Unit 7: The Cardiovascular System

Unit 7: The Cardiovascular System

Objectives: Define all vocabulary words. [BLM 1]
Describe the functions of the cardiovascular system. [BLM 1 – 2] Describe the location of the human heart inside the body using proper directional terminology. [BLM 1 – 2] Trace the path of blood through the blood vessels of the systemic circuit. Compare and contrast the vessel wall thickness, direction of blood flow, oxygenation state, and means of locomotion of the blood in each type of blood vessel. [BLM 1 – 4] Compare and contrast the anatomy of arteries, capillaries and veins. [BLM 1 – 4] Explain the purpose of the pulmonary and the systemic circuits. Compare and contrast these two circuts in terms of vessel nomenclature (names), direction of blood flow, oxygenation states, and side of the heart each enters/exits. [BLM 1 – 4] Explain the purpose of capillaries. Describe what happens when blood reaches the capillaries. [BLM 2] Name and identify (on a diagram/actual heart) the major blood vessels entering/leaving the heart. [BLM 1 – 2] Explain the purpose of the coronary blood circuit; name and identify the relevant blood vessels. [BLM 1 – 2] Identify the three layers of the heart wall, and describe the tissue composition of each layer. [BLM 1 – 2] Name and identify on a diagram/actual heart the chambers, valves, blood vessels and anatomical features of the internal structures of the heart. [BLM 1 – 2] Explain why the myocardium of the ventricles is thicker than that of the atria, and why the myocardium of the left ventricle is significantly thicker than that of the rest of the heart. [BLM 1 – 4] Name and identify the major neurological structures in the heart responsible for the heartbeat. [BLM 1 – 2] Trace, in order, the signal pathway for the heartbeat, starting with the SA node and ending with the contraction of the ventricles. [BLM 1 – 2] Trace the path of blood through the systemic circuit, from the Left atrium to the Right atrium. Name each blood vessel to/from the heart specifically, and name all of the valves it passes through. [BLM 2]Trace the path of blood through the pulmonary circuit, from the Right atrium to the Left atrium. Name each blood vessel to/from the heart specifically, and name all of the valves it passes through. [BLM 1 – 2] Explain what is happening in each step of the cardiac cycle. Describe the direction of blood flow, blood pressure, the action of the myocardium, and the state of all of the valves during each step. [BLM 2] Measure and report systolic and diastolic blood pressure. Explain where each measurement comes from in terms of the heart cycle. [BLM 1 – 4] Analyze blood pressure numbers and categorize them as normal, hypertensive or hypotensive. [BLM 4] List the components of blood, and state the function of each. [BLM 1] Compare and contrast the various formed elements in blood, including cell shape/size, function, appearance, and concentration in normal blood. [BLM 4] Identify the location of blood cell formation (hematopoiesis). [BLM 2] Explain the three steps of hemostasis, in detail. [BLM 2] Describe the symptoms, causative agent, affected areas, and prognosis for various diseases of the skeletal system (myocardial infarction, atherosclerosis, aneurysm, arrhythmia, bradycardia, hemophilia, leukemia, anemia, blood clot). [BLM 1 – 4]

The Cardiovascular System: Contents
Introduction to the Cardiovascular System Blood Vessels External Heart Anatomy Internal Heart Anatomy Regulating the Heartbeat The Human Cardiac Cycle Blood Pressure Blood Hemostasis Diseases of the Cardiovascular System

1. Introduction to the Cardiovascular System
Functions of the cardiovascular system: Deliver oxygen and nutrients to cells and tissues Remove carbon dioxide and other waste products from cells and tissues The cardiovascular system is closed system consisting of the heart and blood vessels The heart pumps blood Blood vessels allow blood to circulate to all parts of the body

1. Introduction to the Cardiovascular System
Location of the Human Heart Thorax between the lungs in the inferior mediastinum Orientation of the Heart Pointed apex directed toward left hip Base points toward right shoulder About the size of your fist

Midsternal line 2nd rib Sternum Diaphragm (a)
Point of maximal intensity (PMI) (a) Figure 11.1a

Mediastinum Heart Left lung Posterior (b)
Figure 11.1b

Aorta Left lung Diaphragm (c)
Superior vena cava Aorta Parietal pleura (cut) Pulmonary trunk Left lung Pericardium (cut) Apex of heart Diaphragm (c) Figure 11.1c

Unit 7: The Cardiovascular System Contents
Introduction to the Cardiovascular System Blood Vessels External Heart Anatomy Internal Heart Anatomy Regulating the Heartbeat The Human Cardiac Cycle Blood Pressure Blood Hemostasis Diseases of the Cardiovascular System

2. Blood Vessels: Types Taking blood to the tissues: Arteries
large, thickest walled carry blood away from heart; blood is moved by the pumping of the heart Arterioles smaller, thinner walled carry blood away from heart; blood is moved by pumping of the heart Capillaries smallest, thinnest vessels one cell layer thick site of exchange of materials between the blood and body tissues

2. Blood Vessels: Types Taking blood back from the tissues: Venules
Thinner walled vessels Carry blood back towards heart Veins Thin walled vessels, large lumen Have valves present which keep blood moving in one direction Blood is moved by “milking” action due to the contraction of skeletal muscles.

Artery Vein (a) Figure 11.10a

2. Blood Vessels: Structure
Three layers (tunics) Tunic interna Endothelium Tunic media Smooth muscle Controlled by sympathetic nervous system Tunic externa Mostly fibrous connective tissue

2. Blood Vessels: Structural Differences
Arteries have a thicker tunica media than veins Capillaries are only one cell layer (tunica intima) to allow for exchanges between blood and tissue Veins have a thinner tunica media than arteries Veins also have valves to prevent backflow of blood Lumen of veins are larger than arteries

2. Blood Vessels: Veins Veins: Have a thinner tunica media
Operate under low pressure Have a larger lumen than arteries To assist in the movement of blood back to the heart: Larger veins have valves to prevent backflow Skeletal muscle “milks” blood in veins toward the heart

2. Blood Vessels: Veins Most arterial blood is pumped by the heart
Veins use the milking action of muscles to help move blood

2. Blood Circulation: Pulmonary and Systemic Pathways
CO2 is given off by the blood into the lungs and O2 is picked up by the blood from the lungs. O2 is given off by the blood and and CO2 is picked up by the blood from the body’s tissue.

2. Blood Vessels: Capillary Beds
Capillary beds consist of two types of vessels Vascular shunt—vessel directly connecting an arteriole to a venule True capillaries—exchange vessels Oxygen and nutrients cross to cells Carbon dioxide and metabolic waste products cross into blood

Precapillary sphincters
Vascular shunt Precapillary sphincters True capillaries Terminal arteriole Postcapillary venule Sphincters open; blood flows through true capillaries. Figure 11.12a

Figure 11.12b

2. Blood Vessels: Major Arteries
Aorta Largest artery in the body Leaves from the left ventricle of the heart Regions Aortic arch—arches to the left Thoracic aorta—travels downward through the thorax Abdominal aorta—passes through the diaphragm into the abdominopelvic cavity Arterial branches of the ascending aorta Right and left coronary arteries serve the heart

Introduction to the Cardiovascular System Blood Vessels External Heart Anatomy Internal Heart Anatomy Regulation of the Heartbeat The Cardiac Cycle Blood Pressure Blood Hemostasis Diseases of the Cardiovascular System

3. External Heart Anatomy
External Coverings of the Heart: Pericardium – a double-walled sac. Fibrous Pericardium Serous Membrane – 2 layers Visceral pericardium Next to heart; also called epicardium Parietal pericardium Outside layer; lines the inner surface of the fibrous pericardium Serous fluid fills the space between the layers of pericardium

Serous fluid is a general name for a typically yellow and transparent water and protein based fluid. A serous membrane is a thin layer of cells that secretes serous fluid. Serous fluid fills the space between the layers of pericardium

3. External Heart Anatomy: Great Vessels of Heart
Aorta (largest blood vessel in the body) Leaves left ventricle carries oxygenated blood to all parts of the body Pulmonary arteries Leave right ventricle carries deoxygenated blood to the lungs

3. External Heart Anatomy: Great Vessels of Heart
Vena cava (Superior and Inferior) Enters right atrium, Superior vena cava brings deoxygenated blood from the upper part of the body and the inferior vena cava brings deoxygenated blood from the lower part of the body Pulmonary veins (four) Enter left atrium brings oxygenated blood from the lungs

3. External Heart Anatomy: Coronary Blood Supply
Blood in the heart chambers does not nourish the myocardium The heart has its own nourishing circulatory system Coronary arteries Cardiac veins Blood empties into the right atrium via the coronary sinus

4. Internal Heart Anatomy: Heart Wall
The Heart Wall has three layers: Epicardium Outside layer This layer is the parietal pericardium Connective tissue layer Myocardium Middle layer Mostly cardiac muscle

4. Internal Heart Anatomy: Heart Wall
Endocardium Inner layer Endothelium a thin layer of cells that lines blood vessels. Reduce turbulence. Line the entire cardiovascular system.

4. Internal Heart Anatomy

4. Internal Heart Anatomy: Chambers
Right and left side act as separate pumps Four chambers, 2 of each type: Atria Receiving chambers Right atrium Left atrium Ventricles Discharging chambers Right ventricle Left ventricle

4. Internal Heart Anatomy: Valves
The valves allow blood to flow in only one direction Four valves, 2 of each type: Atrioventricular (AV) valves – between atria and ventricles Bicuspid/mitral valve (left side) Tricuspid valve (right side ) Semilunar valves – between ventricle and artery Pulmonary semilunar valve Aortic semilunar valve

4. Internal Heart Anatomy: Valves
AV valves Anchored in place by chordae tendineae (“heart strings”) Open during heart relaxation and closed during ventricular contraction Semilunar valves Closed during heart relaxation but open during ventricular contraction Notice these valves operate opposite of one another to force a one-way path of blood through the heart

4. Internal Heart Anatomy: Septa
Interventricular septum Separates the two ventricles Interatrial septum Separates the two atria

4. Internal Heart Anatomy: Septa

5. Regulation of the Heartbeat
The heart’s pacemaker is a special tissue that sets the heart rhythm Sinoatrial node = SA node (“pacemaker”); in the right atrium Atrioventricular node = AV node; at the junction of the atria and ventricles Atrioventricular bundle = AV bundle (bundle of His); in the interventricular septum Bundle branches are in the interventricular septum Purkinje fibers spread within the ventricle wall muscles

Contraction is initiated by the sinoatrial node (SA node) Sequential stimulation occurs at other autorhythmic cells Forces cardiac muscle depolarization in one direction—from atria to ventricles

Once SA node starts the heartbeat Impulse spreads to the AV node Then the atria contract At the AV node, the impulse passes through the AV bundle, bundle branches, and Purkinje fibers Blood is ejected from the ventricles to the aorta and pulmonary trunk as the ventricles contract

5. Regulation of the Heartbeat: Problems
Heart block —damaged AV node releases them from control of the SA node; result is in a slower heart rate as ventricles contract at their own rate Ischemia —lack of adequate oxygen supply to heart muscle Fibrillation —a rapid, uncoordinated shuddering of the heart muscle Tachycardia —rapid heart rate over 100 beats per minute Bradycardia —slow heart rate less than 60 beats per minutes

6. The Cardiac Cycle: Blood Flow Through the Heart

Superior and inferior venae cavae dump blood into the right atrium From right atrium, through the tricuspid valve, blood travels to the right ventricle From the right ventricle, blood leaves the heart as it passes through the pulmonary semilunar valve into the pulmonary trunk Pulmonary trunk splits into right and left pulmonary arteries that carry blood to the lungs

In the Lungs, oxygen is picked up and carbon dioxide is dropped off by the blood. Oxygen-rich blood returns to the heart through the four pulmonary veins. Blood enters the left atrium and travels through the bicuspid valve into the left ventricle.

From the left ventricle, blood leaves the heart via the aortic semilunar valve and aorta. From the Aorta, blood travels through arteries and arterioles to the body’s tissues. In the tissues, oxygen rich blood is exchanged for oxygen poor blood, which is carried back to the heart via the inferior and superior vena cava, which enter the right atrium.

6. The Cardiac Cycle Atria contract simultaneously
Atria relax, then ventricles contract Systole = contraction Diastole = relaxation

6. The Cardiac Cycle The Cardiac cycle: the events of one complete heart beat Mid-to-late diastole – blood flows into ventricles Ventricular systole – blood pressure builds before ventricle contracts, pushing out blood Early diastole – atria finish re-filling, ventricular pressure is low

6. The Cardiac Cycle Mid-to-late diastole Pressure in heart is low
Blood flows from passively into the atria and into ventricles Semilunar valves are closed Atrioventricular valves are open Atria contract and force blood into ventricles

6. The Cardiac Cycle Ventricular systole
Blood pressure builds before ventricle contracts Atrioventricular valves close causes first heart sound, “lub” Semilunar valves open as blood pushes against them Blood travels out of the ventricles through pulmonary trunk and aorta Atria are relaxed

6. The Cardiac Cycle Early diastole
At the end of systole, all four valves are briefly closed at the same time Second heart sound is heard as semilunar valves close, causing “dup” sound Atria finish refilling as pressure in the heart drops Ventricular pressure is low Atrioventricular valves open

6. The Cardiac Cycle

6. The Cardiac Cycle: Valves

6. The Cardiac Cycle: Animations
FOR REVIEW:

7. Blood Pressure Pulse – pressure wave of blood as it passes through an artery Monitored at “pressure points” where pulse is easily palpated Pulse averages 70 to 76 beats per minute at rest

7. Blood Pressure Measurements by health professionals are made on the pressure in large arteries Systolic – pressure at the peak of ventricular contraction Diastolic – pressure when ventricles relax Write systolic pressure first and diastolic last (120/80 mm Hg) Pressure in blood vessels decreases as the distance away from the heart increases

7. Blood Pressure Human normal range is variable Normal
140–110 mm Hg systolic 80–75 mm Hg diastolic Hypotension Low systolic (below 110 mm HG) Often associated with illness Hypertension High systolic (above 140 mm HG) Can be dangerous if it is chronic

Blood Pressure Video & Exercise
Take a pressure cuff and practice taking blood pressure on your partner. DO NOT inflate the cuff over 200mmHg. You will cause injury. Taking blood pressure several times in a row will skew the numbers. You will need to wait at least 2 minutes between each test, so alternate who is tested and who is testing.

8. Blood The only fluid tissue in the human body
Classified as a connective tissue Living cells = formed elements Non-living matrix = plasma Color range Oxygen-rich blood is scarlet red Oxygen-poor blood is dull red pH must remain between 7.35–7.45 Blood temperature is slightly higher than body temperature, at 100.4°F

8. Blood: Whole Blood Composition

Figure 10.1 (2 of 2)

8. Blood: Plasma Composed of approximately 90 percent water
Includes many dissolved substances Nutrients Salts (metal ions) Respiratory gases Hormones Plasma proteins Waste products

8. Blood: Plasma Plasma proteins Most abundant solutes in plasma
Most plasma proteins are made by liver Various plasma proteins include Albumin—regulates osmotic pressure Clotting proteins—help to stem blood loss when a blood vessel is injured Antibodies—help protect the body from pathogens

8. Blood Plasma Acidosis Blood becomes too acidic Alkalosis
Blood becomes too basic In each scenario, the respiratory system and kidneys help restore blood pH to normal

8. Blood: Formed Elements
Erythrocytes = red blood cells (RBCs) Leukocytes = white blood cells (WBCs) Thrombocytes or Platelets = cell fragments Formed in red bone marrow by a process called hematopoiesis.

Erythrocytes (red blood cells or RBCs) Main function is to carry oxygen Anatomy of circulating erythrocytes Biconcave disks Essentially bags of hemoglobin Anucleate (no nucleus) Contain very few organelles 5 million RBCs per cubic millimeter of blood

Lymphocyte Platelets Erythrocytes Neutrophils
Figure 10.2

Hemoglobin Iron-containing protein Binds strongly, but reversibly, to oxygen Each hemoglobin molecule has four oxygen binding sites Each erythrocyte has 250 million hemoglobin molecules Normal blood contains 12–18 g of hemoglobin per 100 mL blood

Leukocytes (white blood cells or WBCs) Crucial in the body’s defense against disease These are complete cells, with a nucleus and organelles Able to move into and out of blood vessels (diapedesis) Can move by ameboid motion Can respond to chemicals released by damaged tissues 4,800 to 10,800 WBC per cubic millimeter of blood

List of the WBCs from most to least abundant Neutrophils Lymphocytes Monocytes Eosinophils Basophils Easy way to remember this list Never Let Monkeys Eat Bananas

Types of White Blood Cells: Neutrophils Function as phagocytes at active sites of infection Numbers increase during infection 3,000–7,000 neutrophils in a cubic millimeter of blood (40–70% of WBCs)

Types of White Blood Cells: Lymphocytes Functions as part of the immune response B lymphocytes produce antibodies T lymphocytes are involved in graft rejection, fighting tumors and viruses 1,500–3,000 lymphocytes in a cubic millimeter of blood (20–45% of WBCs)

Types of White Blood Cells: Monocytes Largest of the white blood cells Function as macrophages Important in fighting chronic infection 100–700 monocytes per cubic millimeter of blood (4–8% of WBCs)

Types of White Blood Cells: Eosinophils Function to kill parasitic worms and play a role in allergy attacks 100–400 eosinophils in a cubic millimeter of blood (1–4% of WBCs)

Types of White Blood Cells: Basophils Release histamine (vasodilator) at sites of inflammation Contain heparin (anticoagulant) 20–50 basophils in a cubic millimeter of blood (0–1% of WBCs)

Platelets Derived from ruptured multinucleate cells (megakaryocytes) Needed for the clotting process Platelet count ranges from 150,000 to 400,000 per cubic millimeter of blood 300,000 is considered a normal number of platelets per cubic millimeter of blood

8. Blood: Hematopoiesis Blood cell formation Occurs in red bone marrow
All blood cells are derived from a common stem cell (hemocytoblast) Hemocytoblast differentiation Lymphoid stem cell produces lymphocytes Myeloid stem cell produces all other formed elements

9. Hemostasis Stoppage of blood flow that results from a break in a blood vessel Hemostasis involves three phases Vascular spasms Platelet plug formation Coagulation

9. Hemostasis Vascular Spasms Anchored platelets release serotonin
Serotonin causes blood vessel muscles to spasm Spasms narrow the blood vessel, decreasing blood loss

9. Hemostasis: Vascular Spasams

Platelet Plug Formation
9. Hemostasis Platelet Plug Formation Collagen fibers are exposed by a break in a blood vessel Platelets become “sticky” and cling to fibers Anchored platelets release chemicals to attract more platelets Platelets pile up to form a platelet plug Positive Feed-back Mechanism

9. Hemostasis: Platelet Plug Formation

9. Hemostasis Coagulation Injured tissues release tissue factor (TF)
PF3 (a phospholipid) interacts with TF, blood protein clotting factors, and calcium ions to trigger a clotting cascade Prothrombin activator converts prothrombin to thrombin (an enzyme) Thrombin joins fibrinogen proteins into hair-like molecules of insoluble fibrin Fibrin forms a meshwork (the basis for a clot)

9. Hemostasis: Coagulation

9. Hemostasis: Forming a Blood Clot
fibrin erythrocytes thrombocytes

9. Hemostasis Blood usually clots within 3 to 6 minutes
The clot remains as endothelium regenerates The clot is broken down after tissue repair

9. Hemostasis: Problematic Clotting
Thrombus A clot in an unbroken blood vessel Can be deadly in areas like the heart Embolus A thrombus that breaks away and floats freely in the bloodstream Can later clog vessels in critical areas such as the brain

10. Diseases and disorders of the cardiovascular system

10. Diseases and Disorders of the Cardiovascular System
Myocardial infarction: Commonly called a heart attack. It is due to the blockage of an coronary artery which supplies the myocardium. The cardiac muscle dies and the heart doesn’t function properly because of this. It can be due to the formation of deposits of cholesterol and lipids called plaques, blood clots called thrombus, or an embolism which is a blood clot that forms somewhere else in the body, breaks free and lodges in a coronary artery stopping the flow of blood

Angina pectoralis is a sharp pain radiating into the left arm and /or neck accompanied by a feeling of pressure within the chest. This is a classic symptom of problems with blood flow to the heart muscle itself.

Atherosclerosis: commonly called “hardening of the arteries”. The arteries begin to loose their elasticity due to aging and the formation of plaques in their walls. They narrow and reduce blood supply to regions of the body particularly the brain and heart.

Aneurysm: An aneurysm is a weakened area within the wall of an artery or arteriole. Because of the high pressure, the vessel wall balloons out and can rupture when the wall becomes stretched too thin. This leads to a serious internal hemorrhage.

Arrhythmia: Arrhythmia is due to the irregular beat of the heart. It may be due to damage to the SA or AV node, or the myocardium itself. It is commonly treated with medications or by the implantation of an artificial pace-maker.

Bradycardia indicates that the heart is beating too slow and tachycardia indicates the heart is beating too fast.

10. Diseases and Disorders of the Blood
Hemophilia: A genetic disorder that is due to the fact that there is a clotting factor missing necessary for clot formation to stop bleeding. These individuals can bleed to death from simple injuries or bruising of the body. The most prevalent form is more common in males than females because it is carried on the X chromosome of the female (sex-linked).

Leukemia: cancer of the bone marrow which produces blood cells. There are many different forms of this disease depending upon which type of blood stem cells are involved. However, the cells typically do not mature and inhibit the production of other types of blood cells necessary for survival. Noamal Bone Marrow AML Bone Marrow

Anemia: Anemia is due to the lack of erythrocytes or low levels of hemoglobin in erythrocytes, or abnormal erythrocytes (sickle cell). This inhibits the proper transport of oxygen in the body. There are several forms of anemia

To draw internal structure of heart

Unit 7: The Cardiovascular System

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