Inquiry into LifeTwelfth Edition

Chapter 12

Lecture PowerPoint to accompany

Sylvia S. Mader

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

12.1 The Blood Vessels

• Three Types of Blood Vessels

– Arteries (carry blood away from the heart)

– Capillaries (permit exchange of materials with tissues)

– Veins (carry blood toward the heart)

12.1 The Blood Vessels

• The Arteries

– Three layers to an arterial wall• Inner layer - simple squamous epithelium with basement

membrane

• Middle layer- thickest layer, contains smooth muscle

• Outer layer - fibrous and loose connective tissue

Blood Vessels

12.1 The Blood Vessels

• The Capillaries

– Capillaries join arterioles to venules

– Capillary walls are one-cell in thickness

– Capillaries form vast networks in all regions of the

body

– Capillary beds can be bypassed by a arteriovenous

shunt

Anatomy of a Capillary Bed

12.1 The Blood Vessels

• The Veins

– The walls of veins are structured similarly to the walls of arteries, but there is less smooth muscle and connective tissue in veins.

– Veins often have valves to prevent the backflow of blood.

– Veins have a greater capacity to expand, they serve as blood reservoir.

12.2 The Heart

• The heart is a muscular organ that lies between the lungs directly behind the sternum.

– Myocardium: The major portion of the heart that consists mainly of cardiac muscle.

– Pericardium: A serous membrane that surrounds the heart.

– Endocardium: A membrane consisting of connective tissue and endothelium that lines the inner surface of the heart.

12.2 The Heart

• The Human Heart• Four-chambers

• Two atria and two ventricles

• A septum separates the right and left sides• Four valves prevent the backflow of blood

• Two atrioventricular valves• Two semilunar valves

External Heart Anatomy

12.2 The Heart

• The Human Heart Continued

– Heart is described as a double pump• Right ventricle sends oxygen-poor blood into the pulmonary

circuit• Left ventricle sends oxygen-rich blood into the systemic

circuit

– Blood must travel through the lungs to go from the right side of the heart to the left side

– Oxygen-rich blood does not mix with oxygen-poor

12.2 The Heart

• Path of Blood Through the Heart

Vena cava right atrium tricuspid valve

right ventricle pulmonary semilunar valve

pulmonary trunk pulmonary arteries lungs

pulmonary veins left atrium bicuspid valve left

ventricle aortic semilunar valve aorta body

Internal View of the Heart

12.2 The Heart

• The Heartbeat (Cardiac Cycle)

• Each time the heart beats:– The two atria contract simultaneously– Then the two ventricles contract simultaneously– All the chambers then relax

• Systole: Contraction of the heart muscle• Diastole: Relaxation of the heart muscle

12.2 The Heart

• The Heartbeat

– Heart Sounds

• Described as a “lup-dup” sound

– “Lup” sound - atrioventricular valves closing

– “Dup” sound - semilunar valves closing

• A heart murmur (swishing sound) may be due to a leaky

valve

Heart Sounds / Cardiac Cycle

12.2 The Heart

• Intrinsic Control of Heartbeat

– The SA (sinoatrial node) • Located in the upper portion of the right atrium wall

• Initiates the heartbeat, sends out an excitatory impulse every

0.85 seconds

• This causes the atria to contract

• The excitatory impulses travels to the AV node

• Called the “pacemaker” of the heart

Conduction System of the Heart

12.2 The Heart

• Intrinsic Control of Heartbeat– The AV (atrioventricular node)

• Located in the base of the right atrium wall

• When impulses (that originated in the SA node) reach the AV

node, there is a slight delay that allows the atria to finish their

contraction

• An impulse travels from the AV node through the branches of

the atrioventricular bundle before reaching the Purkinje

fibers.

• Purkinje fibers are specialized muscle cells that cause the

ventricles to contract.

12.2 The Heart

• Extrinsic Control of Heartbeat– Medulla oblongata (brain)

• Influences heart beat via the autonomic nervous system– Sympathetic division increases heart rate– Parasympathetic system decreases heart rate

12.2 The Heart

• Electrocardiograms (ECG)– A recording of the electrical changes

occurring in the heart

An Electrocardiogram

• P Wave occurs just prior

to atrial contraction

• QRS complex occurs just

prior to ventricular

contraction

• T wave occurs after

ventricular contraction

12.3 The Vascular Pathways

• The cardiovascular system has two circuits:– The Pulmonary Circuit

• Circulates blood through the lungs

– The Systemic Circuit• Circulates blood through the rest of the body

12.3 The Vascular Pathways

• The Pulmonary Circuit– Blood from the body

collects in the right atrium

– Right Atrium Right Ventricle Pulmonary Arteries Arterioles Capillaries Venules

Pulmonary Veins Left atrium

12.3 The Vascular Pathways

• The Systemic Circuit– Blood leaves the left

ventricle, travels through the body and is returned to the heart

– aorta arteries arterioles capillaries

venules veins

vena cava

12.3 The Vascular Pathways

12.3 The Vascular Pathways

Coronary arteries supply In the hepatic portal system,blood to the heart muscle. blood travels from the

intestines through the liver and to a vena cava.

12.3 The Vascular Pathways

• The beat of the heart supplies pressure that keeps blood moving in the arteries– Systolic Pressure results from blood forced into the arteries

during ventricular systole.– Diastolic Pressure is the pressure in the arteries during

ventricular diastole.

• Blood pressure– Normally measured with a sphygmomanometer on the brachial

artery.– Expressed in the form: Systolic “over” Diastolic (120/80)

• Skeletal muscle contraction pushes blood in the veins toward the heart.

Velocity and Blood Pressure Related to Vascular Cross-Sectional Area

Cross Section of Valve in a Vein

12.4 Blood

• Plasma – Liquid portion of the blood

• Formed Elements– Red blood cells– White blood cells– Platelets

12.4 Blood

• Blood has:– Transport functions

– Regulatory functions

– Protective functions

Composition of Blood

12.4 Blood

• Plasma– Contains inorganic and organic substances dissolved

or suspend in water– Plasma proteins

• Various functions – Transport of substances, blood clotting, fighting disease

• Help maintain blood volume

12.4 Blood

• Red Blood Cells (Erythrocytes)– Manufactured in red bone marrow – 4-6 million per mm3 of whole blood– Shape is biconcave disc, they also lack a nucleus– Contain hemoglobin

• Red iron-containing pigment• Heme portion binds oxygen• Carbon monoxide (a pollutant) can also bind at heme sites

– Combines more readily than oxygen– Can be lethal

Physiology of Red Blood Cells

12.4 Blood

• Red Blood Cells Continued– Red blood cells last around 120 days and then are

destroyed in the liver and spleen– Too few red blood cells results in anemia– A lack of iron also causes anemia

12.4 Blood

• White Blood Cells (Leukocytes)– Nucleated

– Lack Hemoglobin

– 4,000 - 11,000 cells per mm3 of whole blood

– Role is to fight infection and provide immunity

12.4 Blood

• White Blood Cells

– Granulocytes-have visible granules in cytoplasm

• Neutrophils- most abundant leukocyte, phagocytic

• Basophils-granules stain deep blue and release histamine

• Eosinophils-granules stain red, fight parasitic worms

– Agranulocytes- lack visible granules

• Lymphocytes-T and B cells, play roles in immunity

• Monocytes-largest WBC’s, phagocytic

12.4 Blood

• White Blood Cells– The number or cell count of specific types of

leukocytes can be used in diagnosing disease.• Infectious mononucleosis• AIDS• Leukemia

12.4 Blood

• The Platelets and Blood Clotting

– The Platelets • Form as a result of fragmentation of large cells in the red

bone marrow • 150,000-300,000 per mm3 of whole blood• Involved in the process of clotting

12.4 Blood

• The Platelets and Blood Clotting– Blood Clotting

• Platelets form a plug for immediate stoppage of bleeding• Vessels release prothrombin activator and injured tissues

release thromboplastin– Thromboplastin stimulates further release of prothrombin

activator– Requires calcium

• Prothrombin activator activates the plasma protein prothrombin to thrombin

• Thrombin activates fibrinogen to fibrin which forms a clot• Clot is composed of network of fibrin threads and trapped

cells• As damage heals, plasmin breaks down the clot

Blood Clotting

12.4 Blood

• The Platelets and Blood Clotting– Hemophilia

• Inherited disorder• Deficiency in a clotting factor• Internal bleeding can cause serious damage to cells and

tissues• Hemophilia is treated by blood transfusions and injections of

clotting factors.

12.4 Blood

• Bone Marrow Stem Cells– Cells which are capable of dividing and differentiating

into particular cell types• Red and white blood cells• Some may even be able to give rise to liver, bone, fat,

cartilage, heart, and nerve cells• May provide solutions for diseases such as Alzheimer’s and

Parkinson’s– Many researchers prefer to work with embryonic stem

cells since they are totipotent (can become any cell type)

Blood Cell Formation in Red Bone Marrow

12.4 Blood

• Capillary Exchange– Two forces control movement through capillary wall

• Osmotic pressure tends to cause water to move from tissues to blood; due to presence of plasma proteins and salts

• Hydrostatic pressure (blood pressure) tends to cause water to move from blood to tissues

– At arterial end of capillary hydrostatic pressure is higher so water moves out-contributes to tissue fluids

– Midway through capillary these forces are equalized so no net movement of water• Solutes now move down their gradients

12.4 Blood

• Capillary Exchange– At the venous end osmotic pressure is greater than

hydrostatic pressure so water moves into capillary– Almost the same amount of water gets reabsorbed

that left the capillary at the arterial end– The small amount of fluid remaining behind can be

absorbed by lymphatic vessels

Capillary Exchange in the Systemic Circuit

Lymphatic Capillaries

12.5 Cardiovascular Disorders

• Atherosclerosis– Plaque formation in vessels caused by fats and

cholesterol– Interferes with blood flow– May be hereditary– Prevention

• Diet high in fruits and vegetables• Low in saturated fats and cholesterol

– Plaques can cause clots to form thrombus• If clot breaks loose it becomes a thromboembolism

12.5 Cardiovascular Disorders

• Stroke, Heart Attack, and Aneurysm– Stroke (cerebro-vascular accident CVA): small cranial

arteriole bursts or becomes blocked • Lack of oxygen to brain can cause paralysis or death• Warning signs: numbness in hands or face, difficulty

speaking, temporary blindness in one eye– Heart attack (myocardial infarction)

• A portion of the heart muscle deprived of oxygen• Angina pectoris-chest pain from partially blocked coronary

artery• Heart attack occurs when vessel becomes completely

blocked

12.5 Cardiovascular Disorders

• Stroke, Heart Attack, and Aneurysm

– Aneurysm- ballooning of a blood vessel• Most often in abdomen or brain• Atherosclerosis and hypertension can weaken walls of

vessels leading to an aneurysm• Bursting of blood vessels can be fatal

12.5 Cardiovascular Disorders

• Coronary Bypass Operations– Bypass blocked areas

of coronary arteries– Can graft another

vessel to the aorta and then to the blocked artery past the point of blockage

– Gene therapy may be a future treatment

12.5 Cardiovascular Disorders

• Clearing Clogged Arteries– Angioplasty

• Catheter is placed in clogged artery

• Balloon attached to catheter is inflated

• Increases the lumen of the vessel

• Stents can be placed to keep vessel open

12.5 Cardiovascular Disorders

• Heart Transplants and Artificial Hearts– Usually successful but shortage of donors– LVAD-left ventricular assist device

• Alternative to heart transplant• Tube passes blood from left ventricle to the LVAD• Blood is pumped to the aorta• LVAD are used as temporary measures until a donor heart

becomes available– TAH-total artificial heart

• Generally only used to very ill patients• Survival rates are not good but may be because patients are

so ill

12.5 Cardiovascular Disorders

• Hypertension (High blood pressure)– Affects about 20% of all Americans– Usually caused by a narrowing of the arteries– Age, gender, and lifestyle can influence blood

pressure• Obesity• Smoking• High dietary salt intake

– Medications can be used to treat this disease