The respiratory system allows organisms to take in oxygen and release carbon dioxide through the process of respiration. Respiration includes ventilation, external respiration where gases are exchanged with the environment, and internal respiration where gases are exchanged at the tissue level. The main respiratory organs are lungs, gills, and in some cases skin or gas bladders. Lungs are found in air-breathing vertebrates like mammals and birds, using an aspiration pump for ventilation. Gills are found in fish and some aquatic amphibians and function via various water pumping mechanisms. Skin respiration also occurs in some amphibians.

1. Ramyr Delos Reyes
Allyson Nicole Manalo
Claudine P. Naz
Janyka Angela B. Roman
Kristel G. Zamora

2. Respiratory system -is a system consisting of specific
organs and structures used for the process of
respiration in an organism.
 General Function
Respiration-the act or process of inhaling or exhaling
Respiration includes:
- Ventilation is the pumping of water in gills and of
air in lungs
-External Respiration- exchange of gases with the
environment
-Internal Respiration- essential gases are then
exchange with the tissues in the respective
capillary beds

3.  GILLS
 Vertebrate gills are designed for water
breathing
 Mechanism of ventilation depends on
whether the gills are located internally or
externally
1. INTERNAL GILLS
2. EXTERNAL GILLS

4.  LUNGS
 Designed for air breathing
 Elastic bags that lie within the body
 Volume expands when air is inhaled and
decreases when air is exhaled
 GAS BLADDERS
 Are air filled with the air
 Swim bladders are used to control the
buoyancy of a fish

6.  Gas bladders differ in lungs in two ways
1. Gas bladders are usually situated dorsal to the
digestive tracts
2. Gas bladders are not paired
 Oxygen is released into the bladder
 Gas in the swim bladder is mainly oxygen
 CUTANEOUS RESPIRATION
 Respiration through the skin
 Amphibians rely heavily in cutaneous
respiration

7.  BREATHING EMBRYOS
 Chorioallantois in birds acts as respiratory
organs in birds
 It sustains the respiratory needs of the chicken
embryo for most of its time in the egg
 VENTILATORY MECHANISM
 CILIA lines the routes along which water
current flows

8.  MUSCULAR MECHANISM
 Ventilation on vertebrates usually depends
much on muscle action
 Ram ventilation is a technique by which the
fish’s own forward locomotion contributes to
gill ventilation
1. Water Ventilation: Dual pump
2. Air ventilation: Pulse pump
3. Air ventilation: Aspiration pump

10.  Gills
 External Gills-develop from surface ectoderm
and extend beyond the head
 Internal Gills- lie within the head
 Comprised of gill arches with gill
filamentslined with rows of lamellae
(increase surface area)

11.  Utilize countercurrent exchange(except for
cartilaginous fishes)
  blood flows oppposite to the direction of
water movementg against gills

12.  INTERNAL GILLS
- develop from the pharynx as evaginations called
pharyngeal pouches
 Visceral grooves (opposite to the pouches)
 Closing plates (separates pouches and grooves)
- The general structure of a mature gill is
composed of several parts:
 Gill bars (support the gills)
 Gill rakers (prevents food particles from entering)
 Gill rays
 Gill filaments and Gill lamellae

14.  3 TYPES OF GILL BARS
 Holobranch
 Hemibranch
 Pseudobranch
 AGNATHAN
 Pouched gills
 6-15 pairs of gill pouches
 No gill Slits
 Hagfishes and lampreys

15.  Cartilaginous fishes
 Septal Gills
 5 “naked” gill slits
 Shark and rays
 Bony Fihes
 Opercular gills (operculum)
 5 gill slits
 Eels, salmon and milk fish

18.  SWIM BLADDERS
Gas or swim bladders of fishes may be located
high in the cavity to remain upright

19. 1. Physostomous
 Function for respiration
2. Physoclitous
 Do not function for respiration

20.  Serves as an hydrostatic organ
 Oxygen and carbon dioxide are exchanged
between the bladder and the blood
 Also important in hearing and sound
production

22.  AMPHIBIANS
 They are cold blooded, meaning they don’t
need much oxygen
 2 simple sacs
 Lungs
 - don’t have diaphragms and they force air into
their lungs by moving their mouth (like
swallowing) Buccal pumping

23.  Four stages of lung ventilation
1.) Buccal cavity expands to draw fresh air in
through the open nares
2.) Glottis opens rapidly, releasing spent air from
the elastic lungs
3.( Nares close, floor the buccal 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

25.  Skin
- Highly vascularized and moist
- Very thin nd allows water to go through it
- Aquatic Amphibians and anurans Cutaneous
respiration
- The short trachea divides into 2 short bronchi
leading to the apex of each lung
- The opening from the trachea to pharynx is called the
glottis supported by the larynx

26.  Gills ( aquatic salamanders and tadpoles)
- Made up of very thin blood vessels surrounded
by water channe;s
- When amphibians undergo metamorphosis
into adult, gills are lost

28.  REPTILES
-Lungs are large and varied
-Rely largely on LUNGS for gas exchange
-Have large lung volumes (10xmore volume
compared to mammals)
-Trachea and bronchi are larger than for
amphibians and are supported by cartilaginous
rings

29. -Supplemental cutaneous respiration is
significant, but for the most part, paired lungs
meet their respiratory needs
-Filling of the lungs in all the reptiles is based on
an aspiration pump
- Exhalation of passive
CROCODALIANS
- Use diaphragm muscle for lung ventilation

31. -Contraction of the diaphragmatic muscles draws
the liver back, increasing the volume of the
lung cavity and dropping pressure within the
lungs
- In caimans and other crocodiles, ribs rotate
forward and outward, expanding the cavity
around the lungs during inhalation
SQUAMATES (Snakes and Lizards )
-Don’t have diaphragm muscles for lung
ventilation

32. -The muscle s used for locomotion are the same
used for their respiratory systems
-Contracting and flexing body muscles move
their ribs and lungs
In most snakes , there are usually two regions of
the lung:
1. Anterior respiratory portion or faveoli
2. Posterior saccular portion or avascular
-Submergence in water- have large lungs for large
amount of oxygen for long dives
(Hydrophinae and Arochordidae)

33. TESTUDINES (Turtles)
-Having shells makes lung expansion more
difficult
-Must use their limbs for lung ventilation
expels air from the lungs and pushing their
limbs out of their shells expands the lungs
-Have complex lungs w/ large surface areas and
volumes

35.  4.) Mammals
- The chief organ in mammalian respiration is the
lungs (located in the pleural cavities in the thorax)
- More finely, homogenously divided and more
efficient
- Aspiration pumps ventilates the lungs of
mammals
- Breathing is dependent to the rib muscles and
diaphragm

37.  SUCTION-PUMP MECAHNISM OF
INHALATION AND EXHALATION
 inhalationwhen the rib cage opens up and
the diaphragm flattens and moves downward;
air rush inside
 lungs expandsdecrease in air pressure
 exhalation the diaphragm and rib muscles
relax to their neutral state that causes the lungs
to contract; air flow out
 squashing of lungs increase in air pressure

39.  AIR FLOW IS BIODIRECTIONAL:
 Trachea primary bronchi secondary
bronchi tertiary bronchi alveoli
 Trachea is a long structure of soft tissue;
supported by rings of hyaline or fibrous
cartilages; elastic connective tissue joins the
ring and completes the tube where cartilage is
absent
 Splits into two bronchi branches, each enters its lung
anterior and dorsal to the center
 Divides into numerous membranous bronchioles
 Alveolus- tiny air sacs; increase surface area; where
actual gas exchange occurs

40.  The trachea, bronchi and bronchioles that
transport gas to and from the alveoli is called
the respiratory tree
 No gas exchange occurs along the conducting
passageway of the respiratory tree until air
reaches the alveoli
 Epiglottis
 Glottis

42.  5.) Birds
- Have one way flow of air in their lungs
-Lungs are small but compact, rigid and have a
fixed volume
-Have two lungs connected to trachea and
ventilated by an aspiration pump
-Birds have air sacs that collect air and then force
the air through their lungs
-Large air sacs joined the lungs and serve to
ventilate them in crosscurrent circulation
-Gas exchange in the blood actually occurs in the
air capillaries
-Bones contain air, not marrow

44. -Lungs receive fresh air during inhalation and
exhalation
-Air is pulled by a suction type pull and gas
exchange are in the capillaries
-Trachea is divided into two primary bronchi,
termed mesobronchi, that do not enter the lung
but extend posteriorly to reach the posterior air
sacs
-Gases diffuse between the lumen of the
parabronchus and the connecting, blind-ended air
capillaries

45. -Oxygen diffuses in turn from the air capillaries
into the adjacent blood capillaries that give up
carbon dioxide to the air capillaries
-Walls of air and blood capillaries constitute the
site of gas exchange
-Air sacs function to lighten the birds like helium
balloon, but air sacs provide no lift, and it is not
the prerequisite for flight

47.  When bird inhales, air is brought into the
posterior air sacs, which expand. Upon
exhalation, air is forced from the posterior sacs
into the lungs; second inhalation will move the
air from the lungs to the anterior air sac and
second exhalation will push the air out
 Advantages of one-way flow:
1.)No residual volume; all old air leaves w/ each
breath
2.)Cross-current blood flow through the lungs

48.  Pattern of Gas Transfer
- Respiratory organ couples blood flow with
ventilation
 Rates of Gas transfer
- Respiratory organs must also be designed to
match the ventilation rate with perfusion rate
- Breathing that is too fast or too slow is inefficient
- Ratio of perfusion to ventilation depends on the
species

49.  Breathing in Water
- Water is considerably denser than air

50. Cartilaginous Fishes Bony Fishes(Teleost) Agnathans
Septal Gills Opercular Gills Pouched Gills
5 “naked” gill slits Usually have 5 gill slits 6 to 15 pairs of gill
pouches
Sharks and Rays Eels, milkfish, salmon Hagfishes and Lampreys

51. Reptiles Amphibians Birds Mammals
No vocal cords Simple saclike lungs Most of the birds has
nine sacs and these are:
anterior and posterior
sacs
Human breathe through
lungs
No True Diahragms Some amphibians have
no lungs like
Salamander
The typical bird trachea
is 2.7 times longer and
1.29 wider than that of
similarly-sized animals.
Alveoli- spongy and has
a little sac
Reptile lungs composed
of three and these are:
Unicameral,
Multicameral and
Paucicameral
Skin- Cutaneous
Respiration
Avian lungs Trachea
Reptiles are capable of
surviving for long
periods without
breathing.
Many amphibians used
gills at least when they
are young.
Bronchi- structure
similar to trachea,
flexible tubes with
stiffening walls of
hyaline cartilage
Bronchioles

52. BIRD FISH MAMMAL REPTILE AMPHIBIAN
•Unidirectional
•Lungs
•Aspiration
pump
•Longer and
wider trachea
compared to
mammals
•Air sacs
•Unidirectional
•Gills
•Dual pump
•5 to 7 pairs of
gills
•Bidirectional
•Lungs
•Aspiration
pump
•Muscles are
used
•Air are filtered
•Bidirectional
•Lungs
•Aspiration
pump
•Much larger
lungs than
mammals
•Can survive
for long
periods
without
breathing
•Muscles are
used
•Bidirectional
•Lungs and
skin
•Pulse pump
•Simple saclike
lungs