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