Cardiovascular System: Anatomy and Physiology

Unit 7: Cardiovascular System

• This unit covers hematology, anatomy and physiology of the heart, and also vasculature, the lymphatic system and cardiovascular examination.

Enabling Learning Objectives

• After completing this unit, students should be able to interpret facts and principles of anatomy and physiology and apply concepts and perform and interpret a physical DDC exam with under 6 mistakes.
• Students should also be able to:
  • Describe blood characteristics and major functions.
  • Define terms related to whole blood components.
  • Differentiate formed blood elements from liquid.
  • Define terms used to identify red and white blood cells.
  • Explain how viral and bacterial infections impact the white blood cell response.
  • Describe platelets and its function.
  • List the major steps in blood coagulation pathways, both intrinsic and extrinsic.
  • Explain the different blood types and their corresponding antigens and antibodies.
  • Explain how blood type antigens/antibodies are used to avoid adverse transfusion reactions.
  • Interpret how blood type reactions can occur between fetal and maternal tissues.
  • Describe anatomical structures and coverings of the heart and distinguish layers making up the heart wall.
  • Understand the circulation path through the heart.
  • Summarize blood supply from coronary arteries during the cardiac cycle.
  • Describe the cardiac cycle and how heart sounds are produced, and also understand what systolic and diastolic blood pressure are and what factors affect each.
  • Identify main organs and functions of the lymphatic system; locate proper landmarks for cardiovascular auscultation points.
  • Analyze different kinds of abnormal valvular conditions causing murmurs.
  • Identify steps of the peripheral vascular exam and interpret said findings.
  • Define and grade the degree of edema.
  • Be able to identify where pulses and valves must be palpated and how to describe findings.
  • Identify anatomical locations to auscultate when assessing for bruits.
  • Discriminate fixed split S2 from physiologic split S2 and what causes them.
  • Identify the PMI and its importance in the cardiac exam.

Overview

• Hematology covers general blood characteristics and major functions.
• Anatomy and Physiology of the Heart will be covered.
• Anatomy and Physiology of the Peripheral Vasculature will be covered.
• The Lymphatic System will be covered.
• Cardiovascular Examination will be covered.

Functions of Blood

• Blood transports nutrients, oxygen, waste, and hormones.
• It maintains the stability of interstitial fluid.
• Blood helps distributes heat.
• The average adult has ~5 liters of blood, which makes about 8% of body weight.
• Blood is a type of connective tissue divided into formed elements or blood cells and plasma.

Blood Types

• Three types of blood exist based on percent per whole blood.
• Hematocrit: this is the percentage of (45%).
• Buffy coat – constitutes WBCs and platelets.
• Plasma makes up (55%) of blood
  • It includes all other components (water, amino acids, proteins, carbohydrates, lipids, vitamins, electrolytes, hormones, and cellular wastes).
  • Serum is plasma without fibrinogen and clotting factors.

Blood Cells

• Red Blood cells (RBC's erythrocytes).
• White blood cells (WBC's, leukocytes).
• Platelets (thrombocytes).
• Hematopoiesis is the production of all blood cells.

Red Blood Cells (RBC's, 12.2-14.7 g/dl)

• RBCs transport oxygen through the body.
• Their biconcave discs provide increased surface area for gas diffusion.
• They travel easily through capillaries.
• RBCs contain no nucleus and cannot reproduce.

RBC Terminology

• Anemia: Loss of total RBC's or reduction of hemoglobin.
• Erythropoiesis: Production of RBC's in bone marrow.
• Hemolysis: Destruction of RBC's.
  • Can be caused by sickle cell, G6PD deficiency, or autoimmune disorders.
  • Lifespan is approximately 120 days.

Hemoglobin (Hgb)

• Hemoglobin is a protein allowing oxygen transport.
• Each unit contains four iron molecules (Fe3+).
• Oxygen molecules attach to each of the Fe3+ within hemoglobin.
• Oxygen attached to hemoglobin is called oxyhemoglobin.
• When oxygen is released, the molecule is called deoxyhemoglobin.
• An RBC is 1/3 Hgb, which imparts its red color (Fe3+).

Dietary Affectations

• Dietary factors affecting erythropoiesis include availability of B-12 and folic acid.
  • B-12 and folate are necessary for RBC DNA synthesis.
  • B-12 deficiency is usually due to absence of intrinsic factor (IF) (autoimmune or genetic), although it can occur through insufficient intake or surgery like gastric bypass.
    • IF is secreted by cells in the stomach lining.
    • The loss of these cells prevents vitamin B-12 absorption which results in pernicious anemia.

White Blood Cells (WBC's, 5-12,000 per mm3)

• The purpose of WBCs is immunity.
• Two broad categories exist distinguished by shape.
  • Granulocytes (grainy in appearance).
  • Agranulocytes.

Granulocytes

• Neutrophils (54%): phagocytize bacteria.
• Eosinophils (1%): mediate allergic reactions and defend against parasitic infections.
• Basophils (< 1%): release histamine at injury site.

Agranulocytes

• Monocytes (3%): Act as macrophages to bacteria and cellular debris.
• Lymphocytes (25%): The second most numerous circulating blood cells, elevated in viral etiology.
  • T Cells - Attack micro organisms.
  • B Cells - Produce antibodies.

Terms Used in Conjunction with WBCs

• Leukocytosis: Elevated WBC's >10,000.
• Leukopenia: WBC counts below 5,000 per mm³.
• WBC differential: Percentage of types of leukocytes present.
• Leukemia: Cancer caused by an abnormal increase of immature white blood cells.
• Diapedesis: Movement of WBCs from circulation, between cells lining vessel walls.

Blood Platelets: (140,000 - 440,000μL)

• Thrombocytes stick to damaged or broken blood vessel surfaces.
• They release serotonin which triggers vasoconstriction.

Human Blood Make Up

• Clear, straw-colored liquid makes 92% water, with cells and platelets.
• Water
  • Plasma proteins
  • Albumin: small, most abundant, assists with colloid osmotic pressure.
  • Bind and transport hormones and medications.
  • Globulins
  • Transport protein
  • gamma globulins used as antibodies
  • Fibrinogen
  • Largest plasma protein
  • Used in coagulation

Blood - Organic Components

• Plasma nutrients: amino acids, lipids, glucose.
• Wastes
  • urea – product of protein catabolism
  • uric acid – product of nucleic acid catabolism
  • creatinine – product of creatine metabolism (from muscle)

Blood - Inorganic Components

• Water makes up blood
• Electrolytes: Na+, K+, Cl-, Ca2+
• Gases: N2, O2, and CO2

Blood Coagulation

• Stoppage of bleeding divided into three mechanisms
  • Blood vessel spasm
  • Automatic response of blood vessel triggered by histamine release.
  • Platelet plug formation
    • Injured tissue releases Von Willbrand's factor (VWF)
      • This causes platelets to adhere to tissue walls.
    • Exposure to collagen "activates" platelets
      • Activated platelets release chemical signals to attract more platelets and encourage vessel spasm.
      • Platelets change shape and interlock.

Blood Coagulation (Fibrin Clot Formation)

• Two Pathways
• Includes Intrinsic and Extrinsic
• Plasma factors activate prothrombin activator
  • These factors are numbered I-XIII
  • Absence of factors can cause a bleeding disorder
• Both require calcium

Intrinsic & Extrinsic Bloodclotting pathways

• Extrinsic pathway is initiated by damage to a vessel or tissue (external trauma).
• Intrinsic happens due to:
  • All components that are in the blood. This could include exposing the blood to collagen, or it coming in contact with a foreign substance.

Blood Coagulation (Cont.)

• Prothrombin activator in the presence of Ca2+ converts prothrombin to thrombin.
• Thrombin converts fibrinogen into fibrin
  • This forms a dense network or creates a clot.
  • Thrombin causes more prothrombin to form more thrombin (positive feedback).
  • The fibrin clot adheres to the platelets and is insoluble.
• Anticoagulants are clot-inhibiting substances.
• Thrombus is an abnormally forming clot in a blood vessel (i.e. DVT).
• Embolus is a circulating thrombus (may cause embolism) (i.e. PE).

Labs

• Prothrombin Time (PT) - in seconds. This evaluates Vitamin K dependent factors (II, VII, X). Coumadin inhibits the action of Vitamin K, so liver cannot produce (II, VII, X).
  • Coumadin makes takes longer to form a clot, hence a higher PT means it takes longer to form the clot.
• Partial Thromboplastin Time (PTT) - in seconds. This evaluates intrinsic mechanism and increased by heparin.
  • Heparin thins the blood as well.

Blood Groups

• ABO blood groups categorized by different genes.
  • Antigen A
  • Antigen B

ABO Blood

• Four possible combinations:
• Type A (antigen A only) on RBCs, antibodies to B in plasma.
• Type B (antigen B only) on RBCs, antibodies to A in plasma.
• Type AB (antigen A and antigen B) on RBCs
  • No antibodies in plasma
  • Universal RBC recipient
• Type O (neither A nor B) on RBCs
  • Antibodies to A & B
  • Universal RBC donor
• If blood types do not match, the cells will clump.

Rh Blood

• Rh blood group includes:
  • Rh positive: contains the Rh gene.
  • Rh negative: absence of the Rh gene.
• If Rh-negative receives Rh-positive blood, anti-Rh antibodies form.
  • Rh factor screening is a part of prenatal care
  • The Rh negative individual has no antibodies to Rh positive blood normally
  • After first exposure to Rh positive blood, antibodies develop
  • Anti-Rh antibodies may cause erythroblastosis fetalis in 2nd fetus

Heart Anatomy Details

• The heart is a fist-sized muscle within the mediastinum
• It's four borders are:
• Sternum (anterior)
• Spine (posterior)
• Lungs (laterally)
• Diaphragm (inferior)
• Base is superior, and the apex is at the 5th intercostal space

Heart Coverings & Walls

• Three coverings:
  • Fibrous pericardium (tough outer sac).
  • Serous membrane is a single layer folded back on itself.
    • Parietal pericardium (lining touches the inner fibrous pericardium).
    • Visceral Pericardium (epicardium) is the lining atop the heart.
    • Pericardial cavity - potential space between parietal and visceral layer Contains pericardial fluid, which decreases friction of each heartbeat.

Walls of the Heart

• Epicardium corresponds to visceral pericardium.
• Myocardium is the thick, cardiac muscle.
• Endocardium is the epithelial layer lining the inside of the heart.
  • Makes the heart "leak-proof"
  • Inflammation of this layer is called endocarditis.
  • Continuous with lining of blood vessels (endothelium).
  • Atria are upper chambers of the heart and thinner walled than ventricles.
  • They receive blood returning to the heart both from the body and lungs, and are divided by an interatrial septum.
  • Ventricles are lower chambers of the heart and are muscular, left > right. They pump blood away from the heart (to body and lungs) and are divided by an interventricular septum.

Heart Values

• Atria are separated from ventricles from atrioventricular valves
  • Tricuspid valve separates right chambers and Mitral (bicuspid) valve separates left chambers.
• Papillary muscles are finger-like muscles in the ventricles, and are attached to AV valves by chordae tendineae.
  • They prevent ventricular blood regurgitation from being pushed into the atria, and contract as the ventricles contract.

Leaving Semilunar Valves

• Blood leaves the heart via semilunar valves.
  • The Pulmonary valve separates right ventricle from lungs.
  • The Aortic valve separates left ventricle from the aorta.

Coronary Arteries

• The ring of connective tissue is situated around the pulmonary trunk and aortic root used as an anchor for valves and muscles.
• Blood low in oxygen enters the heart's right side. It is received from the superior/inferior vena cava, while coronary sinus drains blood from coronary circulation.
• The right atria contracts, pushing blood into right ventricle through the tricuspid valve.
• Next, the right ventricle contracts pushing blood through pulmonary valve into the pulmonary arteries.
• Afterwards, blood comes up to pick up oxygen in the lungs.
• Oxygen-rich blood drains from the lungs into pulmonary veins.
• Four pulmonary veins drain blood into left atria.
• Left atria contract pushing blood through the mitral valve into left ventricle.
• Left ventricle contracts pushing blood through aortic valve into the aorta.

Coronary Arteries Function

• These are arteries located atop the aortic valve, which feed each side during diastole.
• The left main coronary artery (LCA) main branches include:
• Left anterior descending artery which supplies walls of both ventricles.
• The Circumflex artery which supplies and left atrium and ventricle.
• Right coronary artery (RCA) main branches include:
• Marginal artery.
  • Supplies right atrium and ventricle.
• Posterior interventricular artery:
  • Supplies walls of ventricles posteriorly. Smaller vessels connect (anastomose) for collateral circulation. The coronary sinus returns blood back to the heart's atria.

Cardiac Cycle

• Atria contract as the ventricles relax.
  • AV valves are open and ventricles fill with blood
• Ventricles contract as the atria relax.
  • AV valves close with increased ventricular pressure causing the Semilunar valves to open. Blood flows into the lungs and aorta.

Cardiac Sounds.

• S1 is "lub". It represents Ventricular systole and Atrial diastole.
• S2 is "dub", and demonstrates Atrial systole & Ventricular diastole.
• Lub - AV valves closing during systole (S1).
• Dub - Semi lunar valves closing during diastole (S2).
• Split - Slight separation in closure of similar valves
• Murmur - The sound of blood rushing over valves may can indicate valvular disease, particularly if in diastole.

Ascultation

• Areas of Ascultation include:
  • Aortic
  • Pulmonic
  • Tricuspid
  • Bicuspid
• Cardiac muscle fibers are only found here. Functional syncytium occurs in the atria and ventricles-each area contracts as a single unit

Hearts Electrical System

• Electricity is throughout the heart. The sinoatrial (SA) node needs to be located in the right atrium near the superior vena cava. In this case, it exhibits automaticity and is Pacemaker of the heart. Second, the atrioventricular (AV) node should be located in the inferior atrial septum Relay system, to delay atrial impulses for a split second. It also allows atria to completely empty before ventricular systole av node transmits impulses to bundle of HIS, then disrupt the av bundle --> bundle branch block. Furthermore, the purkinje Fibers arise from bundles sending impulses which cause Ventricles contract in twisting motion and squuezing out blood. It is all controlled using the SA node

Control Activity

• Via sympathetic and parasympathetic activity. Continually under parasympathetic activity which decreases heart.
  • Driving with "brakes" on: The parasympathetic fibers which include CNX (medula oblongata, the heart.

Sympathetic activity

• increases the rate/force of contractions, fibers arise from nearby nerves, medulla oblongata cardiac control center balances the Inhibitory and excitatory effects

Electricity Details

• ecords electrical activity, P waves are SA reflecting, QRS in ventricular contraction.
• T wave indicates ventricular relaxation
• Ions can affect activity In the atrium near sv

Vascular Section

• Arterioles
  • Strong and elastic.
  • Tunca externa (advevtiti)
  • Anchors arters, also it is has muscular vasocontrition and internal intima which precent coagulation as get smaller
  • Blood preasure: Stroke volue multiplied.

Peripheral Vascular Details

• Smaller vesseks collatteral cirucualtipm.
• Cardiac cycles consist of: Atria relax with increase pressure to close valves • Systolic pressure • Maximum pressure during ventricular contraction Diastolic pressure • Lowest pressure in arteries before ventricular contraction Strtroke: Clinical: increase venous blood then heart for disctention of greater stoke.

Blood Vessel Examination Details

• Starlings is the converse as volume is dicharged to volume and this is in the chambers

Blood Vessels types

• Aorta
• The right and left veins are used for pulmonary function. Thoracic aorta is the diagram - below multiple brancvhes.

Circulatory System

• Arteris of the pelvis and the ower limbs includes: • Femoral artery
  • Poopietal supplies anky
• Internal to internal jugular veins Veins from abdomen viscera
• Inferior vena cava reciveves from limbo

Vascular Details and System

• Vast collection of biochemicals that travel in lymphatic vessels,
• Network of vessels that assist in circulating body fluids • Vessels have valves similar to veins to prevent backflow • Relies on skeletal muscle contraction and pressure changes to assist flow Closely associated with the cardiovascular system

Vascularity

• Transports interstitial blood away for pathogens adn protection
• Thymus/Spleen organ help the proccess

Nodes

• Cervical nodes help against axiallary ,inuguinal are some node types ,it's importanat . This is also found in supratrochlea where high preassure is

System Details

• What makes the heart output?
• What impacts BP?
• What are lymph nodes?
• Whay organ filters the blood

Auscultation System

• Quiet room with good light with tangenital light. Use a diaphragm for high picth sounds. If u do use a single si,use firm if single sided, if u hear abm normal findigns surround and radiate. Patient needs to stand upright..

Heart Check

• P with hab at 3 and Inspect palpate apical impulse

• Use diag for sounds

• Use bell in s3 AND S4

Heart Areas

• All palapted and asciluatated

• L 2nd ICS

• R 2nd ICS

• Tric

• Erb point

• Impulsations* The high points

• Auscualtion Tips* Five points of examination of rust and ulsb

• In a left.

Explore the cardiovascular system's anatomy and physiology, covering hematology, heart structure, vasculature, and the lymphatic system. Learn to interpret anatomical and physiological principles. Master physical examination techniques and understand blood components, coagulation pathways, and blood types.