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Cardiovascular system 心臟循環器系

 1. Heart
 

 2. Vascular system

      --- Arterial and venous system

 3. Lymphatic system
      --- At present, proved to be absent in fish

Heart 心臟

  --- Protection

        --- Cranioventral end of the pectoral girdle

              ---> Laterally and ventrally surrounding the pericardial cavity

                     --- Located in the pericardial cavity

  --- Location

        --- Just posterior to gill and to some extent ventral to gill
 

             Anterior to the abdominal cavity

              --- True for all gnathostome fishes

                    --- but more posteriorly placed in the agnatha

1. Compostion of heart

      --- S-shaped structure of the heart

           --- The first anlage of the vertebrate heart

                  --- Lined up in a row of cardiac chambers

                         --- 4 chambers in a row

                               --- a. Venous sinus (Sinus venosus)

                                    b. (Cardiac) atrium (Atrium cordis)

                                    c. (Cardiac) ventricle (Ventriculum dordis)
 

                                    d. Cardiac bulb (Bulbus cordis)

                                        --- Connected to truncus arteriosus

                                        --- Arterial cone (conus arteriosus)

                                               --- Shark, Ray
 

                                        --- Reduced form in many teleostei
                                               --- Arterial bulb (bulbus arteriosus)

           --- Original blood-vessels or its anlage

                  --- Originated from yolk-sac veins (Vitelline veins, Venae vitellinae)   

           --- Gubernaculum cordis

                  --- A ligamentous structure

                        --- Attaching the tip of the heart to the pericardium

                  --- Chondrostei\ Teleostei

           --- Venous sinus\ cardiac atrium

                   --- Just widening of the heart tube

                Cardia ventricle\ cardiac bulb

                   --- A thickening of the muscular wall of the heart tube

     --- Species variation in carciac anatomy

           --- Dipnoi\ Latimeria

                 --- Partially divided atrium and ventricle

                       --- 2 symmetrical divisions of each chamber

           --- Protopterus (African lungfish)

                 --- A peculiar kind of A-V valve

                        --- Consisting of collagenous connective tissue surrounding a cartilagenous core

     --- Layers of the heart

           --- a. Epicardium with subepicardium

                    --- Merging into the epithelial lining of the pericardial cavity

                b. Myocardium

                    --- Extremely thin in the sinus venosus
 

                    --- Considerable thickness

                          --- (a) (Cardiac) atrium

                               (b) Cardiac bulb

                               (c) Especially in the cardiac ventricle

                c. Endocardium with subendocardium

                    --- Continuous with the corresponding layer in the blood vessels
 

                    --- Formation of heart valves

                         --- Chordae tendinae (A thin tendon thread)

                               --- Preclusion of the reversion of a valve

     1) Venous sinus

          --- Location
                --- Dorso-caudal region of pericardial cavity

                     Dorsal to ventricle and aortic bulb

                     Relatively small compared to the atrium

          --- Better developed in teleostei than in the elasmobranchii

                --- A very thin layer of heart musculature

                --- V wave in ECG

              Species variation

          --- Associated veins opening into venus sinus

                --- By penetration through the transverse septum

              (1) Common cardinal veins

                    --- Bilateral ones

                          --- Cuvier duct

                    --- Running down along both sides of esophagus

                         Dorsal side of venous sinus

                       # Ductus Cuvieri in the agnatha (Petromyzontes\ Myxini)

                           A portal heart in the myxini

              (2) Hepatic veins

                    --- Generally posterior wall of the sinus through the penetration of diaphragm

                    --- Sphincter in the opening in the elasmobranchii

              (3) Jugular and subclavian veins

     2) Sino-atrial opening and sinoatrial valve (SA valve)

          --- Folding both walls of the sinus and atrium

                --- At the point where the sinus fuses with the atrial muscle

         --- No sinoatrial valve in snakehead
 

              Division of sinoatrial valve into separate portions

                --- Eel and sturgeon

     3) (Cardiac) atrium

          --- Dorsal to ventricle and even the cardiac bulb

                --- Thicker than that of the sinus

                       --- Spongy or trabecular layer of cardiac muscle

          --- mm. pectinati

                --- Running through the atrial lumen
 

                --- Atrio-ventricular opening (Ostium atrio-ventriculare)

                       ---> Radiation in star-like fashion

                              ---> Branching-out like a fan

                                     ---> A muscular net beneath the roof of the atrium

               Muscular trabeculae

                --- Auriculare

                      --- Atrial contractions

                            --- Emptying auriculare of the atrium     

          --- Cardiac auricle 心耳

                --- Frequent ventral protrusions of atrium

                       --- Running along the sides of the ventricles or along the ventral aorta

               Coronary sulcus 冠狀溝

                --- Furrow between the atrium and ventricle

                       --- A portion of nervus vagus (X) and its connective tissue in teleostei

     4) Atrio-ventricular opening

         --- Always located in dorsal wall of the ventricle

               --- a. Usually 2 equal valves

                          --- Designated as primary valves

                    b. Often, a large number of different-sized valves

        --- The distance between the AV valve\ the ostium arteriosum(Fig. 185\188)

               --- a. Petromyzon
 

                    b. Acipencer, esp, salmonidae

                        --- Bulbo-auricular ridge

     5) (Cardiac) ventricles

         --- Thicker wall

               --- a. Round type
 

                    b.Triangular type

                        --- Active fishes

               --- Ventricle in teleostean heart

                     --- Fitting into the angle between the cleithra

                           --- A three-sided pyramid

        --- a. Spongy layer

                 --- Most part of ventricle
                        --- Inner layer of ventricular muscle

             b. Compact layer

                 --- Outer layer of ventricular muscle

                        --- Distribution of coronary artery

                        --- Longitudinally, circularly and spirally arranged muscle fibres

                 --- Correlated with fish activity

                       --- Absent or developed compact layer

     6) Arterial opening

         --- Between the cardiac ventricle and cardiac bulb

     7) Cardiac bulb 心臟球

         --- Species variation
               --- Some modification in fishes

                    No cardiac bulb in the agnatha

         --- Arterial cone
               --- Original form of cardiac bulb found in shark and ray
 

               --- Separated from the other heart divisions

                     --- Heart musculature

                           --- An independant heart-rhythm

               --- Many longitudinal rows of valves on internal surface (Fig. 189)

              Aortic bulb in  many teleosts
               --- Regression from cardiac bulb 
          

         --- Most anterior part of the heart

               --- An elongated barrel

                      --- Elasmobranchii

                           Holocephali\ Dipnoi\ Chondrostei\ Holostei

         --- Functions of cardiac bulb

               --- Maintenence of smooth blood flow leading to prevention of overpressure load to gill

     8) Arterial trunk (Ventral aorta) 動脈幹

         --- The first portion of the arterial vascular system except for teleostei

               --- No heart muscle fibres

                    Smooth musculature

                    Arterial or aortic bulb in teleostei

                      --- The first portion of the arterial system

         --- a. Arterial cone in primitive teleosts 動脈圓錐

                  --- Myocardium and internal valve

             b. Arterial or aortic bulb only in teleostei

                  --- An onion-shaped swelling of the arterial trunk
 

                  --- Organ regressed through arterial cone from cardiac bulb(Conus arteriosus)

                        --- Enlargement of basal part of ventral aorta

                        --- Only distal row of valve flaps
 

                        --- ie., cardiac bulb

                              ---> Arterial cone

                                      ---> Aortic bulb

                  --- Smooth musculature\ Elastic connective tissue

                        --- Not rapidly contractible

                             Absorption of the pressure-wave coming from the ventricle

     9) Ventral aorta (AOv)

     10) Pericardial cavity

          --- Pharyngeal base

               The most anterior part of coelom
 

               Posteriorly, border of pericardial cavity

                --- Anterior border of peritoneal cavity

          --- Thin coelomic epithelium (Mesothelium)

Nutrient vessels of the heart

  1) Arterial supplies

      --- Dorsal aorta\ Last efferent branchial arteries

             ---> Pericardium

                     ---> Cardiac ligament (ligamenta cordalia)

                             ---> Epicardium of the heart
                                     <--- Coronary arteries

          # Coronary arteries in higher vertebrates

  2) Venous system

      --- Coronary sinus\ Capillary-luminar anstomosis in higher vertebrates
 

      --- Capillary-luminar anstomosis

           --- Direct connections between the capillaries and the heart lumen

           --- Exception of the bulbus region         

     (1) Cardiac bulb

          --- Anterior cardinal vein

     (2) Ventricular wall

          --- Pouring into atrial cavity near atrio-ventricular opening (Ostium atrioventriculare)

     (3) Atrial wall

          --- Pouring into atrial cavity by few veins on the border between the ventricle and the venous sinus

Myogenic excitation

   --- Modulation mainly by the adrenergic nervous system
   --- Reference book 1-1)

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