Respiratory System

Main function of respiratory system

Extract oxygen from atmosphere and expel carbon dioxide from the body into the air

Parts of the upper respiratory tract

Nose/nasal cavity & mouth/oral cavity, paranasal sinuses, pharynx, epiglottis, larynx

Parts of the lower respiratory tract

Trachea, bronchi (primary, secondary, tertiary), bronchioles, alveoili

How are the lungs divided?

Lungs are divided into lobes: 3 lobes on the right, 2 lobes on the left

Pleura (description and function)

Tough, protective double membrane that surrounds the lungs and lines the chest cavity; protects the lungs and secretes fluid to allow the lungs to glide smoothly against the chest wall when breathing

Pleural cavity

The space in which the lungs sit in pleural fluid; the space between the visceral pleura (up against the lungs) and the parietal pleura (up against the chest wall)

Functions of the nose & nasal cavity

Starting point of the passage of air; filter, warm, and moisten air during inhalation

Pharynx (description and function)

• Part of the upper respiratory tract

• Muscular tube beginning in the back of the throat and ending at the glottis; connects the nasal/oral cavities to the larynx and esophagus

• Shared passageway for respiratory system (air) and digestive system (food/liquids)

Epiglottis (description and function)

• Leaf-shaped sheet/flap of elastic cartilage located at the top of the larynx

• Protects the larynx—closes when swallowing, cutting off passageway to the glottis/lungs

Glottis (description and function)

• Middle section of the larynx containing the vocal cords & slit-like opening between them

  • Produces sound (when air is forced through vocal cords), allows breath to pass through (vocal cords open), protects airway from food/liquids (vocal cords close along with epiglottis)

Larynx (description and function)

• Hollow tube above trachea and esophagus

• Contains supraglottis, glottis, subglottis

• Allows passage of air and ability to make sounds

Trachea (description and function)

• Aka the windpipe, begins lower respiratory tract

• Rigid tube of cartilaginous rings, anterior to the esophagus

• Connects to the larynx and splits into primary left and right bronchi

Bronchi (function and description)

• Primary bronchi (connected to trachea) branch repeatedly into secondary and then tertiary bronchi in the lungs

• Lined with:

  • Mucus, which moisturizes the air along the way and traps foreign particles, and

  • Cilia, hair-like projects that move in a wave and sweep mucus and debris upward and out of the lungs

Bronchioles

Microscopic tubes that branch off of tertiary bronchi, branch further and terminate in alveoli

Alveoli (description and function)

• Tiny balloon-like air sacs at the end of the respiratory tree (branch off of tertiary bronchi)

• Exchange oxygen and carbon dioxide with the bloodstream/surrounding capillaries during breathing

Diffusion

Process of exchanging gases (oxygen and carbon dioxide) between the alveoli and surrounding capillaries/bloodstream

Structure of alveoli and capillary walls

Single layer of epithelial tissue, allowing for diffusion of gases

Pathway of air during respiration/respiratory tract order

Nose/nasal cavity, pharynx, larynx, trachea, bronchi (primary, secondary, tertiary), bronchioles, alveoli

(Never Put Larry To Bed Before Al)

Ventilation

Movement/process of air in and out of the lungs

Parts of the brainstem involved with respiration

Medulla oblongata and pons

Regarding respiration, what do the medulla oblongata and pons monitor?

Levels of CO₂ and pH in the blood

What stimulates automatic inhalation and why?

Increasing levels of CO₂ cause an increase in H⁺ (positively charged hydrogen) ions, which make the blood more acidic and triggers automatic inhalation

What happens when the diaphragm and intercostal muscles contract?

Inhalation: the volume of the thoracic cavity and therefore the lung volume increases while the alveolar pressure decreases, causing air to flow into the lungs (where there is low pressure compared to outside of the lungs, where there is high pressure)

What happens when the diaphragm and intercostal muscles relax?

Exhalation: the volume of the thoracic cavity and therefore the lung volume decreases while the alveolar pressure increases, causing air to flow out of the lungs (where there is high pressure compared to outside of the lungs, where there is low pressure)

Surfactant (description and function)

• Lipid mixture secreted by cells inside the lungs

• Reduces surface tension within the alveoli, preventing them from sticking to each other and collapsing during exhalation/atelectasis

Atelectasis

The collapse of part or all of the lung, occurring when the alveoli deflate or fill with fluid

Tidal volume

The amount of air moving in and out of the lungs during a single, normal respiratory cycle

Total lung capacity (TLC)

The amount of gas in the lungs after a maximum inspiration

Vital capacity (VC)

The amount of gas that can be exhaled after a maximum inspiration

Residual volume (RV)

The amount of gas remaining in the lungs after a maximum expiration (necessary to prevent lung collapse)

Total lung capacity (TLC) equation

Vital capacity (VC) + Residual volume (RV)

Lung compliance

Measure of the ease of expanding the lungs

What factors affect lung compliance?

The elasticity of the lung tissue and alveolar surface tension

What is an example of a disease that causes increased lung compliance?

Emphysema—destroys elastic lung tissue and causes poor recoil, leading to ruptured/damaged alveoli and therefore less surface area for gas exchange, causing increased residual volume/RV

What is an example of a disease that causes low lung compliance?

Asthma, bronchitis, lung cancer; all cause increased resistance to lung expansion

What is cystic fibrosis and how does it affect the respiratory system?

• An autosomal recessive (genetic) disorder, involving a mutation of the CFTR gene

• Causes thick and sticky mucus in the lungs, leading to clogs in the airway and chronic respiratory infections