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Questions and Answers
The ______ valves are found between ventricles and trunks.
The ______ valves are found between ventricles and trunks.
Semilunar
The ______ venosus becomes the sinoatrial node in birds and mammals.
The ______ venosus becomes the sinoatrial node in birds and mammals.
Sinus
The pacemaker sets the pace for the ______ of the body.
The pacemaker sets the pace for the ______ of the body.
heart
The aortic arches connect the ventral aorta with the ______ aorta.
The aortic arches connect the ventral aorta with the ______ aorta.
Segments of the first pair of aortic arches are lost and remaining sections become ______ pseudobranchial arteries.
Segments of the first pair of aortic arches are lost and remaining sections become ______ pseudobranchial arteries.
The ______ aorta emerges from the heart and passes forward beneath the pharynx.
The ______ aorta emerges from the heart and passes forward beneath the pharynx.
The vertebrate circulatory system transports ______ and various other materials.
The vertebrate circulatory system transports ______ and various other materials.
The blood-vascular system is a ______ system consisting of blood vessels.
The blood-vascular system is a ______ system consisting of blood vessels.
Arteries have muscular and ______ walls.
Arteries have muscular and ______ walls.
The ______ is the site of exchange between the blood and body cells.
The ______ is the site of exchange between the blood and body cells.
The heart is a muscular pump containing a ______ to regulate rate.
The heart is a muscular pump containing a ______ to regulate rate.
Lymph is similar in composition to ______ plasma.
Lymph is similar in composition to ______ plasma.
Lymph vessels are found in most ______ tissues of the body.
Lymph vessels are found in most ______ tissues of the body.
The entire circulatory system develops early from ______ mesenchyme.
The entire circulatory system develops early from ______ mesenchyme.
Chondrichthyan hearts have a single-circuit with ______ chambers.
Chondrichthyan hearts have a single-circuit with ______ chambers.
The ______ receives blood; filled by suction when the ventricle contracts and enlarges the pericardial cavity.
The ______ receives blood; filled by suction when the ventricle contracts and enlarges the pericardial cavity.
The ______ is a thin-walled muscular sac; an A-V valve regulates flow between the atrium & ventricle.
The ______ is a thin-walled muscular sac; an A-V valve regulates flow between the atrium & ventricle.
In teleosts, a ______ arteriosus is present rather than a conus arteriosus.
In teleosts, a ______ arteriosus is present rather than a conus arteriosus.
In lungfish and amphibians, the ______ septum is partial or complete.
In lungfish and amphibians, the ______ septum is partial or complete.
The spiral valve in the conus arteriosus of many dipnoans and amphibians alternately blocks and unblocks the entrances to the ______ pulmonary arches.
The spiral valve in the conus arteriosus of many dipnoans and amphibians alternately blocks and unblocks the entrances to the ______ pulmonary arches.
In birds, the postcava establishes a direct connection with the ______ portal veins.
In birds, the postcava establishes a direct connection with the ______ portal veins.
In mammals, the anterior part of the postcava is formed from the ______ and right subcardinal.
In mammals, the anterior part of the postcava is formed from the ______ and right subcardinal.
The supracardinal veins form the part of the ______ veins.
The supracardinal veins form the part of the ______ veins.
Veins from the legs, tail, and adjacent regions pass directly into the ______ postcava.
Veins from the legs, tail, and adjacent regions pass directly into the ______ postcava.
The ______ portal system vanishes in mammals.
The ______ portal system vanishes in mammals.
The anterior cardinal veins persist in all vertebrates as the ______ jugular vein.
The anterior cardinal veins persist in all vertebrates as the ______ jugular vein.
The reduced detached base of the left precava remains as the ______ sinus of the heart.
The reduced detached base of the left precava remains as the ______ sinus of the heart.
In a developing fetus, blood obtains oxygen and gives up carbon dioxide via the ______, not the lungs.
In a developing fetus, blood obtains oxygen and gives up carbon dioxide via the ______, not the lungs.
In Teleosts, the ______ artery branches off the 6th aortic arch to supply the swim bladder.
In Teleosts, the ______ artery branches off the 6th aortic arch to supply the swim bladder.
The ______ aorta is the source of the common carotid artery.
The ______ aorta is the source of the common carotid artery.
In Tetrapods, the 3rd aortic arches and the paired ______ aortae are called the internal carotid arteries.
In Tetrapods, the 3rd aortic arches and the paired ______ aortae are called the internal carotid arteries.
The 5th aortic arch is usually ______.
The 5th aortic arch is usually ______.
In Anurans, at metamorphosis, the ______ arteriosus of arch 6 is lost, so blood entering this arch goes to the skin and lungs.
In Anurans, at metamorphosis, the ______ arteriosus of arch 6 is lost, so blood entering this arch goes to the skin and lungs.
In Reptiles, the ventral aorta has no ______ valve.
In Reptiles, the ventral aorta has no ______ valve.
In Tetrapods, the 4th aortic arches are called the ______ arches or the aorta.
In Tetrapods, the 4th aortic arches are called the ______ arches or the aorta.
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Study Notes
Vertebrate Circulatory System
- Transports gases, nutrients, waste products, hormones, and various other materials; involved in thermoregulation and immunity.
- Composed of the blood-vascular system and lymphatic system.
Blood-Vascular System
- A closed system consisting of blood vessels where the enclosed fluid travels in a circuit.
- Composed of:
- Arteries: carry blood away from the heart; have muscular, elastic walls; terminate in capillary beds.
- Veins: carry blood back to the heart; have less muscle in their walls than arteries but are very elastic; begin at the end of capillary beds.
- Capillaries: have very thin walls (endothelium only); are the site of exchange between the blood and body cells.
- Heart: a muscular pump (cardiac muscle) containing a pacemaker to regulate rate, which can also be influenced by the Autonomic Nervous System.
Lymphatic System
- An open system consisting of vessels and sinuses that communicate with coelomic spaces of the body.
- Found in all vertebrates and composed of:
- Lymph and lymph vessels: lymph is similar in composition to blood plasma; it bathes all cells and contains WBC, but RBC are absent.
- Lymph nodes: located along lymph vessels; contain lots of lymphocytes and macrophages.
- Lymph hearts: consist of pulsating smooth muscle that propels lymph fluid through lymph vessels; found in some animals.
Development of Circulatory System
- The entire circulatory system develops early from mesoderm mesenchyme.
- In the mesenchyme, central patches of cells give rise to blood cells, peripheral ones form blood vessels.
Chondrichthyans (Cartilaginous Fishes)
- Single-circuit heart with 4 chambers:
- Sinus venosus: receives blood; filled by suction when the ventricle contracts and enlarges the pericardial cavity.
- Atrium: a thin-walled muscular sac; an A-V valve regulates flow between atrium and ventricle.
- Ventricle: muscular walls.
- Conus arteriosus: leads into the ventral aorta; conal valves in the conus arteriosus prevent backflow.
Teleosts (Bony Fishes)
- Heart is similar to that of cartilaginous fishes, except that a bulbus arteriosus (a muscular extension of the ventral aorta) is present rather than a conus arteriosus.
Lungfish and Amphibians
- Modifications are correlated with the presence of lungs and enable oxygenated blood returning from the lungs to be separated from deoxygenated blood returning from elsewhere.
- 2-circuit heart with:
- Partial or complete interatrial septum.
- Partial interventricular septum or ventricular trabeculae to maintain separation of oxygenated and unoxygenated blood.
- Formation of a spiral valve in the conus arteriosus to block and unblock the entrances to the left and right pulmonary arches.
Blood Vessels
- Supply most tissues with oxygenated blood but carry deoxygenated blood to respiratory organs.
- Basic pattern:
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- Ventral aorta emerges from the heart and passes forward beneath the pharynx.
-
- Dorsal aorta (paired above the pharynx) passes caudally above the digestive tract.
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- Six pairs of aortic arches connect the ventral aorta with the dorsal aortae.
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Fishes
- Cartilaginous fishes:
- Ventral aorta extends forward below the pharynx and connects developing aortic arches.
- Segments of the first pair of arches are lost, and remaining sections become efferent pseudobranchial arteries.
- Teleosts: same changes except that the pulmonary artery branches off the 6th aortic arch to supply the swim bladder.
Tetrapods (Four-Limbed Vertebrates)
- Embryos have 6 pairs of aortic arches:
- 1st and 2nd arches are temporary and not found in adults.
- 3rd aortic arches and the paired dorsal aortae anterior to arch 3 are called the internal carotid arteries.
- 4th aortic arches are called the systemic arches or the aorta.
- 5th aortic arch is usually lost.
- Pulmonary arteries branch off the 6th arches and supply blood to the lungs.
Amphibians
- Anurans (Frogs and Toads):
- Have 4 arches early in development (larval stage); arches III, IV, V, and VI supply larval gills.
- At metamorphosis:
- Aortic arch 5 is lost.
- Dorsal aorta between arches 3 and 4 is lost, so blood entering arch 3 (carotid arch) goes to the head.
- Ductus arteriosus of arch 6 is lost, so blood entering this arch goes to the skin and lungs.
- Aortic arch 4 (systemic arch) on each side continues to the dorsal aorta and distributes blood to the rest of the body.
Reptiles
- Similar to amphibians except:
- 2 aortic trunks from the conus arteriosus send blood to arch 3 and 4.
- One pulmonary trunk from the conus arteriosus sends blood to the 6th aortic arch.
- Ventral aorta: no spiral valve, but truncus arteriosus is split into 3 separate passages: 2 aortic trunks and a pulmonary trunk.
Mammalian Fetal Circulation
- In a developing fetus, blood obtains oxygen (and gives up carbon dioxide) via the placenta, not the lungs.
- Features include:
- Vitelline veins from the yolk sac to the heart.
- Subintestinal vein from the digestive visceral to the vitelline vein.
- Umbilical vein from the placenta to the heart.
- Ductus arteriosus and ductus venosus.
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