Circulatory system

• Diffusion : net movement of molecules from a region of high concentration to a region of low concentration.
• Without hemoglobin , the concentration of oxygen within the blood plasma would quickly build up compromising the partial pressure gradient required for oxygen to diffuse into the blood.
• Kidneys absorb nutrients
• Kidneys dispose wastes
• Open circulatory system: Arthropods and most molluscs
• What is the type of fluid for open circulatory systems : Hemolymph 
• Closed circulatory systems: Most mammals
• What is the fluid of closed circulatory systems?

  Blood
• Blood is the medium of transport how we transport glucose and oxygen. 
• Blood is completely confined within vessels. 
• Blood is made up of plasma → Liquid portion carries proteins, lipids, etc.
• Blood is made up of Cells → Do the transporting of gasses (Eritrocites) and fight infections (leukocytes)
• Blood is made up of Platelets→ Help blood clotting. 
• Arteries carry blood AWAY from the heart → Typically oxygen rich 
• Veins carry blood INTO the heart → Typically oxygen poor 
• Capillaries→ Small blood vessels
• Capillary level → Oxygen is delivered to organs and tissues. CO2 will be returned to the lungs. 
• Atria→ Thin walls → Receiving chambers → Receives blood coming back from the body
• Ventricles → Thick walls  → Discharging chambers → Pushes blood out of the heart 
• Valves → One way structure that help separate the chambers. 
• Aorta→ Major artery that carries oxygenated blood throughout the body 
• The heart receives it’s own blood supply through the coronary arteries
• Systole → Contraction of the heart, pushes out the blood out of the heart and into large vessels of the circulatory systems. Blood pressure increases. → 120 mmHg
• Capillaries allow materials to move  in and out of the bloodstream. Connect arteries to veins. 
• Diastole→ Heart muscle relaxes . Chambers fill with blood and pressure decreases. → 80mm/Hg 
• Cardiac muscle tissue → Squat, branched out and interconnected with one or two nuclei 
• Cardiac cells are physically and electrically connected, all of the time. To create coordination for contraction and relaxation. 
• Pacemaker cells: Keep your heart beating at the correct rhythm and ensure that each cardiac muscle cell contracts in coordination with the others. → Generate their own action potentials.