Download L7 - Respiratory system - Moodle

The Respiratory System
Life Science
FLSS
All images used are taken from copyright-free sources e.g. Wikicommons Media or produced by UWS staff.
BruceBlaus (2013) Respiratory System.
http://commons.wikimedia.org/wiki/File:Blausen_0770_RespiratorySystem_02.png
Functions of the respiratory system
• Gas exchange
– cells need oxygen for chemical reactions
which release energy from food
– carbon dioxide is the waste product of this
process
glucose + oxygen → water + carbon dioxide + energy
C 6H 12O6 + 6O2 →
6H 2O + 6CO2 + 36ATP
• respiratory system:
– allows oxygen from atmosphere to enter
body,
– provides route of excretion for carbon
dioxide
• blood provides transport system between
lungs and body cells
Upper respiratory tract
warms, moistens
and filters the
inhaled air in
preparation for
gas exchange.
•BruceBlaus (2013)
•https://commons.wikimedia.org/wiki/File:Blausen_0872_UpperRespiratorySystem.png
Hairs and mucus trap large and small particles
James Gathany (2009)
https://commons.wikimedia.org/wiki/File:Sneeze.JPG
Surefire (2015)
https://commons.wikimedia.org/wiki/File:Hairy_nostrils.jpg
6
Lower respiratory tract
Continues to
warm, moisten
and filter the
inhaled air in
preparation for
gas exchange.
•BruceBlaus (2013
•https://commons.wikimedia.org/wiki/File:Blausen_0865_TracheaAnatomy.png
ciliated epithelium
8
BruceBlaus (2013)
https://commons.wikimedia.org/wiki/File:Blausen_0766_RespiratoryEpithelium.png
Larynx
Samir (2007)
https://commons.wikimedia.org/wiki/File:Larynx_endo_2.jpg
Alan Hoofring (2003)
https://commons.wikimedia.org/wiki/File:Larynx_(top_view).jpg
Alveoli
Alveoli are the
functional units
of lungs (where
gas exchange
occurs)
•Cancer research UK (2014)
•https://commons.wikimedia.org/wiki/File:Diagram_showing_the_lungs_including_the_alveoli_CRUK_309.svg
Alveoli
600 million
alveoli
Total area
100m2
Each
alveolus 1
cell thick
•US Gov (2006) bronchi lungs
•http://commons.wikimedia.org/wiki/File:Illu_bronchi_lungs.jpg
Alveoli
•United States Government (2006) Illu quiz lung.
•http://commons.wikimedia.org/wiki/File:Illu_quiz_lung05.jpg
Surfactant
• Surfactant keeps alveoli open –
– Reduces surface tension
• If surfactant reduced or absent
– alveoli collapse on expiration
–  effort to expand lungs on inspiration
Sufficient surfactant not produced until  28 weeks
gestation
–  respiratory distress in premature babies
Major measure (2008)
https://commons.wikimedia.org/wiki/File:Surfactant.jpg
Pleura
• Thin smooth membrane surrounding each
lung
• Actually very small gap between pleurae
• Pleural cavity contains serous fluid, sliding,
high surface tension
• Allows expansion & contraction in friction
free environment
• If punctured, lungs collapse because of
elastic recoil (pneumothorax)
14
Pleura
OpenStax College (2013) 2313 The Lung Pleurea
https://commons.wikimedia.org/wiki/File:2313_The_Lung_Pleurea.jpg
Pleura
Cancer Research UK (2014)
https://commons.wikimedia.org/wiki/File:Diagram_showing_a_build_up_of_fluid_in_the_lining_of_the_lungs_(pleural_effu
sion)_CRUK_054.svg
16
Henry Gray (1918)
https://commons.wikimedia.org/wiki/File:Gray968.png
Ventilation and Respiration
• Ventilation = movement of air in and out of lungs
• Respiration = exchange of gases
– external respiration
• exchange of gases by diffusion between alveoli in
lungs and blood in pulmonary capillaries
– internal respiration
• exchange of gases by diffusion between blood in
systemic capillaries and body cells
17
Ventilation
• Air flows from high to low pressure
• Inspiration –
– volume of chest cavity increases (intercostal
muscles & diaphragm)
– pressure falls below that of atmosphere,
– air is sucked in
18
Ventilation: inhalation
LadyofHats (2008)
http://commons.wikimedia.org/wiki/File:Inhalation_diagram.svg
Inspiration (breathing in)
1. Diaphragm contracts – pulls down
external intercostal muscles contract – pulls
ribs up and out
– volume of thoracic cavity increased
2. Pleural membranes move with thoracic
walls and diaphragm
– lungs expand
3. Pressure falls in lungs and air moves
in – down the pressure gradient
active process requires energy expenditure by muscles
20
Ventilation : exhalation
LadyofHats (2008)
https://commons.wikimedia.org/wiki/File:Expiration_diagram.svg
Expiration (breathing out)
1. intercostal muscles & diaphragm
relax
– results in downward and inward movement
of rib cage
2. Lung is elastic so returns to initial
volume
3. Pressure in lungs rises and air flows
out
passive process - does not require energy
pause before next cycle begins
Factors affecting ventilation
• lungs easy to inflate if:
– high compliance
– low airway resistance
• problems with ventilation if :
–  compliance (e.g scarring)
–  resistance (e.g. inflammatory swelling)
Respiration
• Oxygen & carbon dioxide move by simple
diffusion down a concentration (pressure)
gradient
• Rate of diffusion
– proportional to:
• Area of surface
• Difference in gas pressure between 2 sides
– inversely proportional to:
• Thickness of surface
Respiratory membrane in alveoli is very thin
and has very large surface area - IDEAL
FOR GAS EXCHANGE
External respiration
• venous blood arrives at lungs
– high levels CO2
– low levels O2
• CO2
– flows from venous blood down concentration
gradient until equilibrium with alveolar air
reached
• similarly O2 diffuses from alveoli into blood
External respiration
Holly Fischer (2013)
https://commons.wikimedia.org/wiki/File:Pulmonary_Blood_Circulation.png
Helix84 (2007) Alveoli
http://commons.wikimedia.org/wiki/File:Alveoli.svg?uselang=en-gb
Internal respiration
• Arterial blood arriving at tissues
– higher concentration of O2 than tissues
– lower
concentration of CO2 than tissues.
• concentration gradient between blood and
tissues
– O2 diffuses through capillary wall  tissues
– CO2 diffuses from cells  extracellular fluid then 
bloodstream towards venous end of capillary
Internal respiration
OpenStax College (2013)
https://commons.wikimedia.org/wiki/File:2320_Fig_23.20_NEW_KGX.jpg
Transport of oxygen in blood
haemoglobin
•‘loads up’ with oxygen
in lungs
•Releases oxygen in
tissue capillaries
•Complex protein,4
polypeptide chains –
•Each has haem group
which contains Fe2+
•One oxygen molecule
binds to each haem
Dcrjsr (2014)
http://commons.wikimedia.org/wiki/File:Hemoglobin_beta_red_whBkg.tif?uselang=en-gb
Carbon dioxide transport
• 23% on haemoglobin
• 7% dissolved in plasma
• Most as bicarbonate ions