Biology - 9 Respiration - 9.3 Anaerobic Respiration & 9.4 Metabolism and the Liver

When does anaerobic respiration take place?

when there is not enough oxygen available

Anaerobic respiration word equation

glucose → lactic acid

Anaerobic respiration symbol equation

C₆H₁₂O₆ → 2C₃H₆O₃

Muscle fatigue

Inability of muscle to maintain its strength of contraction or tension

What can cause muscle fatigue? [3]

- depletion of glycogen
- shortage of oxygen
- lactic acid buildup

Oxygen debt

the amount of oxygen required after physical exercise to convert accumulated lactic acid to glucose

Oxygen debt repayment equation

lactic acid + oxygen → carbon dioxide + water

What is anaerobic respiration called in plants and microorganisms?

fermentation

Fermentation word equation

glucose → ethanol + carbon dioxide

Fermentation symbol equation

C₆H₁₂O₆ → 2C₂H₅OH + 2CO₂

Metabolism

sum of the chemical reactions that occur within an organism or cell

Common metabolic reactions [5]:

- conversion of glucose to starch, glycogen and cellulose
- formation of lipid molecules from glycerol and three fatty acids
- use of glucose and nitrate ions to form amino acids that then form proteins
- respiration
photosynthesis
- breakdown of excess proteins in liver to form urea for excretion by urine

Functions of liver [4]:

- detoxify poisonous substances (e.g. ethanol from alcoholic drinks)
- pass breakdown products into blood so they can be excreted in urine via kidneys
- break down old red blood cells and storing iron until it is needed for synthesis of new red blood cells
- breakdown of lactic acid

Hepatic vein

the vein that collects blood from the liver and returns it to the heart

Hepatic artery

carries oxygenated blood to the liver

Hepatic portal vein

the vein that collects blood from the intestines and carries it to the liver