Post absorptive mechanisms and energy balance

Question 1

What are some diseases associated with metabolic problems?

Answer 1

• Type 1 diabetes
• obesity
• lipid disorders
• people being unable to process enzymes

Question 2

What are carbohydrates broken down into?

Answer 2

glucose

Question 3

What are proteins broken down into?

Answer 3

Amino acids

Question 4

What are fats broken down into?

Answer 4

Triglycerides

Question 5

Where is glucose absorbed?

Answer 5

From the intestine

Question 6

Where is glucose transported to, to be processed?

Answer 6

The liver

Question 7

Where does the liver transport glucose?

Answer 7

Muscle, Brain, RBCs, Adipocytes (fat cells for storage)

Question 8

How is glucose stored and processed in the liver?

Answer 8

• Stored as glycogen, ready to be released at a later time
• Made into Acetyl CoA which is formed into triglycerides or can go into Krebs cycle to make ATP
• the triglycerides made join with a protein to make a lipoprotein e.g. VLDL (which carries triglycerides)

Question 9

What hormone regulates the uptake of glucose?

Answer 9

Insulin. It also facilitates the glycogen storage and well as glucose uptake

Question 10

What happens to glucose in the muscles?

Answer 10

• Glucose in the blood stream is made into glycogen so it can be stored

Question 11

What happens to glucose in the brain?

Answer 11

Made into Acetyl CoA which enters Krebs cycle to form ATP

Question 12

What happens to glucose in the RBCs?

Answer 12

Glucose is not stored in RBCs nor is there a Krebs cycle taking place here
- So it is made into pyruvate and lactate which can be used as sources of energy

Question 13

What happens to glucose in adipocytes?

Answer 13

With the help of insulin, glucose is made into ATP and Triglycerides (for storage)

Question 14

What does amino acids absorbed from the intestine turn into?

Answer 14

• Proteins
• Various compounds e.g. hormones
• Krebs cycle to make ATP

Question 15

What does triglycerides absorbed from the intestine turn into?

Answer 15

They combine with proteins to make them soluble so they can be transported around the blood stream.
- Made into chylomicrons which go into the lymphatic system

Question 16

What do we need to do when fasting?

Answer 16

Blood glucose needs to be maintained so the body’s stores are broken down

Question 17

How does the body obtain glucose when a short fast has taken place?

Answer 17

• Body uses the glycogen stores in the liver which is broken down into glucose and transported to the brain and RBCs
• This process of glycogen to glucose is called glycogenolysis

Question 18

What hormone promotes the breakdown of glycogen to glucose?

Answer 18

Glucagon

Question 19

How does the body obtain glucose when a longer fast has taken place?

Answer 19

• No glycogen stores
• Amino acids (from muscles), lactate (from RBCs), Glycerol (from adipocytes) are fed back into the liver to make glucose within the body from other substances
• This is called gluco-neogenesis

Question 20

How are fats used during a short fast?

Answer 20

• Triglycerides are broken into glycerol and fatty acids which are transported to the liver
• Here they are converted into glucose and ketones
• The ketones are an alternate energy to glucose
• Fatty acids are also used by the kidneys and muscles for energy
• This process is called lipolysis (break down of fats)
• Glucagon promotes this breakdown

Question 21

How do we maintain blood glucose levels on an extreme pro-longed fast when we can’t make new glucose?

Answer 21

• Switch to ketones for energy
• Fatty acids enter the liver, which makes ketones which are used in the brain
• Due to using ketones, there is a decreased use of glucose so any made can be available for RBCs as they can’t use ketones

Question 22

What substances can be measured in the blood?

Answer 22

• Glucose
• Ketones
• Insulin
• Lactate
• Triglycerides

Question 23

What hormones regulate fuel metabolism that come from the pancreas?

Answer 23

• Insulin (Anabolic)
• Glucagon

Question 24

What hormones regulate fuel metabolism that come from the adrenal gland?

Answer 24

• Cortisol
• Adrenaline
• Noradrenaline

Question 25

What hormones regulate fuel metabolism that come from the thyroid gland?

Answer 25

Thyroxine

Question 26

What hormones regulate fuel metabolism that come from the pituitary gland?

Answer 26

• Growth hormone
• Somatostatin

Question 27

Is insulin anabolic or catabolic?

Answer 27

Anabolic (build larger molecules out of small)
- glycogen storage
- fat storage
- protein synthesis

Question 28

Is glucagon anabolic or catabolic?

Answer 28

Catabolic (breaking down large molecules into small)
- glycogenolysis
- gluconeogenesis
- ketogenesis

Question 29

What are the effects of cortisol on fuel metabolism?

Answer 29

Preparation for stress response
- Lipolysis
- Protein breakdown
- Gluconeogenesis
- Glycogen storage
- Protein breakdown
Long term increase in cortisol is bad

Question 30

What are the effects of adrenaline on fuel metabolism?

Answer 30

• Glycogenolysis
• Gluconeogenesis
• Lipolysis
  Fight or flight response

Question 31

What are the effects of thyroxine on fuel metabolism?

Answer 31

• Glycolysis
• Cholesterol synthesis
• Glucose uptake
• Protein synthesis
• Sensitises tissues to adrenaline

Question 32

What are the effects of growth hormone on fuel metabolism?

Answer 32

• Gluconeogenesis
• Glycogen synthesis
• Lipolysis
• Protein synthesis
• Decreased glucose use

Question 33

What are three factors that contribute towards obesity?

Answer 33

• Genetics
• Environment
• Energy dysregulation

Question 34

What does leptin do?

Answer 34

• Found in fat cells, goes to brain and in normal weight it suppresses appetite
• In obesity, high leptin levels so there is leptin resistance so appetite not suppressed

Question 35

What does ghrelin do?

Answer 35

• From the stomach to brain
• Increases before meals
• To stimulate appetite