2-22 Circulatory systems II

2-22 Circulatory systems II - CIRCU LATORY SYSTEMS (PART I...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CIRCU LATORY SYSTEMS (PART I I) LIFE 49.4 – 49.5 49.4 What are the properties of blood and blood vessels?-Blood is a connective tissue that consists of cells suspended in an extracellular matrix (liquid), so blood is a fluid tissue-cells of the blood can be separated from the fluid matrix, called plasma , by centrifugation (cells move to bottom of tube)- packed-cell volume , or hematocrit , is the percentage of the blood volume made up by cells-two elements in blood: the red blood cells and the platelets , which are pinched-off fragments of cells 49.4.1 Red blood cells transport respiratory gases-Most of the cells in the blood are erythrocytes , or red blood cells // packed w/hemoglobin // shape facilitates gas exchange-RBC generated by stem cells in the bone marrow, particularly in the ribs, breastbone, pelvis, and vertebrae. Red blood cell production is controlled by a hormone , erythropoietin , which is released by cells in the kidney in response to insufficient oxygen — hypoxia 49.4.2 Platelets are essential for blood clotting-bone marrow stem cells also produce megakaryocytes: large cells that remain in the bone marrow and continually break off cell fragments called platelets . A platelet is just a tiny fragment of a cell without cell organelles , but it is packed with enzymes and chemicals necessary for its function: sealing leaks in blood vessels and initiating blood clotting-Damage to a blood vessel exposes collagen fibers. An encounter with collagen fibers activates a platelet . The platelet swells, becomes irregularly shaped and sticky, and releases chemicals called clotting factors , which activate other platelets and initiate the clotting of blood • Cascade: cell damage and platelet activation inactive circulating enzyme , prothrombin , converts to active form, thrombin Thrombin cleaves molecules of fibrinogen , a plasma protein , forming insoluble threads of fibrin fibrin threads form the meshwork that clots the blood, seals the vessel, and provides a scaffold for the formation of scar tissue 49.4.3 Plasma is a complex solution- Plasma , the clear, straw-colored liquid portion of the blood, contains dissolved gases,...
View Full Document

This note was uploaded on 09/02/2009 for the course BIO 315H taught by Professor Payne during the Spring '08 term at University of Texas at Austin.

Page1 / 4

2-22 Circulatory systems II - CIRCU LATORY SYSTEMS (PART I...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online