Download - 29 Lecture Ppt
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chapter 29Circulation and Cardiovascular
Systems
A Circulatory System Helps Maintain Homeostasis
29-2
29.1 A circulatory system serves the needs of cells
The circulatory system transports oxygen and nutrients, such as glucose and amino acids, to the cells It picks up wastes, which are later excreted from the
body by the lungs or kidneys Both gas exchange and nutrient-for-waste
exchange occur across the walls of the smallest blood vessels, capillaries No cell in the body of an animal is far from a capillary
29-3
Figure 29.1 Exchanges of gases, nutrients, and wastes takes place across capillary walls
29-4
29.2 Some invertebrates do not have a circulatory system
Cnidarians, such as hydras, and flatworms, such as planarians, do not have a circulatory system
In a hydra The cells are either part of an external layer, or they line
the gastrovascular cavity In either case, each cell is exposed to water and can
independently exchange gases and get rid of wastes In a planarian
Trilobed gastrovascular cavity branches throughout the small, flattened body
No cell is very far from one of the three digestive branches, so nutrient molecules can diffuse from cell to cell
29-5
Figure 29.2 Invertebrates with a gastrovascular cavity
29-6
29.3 Other invertebrates have an open or a closed circulatory system
There are two types of circulatory fluid: Blood - always contained within blood vessels Hemolymph - a mixture of blood and tissue fluid that flows into a body
cavity Open circulatory system - found in arthropods and molluscs
Heart pumps hemolymph via vessels into tissue spaces and eventually hemolymph drains back to the heart
Slow delivery of oxygen and nutrients is sufficient for a sluggish animal (clam)
A grasshopper has colorless blood and doesn’t depend on its open circulatory system to deliver oxygen to its muscles
Tracheae open to outside and take oxygen directly to flight muscles Closed circulatory system - found in annelids (earthworms)
Heart pumps blood, which usually consists of cells and plasma, into a system of blood vessels and valves prevent the backward flow of blood
Blood moves into capillaries, for exchanges with tissue fluid Blood then moves from small veins into the dorsal blood vessel (a vein) This dorsal blood vessel returns blood to the heart for repumping
29-7
Figure 29.3A Open circulatory system in a grasshopper
29-8
Figure 29.3B Closed circulatory system in an earthworm
29-9
29.4 All vertebrates have a closed circulatory system
Two different circulatory pathways in vertebrates Single-loop: heart only pumps blood to gills Two-circuit: systemic circuit - heart pumps blood to all parts of the body
except for the lungs; the pulmonary circuit - heart pumps blood to the lungs Fishes - heart has a single atrium and a single ventricle
Blood is fully enriched with oxygen when it leaves gills, the respiratory organ for aquatic organisms
Amphibians and Reptiles - single ventricle pumps blood in the pulmonary circuit to the lungs Also pumps blood in the systemic circuit to the rest of the body Although both O2 -rich and O2 -poor blood enter the single ventricle, it is kept
separate O2 -poor blood is pumped out of the ventricle to the lungs before O2-rich blood
enters and is pumped to the systemic circuit Birds and Mammals
Two atria and two ventricles in the heart and the complete separation of the pulmonary and systemic circuits
Right ventricle pumps blood under pressure to the lungs, and the larger left ventricle pumps blood under pressure to the rest of the body
29-10
Figure 29.4A Single-loop circulatory pathway in fishes
29-11
Figure 29.4B Two-circuit pathway in amphibians and most reptiles
29-12
Figure 29.4C Complete separation of pulmonary and systemic circuits in birds, mammals, and some reptiles
29-13
The Mammalian Cardiovascular System Consists of the Heart
and Blood Vessels
29-14
29.5 The mammalian heart has four chambers
All vertebrates have a closed circulatory system, called a cardiovascular system because it consists of a heart (cardio) and a system of blood vessels (vascular) Septum divides the heart into left and right sides
Right side of heart pumps O2-poor blood to lungs, and the left side pumps O2-rich blood to tissues
Each side has two chambers Upper, thin-walled chambers are atria (sing., atrium) Lower chambers are thick-walled ventricles
Atria receive blood; ventricles pump blood away from heart29-15
Heart Valves
Atrioventricular valves - between the atria and ventricles
Semilunar valves - between the ventricles and their attached vessels
After the blood passes through the right atrioventricular valve, the right ventricle pumps it through the pulmonary semilunar valve into the pulmonary trunk and pulmonary arteries that take it to the lungs Pulmonary veins bring O2-rich blood back to the left atrium
After the blood passes through the left atrioventricular valve, the left ventricle pumps it through the aortic semilunar valve into the aorta, which takes it to the tissues Heart murmur is often due to leaky atrioventricular valves,
which allow blood to pass back into the atria after they have closed 29-16
Figure 29.5 Structure of the heart
29-17
29.6 The heartbeat is rhythmic The average human heart contracts, or beats, about 70 times a
minute, or 2.5 billion times in a lifetime Each heartbeat, called the cardiac cycle, can be divided into three
phases The atria contract (while the ventricles relax) The ventricles contract (while the atria relax) All chambers rest
Systole refers to contraction of the heart chambers, and the word diastole refers to relaxation of these chambers
When the heart beats, the familiar “lub-dub ” sound is heard as the valves of the heart close Pulse - wave effect that passes down walls of arterial blood vessels
following ventricular systole Rhythmic contraction of heart is due to cardiac conduction
system The SA (sinoatrial) node initiates the heartbeat every 0.85 seconds
and is called the cardiac pacemaker An electrocardiogram (ECG) is a recording of the electrical changes
that occur in the heart during a cardiac cycle29-18
Figure 29.6A The phases of a heartbeat
29-19
Figure 29.6B Conduction system of the heart
29-20
29.7 Blood vessel structure is suited to its function
Arteries (and arterioles) - carry blood away from the heart to the capillaries Arteries have a much thick wall with elastic tissue that allows
arteries to expand and accommodate the sudden increase in blood volume that results after each heartbeat
Smaller arteries branch into a number of arterioles Capillaries - permit exchange of material with tissues
Extremely narrow (8–10 mm wide) and have thin walls composed of single layer of epithelium with basement membrane
The thin walls of a capillary facilitate capillary exchange Veins (and venules) - return blood from the capillaries to
the heart Venules (small veins) - drain blood from the capillaries; then join to
form a vein Veins often have valves that allow blood to flow only toward the
heart when open and prevent the backward flow of blood when closed 29-21
Figure 29.7A Types of blood vessels
29-22
Figure 29.7B Anatomy of a capillary bed
29-23
29.8 Blood vessels form two circuits in mammals
The Pulmonary Circuit O2-poor blood from all regions of body collects in right atrium and then
passes into right ventricle, which pumps it into the pulmonary trunk Pulmonary trunk divides into the right and left pulmonary arteries, which
carry blood to the lungs As blood passes through pulmonary capillaries, carbon dioxide is given
off and oxygen is picked up O2-rich blood returns to left atrium of through pulmonary veins
The Systemic Circuit Aorta and the venae cavae (sing., vena cava ) are the major blood
vessels To trace the path of blood to any organ in the body, start with the left
ventricle, then go the aorta, then the proper branch of the aorta, the organ, and the vein returning blood to the vena cava, which enters the right atrium
Portal systems begin and end in capillaries Hepatic portal system takes blood from the intestines to the liver
29-24
Figure 29.8 Path of blood in the body
29-25
29.9 Blood pressure is essential to the flow of blood in each circuit
Blood pressure is normally measured on the brachial artery of the upper arm A blood pressure reading consists of two numbers that represent
systolic and diastolic pressures, respectively Systolic pressure results from blood being forced into the arteries
during ventricular systole Diastolic pressure is the pressure in the arteries during ventricular
diastole Blood pressure accounts for the flow of blood from the
heart to the capillaries As blood flows from the aorta into the various arteries and
arterioles, blood pressure falls Blood pressure in the veins is low and cannot move blood back
to the heart, especially from the limbs Venous return depends upon three factors:
Skeletal muscle contraction, presence of valves in veins, and respiratory movements
29-26
Figure 29.9A Velocity and blood pressure are related to the cross-sectional area of the blood vessels
29-27
Figure 29.9B How a valve affects the movement of blood in a vein
29-28
APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES 29.10 Blood vessel deterioration results in cardiovascular disease
In U.S., about 20% of population suffers from hypertension, high blood pressure Heredity and lifestyle contribute to hypertension
Hypertension is often seen in individuals who have atherosclerosis, which occurs when plaque protrudes into the lumen of a vessel and interferes with the flow of blood
Plaque can cause a clot to form on the irregular arterial wall As long as the clot remains stationary, it is called a thrombus, but
when and if it dislodges and moves along with the blood, it is called an embolus
A stroke often occurs when a small cranial arteriole bursts or is blocked by an embolus
Heart attack - when a coronary artery is completely blocked, a portion of the heart muscle dies due to lack of oxygen
29-29
APPLYING THE CONCEPTS—HOW BIOLOGY IMPACTS OUR LIVES
29.11 Cardiovascular disease can often be prevented
The Don’ts Smoking - When a person smokes, nicotine enters the
bloodstream and causes the arterioles to constrict and the blood pressure to rise
Drug Abuse - Stimulants, such as cocaine and amphetamines, can cause an irregular heartbeat and lead to heart attacks and strokes
Weight Gain - in persons who are more than 20% above the recommended weight more tissues require servicing, and the heart sends the extra blood out under greater pressure
The Dos Healthy Diet - Physicians advise people to replace harmful
saturated fats and trans fats with healthier ones, such as monounsaturated fats (olive and canola oils) and polyunsaturated fats (corn, safflower, and soybean oils)
Cholesterol Profile - Starting at age 20, all adults are advised to have their cholesterol levels tested at least every five years
Exercise - People who exercise are less apt to have cardiovascular disease
29-30
Figure 29.11 Plaque buildup in a coronary artery
29-31
Blood Has Vital Functions
29-32
29.12 Blood is a liquid tissue
Blood’s numerous functions include the following: Transports substances to and from the capillaries, where
exchanges with tissue fluid take place Helps defend the body against invasion by pathogens (e.g.,
disease-causing viruses and bacteria) Helps regulate body temperature Forms clots, preventing a potentially life-threatening loss of
blood Blood has two main portions
Plasma - composed mostly of water (90–92%) and proteins (7–8%) Also contains smaller quantities of many types of molecules,
including nutrients, wastes, and salts Formed elements - red blood cells, white blood cells, and
platelets29-33
Types of Blood Cells
Red blood cells (erythrocytes) - transport oxygen using hemoglobin, which contains iron, and combines loosely with oxygen
White blood cells (leukocytes) - help fight infections Neutrophils, which are amoeboid, squeeze through the capillary
wall and enter the tissue fluid, where they engulf foreign material Monocytes appear and are transformed into macrophages,
large phagocytizing cells that release white blood cell growth factors
Lymphocytes play important role in fighting infection T cells attack infected cells that contain viruses B cells - produce antibodies
Each B cell produces just one type of antibody, which is specific for one type of antigen
An antigen, which is most often a protein but sometimes a polysaccharide, causes the body to produce an antibody to combine with the antigen
29-34
Figure 29.12 Composition of blood
29-35
29.13 Blood clotting involves platelets
Platelets result from fragmentation of large cells in the bone marrow called megakaryocytes Blood contains 150,000–300,000 platelets per mm3
When a blood vessel in the body is damaged platelets clump at the site of the puncture and partially seal the leak Platelets and the injured tissues release a clotting factor called prothrombin
activator that converts prothrombin to thrombin Thrombin acts as an enzyme that severs two short amino acid chains from
each fibrinogen molecule These activated fragments then join forming long threads of fibrin that wind
around the platelet plug in the damaged area of the blood vessel and provide the framework for the clot
If blood is allowed to clot in a test tube, a yellowish fluid develops above the clotted material, called serum Contains all the components of plasma, except fibrinogen
Hemophilia is a well-known, inherited clotting disorder Due to the absence of a particular clotting factor, the slightest bump can cause
internal bleeding
29-36
Figure 29.13 Blood clotting
29-37
APPLYING THE CONCEPTS—HOW SCIENCE PROGRESSES
29.14 Adult stem cells include blood stem cells
A stem cell is a cell that is capable of becoming different types of cells While embryonic stem cells possess the ability to become
virtually any cell type, adult stem cells are not quite as versatile because they can become only certain other types of cell
Adult stem cells have been identified in many tissues, including the liver, skin, muscle, and even within the brain, but the richest source is in the red bone marrow Adult stem cells from bone marrow are used to treat many white
blood cell and immune system disorders, including leukemia, certain blood cancers, and anemia
Like any organ transplant, a bone marrow transplant poses the risk of rejection
29-38
Figure 29.14 Hematopoietic cells (adult stem cells in red bone marrow) produce cells that become the various types of blood cells.
29-39
29.15 Capillary exchange is vital to cells
Capillary exchange occurs between a systemic capillary and tissue fluid, the fluid between the body’s cells Two forces control movement of fluid through capillary wall
Blood pressure, which tends to cause water to move out of a capillary into the tissue fluid
Osmotic pressure, which tends to cause water to move from the tissue fluid into a capillary
Red blood cells and almost all plasma proteins remain in the capillaries Fluid and other substances that leave a capillary contribute to the
tissue fluid At the venous end of a capillary, blood pressure has fallen so
osmotic pressure is greater than blood pressure, and water tends to move into the capillary Some excess tissue fluid is always collected by the lymphatic
capillaries Tissue fluid contained within lymphatic vessels is called lymph
Lymph is returned to the systemic venous blood when the major lymphatic vessels enter the subclavian veins in the shoulder region
29-40
Figure 29.15A Capillary exchange
29-41
Figure 29.15B A lymphatic capillary bed lies near a blood capillary bed
29-42
29.16 Blood types must be matched for transfusions
ABO System Presence or absence of type A and type B
antigens on red blood cells determines a person’s blood type In the ABO system, there are four types of blood:
A, B, AB, and O Type O blood has no antigens on the red blood cells and
is sometimes called the universal donor
29-43
29-44
Rh System and Erythroblastosis Fetalis
Rh System Another important antigen in matching blood types is the Rh
factor 85% of the U.S. population have this particular antigen on red
blood cells and are called Rh-positive Erythroblastosis Fetalis
During pregnancy, if the mother is Rh-negative and the father is Rh-positive, the child may be Rh-positive
Rh-positive red blood cells may begin leaking across the placenta into the mother’s cardiovascular system, since placental tissues normally break down before and at birth
The mother produces anti-Rh antibodies, which may cross the placenta and destroy the child’s red blood cells during a subsequent pregnancy
29-45
Figure 29.16A No agglutination occurs when the donor and recipient have the same type blood
29-46
Figure 29.16B Agglutination occurs because blood type B has anti-A antibodies in the plasma
29-47
Connecting the Concepts:Chapter 29
It is possible to relate the type of cardiovascular system to the lifestyle of an animal Some small, aquatic animals have no cardiovascular system—
external water passing in and out of a gastrovascular cavity is sufficient to meet the needs of their cells
Grasshoppers have an open circulatory system, but they utilize tracheae to deliver oxygen directly to their muscles
We traced the evolution of the two-circuit circulatory pathway in vertebrates and saw that a two-circuit pathway allows blood to pass to the lungs and to the tissues under pressure This is particularly useful in birds and mammals, which maintain
a warm body and an active way of life Body fluids make ideal culture media for the growth of infectious
parasites, and these fluids often have ways to ward off an invasion. You already know that white blood cells are involved in these endeavors
29-48