Transcript Table of Contents - Milan Area Schools

49
Circulatory Systems: Pumps, Vessels, and Blood
• In open circulatory systems, the blood or
circulating fluid is not kept separate from the
tissue fluid.
• The most simple systems squeeze tissue fluid
through and around intercellular spaces.
• Arthropods, mollusks, and other invertebrates
utilize this type of circulatory system.
49
Circulatory Systems: Pumps, Vessels, and Blood
• A closed circulatory system keeps the blood
and tissue fluid separate.
• One or more muscular hearts and a branching
network of vessels (the vascular system) move
the blood.
• There are different types.
In-Text Art, p. 943(1)
In-Text Art, p. 943(3)
In-Text Art, p. 944(1)
In-Text Art, p. 944(2)
49
Vertebrate Circulatory Systems
• The four-chambered hearts of birds and mammals
completely separate the pulmonary and systemic
circuits.
• The advantages of separate circuits are:
 Oxygenated and deoxygenated blood cannot
mix.
 Gas exchange is maximized because the
lungs receive only blood with low O2 and high
CO2 content.
In-Text Art, p. 945
Figure 49.3 The Human Heart and Circulation (Part 2)
49
The Human Heart: Two Pumps in One
• The right atrium receives blood from the superior
and inferior vena cavas.
• From the right atrium, blood goes to the right
ventricle.
• The right ventricle sends blood through the
pulmonary artery to the lung.
• Pulmonary veins return oxygenated blood to the
left atrium.
• From the left atrium, blood goes to the left ventricle.
• The left ventricle sends blood through the aorta to
the body and the capillary beds.
• Blood returns to the right atrium via veins.
Figure 49.7 The Heartbeat
Figure 49.10 Anatomy of Blood Vessels (Part 1)
Figure 49.13 One-Way Flow
49
Blood: A Fluid Tissue
• Blood is connective tissue: it consists of living
cells within an extracellular matrix.
• The fluid matrix is called plasma.
• The cellular components of blood are the red
blood cells (erythrocytes), the white blood cells
(leukocytes), and the platelets (cell fragments).
Figure 49.15 The Composition of Blood
49
Blood: A Fluid Tissue
• Most of the cells in blood are erythrocytes.
• At maturity they are biconcave, flexible discs
packed with hemoglobin.
• The hemoglobin carries O2, and the flexible shape
of the cell lets them squeeze through narrow
capillaries.
49
Blood: A Fluid Tissue
• Bone marrow makes about 2 million red blood cells
per second.
• Each red blood cell lives about 120 days and then
breaks down.
• The spleen serves as a reservoir for old blood cells
that have been squeezed and ruptured. The cell
remnants are then broken down by macrophages.
49
Blood: A Fluid Tissue
• Cell damage leads to conversion of an inactive
enzyme in the blood, prothrombin, to its active
form, thrombin.
• Thrombin causes a plasma protein, fibrinogen, to
polymerize, forming fibrin threads.
• These threads form a meshwork to seal the
damaged vessel and provide a base for scar
tissue.
Figure 49.16 Blood Clotting (Part 2)
49
Blood: A Fluid Tissue
• Plasma contains gases, ions, nutrients, proteins,
hormones, and other chemicals.
• Nutrient molecules in plasma include glucose,
amino acids, lipids, lactic acid, and cholesterol.
• Circulating proteins include albumin, antibodies,
hormones, and carrier molecules.