Module 16: The Respiratory System Flashcards
Pulmonary ventilation
“Breathing”
Inhalation (inspiration) and exhalation (expiration)
External respiration
Exchange of gases between the blood and the lungs
Transport of respiratory gases
In RBCs and plasma
Internal respiration
Exchange of gases between the blood and tissue cells
Conducting zone (macroscopic)
Nose Pharynx (throat) Larynx (voice box) Trachea (windpipe) Bronchi Terminal bronchioles
Epiglottis
Covers the opening of the larynx
Closes off the larynx during swallowing
Respiratory zone (microscopic)
Respiratory bronchioles
Alveolar ducts
Respiratory bronchioles
Formed from branchings of the terminal bronchioles
Alveolar ducts
Respiratory bronchioles lead into alveolar ducts
Alveolar ducts lead into clusters of alveoli
Alveoli (air sacs)
300 million in each lung provide a lot of surface area
Found in clusters called alveolar sacs
Where gas exchange occurs
Type I alveolar cells
Simple squamous epithelium
Provide the site for gas exchange between the capillaries and the alveoli
Type II alveolar cells
Septal cells Produce surfactant (reduces surface tension between fluid molecules inside the alveoli so they do not adhere to each other and collapse)
Macrophages
Dust cells
Wander around “cleaning up” foreign material
Hilus
Area in each lung where blood vessels, lymphatic vessels,
nerves, and the bronchus enter and leave the lung
Boyle’s Law
With a constant temperature, when volume ↓ then pressure ↑
Gas exchange in the lung
Air is inhaled
Oxygen diffuses from the alveoli into the capillaries
Carbon dioxide diffuses from the capillaries into the alveoli
Carbon dioxide is exhaled
Gas exchange in the body cells
Oxygen leaves the capillary blood and diffuses into the cells where it can be used during cellular metabolism
Carbon dioxide diffuses into the capillary blood as metabolism occurs in the cell
Transport of oxygen
Oxygen diffuses across the alveoli into the capillaries
Oxygen then dissolves in the plasma
About 3% of the oxygen is transported as a dissolved gas in the plasma
97% of the oxygen is carried by hemoglobin molecules in the erythrocytes
Transport of carbon dioxide
Diffuses from the tissue cells into the capillaries
Blood returns the carbon dioxide to the lungs in three ways:
• dissolved in the plasma (7%)
• combined with hemoglobin in the erythrocytes (23%)
• as bicarbonate ions in plasma (70%)
Medullary rhythmicity center
Sets the basic pattern of respiration
In a resting adult, inspiration lasts for about 2 seconds and expiration for about 3 seconds
Normal respiratory rate ranges between 12 and 20 breaths per minute in an adult and from 20 to 40 breaths per minute in a child
Central chemoreceptors
Sensitive to increases in carbon dioxide and hydrogen ion levels
Peripheral chemoreceptors
Detect decreases in oxygen levels
Respiratory distress syndrome (RDS)
Also called hyaline membrane disease (HMD)
Most common cause of death of newborns – almost exclusively in those born before the 37th week of gestation
Caused by a deficient amount of surfactant
Characterized by difficult breathing, which exhausts the infant
Aging and the respiratory system
Airways and tissues become less elastic – oxygen delivery to tissue cells is impaired
More susceptible to diseases due to the decrease in activity of the macrophages and ciliary action of the epithelial lining of the respiratory tract
