Overview – Every cell in a living organism must have direct access to its nutrient supply Single celled organisms – rely on simple diffusion to move materials into the cell Multi-cellular organisms – require some type of system

Functions – Carries nutrients and wastes to and from cells – Carries chemical messages between different cells – Distributes heat throughout the body – Maintains fluid levels in the body – Defends against invading organisms

1.Blood – 55% Plasma – 45% Formed Elements Cells – white blood cells – red blood cells Platelets – (<1%) cell fragments – Humans have ~5L of blood 2.Vessels – Arteries, veins and capillaries 3.Heart 4.Periphery Organs – Kidneys – Liver – Intestines – Lungs

Fig Blood composition

Fluid portion of the blood Contains dissolved materials – gases, glucose, amino acids, ions and vitamins. – wastes and hormones.

Soluble proteins – Albumins along with minerals, maintain fluid levels by osmotically drawing water back into the capillaries – Immunoglobulins antibodies and carrier/transport proteins – Fibrinogens aid in blood clotting Concentration of plasma proteins helps control the osmotic balance in the blood. – Stops excess water from exiting the blood Why malnutrition can cause swelling

Red blood cells (RBCs) – 4-6 million per mm 3 of whole blood Function to transport gas around the body

Structure – biconcave disks, increased surface area, Increases ability to exchange gas – Have no nucleus at maturity Increased space for hemoglobin, increases ability to carry oxygen – proteins in cell membranes determine blood type

Continuously produced in bone marrow – Mainly in large bones the skull, ribs, vertebrae, and ends of the long bones. – Production of red blood cells is stimulated by erythropoietin From kidney In response to decreased oxygen in blood

Contain hemoglobin – Red iron containing pigment – Heme portion of molecule forms an unstable, reversible bond with oxygen. Carries 20 ml oxygen per 100 ml of blood Oxygenated state = oxyhemoglobin – Bright red Reduced state = deoxyhemoglobin – purple-blue.

Fig Structure of Hemoglobin

Lifespan- 120 days Destroyed in liver by fixed macrophages – Hemoglobin is broken down Iron is recycled-taken to bone marrow Heme portion is degraded and excreted as bile pigments

Anemia- decreased red blood cells – Most common type comes from iron deficiency Carbon monoxide poisoning – Carbon monoxide binds at heme sites more strongly than oxygen

White blood cells (WBCs) – General term for a variety of cells without hemoglobin – Less numerous than RBC’s per mm 3 of whole blood – Larger cells, nucleated

Important part of the immune system. – able to enter fluids surrounding tissues to fight infection Blood stream is only a means of transport to location of infection.

Fight infection by destroying pathogens – Other leukocytes will also clean up the mess! – Pus is composed of dead invaders and leukocyte fragments

Fig

Granulocytes – have visible granules in cytoplasm Neutrophils – most abundant WBC, phagocytic Basophils – granules stain deep blue and release histamine Eosinophils – granules stain red, phagocytize allergens

Agranulocytes – lack visible granules Lymphocytes – T and B cells, play roles in immunity Monocytes – largest WBC’s, phagocytic – Differentiate into macrophages and dendritic cells

Lifespan – Different types live different lengths of time – Some live only a few days-die combating invading pathogens – Some live months or years

Change in numbers may indicate disease – Infectious mononucleosis Epstein-Barr virus Increased number of B lymphocytes – AIDS HIV – Human Immunodeficiency Virus Decreased number of T lymphocytes – Leukemia Blood cancer Uncontrolled numbers of WBC’s

Platelets – fragmentation of large cells called megakaryocytes – 150, ,000 per mm 3 of whole blood – Tiny cells that play important role in blood clotting.

Blood clotting – Platelets form a plug for immediate stoppage of bleeding – Vessels release prothrombin activator and injured tissues release thromboplastin Thromboplastin stimulates further release of prothrombin activator This process requires calcium (Ca 2+ )

Clotting cont’d – Prothrombin activator activates a plasma protein prothrombin to thrombin – Thrombin activates fibrinogen to fibrin which forms a clot – Clot is composed of network of fibrin threads and trapped cells

Clotting cont’d – As damage heals, plasmin breaks down the clot If blood is allowed to clot in a test tube, serum develops – Serum-plasma without fibrinogen

Table 12.1

12-28 Fig 12.13

Bone marrow stem cells – Cell which is capable of dividing and differentiating into particular cell types Red and white blood cells Some may even be able to give rise to liver, bone, fat, cartilage, heart, and nerve cells May provide solutions for diseases such as Alzheimer’s and Parkinson’s 12-29

Bone marrow stem cells cont’d – Many researchers prefer to work with embryonic stem cells Totipotent-can become any cell type Ethical issues 12-30

Fig

Anemia – A deficiency in hemoglobin or red blood cells Decreases O 2 delivery Causes low energy levels Common causes are hemorrhages and iron deficiency in the diet – Hematocrit Blood test that measures the percentage of your blood volume that is erythrocytes

Hemophilia – Genetic disorder which causes a defect in the production of clotting factors – blood clotting does not occur properly – Excessive bleeding can result from a minor injury

Sickle Cell Anemia – Genetic disorder which causes erythrocytes to form an abnormal crescent shape – shaped cells deliver less oxygen to the body's tissues – Also break easily preventing healthy blood flow Causes painful episodes