6.2 & D.4: The Blood System and The Heart 2016-09-06

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The Transport System Also known as the Circulatory System or the Cardiovascular System The system responsible for the circulation of blood throughout the body.

Blood About 8% of the human body is blood. Depending on the size of the individual, the human body contains an average of 4 L - 5 L of blood Blood consists of:

Plasma – 50-55% Cells – 45-50%

PLASMA Protein rich liquid 90% water Contains dissolved solutes: Na+, K+, Ca2+, Cl-, HCO- Also contains nutrients, respiratory gases, metabolic waste materials, hormones, and proteins (fibrinogen, globulins, albumins)

Plasma Plasma proteins:

Control blood pH ALBUMINS: Control water balance (the amount of water that enters and leaves the blood stream) GLOBULINS: Transport insoluble lipids, cholesterol, fat-soluble vitamins, minerals Antibodies (immunoglobulins)– guard against foreign micoorganisms FIBRINOGEN: involved in blood clotting

6.2 & D.4: The Blood System and The Heart 2016-09-06

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Cellular Components of Blood Consist of:

ERYTHROCYTES: red blood cells LEUCOCYTES: white blood cells THROMBOCYTES: platelets

They are constantly being replaced. New ones are formed from pluripotent stem cells in bone marrow These cells are initially the same but can specialize into specific ones

Red Blood Cells (rbc) Also called erythrocytes Represent 90% of blood cells 1 mm3 of blood contains 5-6 x 106 rbc!!! Shape: biconcave disk – thinner at the center than the edges (increases surface area)

RBC FUNCTION: deliver O2 and some CO2 A single rbc contains 250 million molecules of hemoglobin! Hemoglobin is a protein with an iron atom (at its heme groups) that binds to gases (O2 and CO2) Anemia = low rbc or low hemoglobin, therefore cannot deliver as much O2 to the body

Usually caused by lack of iron in diet Results in a lack of energy (because O2 needed to make ATP)

6.2 & D.4: The Blood System and The Heart 2016-09-06

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Hemoglobin DID YOU KNOW??? RBCs live only 120 days – are removed by liver and spleen when they die Between 2 -3 million are produced each second to replace lost ones Mammalian RBC lack nuclei (they have one when they are developing but it breaks down and disappears when it is mature and released into bloodstream) http://www.pennmedicine.org/encyclopedia/em_DisplayAnimation.aspx?gcid=000104&ptid=17

White Blood Cells (wbc) Also called leukocytes 5000 – 10000 in a mm3 of blood < 1% of blood cells are WBC These cells protect the body from harmful bacterial, viruses and other foreign invaders Unlike RBC, WBC have a nucleus

WBC 70% are phagocytes

Nonspecific; ingest foreign invaders and antigens 30% are lymphocytes

Produce antibodies that target specific foreign invaders

6.2 & D.4: The Blood System and The Heart 2016-09-06

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Phagocytosis Platelets Also known as thrombocytes 150 000 - 450 000 mm3

Have no nuclei Involved in blood clotting Are actually small pieces that have broken off from cells in bone marrow

Platelets Blood vessels are normally smooth If they are broken, the rough edges will break platelets The broken platelets release chemicals (clotting factors) which help platelets stick together to form a plug With the aide of fibrinogen, platelets form a clot which clogs the tear in the blood vessel and prevents the loss of blood cells

Function of Circulatory System The function of the circulatory system is to transport materials throughout the body via blood. This includes:

Oxygen Carbon dioxide Nutrients (eg : glucose) Hormones (eg: insulin) Antibodies Waste products Heat