Respiration and Gas Exchange

Aerobic respiration

The reaction in cells that releases energy from glucose using oxygen

Anaerobic respiration

A form of respiration that can occur without using oxygen. In this reaction glucose is not completely broken down and less energy is released e.g. in yeast and muscle cells

Aerobic respiration equation

Glucose + Oxygen → Carbon Dioxide + Water

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O

Oxygen debt

The volume of oxygen needed to completely break down the lactic acid build up produced in the body during anaerobic respiration

Lactic acid

Produced in muscles when glucose is broken down anaerobically during strenuous muscular activity

Ventilation

The mechanism that moves air into and out of the lungs

Gas Exchange System

The lungs and associated structures make up this system

Thorax

The part of the human body between the neck and the abdomen, partially enclosed by the ribs and containing the heart and lungs

TERM

Diaphragm

DEFINITION

A shallow dome-shaped, muscular partition separating the thorax from the abdomen. Used in ventilation (contacts to inhale)

TERM

Trachea

DEFINITION

Major airway, reinforced by rings of cartilage, that extends from the larynx to the bronchi

TERM

Bronchus

DEFINITION

Tube leading from the trachea to each lung

TERM

Alveoli

DEFINITION

Microscopic air sacs found at the end of bronchioles. They have a large surface area, moist layer, and lots of capillaries to allow efficient gas exchange with the blood

Cartilage

Tough connective tissue found in the walls of the trachea and bronchi. It supports the airways and keeps them open when we breathe

Intercostal muscles

Muscles found between each rib (external intercostal muscles contract when inhaling)

TERM

Pleural membranes

DEFINITION

Thin, moist membranes that form a continuous envelope around the lungs, creating an airtight seal

Mucus

Secreted into respiratory airways by goblet cells to trap particles of dirt and bacteria that are breathed into the body

Cilia

Fine hair-like projections that line the respiratory tract. They beat rhythmically to sweep mucus and trapped particles towards the mouth and away from the lungs preventing infection

Anaerobic respiration equation

Glucose → Lactic acid

C₆H₁₂O6 → 2C₃H₃O₃

TERM

Inhalation

DEFINITION

Air is drawn into the lungs when external intercostals contract pulling the ribs up and out. The diaphragm muscles contract causing the diaphragm to flatten. This increases chest volume and lowers pressure inside the thorax so air is drawn into the lungs.

TERM

Exhalation

DEFINITION

Air is forced out of the lungs when internal intercostals contract pulling the ribs down and in. The diaphragm muscles relax and the diaphragm returns to a dome shape. This reduces chest volume and raises pressure inside the thorax so air is forced out of the lungs.

To clear the oxygen debt equation

oxygen + Lactic acid (C3H6O3) = carbon dioxide + water (+small amount of energy)

Diffusion

Movement of particles from an area of high concentration to low

TERM

Bronchioles

DEFINITION

smaller tubes feeding off the bronchi into each lung

TERM

Emphysema

DEFINITION

reduces surface area of alveoli by scaring them - caused by smoking

Lung cancer

carcinogens in smoke can cause this - tar and nicotine result in tumours

Carbon Monoxide

Poisonous gas that binds irrefutably to red blood cells - found in car exhaust fumes and citrate smoke

TERM

nasal cavity

DEFINITION

space in the nose for filtering air

TERM

pharynx

DEFINITION

space at the back of the mouth and nasal cavity - basically the throat.

TERM

larynx

DEFINITION

the voice box - part of the trachea with cords for making sounds

TERM

lung

DEFINITION

organ with a large surface area made for gas exchange due to the large demand for oxygen