Aerobic respiration

Metabolism is all the chemical reactions happening in your body building up and breaking down molecules.

Factors like diet, drugs, genetics, age, gender, muscle mass, medications, body size and disease can all affect a persons metabolism

Respiration is the chemical reaction that causes the release of energy from glucose as it is broken down. This happens continuously in the mitochondria of all cells there are two types of respiration aerobic and anaerobic

Breathing and respiration are not the same thing, breathing is the mechanical process of getting air into and out of the lungs, respiration is the chemical reaction that releases energy. Respiration is an exothermic reaction which means that energy is transferred to the environment.

Organisms need energy for many reasons

• Transmission of nerve impulses

• Movement - allows muscles to contract

• Keep warm / a steady body temperature

• Chemical reactions

• Active transport

• To maintain homeostasis

• For cell division

Word equation : Glucose + oxygen → water + carbon dioxide

Balanced symbol equation : C6H12O6 + 6O2 → 6H2O + 6CO2

The alveoli are adapted for absorbing oxygen and transferring carbon dioxide, their three key adaptations are: a large surface area, thin walls, good blood supply

Anaerobic respiration and oxygen debt

Anaerobic respiration happens without oxygen, it is the incomplete breakdown of glucose to form lactic acid so much less energy is released during anaerobic respiration

Word equation: Glucose → lactic acid (+small amount of energy)

Symbol equation : C6H12O6 → 2C3H6O3

During strenuous exercise when there is no oxygen and low glucose the body uses stored glycogen to release glucose

Lactic acid is poisonous to muscles. It stops them contracting and relaxing so they become tired. Lactic acid has to be broken down in the liver into carbon dioxide and water this requires extra oxygen. Oxygen debt is the amount of extra oxygen needed to break down the lactic acid. The muscles recover from their fatigue as the oxygen debt is removed, this is your recovery time, the bigger the debt the longer you will take to catch your breath.

The equation is Lactic acid + oxygen → carbon dioxide + water

Anaerobic respiration in yeast cells is called fermentation and has economic importance in the manufacture of bread and alcoholic drinks

Glucose → ethanol + carbon dioxide

Ethanol is a type of alcohol this cooks off when the bread dough is baking, the carbon dioxide bubbles get trapped in the dough causing the bread to rise

Exercise and respiration

Heart rate - Number of heart beats in one minute

Breathing rate - Number of breaths in one minute

Depth of breathing - Volume of air taken in one breath

Blood vessels - Carry blood containing oxygen and glucose to cells

Metabolism

Metabolic reactions:

• Forming lipids from fatty acids and glycerol

• Converts glucose to starch, glycogen and cellulose

• Respiration

• Using glucose and nitrate ions to make amnio acids

• Photosynthesis

• Breakdown of proteins into urea