Lecture 16: Comparative Anatomy Of The Heart Flashcards

1
Q

Describe the main components of the vertebrate cardiovascular system

A
  • Muscular pump:
  • Heart
  • Vessels carrying blood away from the heart:
  • Arteries
  • Note that whether they are carrying oxygenated or deoxygenated blood is immaterial.
  • Vessels carrying blood toward the heart:
  • Veins
  • A series of connecting vessels associated with the pharyngeal arches:
  • Aortic arches
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2
Q

Describe the layers of the pericardial cavity

A

The heart is enclosed within a sac composed of serous membranes:

  • Layers:
  • Parietal pericardium:
    • Outer layer of the sac
  • Pericardial cavity:
    • The potential space between the inner and outer layers of the sac
  • Visceral pericardium:
    • The inner layer of the sac
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3
Q

Describe the heart

A

The heart is a subdivided, muscular tube made up of several layers:

  • Layers:
  • Epicardium: Thin, outer layer of the heart
  • Myocardium: Thicker, middle layer composed of cardiac muscle tissue. Coronary arteries and veins supply the heart muscle directly with oxygenated blood.
  • Endocardium: Thin, layer lining the cavities. Continuous with endothelium of blood vessels
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4
Q

Describe the fish heart

A
  • Single pass, unidirectional pump
  • Four chambers:
  • Sinus venosus with sinoatrial valve:
    • Thin-walled sac
    • Similar in structure to veins
    • Receives deoxygenated blood from:
    • Common cardinal veins (= ducts of Cuvier).
    • Receive:
  • -Anterior and posterior cardinal veins
    • Hepatic veins
  • Atrium with atrioventricular valve
    • Thicker wall than sinus venosus
  • Ventricle
    • Thickest wall of any heart chamber
    • Main muscular pump
  • Conus arteriosus with semilunar valve(s)
    • Extends cranially as ventral aorta
    • In teleosts = bulbous arteriosus.
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5
Q

The amphibian has a three chambered heart, (Atrium, Ventricle, and the conus truncus arteriosus). Describe the atrium.

A
  • Completely divided in amphibians
  • Partly divided in lungfishes
  • Right atrium receives deoxygenated systemic blood.
  • Left atrium receives oxygenated pulmonary blood via pulmonary vein.
  • Walls of both atria contain trabecular folds.
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6
Q

The amphibian has a three chambered heart, (Atrium, Ventricle, and the conus truncus arteriosus). Describe the ventricle.

A
  • Single ventricle
  • Thicker muscular wall than found in atria
  • Receives deoxygenated blood from right atrium
  • Receives oxygenated blood from left atrium
  • Trabecular arrangement of ventricular wall mostly keeps the two blood supplies separated.
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7
Q

The amphibian has a three chambered heart, (Atrium, Ventricle, and the conus truncus arteriosus). Describe the conus truncus arteriosus

A
  • Partially subdivided by spiral valve
  • Blood from right side of ventricle is preferentially sent to pulmonary arteries.
  • Blood from left side of ventricle is preferentially sent to head and rest of body.
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8
Q

Describe the reptilian heart

A
  • Atria:
  • Completely divided as in amphibian
  • Ventricle:
  • Incompletely divided in most reptiles
  • Completely divided in crocodilians
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9
Q

Describe the turtle heart

A
  • Right atrium receives deoxygenated systemic blood.
  • Left atrium receives oxygenated pulmonary blood.
  • Single ventricle partly subdivided into left and right chambers:
  • Left side = cavum arteriosum.
  • Right side = cavum venosum.
  • Two sides are connected by interventricular canal.
  • Right side of ventricle is further subdivided by a muscular septum.
  • This subdivision creates a ventral cavum pulmonale.
  • Muscular septum serves as a one-way valve for the interventricular canal
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10
Q

Describe the pathway of blood flow through the turtle heart

A
  • Systemic deoxygenated blood from vena cava →
  • Into right atrium →
  • Through right atrioventricular valve →
  • Into cavum venosum→
  • Into cavum pulmonale→
  • Through semilunar valve →
  • Into pulmonary artery →
  • To Lungs
  • Oxygenated blood through pulmonary veins →
  • Into left atrium →
  • Through left atrioventricular valve →
  • Into cavum arteriosum →
  • Through interventricular canal →
  • Into cavum venosum →
  • Through semilunar valves →
  • Into left and right aortae.
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11
Q

What occurs in a turtle heart during atrial and a ventricular contraction?

A
  • During atrial contraction:
  • Atrioventricular valves open and occlude interventricular canal.
  • Keeps oxygenated and deoxygenated blood separated.
  • During ventricular contraction:
  • Interventricular canal opens.
  • Oxygenated blood flows into cavum venosum.
  • Muscular flap closes off cavum pulmonale.
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12
Q

Describe Blood Flow through a Crocodilian Heart

A
  • Ventricles completely divided.
  • Paired ventricles:
  • Each with aorta:
    • Right aorta from left ventricle.
    • Left aorta from right ventricle.
  • Pulmonary trunk also leaves from right ventricle.
  • Crossing of aortae:
  • Communicating hole = Foramen of Panizzae.
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13
Q

What adaptions does a reptile events for “diving”

A
  • Blood shunted from lungs:
  • Action via vagus nerves.
  • Constriction of pulmonary arteries.
  • Slowing of heart rate.
  • Blood from right atrium must by-pass lungs:
  • Shunted to left ventricle in crocodilians:
    • Through foramen of Panizzae.
  • Sent to aortae from right ventricle in other reptiles.
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14
Q

Describe the Early-Stage Development of the Mammalian Heart

A
  • Arises from splanchnic mesoderm.
  • Early stage:
    • Paired double-walled tubes:
    • Outer layer of epimyocardium.
    • Inner layer of endocardium.
  • Linear organization of cardiac tubes:
  • Conus arteriosus (cranial).
  • Ventricle.
  • Atrium.
  • Sinus venosus (caudal).
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15
Q

Describe Further Development of the Mammalian Heart

A
  • Fusion of cardiac tubes:
  • Begins at cranial end of future heart
  • Intrinsic pulsation of tube begins with fusion.
  • Conus arteriosus:
  • Begins to pulsate first.
  • Has slowest intrinsic rate of pulsation.
  • Fusion of cardiac tubes:
  • Sinus venosus is last to fuse and to pulsate:
    • Has fastest rate of pulsation
    • Overrides pulsation rates of other parts of the cardiac tube
    • Becomes adult pacemaker of the heart
  • See Slide 24-29
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16
Q

Describe Mamallian Blood Flow Anatomy From the Fetal Heart to the Right Ventricle

A
  • Blood flow through fetal heart:
  • Oxygenated blood from placenta → right atrium →
  • Foramen ovale into left atrium →
  • Through left atrioventricular valve into left ventricle →
  • Aortic trunk through aortic semilunar valve →
  • Aortic arch and body
  • Blood flow through fetal heart that enters right ventricle:
  • From right atrium → through right atrioventricular valve into right ventricle →
  • Through right semilunar (pulmonary) valve → pulmonary trunk →
  • Through ductus arteriosus →
  • Aortic arch and body
17
Q

Describe the Rest of Mammalian Heart Anatomy

…uh…yeah.

A
  • Completely divided atrium
  • Completely divided ventricle
  • Papillary muscles
  • Chordae tendinae
  • Coronary arteries and veins
  • Blood flow through right heart:
  • From superior and inferior vena cavae → right atrium →
  • Right ventricle through right atrioventricular valve (tricuspid) →
  • Lungs via pulmonary artery →
  • Through pulmonary semilunar valve
  • Blood flow through left heart:
  • From lungs to left atrium via pulmonary veins →
  • Left ventricle through left atrioventricular valve (bicuspid or mitral valve.) →
  • Aortic trunk through aortic semilunar valve →
  • Aortic arch and body
  • See Slide 32-33