~ 7% Blood makes up around 7% of the weight of the human body.

Twice If you could stretch out all of a human's blood vessels, they would be long enough to go around the world twice.

7 days Half your body’s red blood cells are replaced every seven days.

120 days The average life span of a single red blood cell in the circulatory system.

20 – 60 s The time it takes a drop of blood to travel away from the heart and back again.

The number of times the heart beats each day.

Functions of the Cardiovascular System:  delivers vital nutrients (e.g., oxygen) to all body cells  eliminates waste products and carbon dioxide  transports chemical messengers (e.g., hormones) from one part of the body to another  helps to maintain a constant body temperature

Open Circulatory System – Hemolymph (mix of blood and tissue fluid) is pumped directly into the body cavity. -

Closed Circulatory System – Blood is separate from the rest of the body in a network of tubes.

Single-circuit circulatory system – Only one track the blood can travel Two-circuit circulatory system - Circulation to the lungs is separated from circulation to the rest of the body.

Two-Circuit Circulatory System: Circulation to the lungs is separated from circulation to the rest of the body.  pulmonary circuit: the part of the circulatory system that delivers blood to the lungs  systemic circuit: the part of the circulatory system that delivers blood around the body

 Human body contains 4L to 5L of blood depending on the size of the individual  Blood is a connective tissue – a tissue that consists of cells suspended in an intercellular matrix  Using a centrifuge, blood can be separated into its two components – plasma (less dense, rises to top) and cellular components (more dense, sinks to bottom)

 Protein-rich liquid; over 90% is water  Oxygen, proteins, nutrients (glucose, minerals and vitamins), carbon dioxide and other waste products from cellular respiration are dissolved or suspended in plasma

 Blood proteins in plasma include; albumins, globulins, fibrogens  Albumins: helps regulate the amount of water within the body  Globulins: transports lipids, cholesterol, some fat- soluble vitamins, some minerals ▪ Immunglobins (or antibodies) help fight infectious diseases  Fibrogens: play a critical role in blood clotting; plasma with fibrogen removed is called serum

 Plasma also carries a number of dissolved ions: Na +, K +, Ca 2+, Cl -, HCO 3 -. Na + and Cl - are most common ions. When the concentration of Na + in the plasma is high, it creates an osmotic pressure gradient and causes water to enter the blood stream. As more water enters the blood, the total volume of blood increases and the blood pressure rises. This explains why high salt diets lead to hypertension (high blood pressure) 

 Red Blood Cells - For Transport  (erythrocytes) carry oxygen from the lungs to the body cells and carry carbon dioxide from the body cells back to the lungs to be expelled  Formed from stem cells in marrow of vertebrae, ribs, breastbone, skull and bones of the arms and legs  Erythrocytes die after about 120 days ; then removed by the liver and spleen  Between 2million and 3 million erythrocytes are produced each second  When erythrocytes are developing in the marrow, they have a nucleus, but as they mature and are released into the blood stream, their nucleus breaks down and disappears.

- (Leukocytes) are formed in bone marrow and always have a nuclei  first line of defense against harmful bacteria, viruses and other disease causing agents

▪ Granular – have grains in their cytoplasm and attach foreign material and microorganisms ▪ Agranular – specialized for engulfing bacteria and microorganisms through phagocytosis. This involves engulfing the bacteria within the cell membrane and release enzymes to destroy the target and the leucocyte itself  Remnants of leuckocytes and whatever it engulfed are left behind in a whitish substance called pus

 For protection; involved in clotting or coagulation  Small cell fragments produced from stem cells in bone marrow  When blood vessel is broken, chemicals in platelets cause the platelets to stick to collagen fibres in the blood vessel wall. As more and more platelets stick to the fibres, a clot is created to seal the hole in the blood vessel  The permanent clot stops the leakage of blood and allows time for the injury to heal and then the blood clot is absorbed by the body.

 Recall that the four blood types are: A, B, AB, O. The Rhesus Factor:  The Rhesus factor is another inherited factor discovered by studying the blood of rhesus monkeys. The rhesus factor is an antigen on erythrocytes that produce an antibody reaction. This is not as severe as the antibody reaction to blood type markers. The rhesus factor is present in approximately 85% of the population deeming them Rh-positive. The remaining 15% do not have this factor and are considered Rh- negative. Rh-negative people can donate their blood to Rh-positive people, but they cannot receive Rh- positive blood.