Janet Wild, Sept 2014
ASC171 Animal Anatomy and Physiology
The Respiratory System – Part 1
“She talks so that you can
barely hear her.
She talks on the exhale,
because she cannot talk on
the inhale which means
that her sentences are
interrupted 15 times each
minute, for the breathing
machine to make her
breathe, which makes
conversations with her
quite leisurely, long pauses
in the sentences, and
everyone learns to be
patient …” Lorenzo Milam, writing
about his sister, 1984
[The iron lung]
http://www.oobject.com/category/12-iron-lungs/ http://archive.wired.com/images/article/full/2007/10/iron_lung_630x.jpg
www.bagofnothing.com http://amhistory.si.edu/polio/howpolio/enlargeiron_01.htm
http://archive.wired.com/science/discoveries/news/2007/10/dayintech_1012 www.theatlantic.com
Learning Objectives
o Outline the functions of the respiratory tract.
o Describe the gross anatomy of the respiratory system.
o Outline the passage of air from the atmosphere to the alveoli.
o Relate respiratory tract anatomy to function.
o Outline the physiology of respiration including gas exchange, ventilation, O2 and CO2 transport in the blood.
o Describe the pressure changes within the thorax during respiration and explain their effect on gas movement.
o Describe different lung volumes and capacities and explain their significance.
o Describe how respiration is controlled
o Outline some pathological conditions of the respiratory system
o Relate basic mammalian respiration to adaptations in different animals (fish, birds, reptiles)
[Christopher Reeve] http://www.famouspeoplearehuman.com/index.php/famous-
people-with-quadriplegia/
http://images.rapgenius.com/c2cebae13d55ff3fff4fde1f49cbda
d1.1000x750x1.png
Why respiration?
Why does an animal need oxygen?
Why does it need to get rid of carbon dioxide?
The animal needs energy to live
It gets it by oxidising glucose to carbon dioxide and water.
The energy it stores as ATP (initially)
The oxygen it gets from the air via the respiratory system
cardiovascular system every cell
The carbon dioxide it gets rid of in the opposite direction
from every cell cardiovascular system respiratory
system
Background – introduction:
Overview of Respiration
Divided between external respiration (breathing or ventilation +
cardiovascular transport) and internal (cellular) respiration
1. External respiration = transporting O2 and CO2 to and
from the cells
Exchange of oxygen and carbon dioxide between
atmosphere and body tissues
2. Internal respiration = cell metabolism to use O2 and
produce CO2
Oxidative phosphorylation (remember your muscle lectures)
Occasionally anaerobic glycolysis (as in intensive muscular
exercise)
1. External Respiration
Pulmonary ventilation (process of
breathing)
Exchange between lungs and blood
Transport of O2 and CO2 in blood
Exchange of gases between blood
and body tissues
Copyright © 2011 Pearson Education, Inc., publishing as Benjamin Cummings.
2. Internal (Cellular) Respiration
We won’t talk much about
internal respiration in
these lectures.
You’ll cover it elsewhere
in your course – as in
your previous muscle
lectures.
Mitochondria in
cells use O2
The CO2 is waste
Back to external respiration …
Outline of the functions of the respiratory tract.
What does it do? Why is it needed?
o Gas exchange: every cell in the body needs oxygen to survive: O2 goes in (inspired), CO2 comes out (expired)
o pH control: regulation of acid-base balance of blood: CO2 is an acidic gas, so if it in the blood, then the blood becomes more acidic.
o Thermoregulation: e.g. panting in the dog. Dog has only a few sweat glands in the skin.
o Warms and humidifies air to protect lungs. Loses some water too.
o Filters air and can generate immune response: to protect lungs from infective agents
o Vocalisation and voice projection
o Sense of smell: detection of olfactory stimuli. Warning of dangers.
The gross anatomy of the respiratory system
The gross anatomy of the respiratory system (cont)
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Copyright © 2011 Pearson Education, Inc.
Nasal cavity
Oral cavity Pharynx
Epiglottis Larynx
Upper respiratory tract
Lower respiratory tract
Oesophagus
Left lung Right lung
Alveolar sac
Respiratory Bronchioles –
the earliest site at which
gas exchange occurs
Terminal
bronchiole
Terminal
bronchioles
Alveoli
Glottis
Trachea
Primary bronchi
Secondary bronchi
Tertiary bronchi
Diaphragm
Cartilage rings
The gross anatomy of the respiratory system (cont)
Lower
The gross anatomy of the respiratory system (cont)
External opening of the airway:
Most species:
Soft, pliable, easily dilated
Cartilage support
Pig:
Rigid nostrils for digging
Contain bone
NOSTRILS (nares)
The gross anatomy of the respiratory system (cont)
Hard and soft palates
Divided in half = septum (cartilage)
Turbinate or conchae bones = fine & scroll like, surface area
Good blood supply
Mucous membrane covering
Warm & humidify the incoming air
Caudal area of nasal cavity, olfactory sensory cells lead to olfactory
lobe of rostral area of brain
NASAL CAVITY
The gross anatomy of the respiratory system (cont)
Air filled spaces in skull (lighter)
Connect to nasal cavity
Limited exchange of air
Thermal & mechanical protection
Maxillary sinus roots of cheek teeth
Frontal sinus extends into horn in adult sheep & cattle
SINUSES
The gross anatomy of the respiratory system (cont)
SINUSES
The gross anatomy of the respiratory system (cont)
Located at back of throat
Common passage for food & air
Soft palate separates entrance of mouth & nasal
passages
Epiglottis (of larynx) overlaps soft palate
epiglottis & soft palate move when swallowing
PHARYNX
Entrance to lower airways
Connects between pharynx & trachea
Made up of 5 interconnected cartilages
• Epiglottis
• Thyroid = “Adam’s apple”
• 2 x Arytenoid
• Cricoid
Vocal cords – sound production
Allows only gases into lower respiratory tract
The gross anatomy of the
respiratory system (cont)
LARYNX
Textbook of Veterinary Physiology (2002)
Cunningham, Fig 27-4 p. 233
Breathing
Swallowing
PHARYNX
The gross anatomy of the
respiratory system (cont)
Passage of food & air
through pharynx & larynx
Oral cavity
• Non-collapsible tube
• Passes down the neck: larynx lungs
• Incomplete cartilage rings connected dorsally by a muscle
• Bifurcates to become 2 bronchi – one to each lung
• Mucous membrane lining is ciliated
• Mucociliary escalator
• Moves mucus & debris up from lung, swallowed or coughed
TRACHEA
The gross anatomy of the
respiratory system (cont)
Hilus
Bronchus enters
Pulmonary artery & nerve enter
Pulmonary vein & lymphatics leave
Right lung always bigger (why?)
Divided into lobes by fissures
Mucociliary escalator
LUNGS
The gross anatomy of the respiratory system (cont)
2 lungs – fill thoracic space
No fixed shape or size
Pleural sacs
Pleural cavity
Soft, spongy texture
Crackle when squeezed, float in H2O
Colour varies
The gross anatomy of the respiratory system (cont)
Bovine lungs Cranial lobe trachea
Middle lobe
Accessory lobe
Caudal lobe
Caudal lobe
Cranial Lobe
Right lung Left lung
Trachea branches (bifurcates)
L & R principal (main) bronchi
Identical structure to trachea – but smaller
Continual division bronchial tree
Bronchioles do not have supporting cartilage
Respiratory or terminal bronchioles are the smallest
BRONCHI AND BRONCHIOLES
The gross anatomy of the respiratory system (cont)
Allows control of airway diameter
Contracts = narrower
Relaxes = wider
Contracts due to
Irritants- pollen, dust = asthma
nervous system control
Relaxes due to
Adrenaline
SMOOTH MUSCLE
in bronchioles
The gross anatomy of the
respiratory system (cont)
‘Air sacs’
Major site of gas exchange
ALVEOLI
The gross anatomy of the respiratory system (cont)
Air sacs – millions of them!
Gas exchange occurs here
Blood capillaries intimately associated
Bronchiole respiratory bronchiole alveolar sacs
Importance of matching ventilation with blood flow rates optimal gas exchange
Have 2 types of epithelial cells:
Type I alveolar cells – exchange gases
Type II alveolar cells – secrete surfactant to reduce surface tension
ALVEOLI
The gross anatomy of the respiratory system (cont)
Illustration of one alveolus at micro scale
Nostrils
Nasal cavity
Pharynx
Larynx
Trachea
L/R 1 bronchus
Bronchioles
Intralobar bronchioles
Terminal bronchioles
Respiratory bronchioles
Alveolar ducts
Alveoli
What structures does the air pass through
from the atmosphere to the alveoli
(and back again)?
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Relate respiratory tract anatomy to
function Nose (nares) (oral cavity)
Nasal cavity
Pharynx
Larynx
Trachea
Bronchi (1o, 2o, 3o)
Bronchioles (terminal, respiratory)
Alveoli
Blood vessels Respiratory muscles
Airsacs
Nose (nares)
Nasal cavity
Oral cavity
Pharynx
Larynx
Trachea
Bronchi (1o, 2o, 3o)
Bronchioles (terminal,
respiratory)
Alveoli
Relate respiratory tract
anatomy to function (cont)
Conducting zone
Respiratory zone
Efficient gas exchange involves both respiratory &
circulatory systems:
Pulmonary ventilation (breathing – the movement of air
into and out of the lungs)
Exchange of O2 & CO2 between lung air space & blood
(by diffusion)
Transport of O2 & CO2 in blood
Exchange of O2 & CO2 between blood & cells / tissues
(by diffusion)
Relate respiratory tract anatomy to function (cont)
All of these steps have to work for efficient
transport of O2 & CO2 between air and cells
1. Pulmonary ventilation
2. ‘External’ respiration (gas
exchange in lung)
3. Transport of respiratory gases
4. Internal (cellular) respiration
Relate respiratory tract anatomy to function (cont)
Conducting zone:
• Passages for air to enter respiratory zone
• Air is warmed & humidified
• Immune protection
• Goblet cells secrete mucus
• Ciliated cells move trapped particles in mucus up out of the lungs
Respiratory zone:
• surface area,
• thickness of epithelial wall
• no cilia or goblet cells
Respiratory tract anatomy related to function (cont)
Pressure changes within the thorax during respiration
and the effect on gas movement
Movement of air into and out of the lungs is called
pulmonary ventilation
Movement of air is an example of mass flow driven
by pressure gradients
Air moves down a pressure gradient (high
pressure to low pressure)
Inspiration
Pressure in alveoli < atmospheric pressure so air moves in
Expiration
Pressure in alveoli > atmospheric pressure so air moves out