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2 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Sylvia S. Mader Immagini e concetti della biologia

3 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 C5 - Cardiovascular system

4 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The circulatory system The function is to transport O 2 and nutrients to the cells of the body and to carry away CO 2 and other wastes. To do this, the system must keep blood constantly circulating.

5 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The circulatory system All vertebrates have a closed circulatory system where blood is transported in vessels, separate from the interstitial fluid. In an open circulatory system (as in arthropods) fluids return to the heart through ostia or open vessels.

6 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Single-loop circulation Fish have a single-loop circulatory pathway: the heart has a single atrium and a single ventricle.

7 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Two-circuits circulation Amphibians and most reptiles have a two-circuits circulatory pathway, with the heart divided into two atria and one ventricle.

8 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Birds and mammals have a two-circuits circulatory pathway with the heart divided into two atria and two ventricles. Two-circuits circulation

9 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 A circulatory system consists of a pump (the heart), a fluid (the blood) and a series of blood vessels (the vascular system). All together those elements form the cardiovascular system. The cardiovascular system

10 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The heart has four chambers: two atria and two ventricles. A cardiac septum separates the heart into right and left halves. The heart right ventricle right atrium left ventricle left atrium septum

11 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 An artery carries blood away from the heart while a vein takes the blood to the heart. Cardiac valves keep blood moving in the correct direction. The heart superior vena cava semilunar valve atrioventricular valve inferior vena cava pulmonary veins pulmonary artery aorta

12 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Electric rhythmic impulse move the heart. The contraction is called systole, the relaxation of the chambers is diastole. The heartbeat

13 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 The heartbeat starts from the sinoatrial node (SA), the impulse-generating (pacemaker) tissue. The atrioventricular node (AV) causes the ventricle contraction. The cardiac conduction system

14 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Arteries Blood pressure in arteries and arterioles carries blood away from the heart. Blood vessels

15 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Veins Skeletal muscle contractions return blood in veins and venules to the heart. Blood vessels

16 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Capillaries Thin-walled capillaries permit exchange of materials and gas with the tissues. Blood vessels

17 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Cardiovascular systems includes two circuits. Pulmonary circuit: pulmonary arteries take O 2 -poor blood to lungs while pulmonary veins return O 2 -rich blood to the heart. Systemic circuit: left ventricles send O 2 -rich blood to aorta; vena cava takes O 2 -poor blood back to the right atrium. Pulmonary and systemic circuits

18 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Pulmonary and systemic circuits

19 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Blood velocity depends on pressure and on capillaries area. Systolic pressure: is the pressure in arteries during ventricular systole. Diastolic pressure: is the pressure in arteries during ventricular diastole. Blood pressure

20 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 A stroke (or cerebral ictus) occurs when a small cranial arteriole bursts or is blocked by an embolus. A heart attack occurs when a coronary artery (the artery that brings O 2 -rich blood to capillaries of the heart) is completely blocked. Vascular diseases

21 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Healthy life style can help to prevent vascular diseases: refraining from smoking no drugs controlling weight healthy diet monitoring cholesterol exercising Vascular diseases

22 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Vascular diseases Cholesterol is an essential component of cell membranes and is carried by plasmic proteins (LDL and HDL). Anomalies in quantities of LDL or HDL can lead to the formation of cholesterol plaque in blood vessels.

23 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Blood functions Transports substances to and from capillaries where exchanges occur. Helps the organism defend against pathogens. Helps regulate body temperature. Forms clots to prevent hemorrhages.

Blood composition Blood is composed of a liquid portion called plasma and formed elements: red and white blood cells, and platelets. Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012

25 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Clotting Blood clotting involves platelets that release clotting factors at the site of the blood vessel damage. Fibrin threads provide a meshwork for a blood clot.

26 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Blood stem cells Hematopoietic stem cells (HSCs), are multipotent stem cells, found in the bone marrow of adults, that can produce all the blood cell types. HSCs can be easily transplanted from pelvic bone.

27 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Capillary exchange Between the arterial end and the venus end, substances diffuse according to the concentration gradient: CO 2 and waste produced by the cells move in; C 6 H 12 O 6, amino acids and O 2 spread out.

28 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 Capillary exchange Lymphatic capillaries collect excess tissue fluid (called lymph) and return it to the vascular system.

29 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 AB0 classification system RBC membranes carry specific carbohydrates and proteins that behave as antigens when transplanted in incompatible organisms. Those antigens are classified as A and B and determine the type of blood. RH factor is another important antigen in matching blood types.

30 Sylvia S. Mader Concepts of Biology © Zanichelli editore, 2012 AB0 classification system Agglutination: clumping of RBC in the presence of an antibody that binds multiple antigens and joins the cells. AgglutinationNo agglutination