Heart Functions and Anatomy

Functions of the Heart

• Generate Blood Pressure (BP): Forces blood into circulation.
• Separates pulmonary circulation from systemic circulation to ensure enough oxygen.
• Valves ensure unidirectional blood movement, preventing backflow.
• Adjusts blood supply by modifying the speed and effort of heart contractions to fulfill tissue requirements.

Heart Anatomy

• The base is directed posteriorly and slightly superiorly.
• The apex is directed anteriorly and slightly inferiorly.

Pericardium (Pericardial Sac)

• Fibrous Pericardium (Outer): Durable connective tissue anchors the heart inside the mediastinum to protection against overdistension.
• Serous (Inner) Pericardium: An epithelium of single squamous cells.

Components of the Serous Pericardium

• Parietal Pericardium: Lines the fibrous pericardium internally.
• Visceral Pericardium (Epicardium): Sticks to the heart's outer layer.

Pericardial Cavity

• The space located between the serous pericardium layers filled with pericardial fluid, for reducing friction as the heart beats.

Heart Wall Layers

• Epicardium: A delicate serous membrane for smooth surface.
• Myocardium: The thick cardiac muscle layer responsible for contractility.
• Endocardium: Smoother inner layer, facilitating easier blood movement in the heart.

Trabeculae Carneae

• Large muscular ridges and columns located in the interior ventricular walls which facilitate forceful blood ejection.

External Anatomy

• Four Heart Chambers include the right atrium, left atrium, right ventricle, and left ventricle.

Veins Delivering Blood to the Heart

• Blood enters the heart through the Superior Vena Cava, Inferior Vena Cava, and the right and left pulmonary veins.

Large Arteries Exiting the Heart

• Pulmonary Trunk: Emerges from the right ventricle and splits into the right and left pulmonary arteries.
• Aorta: The body's largest artery.

Coronary Sulcus

• A deep groove separates the atria from the ventricles.

Coronary Arteries

• Directly linked to the aorta for circulation.

Left Coronary Artery branches

• Anterior Interventricular Artery that can also be called the Left Anterior Descending Artery.
• Left Marginal Artery that supplies the left side of the heart.
• Circumflex Artery which supplies the left atrium, most of the left ventricle, and part of the right anterior ventricle.

Right Coronary Artery branches

• Right Marginal Artery is a major branch of the Right Coronary Artery.
• Posterior Interventricular Artery is a major branch of the Right Coronary Artery.

General Size of the Heart

• Roughly the size of a clenched fist.
• Physically active individuals may develop more massive hearts.
• As one ages past 65, the heart may decrease.

General Form of the Heart

• Shaped like a blunt cone.
• The apex is blunt and rounded.
• The base is flat and in the superior end.

General Location of the Heart

• Situated in the mediastinum at an oblique angle.

Heart Chambers and Valves

• Right and Left Atria (RA/LA) are separated by the interatrial septum and receive blood from the veins.
• Superior Vena Cava, Inferior Vena Cava and Coronary Sinus open into the Right Atrium (RA).
• Four Pulmonary Veins open into the Left Atrium (LA).
• Right and Left Ventricles (RV/LV) are separated by the interventricular septum and pump blood.
• Atrioventricular Valves allow atrial blood flow into the ventricles which prevent backflow.
• The Tricuspid Valve is between the right atrium and right ventricle.
• The Bicuspid (Mitral) Valve is between the left atrium and left ventricle.

Pulmonary Semilunar Valve

• Found between the right ventricle and pulmonary trunk.

Aortic Semilunar Valve

• Found between the left ventricle and aorta.

Semilunar Valves

• Situated in blood vessels carrying blood from the heart

Route of Blood Flow Through the Heart

• Deoxygenated blood is received into the Right Atrium from the systemic circulation via Superior and Inferior Vena Cava, as well as the Coronary Sinus.
• Right atrium contracts, tricuspid valve opens, and blood flows into the right ventricle.
• The RV pumps and the tricuspid valve shuts while the pulmonary semilunar valve opens for pushing blood to the pulmonary trunk.
• Blood circulates from the pulmonary trunk to the pulmonary arteries, facilitating oxygen exchange in the lungs.
• Oxygenated blood from the lungs flows via the four pulmonary veins into the left atrium.
• Blood continues from the left atrium through the bicuspid valve into the left ventricle.
• The left ventricle contracts, shutting down the bicuspid valve, and pushes the blood to the aortic semilunar valve.
• Finally the blood circulates throughout the parts of the body through the aorta.

Histology of the Heart

• Cardiac Skeleton/Fibrous Skeleton consists of a fibrous connective tissue plate between atria and ventricles, forming rings.
• This fibrous structure provides support for the valves, acts as electrical barrier between atria/ventricles, and functions as attachment location for cardiac muscles.
• Cardiac Muscle contains intercalated discs (desmosomes hold fibers together) and gap junctions (facilitate rapid action potential spread); cells are rich in mitochondria.

Conduction System of the Heart

• Conduction relays action potentials.
• SA Node generates action potentials at a higher frequency (acts as the pacemaker).
• AV Node acts like a gatekeeper, delaying the action potential allowing atrial contraction to complete.
• AV Bundle passes over a small fibrous skeleton into the interventricular septum, where it splits into the right and left bundle branches.
• Purkinje Fibers quickly carry action potential from the apex of the heart through the ventricles, causing ventricles to contract.

Electrocardiogram measures the electrical activity

• P wave = arterial systole
• QRS complex = ventricular systole
• T wave = ventricular diastole

Physiology of the Intrinsic Electrical Activity

• Sinoatrial (SA) Node generates action potentials which spread across both atria, causing them to contract.
• Action potentials pass into the Atrioventricular (AV) Node.
• Action potentials move from the AV node into the Atrioventricular Bundle.
• The AV Bundle splits into the right and left bundle branches and action potentials now run toward the apex of the heart.
• Action potentials are sent by Purkinje fibers, triggering ventricular contraction from the base and upwards.

Action Potential of the Heart

• Resting Membrane Potential (RMP) has a negative charge originally.
• Depolarization occurs as the membrane potential turns increasingly + .
• Repolarization occurs as the membrane potential returns to its initial negativity.
• Pacemaker Potential is a leaky SA node designed for spontaneous entry of positive sodium ions, causing movement toward the threshold.

Cardiac Cycle

• Begins with cardiac muscle contractions and ends upon conclusion of the subsequent contraction.
• Systole refers to the contraction phase.
• Diastole refers to the relaxation phase.

Steps for the Cardiac Cycle

• Heart muscle is relaxed, as the ventricles passively start to get filled with inflowing blood.
• Atrial systole occurs as the SA node produces the action potential (P wave).
• Ventricular systole includes action potential transport via the (QRS complex).
• Isovolumetric contraction begins the ventricular systole phase after action potential is sent throughout the conduction system (QRS complex).
• Ventricular systole includes ejection phase and building ventricular pressure, until pressure overcomes the pulmonary trunk and aorta.
• Ventricular diastole begins with isovolumetric relaxation as blood reduces in volume (T-wave)

Heart Sounds

• "Lub" sound caused by the closing of the AV valves marking the start of ventricular systole
• "Dub" sound caused by closure of the aortic and pulmonary semilunar valves marking the start of ventricular diastole.

Cardiac Pathophysiology: Arrhythmias

• A usual rhythm by the SA node makes for a Normal Sinus Rhythm.
• Any Abnormal rhythm due to conduction defects, caused by stress, caffeine, alcohol, nicotine, etc is an arrhythmia.
• Bradycardia means slow heartbeat rates of <50 bpm.
• Tachycardia = rapid heart rates of >100 bpm.
• Fibrillation is rapid, uncoordinated heartbeats.

Age Related Changes in the Heart

• Common changes include hypertrophy of the left ventricle, gradual aortic thickening, and reduced arterial elasticity.
• Maximum heart rate declines gradually.

Cardiovascular Issues

• Resting and maximum cardiac outputs diminish with age (30-60% by age 85).
• There is an Increased likelihood of coronary artery disease and congestive heart failure.
• Regular aerobic exercise can have a functional benefit.

Blood Vessels

• Vessels carry blood throughout.

Circulatory System Functions

• Transports blood among the heart and body tissues
• Exchanges nutrients, waste products, and gases within tissues.
• Transports hormones, immune components, enzymes, and other elements.
• Governs proper pressure.
• Maintains homeostasis by sending blood to needed tissues.

Circulatory System Overview

• Pulmonary Circulation carries deoxygenated blood from the right ventricle to the lungs, then returns oxygenated blood to the left atrium.
• Systemic Circulation carries blood from the left ventricle to the body, then returns it to the right atrium.

Blood Vessel General Features

• Consist of distinct tissue layers called tunics.
• Tunica Intima (innermost) is composed of simple squamous epithelium, internal elastic membrane and a basement membrane.
• Tunica Media (middle) is largely smooth muscle.
• Tunica Adventitia/Externa (outermost) includes different connective tissue types.

Arteries

• Vessels transport blood away from the heart which become smaller as a capillary is reached.
• Elastic Arteries act are largest in diameter and have high elasticity to regulate blood flow.
• Muscular Arteries are medium-sized with highly controlled vasoconstriction and vasodilation capabilities.
• Arterioles lead to capillaries and can constrict or dilate.

Capillaries

• Have a thin wall (a single layer of endothelium and a basement membrane).
• Primary location for exchange.
• Continuous Capillaries provide uninterrupted fluid leakage.
• Most common capillary type.
• Fenestrated Capillaries contain pores designed rapid absorption.
• Discontinuous/Sinusoidal Capillaries promote macromolecule, transport through blood marrow and liver.

Capillary Network

• Arterioles create a branching matrix in tissue with metarterioles to venules.
• Precapillary Sphincters = smooth muscle at the source allows control via dilation and vasoconstriction.

Veins

• Transport blood back to the heart with thinner walls and wider lumens.
• Thin tunica interna that forms a valve; promotes blood movement only in direction.

Vessel Comparison

• Thick-walled arteries with a restricted diameter deliver blood away from the heart.

Vascular and Capillary Comparison Vessels

• Veins move blood toward the heart, have thinner walls, a larger diameter, and contain valves.
• Capillaries are thin with the primary exchange location.
• No valves exist in the capillaries

Pulmonary Circulation

• Pulmonary arteries move deoxygenated blood to the lungs.
• Pulmonary veins return oxygenated blood to the left atrium.

Systemic Circulation Includes

• Aorta and major branches.

Arteries of the Head and Neck

• Brachiocephalic artery of the right side of both the head and neck.
• Left Common Carotid Artery supplying the left side of both the head and neck.

Pathophysiology of the Arteries

• Arteriosclerosis = artery hardening.
• Atherosclerosis = Narrowing from Plaque.
• Arteriolosclerosis = Small artery hardening.
• Arteritis = general artery inflammation.

Pathophysiology:

• Atherosclerosis can result in ischemia or infarction in coronary, renal, and lower limb arteries.
• Diagnosis through use of Angiogram.
• Modifications, medicine, and intervention are methods of disease management.

Systemic Circulation

• Deoxygenated returns through the coronary sinus, inferior vena cava, and superior vena cava.
• Head and Neck is drained through the jugular veins.
• Upper Limbs are drained through bracial, axillary, and subclavian veins.
• Thorax is drained through veins.
• Abdomen and Pelvis are drained by portal veins.
• Lower Limbs are drained by great and small saphenous veins.

Physiology of Circulation

• Blood pressure is the blood force measured against vascular walls.
• Systolic Pressure is maximum pressure during ventricle contraction.
• Diastolic Pressure is lowest pressure when ventricles relax.
• MAP is cardiac product and resistance together.

Mean Arterial Pressure (MAP)

• Average arterial pressure during one cardiac cycle.
• MAP is the cardiac output * peripheral resistance.
• Cardiac Output (CO) is quantity of blood the heart pumps/minute. Peripheral Resistance (PR) = resistance blood pumped against.

Physiology

• Pulse is the ejection of blood felt in the aorta.
• The Pulse Pressure is the space between both diastolic/systolic directly linked to volume.

Vascular Pathophysiology

• Hypertension can cause arterial pressure problems with systolic reads of 130 mm Hg with diastolic reads of 80+ mm Hg.
• Essential Hypertension = genetics, diet and related factors.
• Secondary Hypertension = other health problems.
• Arteriosclerosis-related narrowing can cause Ischemic Heart Disease.
• Aneurysms, air embolism and fat embolism are alternate causes.

Myocardial Infarction

• Persistant pain is an underlying sign of Myocardial Infarction along with upset stomach, dizziness, breath and sweats.

Heart Regulations

• Cardiac characteristics for Intrinsic regulation.

Extrinsic Regulation Includes:

• Neural (sympathetic & parasympathetic).
• Hormonal regulations (epinephrine & norepinephrine).

Changes Due to Age

• hypertrophy of the left one inside, gradual changes to artery with reduced arterial properties = common.
• Reduced output from both.

General Info About the Lymphatic System

• Lymph ("clear water") = Excess tissue fluids move (3 L /daily) in spaces across vessels that moves it back.
• Water-solutes (ions, nutrition, etc).

Lymph Fluid Balance

• Elaborated drainage system takes waste, returning it.

Lipid Absorption

• Lacteals move items in the tract.

Defense

• Nodes can stop substances.

Functional Anatomy: Lymph Nodes

• The categories are broken down as superficial /deep.
• The superficial is located near items.
• The nodes through the body =450.

Cortex & Medulla: Lymph Nodes

• The nodes have tissues and cords present, as central medulla = macrophages.

Primary Lymphatic Organization Is:

• Bone and Thymus.

Vessels and Lymph

• The node includes affarent vessels to items and vessels for lymphatic movement.

Nodes

• Dense and surrounded which is dense (capsule).

Tissues in Two Class Organs: Lymphatic Organization

• Primary organs.
• Secondary tissues and areas (diffuse is dispersed, with arranged items of density)

Parts in Lymphatic Primary

• Bone (BM.)
• Gland (Thymus.)

Tonsil Description:Secondary Lymphatic Organization

• Nodules are present.
• Types are - Palatine/Pharyngeal and Lingual.

Peyers Patches Description: Secondary Lymphatic Organization

• The look reminds - the walls in both sm sections.

Spleen Description:Secondary Lymphatic Organization

• Clunched fist is one of the size examples here.
• Located at some cavity.
• Tends decrease in weight more with years.

Regions in the Body: White + Red Pulps

• The first region is where tissue surround arteries, and the second is association with blood

Functions :Spleen

• Responds
• Sensing
• Blood

Lymphatic and Ducts: Vessels

• Join to the larger and the ducts that connect thoracic section is primary location or points into them in form.

Main Lymph Movement

• The vessels in there make the valves.
• Move under the muscle contraction.

Pathophysiology related to lymph

• Is bacteria causes.
• Enlargement can occur from fluid.

Bubonic

• Causes of that disorder are death which lead with it with disease.

Elephantiatis

• specific slender warms will cause damage where transport changes, for large swelling worldwide.
• Removal causes more problems.

Immunity

• Intrinsic and Extrinsic systems and more for it