Carbohydrates- Glycolysis Flashcards
What are the dietary forms of carbohydrates?
Starch, sucrose, lactose fructose and glucose
What hormone is released after eating?
Insulin
What does insulin do?
- Stimulates the formation of glycogen from glucose
- Involved in glucose storage and immediate use of glucose after eating
When is glucagon released?
- A while after eating, when glucose levels have dropped in the blood
- Stimulates breakdown of glycogen into glucose
What type of receptor is the insulin receptor on cells?
Tyrosine Kinase Receptor
What do Ras/kinase pathways do?
Control gene expression involved in glucose metabolism
What are the glucose transporters?
- Family of transporters
- GLUT-1 to 4
What is the role of each GLUT transporter?
- GLUT-1: erythrocytes, BBB and foetal
- GLUT-2: bidirectional transporter found in liver, kidney and pancreatic beta cells
- GLUT-3: Nuerons
- GLUT-4: dependent on insulin, adipose tissue and skeletal muscle
What is a sodium dependent glucose transporter (SGLT) and how is it different?
- Energy requiring glucose transporter that moves glucose against a concentration gradient
- Movement coupled to sodium conc. which is co-transported, occurs in intestinal epithelium, renal tubules and choroid plexuses
What happens to excess carbohydrates in the fed state?
- Taken up by liver and converted into fats
- Packaged into vesicles and stored in adipose tissue
- Occurs when you eat beyond energy requirements
What happens to glucose in the fed state?
- Transported to the liver and brain
- Converted to Acetyl CoA and entered into TCA cycle
- Red blood cell consistently takes up glucose
What happens to glucose in red blood cells in the fed state?
- Has no mitochondria
- Glucose does not enter TCA cycle
- Produces some localised ATP through anaerobic respiration
What happens to glucose in muscles in the fed state?
- Generate a glycogen reserve for themselves
- Stores glycogen for future immediate use
When does the basal state occur?
- A short while after eating
- Glucose levels in the blood would have diminished by the point
Where does excess glucose go in the basal state?
- Adipose tissue and muscles
- Similar to fed state
Describe and explain the levels of insulin and glucagon in the basal state
- Insulin decreased
- Glucagon increased in order to draw glucose from glycogen stored
What happens in the liver in the basal state?
- Glycogen reserves are used to maintain blood sugar levels
- Maintenance and prevention of hypoglycaemia
What happens in the brain in the basal state?
- Uses glucose from the blood
What happens in red blood cells in the basal state?
- Converts glucose to lactate
- Lactate goes back to the liver and converts back to glucose
- Lactate cycels
What happens in adipose tissue in the basal state?
- After glycogen stored run out, this is where glucose comes from
- Glycerol in fats is converted into glucose (2 to 1)
- Fatty acid tails are taken up by tissues that need energy are therefore metabolised
What happens in adipose tissue in the prolonged fast state?
- No glycogen left so adipose must be used
- Glycerol is used as raw material
What happens to muscle protein in the prolonged fast state?
- Can be used as fuel for glucose and access of other amino acids
- Does not tend to compromise overall health unless used excessively
What happens in the brain in the prolonged fast state?
- Relinquishes its need for glucose and requires ketone bodies instead
- Preference for glucose diminishes as red blood cells need it more
What molecule are glucose, amino acids and fatty acids converted to for respiration?
Acetyl CoA
