I BACK I RETURN I NEXT I SUMMARY I Any Questions? I

Respiratory system 呼吸器系  
 

 1. Gill

    ---Embryological consideration

         --- Embryonal development of all vertebrates

               --- Lateral wall of pharynx

                     ---> Endodermal viseral sac and ectodermal visceral groove

                             ---> a. Visceral clefts

                                       ---> (a) Hyomandibular clefts

                                                 --- Regression to spiracle in sharks and rays

                                                      Closure in teleosts

                                              (b) Branchial clefts or gill slits

                                  b. Visceral arches (Viscerocranium)

                                       ---> (a) Mandibular and hyoid arches

                                             (b) Branchial or gill arches

                   # Visceral sac = Pharyngeal pouch

                       Visceral groove = Pharyngeal groove

    --- Anatomical position
          --- Within opercular cavity\ gill chamber\ branchial cavity
 

    --- Respiratory and excretory functions

          --- a. Respiration

                   --- Extraction of O₂ \ Excretion of CO₂
 

                   --- Other respiratory tissues

                         --- Skin\ Yolk sac\ Fins\ Gill covers

               b. Excretion 

                   (a) Nitrogenous metabolic wastes

                   (b) Exchange of univalent ions

                          ---> Osmoregulation

          --- Agnatha and elasmobranchii

                --- Only breathing with gills

               Many groups of osteichthyes

               a. Gill
 

               b. Other air-breathing organs

                   --- Lung as one type of air-breathing organ

                         --- Dipnoi and many teleostei

                   --- Associated with unfavorable alteration in the aqueous habitat

                         --- a. Drying-up

                              b. Oxygen-deficiency\ Formation of H₂S

    1) Path of the respiratory water (p 287)

        --- a. Teleosts

                 --- The simplest

             b. Holocephali

                 --- Nasolabial groove or oral opening

                       ---> Opercular gill slit

             c. Elasmobranchii

                 --- Nasolabial groove\ Oral opening\ Spiracle or first gill slit

                       ---> Orobranchial cavity

                                ---> Gills

                                        ---> Parabranchial gill cavity

                                                ---> Gill-slits

         --- Considerable variation in the agnatha

    2) Internal gill

         [Embryological consideration on the internal gill]

           --- Special enlargements of the foregut epithelium

                 ---> Respiratory part

                          <--- Entodermal tissue surrounging the branchial bones

         --- a. Beneath a unitary gill cover in the teleosts and holocephali

              b. In the gill slits in elasmobranchii/ gill pouches in agnatha

         --- Attached to the gill arches of the visceral skeleton

              --- a. Hypo-\ Cerato-\ Epibranchial skeleton

                   b. Often on the pharngobranchial as well

--- A double row on each bone 

        (1) Gill arches 

              --- 5 pairs in left and right side in osteichthyes

                    --- 6∼7 pairs in some chondricthyes

        (2) Gill raker (Branchictenia, 새파)

              --- No gill rakers in certain fish
 

              --- Located on the medial lining of branchial arches

                     --- Grown-up on a cartilagenous or bony nucleus (Gill ray)

                     --- 2 rows originating from papillary projection of branchial mucosa

                           a. Oral row  -+------------ Longer row of gill raker

                           b. Aboral row-+          ---> Generally called 'Gill raker'

              --- Primary raker

                    --- Secondary lateral raker

                           --- Knobs on the sides of the primary raker

                                   --- Rough surface of raker

              --- Functions of gill raker

                  a. Mastication\ Aqusition of foods

                      --- Rakers

                            ---> Formation of a gill filter (Plankton)

                      --- 3 types of filter

                           --- Long oral rakers in b and c

                           a. Biserial- symmetric

                                --- The most common type

                           b. Dimorph-monacanth -

                           c. Dimorph- polyacanth

                   b. Protection of gill filaments

       (3) Gill filaments

             --- No filaments in the last arch of osteichthyes

                   --- Only 4 pairs of gill archs are involved in respiration and feeding of foods (gill rakers)

             a. Primary lamellae or filaments

                  --- Arrangement in a double-row on each bone

                        ---> (a) Anterior or oral row

                                   --- A hemibranch or half-gill

                               (b) Posterior or aboral row

                                   --- Another hemibranch or half-gill

                              ===> Holobranch or entire gill

                  --- Each hemibranch

                        ---> Composed of a series of primary gill-filaments or foliae branchiales

             b. Secondary lamella or Lamellae branchiales

                 # Synonyms
                       --- Respiratory platelets

                            Gill lamellae

                  --- Developed on both the superior and inferior surface of each filament

                        --- Perpendicular to the primary filaments

                              --- The bases of the secondary lamellae

                                   ---> Obliquely running to the longitudinal axis of the filament

                  --- Arrangement of secondary lamellae(Fig. 226)

                      (a) One single row on each surface

                           --- Perch\ Tinca Blica\ Chondrostoma

                                Pleuronectas platessa

                      (b) Double row on each surface

                           --- Anguilla\ Misgurunus\ Lucioperca\ Zoarces

     2) Pseudogill or pseudobranch

         --- No pseudobranch in anguilliformes

         --- Separate gill located on the medial surface of the opercle or on the anterior wall of

              hyomandibular cleft

               --- No respiratory function

                    A few secondary lamella

               --- Control of intraocular pressure

                    An endocrine organ associated with fulfilment of swimbladder gas and expansion of

                    melanophores

        --- 3 types of pseudobranchs (Birtin's differentiation)

             (1) Free type

                  --- Completely identical structure to normal gills

                         --- True hemibranch

             (2) Covered type

                  --- 3 types according to the degree covered by connective tissue

                       Only in teleostei

             (3) Embedded or submerged type (Cypriniformes)

    3) Interbranchial septum(Gill septum)

        --- Between anterior and posterior filaments of each branchial arch

               --- a. Well-developed interbranchial septum

                        --- Sharks and rays

                    b. Regressive interbranchial septum

                        --- Teleostei

   4) External gill

        --- During the early development stages of some species,  ie., embryonic or larval organs

              --- Usually degenerated in the adult
 

              --- a. Often long structures protruding into water alongside the body of the larva
 

                   b. The form of intrauterine respiratory and/or nutritive organs

                       --- Live-bearing species
 

        --- Function

              --- a. Respiratory

                       --- Often not exclusively

                   b. Nourishing the embryo

                       --- (a) From yolk of the egg

                            (b) From special uterine secretions in live-bearing species

       (1) Entodermal external gill

            --- Primarily in the elasmobranchii

                  --- Extremely elongated gill filaments(ex, Urolophus)

                         --- Projected out of the gill slits

            --- Holocephali\ Chondrostei

                  --- Less-developed

                 Certain teleosts

                  --- Osteoglossomorpha

                        --- Gymnarchus\ Heterotis

       (2) Ectodermal external gill

            --- Dipnoi(Proptoterus\ Lepidosiren)
 

            --- Formed exclusively by the skin

                  |  <--- Development before the gill slits\ opercula

                  |         --- Supplied with blood by the larval aortic arch or by the gill

                  |              arteries which develop out of it

                  |

                  +---> Tuft- or tree-shaped structures

                              <--- Their own musculature

                                         ---> Always move to obtain a fresh supply of respiratory water

            --- 3 types according to the systematic position of the species which have ectodermal external

                 gills

                  Proptoterus etc.

                   ① Remaining intact in the adult for a very long time(P. annectens)
 

                   ② Found only in the larvae(P. aethiopicus)

                         --- Also polypteryformes(Branchiopterygii)

                               --- Polypterus\ calamoichthyes

                   ③ Intermediate type between ① and ②(P. dolloi)  

                         --- Found in only one species of teleostei

                               --- Acentrogobous(Gobidae)

                  Lepidosiren

                   --- Degenerated within a few days after hatching

                  Neoceratodus

                   --- Not any external gills

            --- Often long structures which protrude into the water alongside of the larval body

 2. Accessory respiratory organs

    1) Organs of aquatic respiration

        --- Young fishes during the gillless phase

              --- a. Skin or body surface
                   b. Primordial fin

                      <--- A thin fold of skin

                   c. Gill cover in holocephali

                   d. Vascular network which develops around the yolk sac in embryos and larvae

    2) Air-breathing organs

       a. Lung(Dipnoi\ Polypteryformes)

            --- A primitive type similar to that which existed when the lungs and swimbladders first began to

                 evolve

                  ---> ① Teleostean swimbladder

                        ② Tetrapod's lung

            --- Dipnoan lung

                  --- Not very efficient in the excretion of CO₂, even in recent dipnoi
 

                  --- P. aethiopicus

                        --- Lung(About 90% of oxygen\ Not more than 57% of the CO₂)

                            Gill(No more than 17%\ The rest of CO₂)

            --- Electric eels

                  --- Electrophorus electricus
 

                  --- The oral cavity(From the air)

                         --- Taking-up only 78% of the oxygen which the body requires

                         --- 81% of the CO₂ releasing into the water through the skin

                         --- Strongly reduced gills in this species

       b. Swimbladder

            --- Never developed in the agnatha\ the lower gnasthomata, ie., the elasmobranchii and the

                 holocephali

       c. Oral and branchial cavities

       d. Gill-appendages\ Branchial papillae\ Special labyrinthine organs

       e. Stomach\ Intestine

   [Vasculature of the gill]

    --- 2 kinds of vasculatures

          --- a. Respiratory blood pathway

                   --- Arterio-arterial vasculature

              b. Non-respiratory blood pathway

                   --- Arteriovenous vasculature

   1) Respiratory blood vasculature

        --- Ventral aorta
               --- Afferent branchial artery

                    ---> Afferent filamental artery

                           ---> Afferent lamellar arteriole

                                  ---> Efferent lamellar arteriole

                                         ---> Efferent filamental artery

                                                ---> Efferent branchial artery

                                                       --->Dorsal aorta

    2) Non-respiratory blood pathway
 

         --- Efferent branchial artery (or efferent filamental artery)

               ---> Along the long axis of filament

                       ---> Branchial vein (Nutrient vasculature)

                                                 I BACK I RETURN I NEXT I SUMMARY I Any Questions? I