Post absorptive mechanisms and energy balance

Question 1

Examples of metabolic diseases

Answer 1

diabetes
increased bmi
high cholesterol

malnutrition or absorption problems

Question 2

Where does glucose travel in the body once absorbed?

Answer 2

In intestine
Absorbed into blood travels to the liver
Ends up in muscle, brain, erythrocytes, adipocytes

Question 3

What does glucose do in the liver?

Answer 3

Insulin promotes uptake of glucose into the cells
Glucose is stored as glycogen - glycolysis

some glucose is used in metabolism
some glucoses converted to triglycerides - these are combined with a protein to be water soluble, transported around body as VLDL

Question 4

What is a VLDL?

Answer 4

very low density lipoprotein - triglycerides are transported around the body as this when combined with a protein

Question 5

Glucose in the muscles?

Answer 5

insulin promotes uptake of glucose
stored as glycogen - glycolysis

Question 6

Glucose in the brain?

Answer 6

Constant supply of glucose needed
It is converted into acetyl CoA for metabolism

Question 7

Glucose in red blood cells?

Answer 7

They can’t produce their own ATP - no mitochondria, so anaerobic respiration occurs and lactate is produced

Question 8

Glucose in adipocytes?

Answer 8

Glucose used in respiration

Or insulin promotes uptake of glucose
Glucose stored as triglycerides

Question 9

Where are amino acids used after digestion?

Answer 9

Amino acids built up into proteins, proteins broken down into peptides/AAs

used in various compounds e.g. peptide hormones
can be used to produce ATP

Question 10

Triglycerides to adipose?

Answer 10

CHYLOMICRONS
Triglycerides and specific proteins are combined to form a chylomicron.
Chylomicrons travel through the lymph system
Triglycerides stored in the adipose tissue

Question 11

What happens during the short fast between meals? (few hours of fast)

Answer 11

Glycogen in the liver or muscle is broken down and released into bloodstream
Glucagon hormone - promotes glycogenolysis in the liver (and muscles?)
glucose goes to the brain and erythrocytes

Question 12

What happens during a longer-than-a-few-hours fast?

Answer 12

Glycogen stores used up (liver/muscle)
amino acids and lactate(rbc) and glycerol (used for ATP production)
Converted to glucose - gluconeogenesis
Glucose used to supply energy to the brain and RBC

Question 13

Fats during fasting

Answer 13

Release of glucagon

Broken down into glycerol and fatty acids
Glycerol - goes to liver - gluconeogenesis

Fatty acids - can be used into the kidney or muscles OR travel to the liver and used in the production of ketones

Question 14

Lipolysis

Answer 14

lipids/fats being broken down
glucagon promotes breakdown

Question 15

Extremely long fast (starvation nearly)

Answer 15

Decreased gluconeogenesis
Less proteins used for glucose
Fatty acids - energy source in the muscles
- converted to ketones in the liver (ketogenesis)

Ketones supply brain instead of glucose
Muscle uses less ketones

Question 16

In prolonged fasting(severe lack of glucose) where does any glucose go?

Answer 16

Brain using ketones
Any remaining glucose used in red blood cells - they can’t use ketones

Question 17

What substances can be measured in the bloodstream to aid in diagnosis of issues with metabolism?

Answer 17

glucose
ketones
insulin
lactate
triglycerides

Question 18

Hormones affecting metabolism

Answer 18

• cortisol - produced in adrenals - stress
• adrenaline/noradrenaline - adrenals - fight or
  flight - promote energy release when need to run away
• thyroxine
• growth hormone somatostatin
• insulin and glucagon

Question 19

Is insulin anabolic or catabolic?

Answer 19

anabolic
- protein synthesis
- glucose and fat storage

Question 20

Is glucagon anabolic or catabolic?

Answer 20

Catabolic
- glycogenolysis
- gluconeogenesis
- ketogenesis

Question 21

What is DIT?

Answer 21

Diet Induced Thermogenesis - energy used in processing diet

Question 22

What uses up energy from food in order to maintain an energy balance?

Answer 22

BMR
DIT
activity

Question 23

Which hormones control appetite?

Answer 23

ghrelin
leptin

Question 24

What is leptin? What happens in an overweight person?

Answer 24

A hormone that in normal weight suppresses appetite
Too much fat (in obesity) - constantly high levels - can become immune

Question 25

What is ghrelin?

Answer 25

Hormone that stimulates appetite
Increases before meals

Question 26

What are the effects of cortisol on fuel metabolism?

Answer 26

Preparation for stress response
- lipolysis
- protein breakdown
- gluconeogenesis
- glycogen storage

Question 27

Why is long term increase in cortisol bad?

Question 28

What are the effects of adrenaline on fuel metabolism?

Answer 28

Fight or flight response
- glycogenolysis
- gluconeogenesis
- lipolysis

Question 29

What are the effects of thyroxine on fuel metabolism?

Answer 29

• glycolysis
• cholesterol synthesis
• glucose uptake
• protein synthesis
• sensitises tissues to adrenaline

Question 30

Why is too much thyroxine bad(?) ?

Answer 30

too much thyroxine is catabolic

Question 31

Effects of growth hormone on fuel metabolism?

Answer 31

• gluconeogenesis
• glycogen synthesis
• lipolysis
• protein synthesis
• decreased glucose use

Question 32

What is weight determined by? Influenced by?

Answer 32

Balance of energy intake and expenditure

Influenced by genetics, environment, energy regulation

Question 33

What health problems is obesity associated with?

Answer 33

Type 2 diabetes
Heart disease
Cancer
Breathing problems
Liver disease
Joint problems