Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Circulation Chapter 52 Copyright © McGraw-Hill Companies Permission required for reproduction or display

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Open and Closed Circulatory Systems  Open - No distinction between circulating fluid and extracellular body fluid. - Hemolymph  Closed - Circulating fluid is always enclosed within blood vessels that transport blood away from, and back to, a pump (heart).

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Open and Closed Circulatory Systems Functions of Vertebrate Circulatory System  Functions in transporting oxygen and nutrients to tissues by the cardiovascular system. - Arteries carry blood away from the heart. - Veins return blood to the heart.  Capillaries carry blood from the arterial to the venous system.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Open and Closed Circulatory Systems Principal Functions  Transportation - Respiratory - Erythrocytes transport oxygen to tissue cells. - Nutritive - Absorbed food. - Excretory - Metabolic wastes.

Regulation - Hormone Transport - Temperature Regulation  Endotherms (animals that regulate body temperature)  Counter-current heat exchange - Vessels carrying warm blood from deep within the body pass next to a vessel carrying cold blood from the surface of the body. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Open and Closed Circulatory Systems  Protection - Blood Clotting - Immune Defense Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Blood Plasma Blood plasma is the matrix in which blood cells and platelets are suspended.  Plasma contains solutes: - Metabolites, wastes, and hormones - Ions - Proteins  Albumin  Globulins

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Blood Cells Erythrocytes and Oxygen Transport  Hematocrit - Fraction of total blood volume occupied by erythrocytes. - Erythrocytes develop from unspecialized cells (stem cells).  New erythrocytes are constantly formed in the bone marrow.

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Blood Cells Leukocytes Defend the Body  Less than 1% of the cells in the human body are leukocytes. - Granular Leukocytes  Neutrophils, esinophils, and basophils. - Nongranular Leukocytes  Monocytes and lymphocytes

Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies Blood Cells Platelets Help Blood to Clot  Platelets accumulate at an injured site and form a plug by sticking to each other and to the surrounding tissues. - Reinforced by threads of protein (fibrin).

Characteristics of Blood Vessels Blood leaves heart through arteries.  Arterioles are the finest microscopically-sized branches of the arterial tree. - Blood from arterioles enters capillaries.  Collected in venules that lead to larger vessels, veins, that carry blood back to the heart. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Characteristics of Blood Vessels Arteries and Arterioles  Contraction of smooth muscle layer of arterioles results in vasoconstriction which greatly increases resistance and decreases blood flow.  Relaxation of smooth muscle layer results in vasodilation decreasing resistance and increasing blood flow.

Characteristics of Blood Vessels Venules and Veins  Made up of same tissue layers as arteries, but have thinner layer of smooth muscles. - Pressure in veins is only about one-tenth that in arteries. - Skeletal muscles surrounding veins can contract to move blood by squeezing the veins.  Venous valves. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

The Lymphatic System Lymphatic system consists of lymphatic capillaries, lymphatic vessels, lymph nodes, and lymphatic organs.  Excess fluid in the tissues drains into the blind-end lymph capillaries. - Lymph passes into progressively larger vessels with one-way valves.  Encounters lymphocytes. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

The Fish Heart Gills required a more efficient pump.  First two chambers sinus venosus and atrium are collection chambers.  Second two chambers ventricle and conus arteriosus are pumping chambers. - Heartbeat is peristaltic sequence. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

The Fish Heart Greatest advantage is that the blood passing through the gills is fully oxygenated when it moves into the tissues. Greatest limitation is that in passing through the gills, blood loses much of its pressure developed by contraction of the heart.  Limits rate of oxygen delivery to the rest of the body. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Amphibian and Reptile Circulation After blood is pumped by the heart through the pulmonary arteries to the lungs, it is returned to the heart via pulmonary veins.  Results in two circulations: - Pulmonary Circulation between heart and lungs, and Systemic Circulation between the heart and the rest of the body. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Amphibian and Reptile Circulation Oxygenated blood from the lungs is kept relatively separate from the deoxygenated blood from the rest of the body due to incomplete divisions within the heart.  Amphibians in water can obtain additional oxygen by diffusion through their skin. - Cutaneous Respiration. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Mammalian and Bird Hearts Mammals, Birds, and Crocodiles have a four-chambered heart with two separate atria and two separate ventricles.  Right atrium receives deoxygenated blood from the body and delivers it to the right ventricle, which pumps it to the lungs.  Left atrium receives oxygenated blood from the lungs and delivers it to the left ventricle, which pumps the oxygenated blood to the rest of the body. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

The Cardiac Cycle The heart has two pairs of valves. Atrioventricle (AV) valves guards the opening between the atria and the ventricles.  Right Valve - Tricuspid  Left Valve - Bicuspid Semilunar Valves guard the exits from the ventricles to the arterial system.  Right Valve - Pulmonary  Left Valve - Aortic

The Cardiac Cycle Valves open and close as the heart goes through the cardiac cycle of rest (diastole) and contraction (systole).  Right and Left Pulmonary arteries deliver deoxygenated blood to the right and left lungs. - Return blood to left atrium via pulmonary veins. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

The Cardiac Cycle Aorta and all its branches are systemic arteries, carrying oxygen-rich blood from left ventricle to the rest of the body. Coronary arteries supply the heart muscle itself. Superior vena cava drains the upper body Inferior vena cava drains the lower body.  Empty right atrium and complete systematic circulation.

The Cardiac Cycle Measuring Blood Pressure  Systolic pressure is peak pressure during ventricular systole.  Diastolic pressure is minimum pressure between heart-beats. - Blood Pressure written as ratio of systolic over diastolic. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Electrical Excitation and Contraction of the Heart Contraction of heart muscle is stimulated by membrane depolarization.  Depolarization triggered by sinoatrial (SA) node. - Acts as pacemaker for rest of the heart by producing depolarization impulses spontaneously at a particular rate. Atrioventricular (AV) node allows depolarization to pass to the ventricles.  Depolarization is conducted rapidly over both ventricles by atrioventricular bundle (Bundle of His). - Transmitted by Purkinje Fibers. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Electrical Excitation and Contraction of the Heart Electrical activity recorded on an electrocardiogram (EKG or ECG).  First peak (P) is produced by depolarization of atria (Atrial Systole).  Second peak (QRS) produced by ventricular depolarization (Ventricular systole).  Last peak (T) produces by ventricular repolarization. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Blood Flow and Blood Pressure Cardiac Output  Volume of blood pumped by each ventricle per minute. - Increases during exercise because of an increase in heart rate and stroke volume. Blood Pressure and Baroreceptor Reflex  Arterial blood pressure depends on two factors: - Cardiac Output - Resistance to Flow Baroreceptors detect changes in arterial blood pressure.  Activate sensory neurons that relay information to cardiovascular control centers. - When blood pressure falls, they stimulate neurons causing arteriole to constrict and raise blood pressure. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

Blood Flow and Blood Pressure Blood Volume Reflexes involve effects of four hormones:  Antidiuretic Hormone  Aldosterone  Atrial Natriuretic Hormone  Nitric Oxide

Blood Flow and Blood Pressure Cardiovascular Diseases  Cardiovascular diseases are the leading cause of death in the United States. - Insufficient supply of blood reaching one or more parts of the body.  Heart Attacks - Blocked arteries.  Strokes - Interference with blood supply to the brain. Atherosclerosis - Accumulation within the arteries of fatty materials and various kinds of cellular debris. Arteriosclerosis - Hardening of the arteries.  Occurs when calcium is deposited in arterial walls. Raven - Johnson - Biology: 6th Ed. - All Rights Reserved - McGraw Hill Companies

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