comparative anatomy of respiratory system

1. COMPARATIVE ANATOMY OF RESPIRATORY
SYSTEM OF VERTEBRATES
By
Dr. T. RAMESH
Assistant Professor of Zoology
PG & Research Department of Zoology
Vivekananda College Tiruvedakam, Madurai DT.
faunaldiversity@gmail.com

2. RESPIRATORY SYSTEM
It is the process of obtaining oxygen from the
external environment & eliminating CO2 from the
body of an organisms.
Kind of respiration
1. External respiration - oxygen and carbon dioxide
exchanged between the external environment &
the body cells
2. Internal respiration - cells use oxygen for ATP
production (& produce carbon dioxide in the
process)

3. Respiratory organs
1. CUTANEOUS RESPIRATION- respiration through the
skin can take place in air, water, or both most important
among amphibians (especially the family
Plethodontidae).
2. GILLS- Vertebrate gills are designed for water breathing
Mechanism of ventilation depends on whether the gills
are located internally or externally
1. Internal Gills- Lie within the head
2. External Gills-Develop from surface ectoderm and
extend beyond the head

4. 3. LUNGS
 Designed for air breathing
 It is elastic bags that lie within the body
 Volume expands when air is inhaled and decrease
 When air is exhaled
4. GAS BALDDERS
 Are air filled with the air
 Swim bladders are used to control the buoyancy
of a fish
 Gas bladders differ in lungs in two ways
 Gas bladder are usually situated dorsal to the
digestive tracts
 Gas bladders are not paired

5. KEY DIFFERENCE IN FISHES
1. Cartilaginous fishes:
•5 ‘naked’ gill slits
•Anterior & posterior walls of the 1st 4 gill
chambers have a gill surface (demibranch).
Posterior wall of last (5th) chamber has no
demibranch.
•Interbranchial septum lies between 2
demibranchs of a gill arch
•2 demibranchs + septum & associated cartilage,
blood vessels, muscles, & nerves = holobranch
2. Bony fishes (teleosts): (See 'Ventilation in
Teleost Fishes')
•usually have 5 gill slits
•operculum projects backward over gill chambers
•interbranchial septa are very short or absent
3. Agnathans:
•6 - 15 pairs of gill pouches.. Pouches connected
to pharynx by afferent branchial (or gill) ducts &
to exterior by efferent branchial (or gill) ducts.

6. MECHANISMS OF EXCHANGE OF GASES IN FISHES

7. Swim bladder & origin of lungs Swim bladder & origin of
lungs
Most vertebrates develop an
out pocketing of pharynx or
oesophagus that becomes
one or a pair of sacs (swim
bladders or lungs) filled with
gases derived directly or
indirectly from the
atmosphere.
Similarities between swim
bladders & lungs indicate
they are the same organs.

8. LUNGS
1. It is respiratory organ of higher vertebrates.
2. Lungs are developed from pharynx, arise in
embryo an endo dermal diverticulam from the
ventral wall of pharynx
3. The diverticulam divided into two portions- Right
& Left lungs
4. Windpipe trachea connects the lungs and
pharynx
5. The birds has sound producing organ is called
Syrinx.
6. Lungs is branched- Primary Secondary bronchi
Tertiary and Bronchides

9. RESPIRATION OF AMPHIBIANS
 It has respiratory surfaces on its body
that it uses to exchange gas with the
surroundings: the skin, in the lungs and
on the lining of the mouth.
A frog may also breathe much like a
human, by taking air in through their
nostrils and down into their lungs.
The mechanism of taking air into the
lungs is however slightly different than in
humans.
Frogs do not have ribs nor a diaphragm,
which in humans helps serve in expand
the chest and thereby decreasing the
pressure in the lungs allowing outside air
to flow in.
Respiratory organs of Amphibians

10. RESPIRATION OF AMPHIBIANS
1. In order to draw air into its mouth the frog lowers the floor of its
mouth, which causes the throat to expand.
2. Then the nostrils open allowing air to enter the enlarged mouth.
3. The nostrils then close and the air in the mouth is forced into the
lungs by contraction of the floor of the mouth.
4. To eliminate the carbon dioxide in the lungs the floor of the mouth
moves down, drawing the air out of the lungs and into the mouth.
5. Finally the nostrils are opened and the floor of the mouth moved
up pushing the air out of the nostrils.
6. 2-simple, long spindle shaped, semi transparent, elastic, delicate,
thin walled and sac like structure.
7. Internal lining may be smooth or have simple scaculation or
packets
8. Air exchanged via positive pressure ventilation.

12. Four stages of frog lung ventilation
1. Buccal cavity expands to draw fresh air through the
open nares
2. Glottis opens rapidly, releasing spent air from the
elastic lungs.
3. Nares close, floor the bauccal cavity rises forcing
the fresh air held in this cavity into the lung through
the open glottis
4. Glottis closes retaining the air that has just filled the
lungs and nares open again.

13. SKIN RESPIRATION
Respiration through the skin can take place in air & water or
both. It is very common in the family of Plethodontidae
Cutaneous respiration is the absorption of oxygen and
disposal of carbon dioxide thorough the skin.
While completely submerged all of the frog's respiration
takes place through the skin.
The skin is composed of thin membranous tissue that is
quite permeable to water and contains a large network of
blood vessels.
The thin membranous skin is allows the respiratory gases to
readily diffuse directly down their gradients between the
blood vessels and the surroundings.
When the frog is out of the water, mucus glands in the skin
keep the frog moist, which helps absorb dissolved oxygen
from the air.

14. Reptilian lungs
Simple sacs in Sphenodon & snakes
Lizards, crocodilians, & turtles - lining is septets, with
lots of chambers & sub chambers
Air exchanged via positive-pressure ventilation.
Specialized adaptation exist depending on the lizard's
natural habitat way of life etc
Crocodilians - bony secondary palate for breathing
underwater
Snakes- Tracheal extension for protection against
asphyxiation while swallowing prey
buccal pumping allows some lizards to increase
stamina and oxygen capacity

15. Reptilian lungs
Inspiration is caused by the
movement of intercostals muscles,
raising the ribs that increases the
volume of the thorax and reduces
the lung pressure causing the
inflow of air into the lung.
Oxygen of the air enters the blood
of the blood capillaries and CO2 of
the blood enters the alveoli.
Expiration is done by lowering the
ribs that decreases the volume of
the thoracic cavity, flows back to
the exterior.

16. Avian lungs
The avian respiratory system delivers oxygen from
the air to the tissues and also removes carbon dioxide.
In addition, the respiratory system plays an important
role in thermoregulation (maintaining normal body
temperature).
The avian respiratory system is different from that of
other vertebrates, with birds having relatively small
lungs plus nine air sacs that play an important role in
respiration (but are not directly involved in the
exchange of gases).

17. Avian lungs
Birds must be capable of high rates
of gas exchange because their
oxygen consumption at rest is higher
than that of all other vertebrates and
it increases many times during flight.
The air sacs permit a unidirectional
flow of air through the lungs.
Unidirectional flow means that air
moving through bird lungs is largely
'fresh' air & has a higher oxygen
content. So, in bird lungs, more
oxygen is available to diffuse into the
blood (avian respiratory system).

18. Avian Respiratory system

19. Avian lungs
The air sacs permit a unidirectional flow of air
through the lungs. Unidirectional flow means that air
moving through bird lungs is largely 'fresh' air & has a
higher oxygen content.
In contrast, air flow is 'bidirectional' in mammals,
moving back and forth into and out of the lungs. As a
result, air coming into a mammal's lungs is mixed with
'old' air (air that has been in the lungs for a while) &
this 'mixed air' has less oxygen. So, in bird lungs,
more oxygen is available to diffuse into the blood
(avian respiratory system).

20. Mammalian lungs
Air is inhaled through the lungs (breathing).
Mammalian lungs are subdivided internally. The
repetitive subdivisions of the lung airways provide gas
to the tiny alveoli (gas sacs) that form the functional
gas-exchange surface area of the lungs.
Haemoglobin molecules inside red blood cells
capture oxygen. Blood with oxygen is pumped through
the body to all tissues.
In capillaries, cells release carbon dioxide into the
blood and pick up fresh oxygen.
Oxygen diffuses into the cell and is used in the
mitochondria to break down glucose molecules and
make ATP.

21. Human lungs

25. Reference
http://people.eku.edu/ritchisong/birdrespiration.html
https://www.britannica.com/science/respiratory-system/Birds
http://people.eku.edu/ritchisong/342notes8.html

26. Thank you