Circulatory system

• Components of the circulatory system

  • The heart
  • The blood vessels
  • The blood
• Faulty valves (varicose veins)


  Backflow of blood in veins causes the veins to distend and bulge
• Circulatory system functions

  1. Transport oxygen to body cells/tissue and carry waste

  2. Regulate internal body temperature

  3. Protect against blood loss from injury and microbes
• ECG (electrocardiogram)


  Measures change in the electrical signal of the heart as it relaxes and contracts
• Blood pressure is measured using a sphygmomanometer
• When valves in veins become faulty, they can cause varicose veins
• The Beating Heart

  1. Sinoatrial node (specialized muscle tissue) known as the "Pacemaker" generates electrical signals

  2. Signal spreads over the atria

  3. Atria contract

  4. Atrioventricular node is stimulated

  5. Elastic signal transmitted through "bundle of His", signal goes to purkinje fibers, ventricles contract
• Maximum pressure from ventricles contracting = Systolic pressure, lowest pressure when ventricles are at rest = Diastolic pressure
• blood exerts pressure against vessel walls, ventricles contract and exert pressure on aorta and pulmonary arteries
• Sounds of the heart

  1) LUB - AV valve closing (ventricles contracting)

  Loud and long

  2) DUB - SL valve closing (ventricles relax, atria are going to contract)

  Soft and short
• Hypertension


  high blood pressure
• hypotension

  low blood pressure
• Cardiac output


  the amount of blood pumped by the heart per minute - beats/min (heart rate x stroke volume)
• stroke volume


  The amount of blood forced out of the heart with each heart beat (average = 70mL/beat)
• heart rate indicators for good cardiovascular health

  1. low heart rate

  2. high stroke volume

  3. short recovery times

  4. lifting weights/running
• The "Lub" sound of your heart is caused by the AV valves closing
• The "dub" sound of your heart is caused by the Semilunar valves shutting
• 3 main components of blood

  plasma, red blood cells, white blood cells, platelets
• red blood cells (erythrocytes)


  (44% of blood) small disk-shaped cells (biconcave shape) that are used for oxygen transport, cannot divide, and do not have a nucleus
• anemic


  lacking blood cells and hemoglobin

  symptoms: pale skin, fatigue
• white blood cells (leukocytes)


  fight infection (2x more white blood cells during an infection) have a nucleus, life span is short, and it matures in the lymph nodes
• Three groups of leukocytes

  1. Granulocytes (engulf foreign particles, leave blood stream to do so)

  2. Monocytes (engulf foreign particles, leave blood stream to do so)

  3. Lymphocytes (play a role in the formation of antibodies- defence function)
• Platelets (thrombocytes)


  cell fragments that play a role in the clotting of blood, have no nucleus and break down quickly in blood (2-8 day life span)
• Plasma


  (roughly 60% of blood) fluid portion of the blood
• Main constituent of plasma

  water
• Carbon dioxide transport in plasma

  CO2 dissolves in water→ forms carbonic acid → diffuses into plasma (as bicarbonate ions) → carried from tissue to lungs for gas exchange
• constituents of plasma

  Water, blood proteins, organic substances, and inorganic ions
• Pulmonary pathway


  The circulatory pathway that carries oxygen poor blood from the heart to the lungs and oxygen rich blood from the lungs to the heart (via pulmonary veins)
• systemic pathway


  The circulatory pathway that carries oxygen rich blood from the left ventricle to the body tissues and waste moves out of the tissue into the blood
• Coronary pathway


  Provides O2 blood to the heart tissues (aorta→ coronary arteries → heart capillaries → pulmonary veins → heart)
• Components of the lymphatic system

  • Lymph vessels, lymph nodes, lymph (adenoids, tonsils, spleen, thymus)
• Lymph forms in closed-ended tubes in capillary beds and is delivered to the heart to be mixed back into the general blood circulation
• Interstitial fluid (extracellular fluid/tissue fluid) surrounds cells. Blood moves slowly through capillaries to increase the time over which diffusion may occur
• Functions of the lymphatic system

  1. Helps maintain the balance of fluid in the body

  2. Works with white blood cells to protect the body against infection (White blood cells mature in lymph nodes)
• Pathogen - anything that can cause a disease
• Platelets are fragments (NOT a blood cell)
• There are 600-700 lymph nodes in the body that filter the lymph before returning to the circulatory system
• Blood clotting stages

  1. Get injury

  2. Platelets go to injury & rupture

  3. clotting factors (pro___)

  4. Fibrin forms a clot (to stop bleeding)
• Immunity is related to the lymphatic system
• Lymphatic vessels collect lymph (fluid) that is made up of interstitial fluid