Porth - Respiratory Function Flashcards
Primary Function of Respiratory System
Gas Exchange
- O2 from the air transferred into the blood
- CO2 from blood eliminated into atmosphere
2 Parts of the Respiratory System (Functionally)
- Conducting airways:
- Air moves as it passes btwn atmosphere and lungs
- Filters, humidifies, & warms air
- Respiratory Tissues:
- . Gas exchange occurs here in the lungs
Mediastinum
- “The Space Between the Lungs”
- Separates lungs
Conducting Airway Structures
- Nasal passages
- Mouth
- Pharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
The Conducting Airways Wall has 3 components… What are they?
- Mucosal Lining (epithelial & conductive tissue)
- Smooth Muscle Layer
- Supporting Connective Tissue Layer
–Lined with ciliated pseudostratified columnar epithelium (provides moisture)
—Cigarette smoking slows down/paralyzes cilia’s motility: creates particle accumulation in lungs; decreases defenses
Ventilation
Movement of gases into and out of the lungs through a system of open airways & along a pressure gradient resulting from a change in chest volume.
Perfusion
Movement of blood through the lungs
Innvervation of the Lung
- Sympathetic & Parasympathetic NS divisions
- Parasympathetic = Vagal Nerves
- Sympathetic = Upper Thoracic & Cervical Ganglia
– Together, these guys form the Pulmonary Plexuses
Nervous System-wise, what do you NOT find in the Lungs?
- NO Voluntary Motor Innervation
- NO Pain Fibers
- Pain fibers are found in the pleura
Parasympathetic NS & Stimulation
- Airway constriction
- Blood Vessel Dilation
- Increased Glandular Secretion
- Excitatory/Cholinergic motor neurons are located here & respond to ACH
The smooth muscle of the lung under Normal Resting Conditions is…
Slight constricted
Due to parasympathetic stimulation
Sympathetic NS & Stimulation
- Airway Dilation
- Blood Vessel Constriction
- Inhibition of glandular secretion
Pleura
- Thin, transparent, double-layered serous membrane.
- Lines thoracic cavity
- Encases Lungs
- Thin flim of serous fluid separates the layers
Pleural Cavity
- Potential space in which serous fluid or inflammatory exudate can accumulate
- *Pleural effusion = Abnormal collection of fluid in the pleural cavity*
Partial Pressure
Pressure exerted by a single gas in a mixture. Denoted by a “P”.
A little bit of physics…
- Air moves between the atmosphere and lungs b/c of a pressure different (or gradient).
- Inspiration = air moves into lungs as size of chest cavity increases
- Expiration = air moves out of lungs as size of chest cavity decreases
- Movement is from the area of greater pressure to less.
Minute Volume
- The amount of air that is exchanged each minute.
- Determined by the metabolic needs
- Tidal Volume x Respiratory Rate
What causes the negative pressure in the Pleural Cavity?
- Opposing forces of the chest wall and lungs
During Inspiration….
- Chest cavity size increases
- Intrathoracic pressure decreases (becomes more negative)
- Diaphragm contracts
- Air is brought into Lungs!
During Expiration…
- Chest wall & lung structures recoil
- Diaphragm relaxes
- Chest cavity size decreases
- Pressure inside the cavity increases
- Expiration is largely passive
Diaphragm
The Principle muscle of inspiration!
- During normal levels of inspiration, the diaphragm moves ~1cm.
- Innvervated by the Phrenic Nerve (C3,C4,C5)
Lung Compliance
- The ease with which the lungs can be inflated
- “Measure of change in lung volume that occurs with a change in intrapulmonary pressure.”
Lung Diseases that mess with the elasticity of the Lungs
- Interstitial Lung Disease
- Pulmonary Fibrosis
- Elastin fibers replaced by collagen
- Pulmonary congestion
- PE
- Increase water content in lung, thus decreasing compliance
Elastic Recoil
- Ability of the lung to recoil to their original position after being stretched
- Emphysema overstretches lung tissues
- Easy in inflate
- Harder to deflate
