Respiratory System

Comparative vertebral respiration

1. Respiratory System
By : Geonyzl L. Alviola

2. Respiration
is the process of obtaining oxygen from the
external environment & eliminating CO2.
= External respiration - oxygen and
carbon dioxide exchanged between the
external environment & the body cells
= Internal respiration - cells use oxygen
for ATP production (& produce carbon
dioxide in the process)

3. Adaptations for external
respiration
1 - Primary organs in adult vertebrates are
external & internal gills, swim bladders or
lungs, skin, & the buccopharyngeal mucosa
2 - Less common respiratory devices include
filamentous outgrowths of the posterior trunk
& thigh (African hairy frog), lining of the
cloaca, & lining of esophagus

5. Gills (see Respiration in Fishes)
Adult fish have a pair of gills. Each gill is covered by a
boney lid (removed from the picture). A fish draws in water
by closing the lid over its gills and opening its mouth. When
the fish closes its mouth and opens the gill lid the water is
forced out and over the respiratory surfaces of the gill
filaments.

9. Due to the low concentration of oxygen in
water, the gills must be as efficient as
possible in order to extract oxygen.
The gills consist of bony or cartilaginous
arches which hold pairs of gill filaments.
Each gill filament consists of an upper and
lower surface covered with minute ridges
known as lamellae.

11. 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

12. These lamellae are made of extremely thin
membranes (1 cell thick) and are the primary sites of
gas exchange. Water flows across the gill filaments
and oxygen is removed and passes into the blood by
diffusion. To increase the efficiency of oxygen uptake
a countercurrent method is used (the same principle
as used in force air furnaces); blood flows through the
lamellae in a direction opposite to the water flow
through the gill filaments. Countercurrent flow insures
a steady oxygen

13. 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
Gill rakers protrude from gill cartilage & ‘guard’
entrance into gill chamber
2 demibranchs + septum & associated cartilage,
blood vessels, muscles, & nerves = holobranch
Cartilaginous fishes:

14. 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

17. The respiratory system of
sharks is markedly different
from that of bony fishes.
Where bony fishes usually
have five gilled arches and
only one external gill opening,
sharks may have as many as
seven openings, but the most
common number is five. Also,
where the gill arches of bony
fishes are protected by
an opercle, or plate, the gills of
sharks are not.

18. Sharks generally inhale most of the necessary
water through their mouths, but they are also
able to inhale water by way of spiracles, which
are opening located close to the gills. When
resting, sharks propel water over their gills
using the muscles of their jaws and pharynx.
Oxygen from the incoming water is absorbed
into the blood system by way of the gill
filaments. Water exits through the gill slits
.(Davies, 1964).

19. Respiratory organs:
Cutaneous respiration
respiration through the skin can take place in air,
water, or both
most important among amphibians (especially the
family Plethodontidae)
Female P. shermani (Red-legged
Salamander) from North Carolina

20.  Larval gills:
External gills
outgrowths from the external surface of 1 or more
gill arches
found in lungfish & amphibians
Filamentous extensions of internal gills
project through gill slits
occur in early stages of development of
elasmobranchs
Internal gills - hidden behind larval operculum of
late anuran tadpoles

22. - most vertebrates develop an outpocketing of
pharynx or esophagus 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.
Swim bladder &
origin of lungs

23. Vertebrates without swim bladders or
lungs include cyclostomes, cartilaginous
fish, and a few teleosts (e.g., flounders
and other bottom-dwellers).

24. Swim bladders:
may be paired or unpaired (seen previous slide)
have, during development, a pneumatic duct that usually
connects to the esophagus. The duct remains open
(physostomous) in bowfins and lungfish, but closes off
(physoclistous) in most teleosts.
serve primarily as a hydrostatic organ (regulating a fish's
specific gravity)
gain gas by way of a 'red body' (or red gland); gas is
reabsorbed via the oval body on posterior part of bladder

25. May also play important roles :
hearing - some freshwater teleosts (e.g., catfish,
goldfish, & carp) 'hear' by way of pressure waves
transmitted via the swim bladder and small bones
called Weberian ossicles (see diagram below)
sound production - muscles attached to the swim bladder
contract to move air between 'sub-chambers' of the bladder.
The resulting vibration creates sound in fish such as croakers,
grunters, & midshipman fish.
respiration - the swim bladder of lungfish has number
subdivisions or septa (to increase surface area) & oxygen and
carbon dioxide is exchanged between the bladder & the blood

26. Lungs & associated structures
Larynx
Tetrapods besides mammals - 2 pair of cartilages:
artytenoid & cricoid
Mammals - paired arytenoids + cricoid + thyroid +
several other small cartilages including the
epiglottis (closes glottis when swallowing)
Amphibians, some lizards, & most mammals - also
have vocal cords stretched across the laryngeal
chamber

28. Trachea & syrinx
Trachea
usually about as long
as a vertebrates neck
(except in a few birds
such as cranes)
reinforced by
cartilaginous rings (or
c-rings)
splits into 2 primary
bronchi &, in birds
only, forms the syrinx
at that point

29. Found in
songbirds

30. Lungs
Amphibian lungs
2 simple sacs
internal lining may
be smooth or have
simple sacculations
or pockets
air exchanged via positive-pressure ventilation

31. Reptilian lungs
simple sacs in
Sphenodon &
snakes
Lizards,
crocodilians, &
turtles - lining is
septate, with lots
of chambers &
subchambers
air exchanged via
positive-pressure
ventilation

32. Avian lungs -
modified from those
of reptiles:
air sacs (diverticula
of lungs) extensively
distributed
throughout most of
the body
arrangement of air
ducts in lungs ---->
no passageway is a
dead-end
air flow through
lungs (parabronchi)
is unidirectional

33. Mammalian lungs:
multichambered & usually
divided into lobes
air flow is bidirectional:
air exchanged via negative
pressure ventilation, with
pressures changing due to
contraction & relaxation of diaphragm &
intercostal muscles

34. The End