Respiratory System Pt.2

Respiration

4 continuous processes

• Pulmonary ventilation

• Alveolar gas exchange

• Gas transport

• Systemic gas exchange

Pulmonary ventilation

• Movement of gases between atmosphere and alveoli (breathing)

• Involved 4 organ systems: respiratory, skeletal, muscular, and nervous

Alveolar Gas Exchange

• Exchange of gases between the alveoli and the blood. Exclusively in the lungs

• Oxygen diffuses from alveoli into the blood, CO₂ transports out

Gas Transport

Movement of gases in the blood between the lungs and erythrocytes

Systemic Gas Exchange/Internal Respiration

• Exchange of gases between blood & systemic cells. All throughout the body

• Oxygen diffuses from blood into cells/tissues, CO₂ transports out

• Oxygen diffuses from capillaries (blood) into cells because PO₂ is higher in capillaries than in the cells

• Carbon dioxide diffuses from cells into capillaries because PCO₂ is higher in the cells

Expiration (Thoracic Pressure)

• As the diaphragm and external intercostals relax, the volume in the thoracic cavity decreases → increase in both intrapulmonary & intrapleural pressures

• When intrapulmonary > atmospheric pressure, the air is forced out of alveoli into the atmosphere

Inspiration (Thoracic Pressure)

• As the diaphragm and external intercostals contract, the volume in the thoracic cavity increases → decrease in both intrapulmonary & intrapleural pressures

• When intrapulmonary < atmospheric pressure, the air move from atmosphere into the lungs

Breathing Mechanics

• Autonomic nuclei triggers skeletal muscles to contract & relax → change in the thoracic cavity volume

• Volume changes → pressure change leads to gradient establishes between the lungs and atmosphere

Intrapulmonary Pressure

Pressure exerts by the alveoli within the lungs (alveolar volume)

Intrapleural Pressure

• Pressure exerts within the pleural cavity

• Always lower than intrapulmonary pressure so the lungs remain inflated

• The serous fluid in the pleural cavity create surface tension → the lungs cling to the chest wall as they expand (outward pull)

• This inward & outward pull of the lungs create a vacuum and is the main source of the pressure

• Lungs remain inflated as long as intrapleural < intrapulmonary

Ventral Respiratory Group

Forced breathing initiates by neutral impulses for inspiration & expiration

Chemoreceptors (Influenced By)

• Breathing rate and depth influence by blood CO₂ levels

• Increase blood CO₂ → increase breathing rate

Airflow

Amount of air passes into and out of the lungs with each breath

Resistance

What opposes airflow

• Decrease in chest wall and lung elasticity

• Change in bronchiole diameter

• Collapse of alveoli, the production of pulmonary surfactant decreased (premature infants)

Tidal Volume

Amount of air inhaled or exhaled per breath during quiet breathing

Inspiratory Reserve Volume (IRV)

Maxiumum amount of air that can be inhaled beyond tidal volume

Expiratory Reserve Volume (ERV)

Maximum amount of air that can be exhaled beyond tidal volume

Residual Volume (RV)

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

Vital Capacity (VC)

• Represents amount of air an individual can exchange through forced breathing

• TV + IRV + ERV

Total Lung Capacity (TLC)

• Maximum amount of air the lungs can hold

• TV + IRV + ERV + RV

Oxygen Transport

• 98% of blood’s oxygen transported by the heme group in the hemoglobin

• 2% of soluble oxygen is dissolved in plasma

Carbon Dioxide Transport

• 70% of CO₂ combines with water to form bicarbonate ion and diffuses into plasma

• 23% attached to globin portion of hemoglobin

• 7% dissolved in the plasma

Hemoglobin

• Has 4 iron atoms, which means it can bind to maximum of 4 oxygen molecules

• As PO₂ increases, hemoglobin saturation increases

• High partial pressure of oxygen favors loading of O₂ onto Hb

• Low PP favors unloading of O₂ from Hb

pH on Hemoglobin

• acidic pH favors unloading of O₂ from Hb. Proton binds to Hb and alter it’s structure

• basic pH favors loading of O₂ from Hb. Hb becomes deprotonated and promote oxygen binding

• Increased CO₂ → increased H+ → increased O₂ from hemoglobin

Respiratory System

Exchange of gases between the atmosphere and lungs

Skeletal & Muscular Systems

Alter the volume → change in pressure → air moves in & out of the lungs

Nervous System

Innervate & coordinates the muscle of breathing

Cardiovascular System

Transport oxygen and carbon dioxide between the lungs & cells