Comprehensive Final: Carbs Flashcards
How do plants synthesize carbohydrates?
Through photosynthesis, combining water and carbon dioxide with solar energy to produce glucose
Can humans synthesize carbohydrates?
Yes, but only starting from energy-endowed molecules, not from scratch
What is the goal of carbohydrate digestion?
To liberate monosaccharides, primarily glucose, for absorption
Where does carbohydrate digestion begin?
In the mouth, with salivary amylase breaking α1-4 links in amylose
List Simple carbohydrates
Monosaccharides (Galactose, glucose, fructose) and disaccharides (Maltose, sucrose, lactose).
List Complex carbohydrates
Polysaccharides like starch (amylose, amylopectin), glycogen, and fiber (cellulose)
What is amylopectin?
A plant-based polysaccharide with branch points every 20-24 glucose units, used for energy storage.
What is glycogen?
An animal-based polysaccharide with branch points every 8-12 glucose units, stored in liver and skeletal muscle
difference between amylopectin and glycogen
Glycogen has more frequent branch points, allowing faster energy release during metabolism.
Which hormone primarily regulates blood glucose levels?
Insulin, which lowers blood glucose by promoting uptake and storage in tissues.
Which enzymes in the small intestine break down starch?
Pancreatic amylase and dextrinase
What role do disaccharidases play in digestion?
They break disaccharides into monosaccharides, such as:
Sucrase: Sucrose → Glucose + Fructose
Lactase: Lactose → Glucose + Galactose
Maltase: Maltose → Glucose + Glucose.
How does insulin affect skeletal muscle and adipose tissue?
It promotes glucose uptake by mobilizing GLUT4 receptors to the cell membrane
What happens to excess glucose in the liver?
It is taken up via glucokinase and stored as glycogen.
How does exercise intensity affect insulin release?
Insulin release decreases above 50% VO₂max due to catecholamines and growth hormone.
How does epinephrine affect blood glucose during exercise?
It increases glycogen breakdown in the liver and glucose release into the blood.
What is the role of triglycerides in muscle energy?
They serve as a consistent energy source, particularly at lower intensities.
How much carbohydrate should an athlete consume daily?
General fitness: 45-55% of total energy.
Moderate training: 55-65% or 5-8g/kg body weight.
High-intensity training: 8-10g/kg body weight.
How much carbohydrate should be consumed 30-60 minutes before exercise?
50-70g.
What is the benefit of consuming ≤50g carbohydrate immediately before exercise?
It can enhance performance, similar to carbohydrates consumed during exercise.
What is the optimal post-exercise carbohydrate intake?
1.5g/kg body weight within the first 30 minutes, and every 2 hours for 4-6 hours afterward.
What is insulin’s effect on the liver?
It promotes glycogen synthesis and inhibits glucose production by enhancing glucokinase activity.
What are insulin’s anabolic effects?
It supports the storage of glucose as glycogen, fat synthesis, and protein metabolism.
What are the actions of glucagon?
Stimulates glycogen breakdown in the liver.
Promotes gluconeogenesis.
Mobilizes fat stores for energy.
What are the actions of insulin?
Increases glucose uptake in muscle and fat cells.
Promotes glycogen synthesis.
Reduces fat breakdown.
What are the actions of epinephrine?
Stimulates glycogen breakdown in liver and muscle.
Mobilizes fat stores for energy.
What are the actions of cortisol?
Increases protein breakdown for gluconeogenesis.
Mobilizes fat stores.
Enhances liver glucose release.
What is intermediate hyperglycemia?
Blood glucose levels between 110-140 mg/dL.
What is hyperglycemia?
Elevated blood glucose levels above 140 mg/dL, typically after meals or in conditions like diabetes.
What is hypoglycemia?
Low blood glucose levels below 70-75 mg/dL, often causing symptoms like dizziness, fatigue, and confusion.
