue
What is the process of glucose metabolism in the liver? (Gonzalez & Belts 2019)
Glucose is phosphorylated into glucose-6-phosphate by glucokinase (rate-limiting step)
Glucose can be metabolised into liver glycogen
- glucose-6-phosphate -> glucose-1-phosphate -> UPD-phosphate -> liver glycogen
Glucose can be metabolised into trioses
Fructose metabolism in the liver? (Gonzalez & Belts 2019)
Metabolised into trioses
Fructose -> fructose-1-phosphate -> trioses
In what processes are trioses metabolised in the liver? (Gonzalez & Belts 2019)
Gluconeogenesis = glucose Glycolysis = pyruvate (ATP)
The role of glucose kinase receptor protein (GKRP) in glucose metabolism?
In a normal state has a greater affinity to glucokinase
- inhibit phosphorylation of glucose to glucose-6-phosphate
- reduces glucose uptake in the liver
Fructose binds to GKRP and causes an increase in glucokinase
- increases glucose uptake and downstream glycogen
Glucose uptake in the muscle? (Rose & Richter 2005)
Glucose -> glucose-6-phosphate by hexokinase
Glucose-6-phosphate used for glycolysis or glycogenolysis