Effects of Nutrition

Question 1

what percentage of your diet should these major nutrients make up:

• CHO
• FAT
• PRO

Answer 1

CHO: 45-65%
FAT: 20%
PRO: 10-15%

Question 2

why does muslce mass remain constant in healthy weight bearing humans that feed normally?

Answer 2

this is because of the dynamic equilibrium in protein turnover, as MPB is greater than MPS when fasted, but MPS is greater than MPB when fed, so everything balances out.

Question 3

what 2 macronutrients stimulate insulin secretion

Answer 3

CHO and PRO

Question 4

is exercise anabolic or catabolic?

Answer 4

it is BOTH. It is more catabolic than anabolic though

Question 5

what amino acid can inhibit catabolism via the insulin pathway?

Answer 5

Leucine

Question 6

what amino acid has a unique anabolic signalling capability to drive Muscle protein synthesis and what does it act as to do this?

Answer 6

Leucine

• to do this it can act as a substrate

Question 7

what are 3 internal structures are glucose-dependent in the body during a fed (postprandial) state?

Answer 7

• brain
• blood cells
• renal medulla

Question 8

what percentage of available glucose does the brain use

Answer 8

50%

Question 9

what are 3 examples of preferential users of glucose during the postprandial state (they want to use glucose but if they can’t isnt detrimental to function)

Answer 9

• heart
• renal cortex
• white skeletal muscle (type II muscle fibres)

Question 10

what does the redness of a muscle fibre indicate and what type of fibres are red and what type of fibres are more white in colour?

Answer 10

how glycolitic the muscle fibre is

Red: type I

white: type II

Question 11

name 2 examples of internal structures that use fatty acids as a fuel source in the postprandial state

Answer 11

• liver
• red skeletal muscle

Question 12

when are protein used as a fuel source?

Answer 12

if there is excessive intake of it

Question 13

what is the main functions of:
- glucose
- Amino acids (protein)

in the postprandial state

Answer 13

glucose:
- converted to glycogen to be stored for later use
- used for triglyceride synthesis

Amino Acids:
- protein synthesis in skeletal muscle mainly

Question 14

what are 5 consequences of protein calorie malnutrition?

Answer 14

• poor wound healing
• higher rate of infections
• greater length of stay at the hospital
• greater costs at hospital
• increased morbidity and mortality

Question 15

Define Fasted state

Answer 15

• exculsion of all food energy

Question 16

define starvation

Answer 16

Prolonged inadequate intake of protein and/or energy

Question 17

define cachexia

Answer 17

muscle wasting induced by metabolic stress

Question 18

when does the fed state end and what happens in terms of hormones when it ends

Answer 18

• when the last nutrient is absorbed
• when fed state ends, there is decrease level of insulin and increase in glucagon

Question 19

what are 3 endogenous fuel sources that are used when the fasted/postabsorptive state starts?

Answer 19

• release, transfer and oxidation of fatty acids
• release of glucose from liver glycogen
• release of amino acids in proteins from muscle as a source of fuel

Question 20

how long does the post-absorptive state last?

Answer 20

12 hours

Question 21

in the post-absorptive/fasted state what are the 3 sources of energy used and how long before they are all used up?

Answer 21

• short term reserves to maintain blood glucose levels for glucose dependent tissues
• release and oxidation of fatty acids from adipose tissue/ectopic stores
• release of glucose from liver glycogen

these are all used up within 24 hours

Question 22

what is the liver glycogen capacity in kcal and what is this equivalent to in grams of CHO/glucose

Answer 22

• 1000 kcal
• equivalent to 250g of Carbohydrates/glucose

Question 23

state 4 things that happen when you fast for longer than 24 hours

think insulin and glucagon, amino acids and proteins usage, lipases, glucose production

Answer 23

• further decrease in insulin and increase in glucagon
• proteolysis and release of amino acids from muscle as a source of fuel
• activation of hormone sensitive lipase to increase lipolysis and circulating FFA and TG
• increase in gluconeogenesis

Question 24

where does the cori cycle occur?

Answer 24

in the skeletal muscle and the liver

Question 25

# gluconeogenesis outline how gluconeogenesis occurs through the **cori cycle**

Answer 25

1. glucose is converted in ***skeletal muscle*** to **lactate** 2. this **pyruvate/lactate** travels back to the **liver** for conversion back into **glucose**

Question 26

is the **Cori** cycle anaerobic or aerobic **mostly**?

Answer 26

- mostly **anaerobic**

Question 27

outline 5 steps of how gluconeogenesis occurs in the **Gluose-alanine** ***(Cahill)*** cycle

Answer 27

1. **Glucose** (from **glycogen**/**GNG**) in **skeletal** **muscle** is broken down to **pyruvate** 2. **pyruvate** is transaminated to produce **alanine** 3. **alanine** returns to the **liver** via **absorption** through **hepatocytes** for **deamination**, where **pyruvate** and **NH2** is produced 4. after **demination** in the **liver**, **NH2** is used in **urea** for **excretion** 5. **pyruvate** in the **liver** is converted to **glucose** via **gluconeogenesis**, ready to be transfered and used in the muscle again

Question 28

where does the **cahill** cycle occur?

Answer 28

in the skeletal muscle and liver

Question 29

where doe the **glutamine** cycle happen

Answer 29

in the kidneys

Question 30

outline the **3 steps** of the **glutamine cycle** for **gluconeogenesis**

Answer 30

1. muscle glutamine goes to kidney 2. **glutamine** is converted to glutamate + excess **ammonia (NH3)** 3. this is then converted to **a-ketoglutarate** and is sent through the **Krebs/TCA cycle** to be converted back into glucose to create more glucose

Question 31

what process occurs if you fast for longer than 2-3 days?

Answer 31

**ketosis**

Question 32

what characterises ketosis and what molecule causes smelly breath that is found in people on a keto diet?

Answer 32

- characterized by presence of **ketone bodies** - acetone causes the smelly breath

Question 33

what are **ketone bodies** and what can they be used for?

Answer 33

- **ketone bodies** are bi-products of fatty acid oxidation in the liver - can be used by all tissues with mitochondria to allow for energy release

Question 34

when is there significant muscle protein loss during the fasted state?

Answer 34

in the first **7-10 days**

Question 35

how much **protein** is lost in **urination** when someone is in the **fasted** state for **7-10** days and what is this equivalent to in **Lean body mass (LBM)** per day **intially** and over first **7 day period**

Answer 35

**urinary loss:** - **10-12 g** urinary Nitrogen/day - **360g** LBM per day **initally** - **1-2kg** LBM over first 7 days

Question 36

what happens if you consume more protein that needed?

Answer 36

- oxidation of the **excess amino acids** and then excretion out the body - used to make new glucose and fatty storage