Metabolism

Question 1

What is The difference between respiratory exchange ratio and respiratory quotient?

Answer 1

Respiratory quotient: indicates how much CO2 produced by a cell
Respiratory exchange ratio: ratio of CO2/O2

Question 2

What are the differences in RQ between CHO, protein and fat?

Answer 2

CHO: 1.0
Fat: :0.7
Protein: 0.82

Question 3

Why does respiratory quotient rise during severe exercise?

Answer 3

More CO2 is produced because hyperventilation will result from lactic acidosis

Question 4

What is the most important source of energy for cellular metabolism?

Answer 4

ATP

Question 5

Does glucose or glycogen produce more ATP when metabolised to pyruvate?

Answer 5

Glycogen

Question 6

What are the key functions of phosphocreatine?

Answer 6

Resynthesizes ATP during exercise

Most abundant source of high energy phosphate bonds

Question 7

What are high energy phosphate compounds?

Answer 7

Anything that contains phosphoric acid bound to something

includes; ATP, phsophocreatinine, CoA

Question 8

What is oxidation?

Answer 8

Adding O2 to something or taking hydrogen away, or losing an electron

Question 9

What is oxidative phosphorylation?

Answer 9

AN oxidation reaction that generates ATP

Question 10

What type of reaction is the conversion of NADH2 to NAD coupled with conversion of ADP to ATP?

Answer 10

Oxidative phosphorylation

Question 11

How does the energy content of acetyl CoA differ from acetic acid?

Answer 11

More energy in Acetyl CoA

Question 12

What is one end product of flavoprotein cytochrome system?

Answer 12

Water

Question 13

Where does oxidative deamination take place?

Answer 13

Liver

Question 14

What is the major site of liver formation?

Answer 14

Liver

Question 15

Where are FFAs oxidized?

Answer 15

Muscle and heart

Question 16

How many ATPs does glucose become in aerobic/anaerobic conditions?

Answer 16

Anaerobic: Glucose-> 2 lactate-> 2 ATP

Aerobic: Glucose-> 38ATPs

Question 17

Describe the process of carbohydrate metabolism

Answer 17

Glucose enters cell- via facilitated diffusion converted to G6P
Stored as glycogen or broken down
Can be broken down either via Embden-meyerhof or hexose monophosphate shunt. Becomes pyruvate which enters mitrochondria and becomes acetyl CoA->krebs cycle-> energy

Question 18

How is high intake of glucose dealt with in the body?

Answer 18

Stored as fat (30-40%) and glycogen 5% because high glucose causes insulin secretion and glycogen formation

Question 19

How does fat travel in the blood?

Answer 19

Primarily as VLDL
Increased by carbohydrate excess in the diet
Removed from the circulation by muscle and adipose tissue
NOT increased when plasma cholesterol rises

Question 20

Where is intracellular lipase found?

Answer 20

Only in adipose tissue
Hormone sensitive
Does not enter the circulation

Question 21

What increases intracellular lipase?

Answer 21

Starvation, stress, cortisol, thyrotoxicosis, GH, catecholamines released from sympathetic nerves

Question 22

What decreases activity of intracellular lipase?

Answer 22

Insulin and food

Question 23

Where do peripheral tissues get their energy from?

Answer 23

Fat supplies

But fat is not readily converted to carbohydrates in periphery, fatty acids become Acetyl CoA->ketones

Question 24

What is the difference between brown fat and neutral fat?

Answer 24

Brown fat: produces heat and aids thermoregulation

Neutral fat: gets burned first in starvation

Question 25

How is uric acid formed?

Answer 25

Breakdown of purines and synthesis from 5-PRPP and glutamine-> powered by xanthine oxidase

Question 26

Where is uric acid excreted?

Answer 26

Kidney Normal plasma level (0.2-0.4mmol/L) Can be inhibited by probenecid

Question 27

What is the difference between primary and secondary gout?

Answer 27

Primary: uric acid production increased or impaired renal tubular transport Secondary: uric acid elevated by decreased excretion (thiazide diuretics) or increased production from another disease (leukemia)

Question 28

How does allopurinol work?

Answer 28

Inhibits xanthine oxidase Decreases uric acid production rEduced urinary uric acid excretion

Question 29

Why does plasma ketone production increase in starvation?

Answer 29

Initially energy taken from glyocogen but this only last about 24 hours Fat becomes major energy source, resulting increased plasma ketones and a decrease in respiratory quotient

Question 30

What is the process by which there is increased ketone synthesis in starvation?

Answer 30

Increased hepatic gluconeogenolysis Increased hepatic and muscle glycogenolysis Muscle protein catabolism Increased activity of hormones sensitive lipase Increased ketone synthesis from fatty acids

Question 31

How is urea affected by protein catabolism in starvation?

Answer 31

Reduced urea production and renal excretion

Question 32

What does metabolic acidosis secondary to starvation lead to?

Answer 32

Increased renal excretion of acid Increased rate of bicarbonate production Increased urinary NH4 excretion Decreased pCO2 of arterial blood

Question 33

What is the main metabolic fuel in the post operative period?

Answer 33

Fatty acids

Question 34

Why does ketosis not uncommonly occur in starvation?

Answer 34

Carbohydrate is anti-ketogenic

Question 35

What are the key changes in metabolism that occur in trauma?

Answer 35

``` Increased resting metabolic rate Protein catabolism and muscle wasting Elevated excretion of urinary nitrogen Increased lipolysis Resistance of peripheral tissues to insulin Increased gluconeogenesis ```

Question 36

When is urinary nitrogen loss increased?

Answer 36

Parenteral sources of nitrogen are provided Patient has a fever NOT WHEN: patient has adrenal insufficiency or patient is chronically ill/debilitated before trauma

Question 37

Which 3 things produce heat?

Answer 37

Basic metabolic processes Food intake Muscular activity

Question 38

What are the ways the human body loses heat?

Answer 38

Radiation and conduction 70% Vaporization of sweat 27% Respiration 2% Urination and defecation 1%

Question 39

What is the difference between conduction, convection and radiation in terms of heat transfer?

Answer 39

Conduction: loss of heat to surrounding air Radiation: loss to colder objects nearby Convection: if you're swimming in water

Question 40

How does the body respond to cold?

Answer 40

Reducing heat loss by radiation Mobilising free fatty acids Increasing metabolic activity in muscles Increasing catecholamine secretion

Question 41

Why do we keep patients with severe burns in really hot rooms?

Answer 41

Heat losses are minimised by raising the room temperature which combats the high metabolic rate

Question 42

Why will a man get colder in water at 25 degrees than air at 25 degrees?

Answer 42

The thermal conductivity of water is greater than air

Question 43

What are some key facts about sweating?

Answer 43

1. When sweating is minimally stimulated, sweat urea is very concentrated 2. Maximal sweat production in a heat acclimatised person is 2L per hour 3. Heat acclimatised people secrete less sodium into their sweat by and aldosetone-dependent mechanism 4,. K+ concentration in sweat is greater than in plasma 5. Sweating occurs whenever temp is high, not just when it is rising

Question 44

Why do we feel cold when we have a fever?

Answer 44

Internal thermostat is set higher Temperature receptors think that the environment is a lot colder We feel coldest when central body temperature is rising ->metabolic rate rises to keep us warm Temperature swings do not occur with changes in environmental temperatures

Question 45

Why do skin vessels dilate?

Answer 45

To allow skin temperature to approach core temperature