Biology - Respiratory System

Ventilation vs. Gas exchange vs. respiration

• THE 3 FUNCTIONS OF RESP SYSTEM

• Ventilation = Movement of air in and out of alveoli (inhalation + exhalation)

  • Controlled by movement of ribcage, uses intercostal and diaphragm muscles

• Gas Exchange = Diffusion of gasses (oxygen and carbon dioxide) in and out of blood

  • Air entering alveoli has higher Oxygen concentration than in blood surrounding

  • Oxygen diffuses alveoli → blood, CO2 diffuses blood → alveoli

  • CO2 concentration high in bloodstream, low in alveoli

  • Oxygen diffuses blood → tissue cells, Carbon Dioxide diffuses tissue cells → blood

• Cell Respiration = Produces ATP by mitochondria and waste product carbon dioxide

  • aerobic respiration = uses oxygen, anaerobic respiration doesn’t

Inhalation vs exhalation

• Inhalation = air taken in to lungs

  • diaphragm contracts and moves downward

  • Ribs move up and out

  • Intercostal Muscles: Internal relax, External contract

• Exhalation = air removed from lungs

  • diaphragm relaxes and moves upward

  • Ribs move down and inward

  • Intercostal muscles: Internal contract, External Relax

Nasal Cavity

• Air moves inside nose and mouth

• Air is warmed and moistened, prevents damage to respiratory membrane tissue

• Lined with Tiny Hairs and Mucus, prevents dust and airborne particles from entering lungs

Pharynx

• Throat

• Epiglottis at bottom of it prevents food from entering trachea (open for breathing, closed for eating)

• Air travels through it

Larynx

• Voicebox

• Produces sound - vocal chords are pulled together when air is expelled

Trachea

• Flexible tube through which air passes

• Secretes Mucus - traps dust and other particles bc sticky

• Cilia - Wave like motions sweep trapped material up. its swallowed/expelled from body (cough, sneeze)

Bronchi

• Branch off trachea, enter each lung to conduct air into lungs

Bronchioles

• Each bronchi branches into smaller tubes that lead into alveoli

Alveoli

• site of gas exchange

• Epithelium = single layer of cells on wall of each alveolus

• Type 1 Pneumocytes (95%) involved in gas exchange

• Type 2 Pneumocytes (5%) secrete fluid that has pulmonary surfactants, reduce surface tension and prevent lungs collapsing

Diagram

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