Metabolic fuel of diffrent human tissues

Question 1

what does skeletal muscle break down for energy

Answer 1

carbohydrate catabolism generates ATP fastest when compared to fat or amino acid

can support higher intesity of exercise

Question 2

cardiac muscle
(type of metabolism, enriched, fuel)

Answer 2

• contracts continuously -> aerobic metabolism (oxy)
• enriched with mitochondria

fuels:

• fatty acids
• ketone
• lactate (produced by skeletal muscle)

Question 3

skeletal muscle

store, contraction via, fuel

Answer 3

• stores LOTS of glucose as glycogen
• muscle contraction via ATP hydrolysis

fuels:

• glucose
• fatty acids
• ketones

Question 4

liver

function, rate of catabolism, store/convert, fuels

Answer 4

• major function is to buffer blood glucose concentration
• high rate of catabolism to support rapid and constant rate of ATP utilisation
• maintains neccesary levels of circulating fuels for use of other tissue
• stores glucose as glycogen
• converts excess glucose (and amino acids) into fatty acids

fuels:

• 1. fatty acids -> when metabolic needs are high
• glucose
• lactate
• amino acid (oxidation to CO2/H20 or convert to glucose & ketone)
• NO KETONES

Question 5

brain (neuronal cells)

rate, fuel

Answer 5

• high rates of catabolism to support rapid and constant ATP use

fuel:

• glucose
• ketone bodies (starvation)
• NO FATTY ACID

Question 6

adipose tissue (tags)
(rate, release, fuel)

Answer 6

• low rates of catabolism
• main site of tag storage
• releases fatty acids into blood during fasting and exercise

fuel:

• glucose
• fatty acids
• ketone bodies

Question 7

rbc

structure, rate, fuel

Answer 7

• lacks mitochondria
• therefore low rate

fuel:
- can only break down glucose anaerobically (to lactate) for ATP

Question 8

ocular tissues

• corneal epithelium
• lens fibre cells
• retina (glucose flux)
• photoreceptor cells

Answer 8

• corneal epithelium (CL wear) and lens fibre cells (distal from blood supply)
• therefore relies heavily on anaerobic metabolism (no oxy)
• CE > LFC energy demand
• retina glucose flux through GLYCOSIS much higher than any other part of eye
• photoreceptors highest demands for glucose and oxygen

Question 9

where is glycogen located in occular tissues

Answer 9

• small amounts of glycogen in corneal epithelial cells
• some in retina
• glycogen from liver able to be suplied to other parts of eye as needed

Question 10

function of gluconeogenesis

Answer 10

• carried out via liver (or kidneys)

- primarily to supply glucose for brain and photoreceptor cells

Question 11

sprinter energy consumption breakdown

Answer 11

• uses atp reserves in muscle cells
• regenerates ATP using substrate level phosphorylation (in first 5-6 sec) -> creatine
• then powered by anaerobic glycolysis of muscle glycogen

muscle glycogen can generate ATP for longer but SLOWER than creatine

Question 12

middle distance runner energy breakdown

Answer 12

• ATP yield via anaerobic glycolysis of muscle glycogen to form lactate
• sufficient for 3 mins

Question 13

long distance runner energy breakdown

Answer 13

• glycogen supplies glucose for aerobic breakdown to CO2 and H2O
• glycogen from muscle and liver sufficient for 2 hours
• carb loading increases glycogen supplies
• ATP via fatty acids is too slow
• elite runners consume fatty acids & glycogen (increase acetly CoA -> inhibits pyruvate dehydrogenase -> saves glucose for last sprint)