The Respiratory System: Physiology

Oxygen Transport

98% of the blood's oxygen is transported by hemoglobin

Airflow

Amount of air that moves into and out of lungs in each breath Resistance: what opposes airflow 1) decrease in chest wall and lung elasticity 2) change in bronchiole diameter 3) collapse of alveoli

Quiet Breathing: Expiration

As the diaphragm and external intercostals relax, pleural cavity volume decreases, so intrapleural pressure increases Lungs are pulled inward (recoil of elastic tissure), so intrapulmonary pressure in creases Pressure gradient: intrapulmonary pressure is greater than atmosphereic pressure, so air is forces out of alveoli into the atmosphere

Total lung capacity (TLC)

Maximum amount of air that lungs can hold TV + IRV + ERV + RV (Residual Volume)

Systemic Gas Exchange

Oxygen diffuses out of systemic capillaries into the interstitial fluid prior to entering the cells Carbon Dioxide exits the cells and enters into the capillaries

Alveolar Gas Exchange (external respiration)

Oxygen diffusing from the alveoli into the blood and carbon dioxide diffusing from the blood into the alveoli Oxygen diffuses from the alveoli into the blood because the pressure is greater in the alveoli and less in the blood so the oxygen moves down its gradient Carbon dioxide diffuses from the blood into the alveoli by moving down its pressure gradient

Quiet Breathing: Inspiration

Pleural cavity volume increases leads to a decrease in intrapleural pressure Lungs expand due to surface tension, alveolar volume increases, resulting a decrease in intrapulmonary presssure Pressure gradient: when intrapulmonary pressure is less than atmospheric pressure, air moves down its gradient from the atmosphere into the lungs

the 4 continuous processes respiration

Pulmonary Ventilation: movement of gases between the atmosphere and the cells of the body Alveolar gas exchange: exchange of gasses between alvelioli and the blood Gas transport: movement of gases in the blood between the lungs and the cells of the body Systemic gas exchange: exchange of gases between blood and the systemic cells

Vital Capacity (VC)

Represents amount of air an individual can exchange through forced breathing VC= TV (Tidal Volume) + IRV (Inspiration Reserve Volume) + ERV (Expiration Reserve Volume)

Intrapleural Pressure

The pressure exerted within the plural cavity The serous fluid in the pleural cavity creates surface tension, that causes the lungs to cling to the chest wall as it expands (outward pull) Elastic connective tissue in the lungs cause lungs to recoil as it expands (inward pull) The outward pull of the chest wall and inward pull of the lungs create a vacuum or "suction" in the pleural cavity, which is called intrapleural pressure Intrapleural pressure is lower than the intrapulmonary pressure so that the lungs remain inflated

Tidal Volume (TV)

amount of air inhaled or exhaled per breath during quiet breathing

Expiratory Reserve Volume (ERV)

maximum amount of air that can be exhaled beyond tidal volume ( normal exhalation)

Inspiratory Reserve Volume (IRV)

maximum amount of air that can be inhaled beyond tidal volume (normal inhalation)

Carbon Dioxide Transport

most of CO2 diffuses into erythrocytes, as biacarbonate dissolved in plasma

quiet/ involuntary breathing

moved by diaphragm and external intercostals breathing that occurs when you are relaxed air moves into and out of lungs as they contract/relax

volume change in the thoracic cavity cause?

pressure changes which result in a pressure gradient

Pleural cavity

space between the visceral and parietal membranes, contains serous fluid that is produced by the serous membranes

Residual Volume (RV)

the amount of air left in the lungs after forceful expiration (beyond ERV)

Atmospheric Pressure

the pressure all the gasses in the air exert in the environment

Intrapulmonary Pressure

the pressure exerted by the aleveoli within the lungs

Boyle's Gas Law

volume of the thoracic cavity and pressure are inversely proportional if the volume of the thoracic cavity increases the pressure decreases, establishing a pressure gradient