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Home , External gills, Gill, Gill slit

COMPARATIVE OF RESPIRATORY SYSTEMS: , , PIGEON AND RABBIT

What is ?

 Exchange of gases (O2 and CO2)  The process in which is taken inside the body from the envt for oxidation of food to release energy & CO2 so produced is expelled out Physiology of respiration

1. External respiration: Inspiration & expiration 2. Exchange of gases between alveolar air and 3. Internal respiration :Transportation of O2 from blood to tissues, oxidation of food, energy release, Co2 back to resp. surface for expulsion

MovementFlowchart of Oxygen and Carbon

SectionDioxide 37-3 In and Out of the

Oxygen-rich Nasal air from environment cavities Bronchi

Oxygen and

Bronchi Bronchioles Alveoli Bronchioles exchange at alveoli

Carbon

Nasal dioxide-rich Trachea Pharynx cavities air to the environment

BIG QUESTION WHY DO ANIMALS BREATHE? … Why?

 Just like machines, we also need energy!!!  Energy is unlocked from macromolecules like CHO, fats & proteins by oxidation

Evolutionary significance of pharynx

 Organs of resp. (both aq. & terrestrial) are derived from pharynx  Pharynx for food passage from mouth to oesophagus  It opens to through trachea by means of an opening, glottis  Dorsally open to Eustachian tube  Not much used now in - vestige

Respiration in animals

 Whether they live in or on land, all animals must respire. ◦ To respire means to take in oxygen and give off carbon dioxide.  Some animals rely of simple diffusion through their skin to respire.  While others…  Have developed large complex organ systems for respiration.

Respiratory organs 1. : Fish, larval , adult urodeles 2. : 3. Lungs: 4. Skin/ cutaneous resp: Amphibians

The basic necessities of any respiratory organ 1. The respiratory organs must be thin walled so that there is easy diffusion of gases 2. It must be richly supplied with blood enable exchange of gases 3. It should have large area for contraction and expansion.

I. GILLS

1. Fishes 2. ’s / 3. Adult urodelian amphibians

Gills are the respiratory organs.

Development of gills

1. In the embryo the pharynx develops paired pouches due to evagination or pushing out. 2. At the same time skin develop grooves due to invagination or pughing in 3. when the pouch and the groove meet the membrane between the two disentigrates and a slit develops to form slit

Development of gills 4. The gill cleft or slit contains gills which are present in a gill chamber 5. Each gill chamber has an internal branchial aperture opening to pharynx 6. An external branchial aperture opens to external 7. The gill chambers are separated by inter branchial septa and supported by gill rays

Development of gills 8. Each half of the gill filament is called Demibranch. 9. The demibranch on either side of interbranchial septum. gillrays, connective tissue and associated blood vessels with nerves form a holobranch. 10. The demibranch at the anterior end is called pretrematic demibranch and at the posterior end is called post trematic demibranch.  Gills in fishes

 The gills are internal and vary in number depending on the classes they belong to.  is a bony flap like covering that is seen over the gill slits on either sides in bony fishes. Aquatic Gills

 Water flows through the mouth then over the gills where oxygen is removed  Carbon dioxide and water are then pumped out through the operculum What are bony fishes and cartilaginous fishes?

Cartilaginous fishes Bony fishes (Elasmobranches or ) (/ ) 1. 5 pairs of gill slits 1. 4 pairs of gill slits

2. A pairs of in front of the 2. No Spiracles hyomandibular arch

3. Operculum is absent 3. Operculum present

4. Gills open to the exterior by inter 4. Gills open to the opercular branchial aperture chamber 5. No opercular chamber 5.Opercular chamber is present

6. 1 demibranch & 5 Holobranches 6. 4 holobranch, the demibranch of the first gill is lost GILLS IN AMPHIBIANS

 Amphibian are purely aquatic, they need to utilize oxygen in the water- help of gills.  Initially 3 pairs of (gills that are constantly bathed in water)- internal gills-Lungs  Only in Urodeles like and Necturus, 3 pairs of external gills persist through out the life.

ANURA Anya Urodeles? SWIM BLADDER/ AIR BLADDER- Development  Swim bladder or air bladder are paired or unpaired structures arise from the pharynx or oesophagus of bony fishes  The air bladder arise as an outgrowth of the pharynx on either side, initially lateral in position then becomes dorsal  It is below vertebral column and outside . SWIM BLADDER/ AIR BLADDER  Connection between b/w the pharynx and airbladder is called pneumatic duct.  SB serves both as respiratory and hydrostatic organ.  Richly supplied with blood capillaries  In fishes the SB resembles the lungs & makes respiration more effective eventhough they have lesser no of demibranches SWIM BLADDER/ AIR BLADDER- How is it working?

 When the fish gulps in air, it enters through mouth, pharynx, pneumatic duct  Oesopharyngeal pumb forces air into pneumatic duct  When air bladder is compressed, & CO2 is expelled through the mouth as bubbles.

SectionFigure 33-3 33–10: Lungs

Nostrils, mouth, and throat Trachea Lung Air sac

Salamander Lizard Primate Pigeon Figure 37-13 The Respiratory System SectionThe 37-3 Human Respiratory System Lungs From amphibians to mammals all terrestrial org. has lungs Formation of lungs 1. Lungs develop from the floor of pharynx at its posterior end as a small bud called lung bud single through single evagination. 2. The lung bud slightly elongates & bifurcates into two 3. The opening of lung bud into the pharynx develops a small slit & form the glottis. 4. The part after glottis forms the larynx (voice box) 5. The elongated part of the lungs before bifurcation forms Trachea (air pipe) 6. The bifurcated part becomes the bronchi 7. The ends of bifurcated parts of the lung buds expand to form lungs. 8. The lungs push backwards & come to lie on either side of the . 9. Lungs get surrounded by coelomic epithelium

LARYNX

TRACHEA

AIRSACS IN BIRDS

LUNGS LARYNX  Part between glottis and upper end of trachea, well developed in tetrapods Larynx in Amphibia a. In anurans there is a laryngo-tracheal chamber for production of sound (urodeles and apodans do no not produce sound) b. Laryngo-tracheal chamber: 3 cartilaginous structure to keep it stretched-one ring like cricoid cartilage and two semicircular arytenoids cartilage

Larynx in Reptiles  Similar as in frog.  Has well developed hyoid cartilage to hold larynx in position Larynx in Birds  Simple  Another organ for sound Production- Syrinx

Larynx in Mammals  Highly developed-3 cartilages  Thyrenoid/ thyroid cartilage: @ end of larynx  Dorsal to thyroid cartilage is the arytenoids  Below arytenoids is the crinoids, followed by trachea.  Epiglottis (fold of mucous membrane of pharynx)-@ ant to glottis  Erect while breathing, close the glottis while eating  Sound: a pair of vocal cords b/w thyroid & arytenoids cartilages TRACHEA

 A duct that connect pharyngeal cavity to lungs  Trachea bifurcates into - two bronchi – Each bronchus enter to lungs – bronchioles (pimary, secondary , tertiary and terminal)