L2

• Circulatory system


  Also known as the internal transport system
• Components of the circulatory system

  • Cardiovascular system
  • Lymphatic system
• Functions of the circulatory system

  • Transports nutrients and oxygen to cells
  • Collects wastes and transports them to organs for excretion
  • Helps maintain fluid balance and normal body temperature
  • Acts as a defense against harmful bacteria
• Types of circulation


  • Coronary - circulation of blood within the heart
  • Pulmonary - circulation of blood between the heart and the lungs
  • Systemic - circulation of blood between the heart and the cells of the body

  
• Cardiovascular system


  Transports important nutrients throughout the body and removes metabolic wastes
• Components of the cardiovascular system

  • Heart
  • Blood
  • Blood vessels

  
• Heart


  • A hollow muscular organ
  • Composed primarily of cardiac muscles and some connective tissues
  • Is the pumping station of the circulatory system
  • It is as big as your fist
  • It is situated at the center of your chest and slightly tilted to the left
  • It is covered by a membrane called pericardium

  
• Pericardium


  Connective tissue that encloses the heart<|>Contains a fluid that reduces friction between the surrounding organs when the heart is beating

  
• Chambers of the heart

  • Right atrium - receives deoxygenated blood from all parts of the body
  • Left atrium - receives oxygenated blood from the lungs
  • Right ventricle - pumps deoxygenated blood toward the lungs
  • Left ventricle - pumps oxygenated blood to the aorta and then to all parts of the body

  
• Valves


  Structures that prevent the backflow of blood, allowing blood to flow in one direction
• Tricuspid valve


  The valve between the right atrium and the right ventricle
• Mitral valve / Bicuspid valve


  The valve between the left atrium and the left ventricle
• Septum


  A special wall separating the right and the left atria<|>Prevents blood from flowing between the two atria or the ventricles
• Types of blood vessels

  • Arteries
  • Veins
  • Capillaries
• Arteries


  • The largest blood vessels consist of three layers
  • They carry oxygenated blood away from the heart
  • Their elastic walls accommodate the pumping of blood
  • The pulmonary artery carries the deoxygenated blood toward the lungs

  
• Veins


  • Are thinner compared to arteries
  • Their function is to carry deoxygenated blood toward the heart, except the pulmonary vein which carries oxygenated blood to the heart
  • The largest vein in the human body is the vena cava
  • Pulmonary vein is the only vein that carries oxygen-rich blood

  
• Capillaries


  • Are the smallest blood vessels in the body
  • They enable the exchange of oxygen, nutrients, and carbon dioxide between the blood and the cells surrounding them
• Blood


  A connective tissue that looks like a plain red fluid<|>Composed of plasma (liquid portion of blood) that forms blood cells
• Components of blood


  • Plasma - clear, yellowish portion of the blood that makes up about 55% of the blood
  • Red blood cells (erythrocytes or RBCs)
  • White blood cells (leukocytes or WBCs)
  • Platelets (thrombocytes)
• Red blood cells (RBCs)

  • Cells with lack of nuclei
  • Produced in the bone marrow, circulating for 120 days in the body before they are recycled
  • After 120 days, the liver destroys the RBCs and decomposes into heme and globin
  • Help carry carbon dioxide from the capillaries then back to the lungs where it is exhaled
  • Heme is further decomposed into iron and bilirubin
  • Globin is a protein needed for growth and development
  • Iron is a mineral needed by the body to produce RBCs
  • Bilirubin gives the bile its greenish-gray color
  • The main function of RBCs is to carry oxygen throughout the body
  • Rich in hemoglobin which binds with oxygen
• White blood cells (WBCs)

  • Are cells with nuclei
  • They are produced by multipotent cells in the bone marrow
  • They are larger than RBCs in size but are fewer in number
  • An increase in their number indicates infection
  • Act as soldiers that defend the body from infections
• Platelets (thrombocytes)


  • Cells without nuclei
  • Derived from megakaryocytes
  • They are considered the smallest blood cells
  • Their function is to prevent blood loss by clogging injured blood vessels
  • A protein called fibrin traps platelets that causes the clogging of damaged blood vessels
• Blood flow through the heart

  Vena Cava (superior or inferior) → right atrium → tricuspid valve → right ventricle → semilunar valve → pulmonary artery → lungs → pulmonary vein → left atrium → bicuspid valve → left ventricle → aortic valve → aorta → body