Respiratory System

Human respiratory system

A system of organs, functioning in the process of gas exchange between the body and the environment, consisting of the trachea, bronchi, alveoli and lungs

Need for a respiratory system

Large organisms require a complex respiratory system in order to obtain a sufficient volume of oxygen to maintain a high level of aerobic respiration and to remove an equivalent volume of waste carbon dioxide

Gaseous exchange

The process where oxygen is taken in and exchanged for carbon dioxide which is a waste product of respiration

Sites of gas exchange

The alveoli of the lungs and respiring cells around the body

Oxygen

A gas that is needed for aerobic respiration to release energy, oxygen is transported into the body by the respiratory system and around the body by the circulatory system

Carbon dioxide

A waste product of respiration that needs to be removed from cells via the blood and removed from the body via the respiratory system

Lungs

The main organs of the respiratory system, responsible for gas exchange where oxygen is exchange with carbon dioxide in the blood

Nasal cavity

A hollow space behind the nose that regulates the flow of air into the respiratory system

Trachea

Allows air to pass to and from lungs

Bronchi

Two short branches at the lower end of the trachea that carry air into the lungs

Bronchioles

Airways in the lungs that are made up of multiple branches, leads from the bronchi to the alveoli

Alveoli

Tiny sacs of lung tissue where gaseous exchange takes place with the blood

An effective exchange surface

Has a large surface area, a good blood supply, is well ventilated for gas exchange and has a thin membrane for diffusion

Capillary network

An interconnecting network of capillaries surrounding the alveoli for optimised gas exchange

Capillaries

Small and thin blood vessels where the exchange of molecules such as oxygen and carbon dioxide takes place, they consist of a single layer of cells

Diaphragm

A large muscle at the bottom of the chest cavity that helps control breathing, when the diaphragm pulls down and contracts to become flat, air can easily enter the lungs

Intercostal muscles

Muscles in between the ribs which move the rib cage during breathing

Pleural membrane

Double-layered membrane that encloses and protects each lung

Pleural fluid

Fluid necessary to prevent friction between the pleural membranes

Mucus and cilia

Help protect the respiratory system, particles and bacteria stick to mucus and the cilia moves the mucus out of the respiratory system to the back of the throat

Surface area to volume ratio

The amount of surface area in relation to how large something is, a larger surface area to volume ratio leads to faster diffusion rates

Diffusion

The movement of substances such as gas particles or substances in solution, from a higher concentration to a lower concentration

Adaptations of the respiratory system

Large surface area due to multiple branches of bronchioles and many alveolar sacs, good blood supply for quick diffusion, well ventilated, ventilation is optimised by effective involuntary muscular action