Lecture 23 - Glucose as a fuel molecule 1 Flashcards
What happens to carbohydrates during digestion
Amylase breaks down carbohydrates like into smaller sugars, starting from oligosaccharides and then disaccharides
What happens to disaccharides in digestion
Disaccharides are broken down by specific enzymes into monosaccharide such as glucose
Why cannot glucose easily be absorbed by passive transport
Sugars are high polar and cannot simply diffuse across cell membranes
Types of glucose transport
- Active transport - against gradient via SFLT
- Facilitated transport - No energy needed via GLUT
How does glucose get from gut into epithelial cells
Glucose enters via the SGLT1 transported, which moves glucose along with sodium into the cell. It is a symport. Glucose up its gradient and Na down the gradient
Glucose transporting into blood
Glucose moves into the blood through the GLUT2 Transporter, which allows glucose to pass down its conc gradient
How is the sodium gradient maintained in epithelial cells
The Na/K ATPase pump uses energy to pump Na out of the cell and potassium into the cell, maintaining the gradient
Why can’t red blood cells use fats or protein for energy
Red blood cell don’t have mitochondria, so they can only use glucose through glycolysis for energy
Which cells in the body need or prefer glucose as fuel
- Red blood cells
- The brain
- The eyes
- The white muscle
Why does brain prefer glucose
- Crosses the blood-brain barrier easily
- Provide energy quickly without needing too much oxygen, lowering the risk of damage
How much glucose does the brain need per day
120 g per day
Why does the eye use glucose
The eyes uses glucose to avoid blood vessels or mitochondria from getting in the way of light and interfering with vision
Which muscle cells prefer glucose
White muscles use glucose while red muscles use fats
Why is glucose a safer energy source than fatty acids for the brain
Producing ATP from fattly acids requires more oxygen and increases the risk of reactive oxygen species, which can damage neurons
