Exam 1 Flashcards
Respiration
Exchange of gases between a living organism and its environment
Three processes of respiration
Ventilation
Diffusion
Perfusion
Ventilation
Mechanical process of moving air in and out of the lungs (inspiration and expiration)
Diffusion
Movement of molecules through a membrane from an area of greater concentration to an area of lesser concentration
Perfusion
Circulation of blood through the capillaries
What is the upper airway responsible for?
Warming and humidifying incoming air
What is the lower airway responsible for?
Area where the respiratory exchange of oxygen and carbon dioxide occurs
Five functions of the nose
- Passage of air into respiratory system
- Warms air prior to entering lungs
- Moistens air before entering lungs
- Filters/cleans air of particles before entering lungs
- Speech resonating chamber
Three regions of Pharynx
Nasopharynx, oropharynx, laryngopharynx
Type 1 epithelial cells
Simple squamous
Assist with diffusion of gases
Type 2 epithelial cells
Septal cells
- Produce surfactant Wichita lowers surface tension of fluid on alveoli
- Prevents collapse of alveoli
Alveolar macrophages
Wandering phagocytes that remove fine dust particles and other debris in the alveolar spaces
Requirements for pulmonary perfusion
- Adequate blood volume
- Intact pulmonary capillaries
- Efficient pumping action by the heart
Boyle’s Law
When temperature is constant, the pressure of a gas varies inversely with its volume
- Lungs function by increasing/decreasing pressure to cause air to rush in or out
Dalton’s Law
Each gas in a mixture of gases exerts its own pressure (as if all other gases were not present)
Partial pressure of atmosphere and alveolar is 760 mmHg (torr)
Henry’s Law
Quantity of gas that will dissolve in a liquid depends upon the amount of gas present and its solubility coefficient
How does respiratory drive work?
Chemoreceptors in medulla are stimulated by an increase in PaCO2 or a decrease in pH
How does hypoxia drive work?
Chemoreceptors in aortic arch and carotid bodies are stimulated by a decrease in PaCO2
- Increases respiratory stimulation in people with chronic respiratory disease
What is the main respiratory centre?
Medulla oblongata
Apneustic centre
Assumes respiratory control if medulla fails to initiate impulses
Pneumotaxic centre
Controls expiration
Pons
Influences activity of medulla responses and smooths out transition between both respiratory phases
Two areas of medulla oblongata
Dorsal respiratory group - inspiratory centre that controls external intercostal and diaphragm
Ventral respiratory centre - inspiratory and expiratory centres, but mainly activated when O2 demands increase
External expiration
Gases diffuse from an area of high partial pressure to areas of low partial pressure
- exchange of gases between air and blood
- deoxygenated blood becomes saturated
Internal respiration
Exchange of gases between blood and tissues
Conversion of oxygenated blood into deoxygenated blood
Observe diffusion of O2 inward, and CO2 outward
Factors affecting hemoglobin binding
- Acidity
- Partial pressure of CO2
- Temperature
- BPG (2,3- biphoshoglycerate)
Average lung capacity of adult male
6 litres
- only a fraction is used during normal breathing
Tidal volume
Measure of depth of breathing
- Volume of air inhaled/exhaled during a single respiratory cycle
- Inspiratory reserve volume and dead space
Alveolar volume
Remaining volume of inhaled air
- reaches alveoli and undergoes gas exchange
alveolar volume = tidal volume - dead space volume
Minute volume
Amount of air that moves into and out of the respiratory tract per minute
- normally about 5600 mL
- increases if tidal volume or respiratory rate increase and vice versa
Tidal volume (minus dead space) x respiratory rate
