Circulatory System

• Circulatory System

  Function: 

  • transport respiratory gases, food materials, waste products, hormones, and minerals within the body 
  • Defense against foreign organisms (white blood cells which helps fighting pathogens) 
  • Maintenance of body temperature in warm-blooded or homeothermic animals (such as us)
• Open circulatory system

  •   blood is not enclosed in blood vessels 
• Closed circulatory system

  • blood is enclosed in the vessels 
  • vertebrates such as toads have a closed type of circulatory system composed of heart, arteries, arterioles, veins, venules, and capillaries 
• Heart pumps deoxygenated blood to the lungs and distributes oxygenated blood to the organs 
• Vessels called arteries and arterioles  convey oxygenated blood from the heart to the smallest vessels called capillaries  found in various tissues and organs of the body, with the exception of the pulmonary artery  that delivers deoxygenated blood to the lungs for oxygenation 
• Deoxygenated blood is then collected from the capillaries to the venules and to the veins before it returns to the heart
• Heart → arteries & arterioles → capillaries → venules and veins → heart
• Heart

  • A muscular central pumping station 
  • Lies mid-ventrally inside the anterior trunk region
  • Triangular in shape 
  •  broad base - anteriorly 
  • narrow apex - posteriorly
• Pericardium: a thin transparent 2-layered sac, a sac-like structure that contains lubricating pericardial fluid 
• Pericardial cavity - coelom/cavity where the heart is situated
• Paritel pericardium: Outer wall of pericardium
• Visceral peridardium: Inner wall of pericardium
• Internal structure: hollow and muscular 
• in order to keep the unidirectional flow of the blood the various chambers are separated by the vaults 
• Atria / atrium - two globular structures atop the ventricle 
• Ventricle - most posterior conical structure of the heart 
• Conus arteriosus - cone-shaped tube arising from the ventricle on its ventral side 
•  Interatrial septum - wall separating the right and left atrium 
• Atrioventricular valves - thin flaps between the atria and ventricles; may not be seen in the specimen
• Semilunar valves - flaps that open into conus arteriosus; may not be seen in specimen 
• The hear has 3 chambers: 2 auricles, 1 ventricle.
• Dorsal 

  
  

  auricles

  dark in color

  Bulb like shape

  lies anteriorly

  
  

  ventricle

  -pink colored, - conical/triangular

  lies posteriorly 

  
  

  Sinus vinosus

  dark colored thin-walled 

  • triangular chamber

  lies dorsally to the heart and continuous with the right atrium 
• Ventral 

  
  

  Truncus arteriosus

  Tubular chamber 

  Rises anteriorly from the right ventral side of the ventricle
• Arteries: (except pulmonary arteries) supply oxygenated blood to different parts of the body 
• Pulmonary arteries: supply deoxygenated blood 
• The blood vessels which may carry the blood away from the heart to the different parts of the body constitute the arterial system 
• Arterial system

  
  

  Begins with truncus arteriosus that divides into 2 large right and left branches 

  • Each branch divides into 3 aortic arches
• Anterior carotid arch - supplies the head
• Middle Systematic arch - supplies the body 
• Pulmocutaneous arch - supplies the lungs and skin
• Common carotid arch - a short vessel that runs forward and outward 
• External carotid artery - also known as the lingual artery; goes to the lower jaw/ tongue; smaller; inner branch that supplies the tongue and adjacent parts
• Internal carotid artery - supplies the orbit and brain; larger and outer branch; forms a little swelling at its base called carotid labyrinth / gland
• cerebral artery - supplies the brain

  palatine artery - supplies the roof of the mouth

  ophthalmic artery - supplies the eyes
• Conus Arteriosus  → (2) Truncus Arteriosus  → common carotid artery, systemic arch, & pulmocutaneous artery
• Systemic Arch  → esophageal artery, occipito-vertebral artery, & subclavian artery
• Systemic arch - longest of the 3 arches; greatest distribution of blood; the two systemic arches curve dorsally around the esophagus and joined with each other behind the heart to form the dorsal aorta
• Each systemic arch divides into 3 arteries all these arteries exhibit bilateral symmetry
• Esophageal artery - small artery to esophagus; may arise from the occipital vertebra
• Common carotid artery  → internal carotid artery  → cerebral artery, palatine artery, & ophthalmic artery

  Common carotid artery  → external carotid artery