Respiratory System - Part 1
Respiratory SystemWithout oxygen our cells will begin to die within minutes
nitrogen78.02%
oxygen21.01%
argon and other gases
0.94%
carbon dioxide0.03%
Respiratory system brings air into body so that respiratory gases may be exchanged with bloodAir that we breath contains:
Respiratory System
nasal cavity
oral cavitypharynxepiglottislarynxtrachealungbronchi
bronchiole
rib cage
diaphragm
bronchiole
alveolar sac
capillary network
Breathing and respiration are sometimes used interchangeably, but they are different
Breathing and Respiration
air enters lungs (breathing)
gas exchange between lungs
and blood
cellular respiration
gas exchange between blood
and cell
Breathing or ventilation is method by which air moves into and out of lungsRespiration occurs within cell and results in nutrients being converted into metabolic energy (ATP)Between process of breathing and cellular respiration, there must be gas exchange
Atmospheric pressure is essentially constant, so it is changes in thoracic pressure that moves air
Lungs do not contain skeletal muscle, so they cannot contract or relax to allow breathingMovement of air into and out of lungs is due to pressure differences between atmosphere and thoracic cavity
Breathing
thoraciccavity rib cage
diaphragm
trachea
Breathing
What causes thoracic pressure to change?
Changes in thoracic volume!
Volume Pressure
Atmospheric pressure is essentially constant, so it is changes in thoracic pressure that moves air
Lungs do not contain skeletal muscle, so they cannot contract or relax to allow breathingMovement of air into and out of lungs is due to pressure differences between atmosphere and thoracic cavity
Diaphragm contracts, causing it to move downwardMuscles between ribs (intercostal muscles) contract, causing rib cage to move upward and outwardThis increases volume of thoracic cavityResulting decrease in pressure sucks air into lungsDiaphragm and intercostal muscles relax, decreasing volume of thoracic cavity
Breathing
inspiration
Volume Pressure Volume Pressure
exhalation
This increases thoracic pressure and forces air out of lungs