Respiratory System Physiology Flashcards
What gradient does air follow, and what happens without it
High to low, no air movement
What does inspiration require within the body
A lower alveolar pressure than atmospheric pressure
Describe normal inspiration
Contraction of respiratory muscles = enlargement of the thoracic cage & lung expansion = decrease in pressure inside lungs = air moves in
What is the principle muscle of inspiration
The diaphragm
Describe the diaphragm
Large, dome-shaped sheet
What muscle may be the only one used during quiet breathing
The diaphragm
When the diaphragm contracts, what happens
There is a downwards pull enlarging the thoracic cavity
During max ventilation the diaphragm can move as much as __ cm
10 cm
What controls the diaphragm
The phrenic nerve, innervated through the 3rd-5th cervical vertebrae
What can be a complication with a cervical spine injury at or below C3
Paralysis of the ventilatory muscles
What do the intercostal muscles do
Increase the anterior-posterior diameter of the thorax by moving the anterior end of ribs up & out
What does contraction of the intercostal muscles do
Tenses the intercostal spaces so they aren’t sucked in during inspiration
Where are the nerves that control the intercostal muscles
C1-11
What are the accessory muscles of inspiration
Scalenes & sternocleidomastoids
What do the accessory muscles do
Contraction raises the 1st rib, manubrium & sternum, while helping to stabilize the thoracic cage so the intercostal muscles can function accordingly
Max contraction of the inspiratory muscles can decrease intrapleural pressure by how much
60-100mmHg
Expiration is usually __
Passive
How is potential energy stored in the inspiratory muscles, and why is it important for expiration
Through contraction causing the elastic tissues of the lungs & thorax to stretch, which recoil & release the stored energy producing expiration
When do expiratory muscles actively contract
At high respirates or with partial/moderate airway obstructions (ie asthma/emphysema)
What abd muscles are pertinent for expiratory
External & internal obliques, rectus abdominus, transverse abdominus
How do the abdominal muscles contribute to expiration
Contraction increases intra-abd pressure therefore pushes the diaphragm up & depresses the lower ribs which decreases the thorax circumference
How do the internal intercostal muscles assist with expiration
The depress the ribs down & in, while stiffening the intercostal spaces so they dont bludge during expiratory efforts
What are the respiratory reflexes
Sneeze & cough
What are the mechanics of a cough
Violent expiratory blast against a partially closed glottis
What induces a cough
Irritation/stimulant of a sensory nerve endings in either the larynx, trachea, or larger bronchi which transmits impulses to the cough center in the medulla
What are some examples of irritant/stimulus that may cause a cough
Irritation/stimulant of a sensory nerve endings in either the larynx, trachea, or larger bronchi which transmits impulses to the cough center in the medulla
Describe the process of a cough
Deep inspiration —> tight closing of glottis (accumulates pressure in the air passages) —> expiration against the glottis —> glottis partially opens to expel the material
