Respiratory System Flashcards
(48 cards)
What is the function of the respiratory system?
Exchange of O2 and CO2 between external environment and body’s circulatory system
What is ventilation?
The process by which air enters and exits the lungs
Inspiration: Air moves into the lungs
Expiration: Air moves out of lungs
What is the upper respiratory tract and what’s the function?
A system of organs and structures that functions to warm, moisten and clean air as it conducts from outside, down to the lower respiratory tract
What structures make up the upper respiratory tract, and does food or air (or both) pass through them?
Nasal Cavity (air only)
Oral Cavity (air and food)
Pharynx:
- Nasopharynx (air only)
- Oropharynx (air and food)
- Laryngopharynx (air and food)
What is the function of the lower respiratory tract?
Conducts air from the upper respiratory tract, down to the gas exchange surface
What structures make up the lower respiratory tract?
Larynx: epiglottis closes over trachea to prevent food entering airway
Trachea: rigid tube that maintains an open pathway for air
Bronchi: primary (1 each lung) and secondary (2 in the left, 3 in the right)
Bronchioles
Alveolar ducts
Alveoli: gas exchange surface
What happens in asthma?
Swelling, and bronchoconstriction can restrict or prevent airflow. lumen gets smaller which narrows the airway which means air can’t get through
What’s the alveoli?
Lined with really thin cells (simple, squamous epithelium). In clusters surrounded by pulmonary capillaries. The place where gas exchange occurs
What is surfactant?
Secreted by the alveoli cells to reduce the surface tension and keep alveoli open.
How do we generate airflow?
Diaphragm: our main respiratory muscle
Intercostal muscles: Internal and external
Accessory Muscles: used for forced breathing.
The diaphragm and external intercostal muscles are used at rest.
What is Boyle’s Law?
The pressure-volume relationship.
They are inversely related (when one increases, the other decreases)
What is inspiration and how is volume increased?
An active process and occurs when pressure in the lungs (Palv) is lower than the atmosphere (Patm) - air moves in.
Volume increases by contraction of external intercostal muscles elevating the ribs and contraction of the diaphragm flattens the floor of thoracic cavity.
What is expiration and how is volume decreased?
A passive process and occurs when pressure in the lungs is higher than the atmosphere - air moves out.
Volume decreases when diaphragm and intercostal muscles relax. Lungs have elastic elements causing elastic recoil inwards.
Mechanics of Breathing
The chest wall tends to recoil outwards and the lungs tend to recoil inwards.
This develops a negative pressure within the pleural space/cavity relative to the atmospheric pressure called the intrapleural pressure (always negative)
i.e when the chest wall expands outwards, the lungs expand with it
What is Tidal Volume (Vt)?
Volume of air that moves in and out with each breath. (normal quiet breathing)
What is Inspiratory Reserve Volume (IRV)?
The maximum volume of air that can be inspired beyond a normal tidal inspiration (forced inspiration)
What is Expiratory Reserve Volume (ERV)?
The maximum volume of air that can be exhaled after a normal tidal expiration (forced expiration)
Residual Volume (RV)
The amount of air remaining in the lungs after maximal forced expiration.
What is the vital capacity (VC)?
The maximum volume of air that can be expired after maximal inspiration (ERV + Vt + IRV)
What is total lung capacity (TLC)?
The maximum volume of air in the lungs after a maximal inspiration (VC + RV)
What is inspiratory capacity (IC)?
The maximum volume of air that can be inspired after a normal tidal expiration (Vt + IRV)
What is functional residual capacity (FRC)?
The amount of air in the lungs after a normal tidal expiration (RV + ERV)
How to calculate minute ventilation (Ve)?
Minute ventilation (Ve) = tidal volume (Vt) x breathing frequency (f)
What is dead space (Vd)?
The inhaled air that never gets to the alveoli so cannot gas exchange
