Exercise 19: The Circulatory System

• Circulatory system - transport of gases, nutrients and other substances to and from the different parts of the body
• Close circulation - blood transported via blood vessels
• Open circulation - blood referred to as hemolymph which freely moves within the body cavity
• Which animals have an open circulation?

  Arthropods, mollusks
• Which animals have closed circulation?

  Vertebrates, annelids, cephalopods
• Which animals do not have a circulatory system?

  Flatworms, sponges
• The heart of the cockroach is divided into diamond-shaped chambers which are guarded by valves known as what?

  Ostia
• What allows inflow of hemolymph to the heart as the valves prevent backflow?

  Ostia
• The cavity where the heart is located in the cockroach is known as what?

  Pericardial sinus
• Dorsal diaphragm - Membranous sheet that separates the pericardial sinus from the rest of the body
• Alary muscles - contract the abdomen of insect to allow movement of hemolymph
• During systole, is the ostia of the cockroach closed or open?

  Closed
• Label the following in the open circulatory system of a COCKroach ;).

  A) Heart

  B) Dorsal aorta

  C) Ostia

  D) Dorsal diaphragm

  E) Pericardial sinus

  F) Hemocoel

  
• Heart - serves a the pump, sending blood to the different parts of the body via the arteries
• Veins - return blood to the heart
• Capillaries - smallest blood vessels where gas and nutrient exchange occur
• What blood vessel contains thicker smooth muscular walls?

  Artery
• The surface of the heart is covered by what membranous layer?

  Visceral pericardium
• The surface of the heart of the toad is continuous with the lining of pericardial cavity which is?

  parietal pericardium
• Sinus venosus - receives all deoxygenated blood from the body and deposits it into the right atrium
• Label the following in the external anatomy of the toad heart.

  A) Right atria

  B) Left atria

  C) Sinus venosus

  D) Conus arteriosus

  E) Ventricle

  
• The two atria of the toad heart are separated by what?

  interatrial septum
• Sinoatrial aperture - opening found in the dorsal wall of the right atrium and serves as the entrance of blood from the sinus venosus
• Blood passes through the right and left atrium towards the ventricle via the right and left atrioventricular apertures
• Valves - prevent backflow of blood
• On the walls of the ventricle, what can be seen?

  Muscular pockets
• Label the following in the following in the internal anatomy of the toad heart.

  A) Right atria

  B) Left atrium

  C) Interatrial septum

  D) Sinoatrial aperture

  E) Ventricle

  F) Semilunar valves

  G) Spiral valve

  
• Coronary veins and arteries - serve to drain and supply the cardiac muscles respectively
• The two ventricles of the mammalian heart are separated into the left and right chambers by what?

  Interventricular septum
• On each side of the heart, an opening, the atrioventricular aperture will be found between the atrium and ventricle
• What borders the right atrium and right ventricle?

  Tricuspid valve
• What borders the left atrium and the left ventricle?

  Mitral valve
• Two valves are connected to projections from the wall of the ventricles the papillary muscles via tough thread-like structures called chordae tendinae
• What two structures aid in the opening and closing of the valves?

  Papillary muscles, chordae tendineae.
• The sinus venosus in mammals has been reduced to the sino-atrial node which is found at the area where the pre and post caval veins exit the left atrium
• Label the following in the internal anatomy of the mammalian heart.

  A) Superior vena cava

  B) Inferior vena cava

  C) Right atrium

  D) Tricuspid valve

  E) Right ventricle

  F) Chordae tendinae

  G) Papillary muscles

  H) Pulmonary artery

  I) Pulmonary vein

  J) Mitral valve

  K) Left ventricle

  L) Trabeculae carnae

  M) Interventricular septum

  N) Aorta

  
• Systemic veins - carry deoxygenated blood into the sinus venosus
• portal veins - carry deoxygenated blood into a filtering organ
• Pulmonary veins - carry oxygenated blood from the lungs directly into the left atrium
• The external jugular veins can be divided into what other veins?

  Lingual vein, maxillary vein