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Respiratory System Gross and Microscopic Anatomy

← Builds on Cell Biology and Histology Fundamentals

Terms you will need

  • nasal cavityThe nasal cavity is the space inside your nose where air goes first when you breathe. It helps clean, warm, and moisten the air before it moves deeper into your body.
  • pharynxThe pharynx is a tube that connects your nose and mouth to your windpipe and food pipe. It helps you breathe and swallow.
  • larynxThe larynx is the voice box. It helps you make sounds and keeps food from going into your lungs when you swallow.
  • tracheaThe trachea is a tube made of rings that carries air from your throat to your lungs. It keeps the airway open so you can breathe.
  • bronchiThe bronchi are two large tubes that branch off from the trachea and carry air into each lung.
  • bronchiolesBronchioles are small tubes that branch off from the bronchi. They carry air deeper into the lungs.

How this topic runs

  1. 1Start here
  2. 2How it works
  3. 3At competition depth

The respiratory system is essential for sustaining life by enabling gas exchange between the body and the environment. It consists of structures that transport air into and out of the lungs and microscopic surfaces where oxygen and carbon dioxide are exchanged. Without this system, cells cannot perform oxidative respiration, the process that produces energy in the form of ATP. Oxygen is necessary for this process, and carbon dioxide, a waste product, must be removed. The respiratory system includes the nose, pharynx, larynx, trachea, bronchi, bronchioles, and alveoli. The upper respiratory tract filters, warms, and moistens air, while the lower respiratory tract delivers air to the alveoli, where gas exchange occurs. The alveoli are tiny air sacs surrounded by capillaries, allowing oxygen to enter the bloodstream and carbon dioxide to be expelled. This system is vital for maintaining cellular function and overall health.

Figures (10)

Alveoli and their capillary networks
The lungs as main part of respiratory tract
On inhalation, air travels to air sacs near the back of a bird. The air then passes through the lungs to air sacs near the front of the bird, from where the air is exhaled.
The left lung
The right lung
Chest CT (axial lung window)
Cross-sectional detail of the lung
Thick elastic fibres from the visceral pleura (outer lining) of lung
TEM image of collagen fibres in a cross sectional slice of mammalian lung tissue
A lobule of the lung enclosed in septa and supplied by a terminal bronchiole that branches into the respiratory bronchioles. Each respiratory bronchiole supplies the alveoli held in each acinus accompanied by a pulmonary artery branch.

The trachea branches into bronchi, which further divide into smaller bronchioles, ending in alveoli. The system is divided into a conducting zone, which moves air, and a respiratory zone, where gas exchange occurs. The respiratory zone includes the alveoli and structures leading to them.

The lungs are protected by the rib cage and are surrounded by pleurae, which reduce friction during breathing. The diaphragm is the main muscle for breathing, contracting to expand the chest cavity and relax to allow exhalation. It also helps regulate body temperature and pH.

The system is vulnerable to infections and diseases, such as pneumonia, COPD, and asthma, which affect gas exchange and breathing. Understanding the anatomy and function of the respiratory system is key to grasping how the body maintains life through gas exchange.

Key Points

  • The nasal cavity is a space within the nose that filters, warms, and humidifies incoming air using a layer of nasal mucosa and turbinates.
  • The pharynx is a passage that connects the nasal cavity and mouth to the larynx and serves as a shared pathway for air and food.
  • The larynx is a structure in the upper respiratory tract that contains the vocal cords and is covered by the epiglottis to prevent food from entering the airway during swallowing.
  • The trachea is a tube reinforced with C-shaped rings of hyaline cartilage that carries air from the larynx to the bronchi.
  • The bronchi are the primary branches of the trachea that enter each lung and further divide into smaller airways called bronchioles.
  • Bronchioles are small airways that branch from the bronchi and lead to the alveoli, lacking cartilage and composed mainly of smooth muscle.

Terms

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