Respiration In Fish: How Do Fish Breathe | Process of Respiration in Fishes | fish respiratory system | fish respiratory system diagram | Respiratory system of fish /Respiration of fish? How do fish breathe in water/ fish breathing?

             Respiratory system of fish /Respiration of fish?                                   How do fish breathe in water/ fish breathing?

Fish  is a gill breather . respiration is aquatic.

The respiratory organs are 4 pairs of gills. They are located inside two gill      

chambers (branchial chambers).the gill chambers are located on either side of the pharynx in the head  region. Each gill chamber is covered by a flap of skin called operculum .  the gill chamber opens to the out side by a crescentic opening called gill aperture in front of the pectoral fin and behind the operculum.

 the posterior margin of the operculum is attached with a membrane called branchiostegal membrane . 

The pharynx has 5 pairs of gill slits on the lateral wall of the pharynx and they open into the gill chamber . the wall of the pharynx between the gill slits is called the interbrain-chial septum. There are ,thus fore pairs of  interbranchial septa . Each interbranchial  septum is supported by branchial arch ( gill arch).the fast 4 pairs of branchial arches support the 4pairs of interbranchial septa.

Fish  has 4pairs of gills. Each gill chamber accommodates 4gills . each gill is formed of a gill arch and gill filaments .The gill filaments are attached on the anterior and posterior faces of the gill arch in two rows. Thus each gill is a holobranched formed of two hemibranchs.   each hemibranch   is  a row of gill filaments .

            In fish  the interbranchial septa are reduced and the gill filament hang freely into the gill chamber.this type of gill is called filiform or pectinate. 

The inner end of each branchial arch is produced into teeth like processes inside the pharyngeal cavity.There called gill rakers.
They prevent the entry of food materials into the gill chamber.
The gill filaments are covered by thin epithelium with blood capillaries.

An afferent artery supplies deoxygenated blood to the gill . the oxygenated blood is collected by an efferent artery .

                            
                                   

                     : MECHANISM OFRESPIRATION:

Fishes exhibits gill respiration and aquatic respiration .

• ·         During breathing , the gill apertures are closed tightly by pressing the opercular     against the body.

• ·        The interbranchial septam swells out , the floor of the buccopharyngeal cavity lowers.

• ·        As a result, the Bucco pharyngeal cavity enlarges .
  

• ·        The mouth opens .
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• ·        Water flows in through the mouth and the buccopharyngeal cavity is filled with water .
  

  

• ·        Now the mouth is closed.

• ·        The interbranchial septum contracts ; the floor of the buccopharyngeal cavity moves up .

• ·        The opercula lift up and the gill apertures open .

• ·        The water from the buccopharyngeal cavity flows over the gills through the gill slits .

• ·        The gills are bathed in water .
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• ·        The blood of gill filaments absorb O²  and gives out CO² .

• ·        This process is repeated. This process brings out the regular opening and closing of the mouth and operculum.

GILL