KNES 260 Lecture Notes - Lecture 14: Pleural Cavity, Respiratory Minute Volume, Sympathetic Nervous System
27 Feb 2017
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Functions of the Respiratory System
● Gas exchange
● Acid-base balance
● Thermoregulation
● Immune function
● Vocalization
● Enhances venous return
Bronchioles
● Can bronchoconstrict or dilate to control airflow
○ Uses smooth muscle to do this
● Epinephrine causes bronchodilation (sympathetic nervous system)
Alveoli
● Site of gas exchange
● Thin walls
● Large surface area for diffusion
● Blood can be directed to the alveoli which are getting the most air
○ Helpful for times like when you’re sick and part of your lungs are congested
● The Pores of Kohn connect adjacent alveoli to equalize air pressure
Two types of alveolar cells
● Type I make up the walls
● Type II secrete surfactant to decrease surface tension
Respiration
There are four main stages: Ventilation (air moving in and out of lungs), external respiration (gas
exchange between alveoli and blood), gas transport, internal respiration (gas exchange between
blood and tissues)
Ventilation
● Inspiration: gases flow into lungs
● Expiration: gases flow out of lungs
● Dependent upon pressure differences
● Pneumothorax: when a hole is torn in the chest wall and the pleural sac air has a new way
to equalize the pressure in the chest and so it does so, causing the lung to collapse undeer
the pressure
Quiet Inspiration: occurs when you are not consciously aware of your breathing
● External intercostals and diaphragm are the muscles involved in this
Forced inspiration; occurs when you intentionally/consciously breathe in
● Recruit scalenus and sternocleidomastoid
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Document Summary
Can bronchoconstrict or dilate to control airflow. Blood can be directed to the alveoli which are getting the most air. Helpful for times like when you"re sick and part of your lungs are congested. The pores of kohn connect adjacent alveoli to equalize air pressure. Type ii secrete surfactant to decrease surface tension. There are four main stages: ventilation (air moving in and out of lungs), external respiration (gas exchange between alveoli and blood), gas transport, internal respiration (gas exchange between blood and tissues) Quiet inspiration: occurs when you are not consciously aware of your breathing. External intercostals and diaphragm are the muscles involved in this. Forced inspiration; occurs when you intentionally/consciously breathe in. Dead space: inspired air that doesn"t contribute to gas exchange. Anatomical dead space is the volume of air passageways. Alveolar dead space if alveoli with no gas exchange due to collapse of obstruction.
