Human Respiratory System (WJEC GCSE Biology)

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Cara Head

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Cara Head

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Human Respiratory System

  • Large organisms require specifically adapted gas exchange surfaces to make sure that oxygen can be delivered to respiring cells at a fast enough rate
  • The human respiratory system is adapted to
    • take in sufficient oxygen to support aerobic respiration
    • remove the carbon dioxide that is produced during respiration 

Structures of the human respiratory system diagram

structures-in-the-human-breathing-system-igcse-and-gcse-biology-revision-notes

The main structures of the human respiratory system

Structure & function table

Structure Function
Nasal cavity

Interior of the nose

Humidifies and warms inspired air and removes airborne particles and debris before the air reaches the lungs

Lungs Pair of organs enclosed in the thorax is required for breathing
Trachea

Windpipe that connects the nose and the mouth to the lungs

Lined with goblet cells and ciliated epithelial cells

Bronchi (singular = bronchus)

Large tubes branching off the end of the trachea

Lined with goblet cells and ciliated epithelial cells

Bronchioles

Smaller tubes that branch from the bronchi connecting to the alveoli

Alveoli

Tiny air sacs surrounded by a network of capillaries

The site of gas exchange between oxygen and carbon dioxide

Diaphragm Sheet of connective tissue at the bottom of the lungs that helps change the volume inside the thorax allowing inspiration and expiration
Ribs

Bone structures that surround and protect the lungs.

Aid in the action of breathing

Intercostal muscles Muscles between the ribs that control the movement of the ribs, causing inspiration and expiration

The function of mucus and cilia

  • The passages down to the lungs are lined with ciliated epithelial cells
  • Cilia cells have tiny hair-like structures on the end of them that beat and push mucus up the passages towards the nose and throat where it can be removed
  • The mucus is made by special mucus-producing cells called goblet cells (named this because they are shaped like a goblet or cup)
  • The mucus traps particles, pathogens like bacteria or viruses, and dust and prevents them from getting into the lungs and damaging the cells there

Cilia and mucus diagram

cilia-2

Mucus traps particles, dust and pathogens and cilia beat and push it up and away from the lungs

Examiner Tip

You need to be able to label the structures covered above in diagrams so do make sure you are confident in doing this on a range of diagrams

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Cara Head

Author: Cara Head

Expertise: Biology

Cara graduated from the University of Exeter in 2005 with a degree in Biological Sciences. She has fifteen years of experience teaching the Sciences at KS3 to KS5, and Psychology at A-Level. Cara has taught in a range of secondary schools across the South West of England before joining the team at SME. Cara is passionate about Biology and creating resources that bring the subject alive and deepen students' understanding