MMED2931 Lecture Notes - Lecture 10: Exhalation, Mammalian Diving Reflex, Vital Capacity
4 Jun 2018
School
Department
Course
Professor
Respiratory System Lecture 2: respiratory cycle and regulation
Learning objectives:
1. Air movement during breathing
2. Changes in lung V during respiration
a. Respiratory muscle Lung V and capacities
3. Regulation of respiration
a. General principles Central controller Central chemoreceptors
b. Peripheral chemoreceptors Integrated responses
The breathing cycle:
- During inspiration: thorax expands → intrapleural P → transpulmonary P (now >
lungs elastic recoil) → lungs expand → alveolar P air → alveoli
- During expiration: chest wall recoils inward → intrapleural & transpulmonary P →
lungs return to pre-inspiration size → alveoli compressed, air forced out
-
Respiratory muscles:
- During normal quiet breathing:
o Inspiration is active: diaphragm contraction ( vertical thorax dimension
external intercostals (angled obliquely between ribs,
forward & downward) contraction ( side/side & front/back dimensions)
o Expiration is passive – muscles relax. 1/3 due to elastic fibre pull back, 2/3
surface tension
- During active breathing (exercise)
o Inspiration is active: diaphragm & external intercostal muscle (also
accessory muscles)
o Expiration is active: abdominal muscles contraction and
internal intercostals (angled obliquely between ribs,
backward & downward)
Lung volumes and capacities:
-
- Tidal V (TV): amount of air inhaled/exhaled with each breath under resting
conditions
- Inspiratory reserve V (IRV): amount of air that can be forcefully inhaled after normal
tidal inhalation
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Respiratory system lecture 2: respiratory cycle and regulation. Learning objectives: air movement during breathing, changes in lung v during respiration, respiratory muscle. Lung v and capacities: regulation of respiration, general principles, peripheral chemoreceptors. During inspiration: thorax expands intrapleural p transpulmonary p (now > lungs elastic recoil) lungs expand alveolar p air alveoli. During expiration: chest wall recoils inward intrapleural & transpulmonary p lungs return to pre-inspiration size alveoli compressed, air forced out. Inspiration is active: diaphragm contraction ( vertical thorax dimension external intercostals (angled obliquely between ribs, forward & downward) contraction ( side/side & front/back dimensions: expiration is passive muscles relax. 1/3 due to elastic fibre pull back, 2/3 surface tension. Inspiration is active: diaphragm & external intercostal muscle (also accessory muscles: expiration is active: abdominal muscles contraction and backward & downward) internal intercostals (angled obliquely between ribs, Tidal v (tv): amount of air inhaled/exhaled with each breath under resting conditions.
