Respiratory System Flashcards
Functions of the respiratory system
-Gas exchange
-Acid-base balance
-Thermoregulation
-Immune function
-Vocalization
-Enhances venous return
What is the order of structures that air passes through to get to the alveoli?
1) pharynx
2) larynx
3) trachea
4) bronchi
5) bronchioles
6) alveoli
What type of muscle are bronchioles?
Smooth muscle
How do bronchioles control air flow?
Through constriction or dilation
Where is the site of gas exchange?
Alveoli
Characteristics of alveoli
-Thin walled (simple squamous)
-Large surface area for diffusion (75 m square)
-Contain fine elastic fibres
-Pores of Kohn connect to adjacent alveoli
Why are the pores of kohn important?
-They help equalize air pressure so that alveoli do not burst
Type 1 vs Type 2 Alveolar cells. What is a third cell?
Type 1: make up the walls
Type 2: secretes surfactant
Alveolar macrophages: immune response
Define ventilation
The gas exchange between the atmosphere and alveoli in the lungs
Define external respiration
the gas exchange between alveoli and blood
Define internal respiration
gas exchange between blood and tissues
What is inspiration/expiration dependent upon?
Pressure gradients.
Bigger gradient = more air moving
What are the different pressures?
Atmospheric: air, typically 760 mmHg at sea level
Intra-alveolar: in alveoli
Intra-pleural: in pleural space, typically 756 mmHg
Transpulmonary: difference between intrapulmonary and intrapleural, typically 760 mmHg
What is Boyle’s law?
The pressure exerted by a gas varies inversely with the volume of a gas
If volume increases, then pressure decreases.
If pressure changes, gases will flow to equalize pressure.
Muscles of quiet inspiration
Diaphragm and external intercostals (move upwards)
Volume during quiet inspiration
Thoracic volume increases (vertically) and lungs stretch
Pressure during quiet inspiration
Intrapulmonary pressure decreases
-Air flows into the lungs down its pressure gradient until pressure is the same as atmospheric
Muscles of forced inspiration
-Diaphragm and external intercostals
-Recruit scalenus and sternocleidomastoid
Volume during forced inspiration
-Greater increase in thoracic volume (vertically)
Pressure during forced inspiration
Larger decrease in thoracic pressure
-Larger pressure gradient
-More air flows in
Muscles during quiet expiration
-Inspiratory muscles relax (there is no contraction)
Volume during quiet expiration
-Thoracic cavity volume decreases and lungs recoil
Pressure during quiet expiration
-Increase in alveolar pressure
-Air flows out of the lungs until pressure gradients are equal
Muscles during forced expiration
-Relaxation of inspiratory muscles still occurring
-Recruit abdominals and internal intercostals (push up on diaphragm and make space smaller)