Anatomy & Phys: Chapter 19

Cardiovascular system

The system in the body that consists of the heart and blood vessels and is responsible for transporting blood throughout the body.

Blood vessels

Tubes in the body that carry blood.

Arteries carry blood AWAY from the heart

veins carry blood BACK TO the heart

capillaries are sites of EXCHANGE between blood and body cells.

Heart

The muscular organ that pumps blood throughout the body.

It has four chambers - atria and ventricles

responsible for maintaining perfusion.

Perfusion

The delivery of blood per time per gram of tissue.

It is necessary for maintaining the health of cells and requires the continual pumping of the heart and open, healthy vessels.

Pulmonary circulation

The circulation of BLOOD between the HEART and the LUNGS.

Deoxygenated blood from the RIGHT side of the heart is pumped to the lungs to pick up oxygen and release carbon dioxide.

Systemic circulation

The circulation of OXYGENATED BLOOD from the left side of the heart to SYSTEMIC cells (e.g., skin, muscles)

where it exchanges gases, nutrients, and wastes. Blood vessels then return the blood to the right side of the heart.

Atria

The superior chambers of the heart that RECIEVE BLOOD and send it to the VENTRICLES.

Ventricles

The inferior chambers of the heart that pump blood AWAY from the heart.

Atrioventricular (AV) valves

Valves that sit between the atrium and ventricle of each side of the heart.

The right AV valve is called the TRICUSPID valve and the left AV valve is called the BICUSPID or mitral valve.

Fibrous pericardium

The outermost layer of the pericardium, made of dense irregular connective tissue.

Parietal layer of serous pericardium

The layer of the serous pericardium that attaches to the fibrous pericardium.

Visceral layer of serous pericardium

The layer of the serous pericardium that attaches directly to the heart.

Pericardial cavity

The space between the two serous layers of the pericardium, filled with serous fluid.

Pericardial sac

Formed by the fibrous pericardium and the parietal layer of serous pericardium, it encloses the heart.

Anterior view

the chambers and great vessels.

Posterior view

left atrium and left ventricle.

Coronary sulcus

The groove that separates the atria from the ventricles

Interventricular sulci

The grooves that separate the left and right ventricles

Epicardium

The outermost layer of the heart wall, also known as the visceral layer of serous pericardium.

Myocardium

The middle layer of the heart wall is made of CARDIAC MUSCLE TISSUE that contracts to pump blood.

Endocardium

The innermost layer of the heart wall, covering the internal surface of the heart and the external surface of the valves

Interventricular septum

The wall that separates the left ventricle from the right ventricle in the heart.

Coronary sinus

A vein that carries blood from the heart wall into the right atrium.

Superior vena cava

A large vein that carries DEOXYGENATED blood from the UPPER body into the right atrium.

Inferior vena cava

A large vein that carries deoxygenated blood from the LOWER body into the right atrium.

Right AV valve

Also known as the tricuspid valve, it is located between the right atrium and right ventricle and has three flaps.

Papillary muscles

Cone-shaped projections extending from the internal ventricle wall, typically three in the right ventricle, that anchor the chordae tendineae.

Chordae tendineae

Thin strands of collagen fibers that attach to the AV valves, preventing them from inverting into the atria.

Pulmonary semilunar valve

Located between the right ventricle and the pulmonary trunk, it prevents backflow of blood into the ventricle.

Left atrium

The chamber of the heart that receives OXYGENATED blood from the pulmonary veins.

Left ventricle

The chamber of the heart that pumps oxygenated blood to the REST of the body.

Aortic semilunar valve

Located between the left ventricle and the aorta, it PREVENTS BACKFLOW of blood into the ventricle.

Valves

Structures in the heart that ensure one-way blood flow, including atrioventricular valves and semilunar valves.

Atrioventricular valves

Valves located between the atria and ventricles that prevent backflow of blood to the atria.

Semilunar valves

Valves located between the ventricles and arteries that prevent backflow of blood to the ventricles.

Heart murmur

An abnormal heart sound caused by turbulence of blood passing through the heart.

Fibrous skeleton of the heart

A dense irregular connective tissue that provides structural support, anchors valves, and acts as an electrical insulator in the heart.

Myocardium

The muscular tissue of the heart.

Sarcolemma

The plasma membrane of a cardiac muscle cell.

T-tubules

Invaginations of the sarcolemma that extend into the sarcoplasmic reticulum of a cardiac muscle cell.

Sarcoplasmic reticulum

A network of membranous sacs surrounding the myofilaments in a cardiac muscle cell.

Sarcomeres

The basic contractile units of a muscle, composed of myofilaments.

Striated appearance

The striped pattern observed under a microscope due to the organization of myofilaments in sarcomeres.

Optimal length

The length at which the filaments in a cardiac muscle cell have maximum overlap, allowing for greater force of contraction.1. Sarcolemma:The cell membrane of cardiac muscle cells that is folded at connections between cells, increasing structural stability and facilitating communication between cells.

Intercalated discs

Structures that connect cardiac muscle cells, consisting of desmosomes that mechanically join cells with protein filaments and gap junctions that electrically join cells, allowing ion flow and making each heart chamber a functional unit.

Myocardium

The muscular tissue of the heart.

Mitochondria

Organelles within cardiac muscle cells that are responsible for producing energy through aerobic metabolism.

Myoglobin

A protein found in cardiac muscle cells that stores oxygen and helps facilitate aerobic cellular respiration.

Creatine kinase

An enzyme found in cardiac muscle cells that helps facilitate the conversion of creatine to phosphocreatine, providing a quick source of energy.

Ischemic

Referring to a condition where there is a reduced blood supply to a tissue or organ, leading to low oxygen levels.

Fibrous skeleton

A network of connective tissue in the heart that provides structural support and separates the atria from the ventricles, allowing them to contract separately.

Coronary arteries

Arteries that supply oxygenated blood to the heart muscle.

Coronary veins

Veins that drain deoxygenated blood away from the heart muscle.

Anastomoses

Connections between blood vessels that allow blood to flow by more than one route.

Angina pectoris

Chest pain caused by reduced blood flow to the heart muscle.

Myocardial infarction

A heart attack, which occurs when there is a sudden and complete blockage of a coronary artery, leading to tissue death in the heart muscle.

undefined

Conduction system

Specialized cardiac muscle cells that initiate and conduct electrical events to ensure proper timing of contractions.

Sinoatrial (SA) node

The pacemaker of the heart, located high in the posterior wall of the right atrium.

Atrioventricular (AV) node

Located in the floor of the right atrium, near the right AV valve.

Atrioventricular (AV) bundle (bundle of His)

Extends from the AV node through the interventricular septum and divides into left and right bundles.

Purkinje fibers

Extend from the left and right bundles at the heart's apex and course through the walls of the ventricles.

Cardiac center of medulla oblongata

Contains cardioacceleratory and cardioinhibitory centers, receives signals from baroreceptors and chemoreceptors in the cardiovascular system, and influences the rate and force of the heart's contractions.

Parasympathetic innervation

Decreases heart rate, starts at the medulla's cardioinhibitory center, and is relayed via vagus nerves (CN X).

Sympathetic innervation

Increases heart rate and force of contraction, starts at the medulla's cardioacceleratory center, and is relayed via neurons from T1-T5 segments of the spinal cord.

Nodal cell

Specialized cells in the SA node that spontaneously depolarize and generate action potentials, initiating the heartbeat.

Autorhythmicity

The ability of nodal cells to reach threshold and fire action potentials without stimulation.

Pacemaker potential

The ability of nodal cells to reach threshold without stimulation, contributing to the spontaneous firing of action potentials.

Vagal tone

Parasympathetic activity relayed by the vagus nerve that keeps the resting heart rate slower.1. Action potential:The electrical signal that travels through the cells of the heart, causing them to contract.

SA node

The sinoatrial node, located in the right atrium, is the natural pacemaker of the heart and initiates the action potential.

AV node

The atrioventricular node, located between the atria and ventricles, delays the action potential to allow the ventricles to fill with blood before contracting.

Gap junctions

Specialized connections between cells that allow the action potential to spread quickly and efficiently.

AV bundle

Also known as the bundle of His, it is a collection of specialized cells that conduct the action potential from the AV node to the bundle branches.

Purkinje fibers

Specialized cardiac muscle fibers that rapidly conduct the action potential to the ventricles, causing them to contract.

Fibrous skeleton

A network of connective tissue that insulates the AV node, acting as a bottleneck for the action potential.

Resting membrane potential (RMP)

The electrical charge across the cell membrane of nodal cells when they are at rest, which is approximately -90 mV.

Autorhythmicity

The ability of nodal cells to spontaneously depolarize and generate their own action potentials, making them the pacemakers of the heart.

Refractory period

The period of time after an action potential when the cardiac muscle cell cannot be stimulated again, preventing sustained (tetanic) contractions.

Plateau phase

A phase in the action potential of cardiac muscle cells where the membrane potential remains depolarized, allowing for sustained contraction.

ECG reading

An electrocardiogram reading that shows the electrical activity of the heart, including the P wave, QRS complex, and T wave.1. Electrocardiogram (ECG/EKG):A common diagnostic tool that uses skin electrodes to detect electrical signals of cardiac muscle cells.

P wave

Reflects electrical changes of atrial depolarization originating in the SA node.

QRS complex

Electrical changes associated with ventricular depolarization, with the atria also simultaneously repolarizing.

T wave

Electrical change associated with ventricular repolarization.

P-Q segment

Associated with atrial cells' plateau during atrial contraction.

S-T segment

Associated with ventricular plateau during ventricular contraction.

P-R interval

Time from beginning of P wave to beginning of QRS deflection, reflecting the time from atrial depolarization to beginning of ventricular depolarization.

Q-T interval

Time from beginning of QRS to the end of T wave, reflecting the time of ventricular action potentials. Its length depends upon heart rate and changes may result in tachyarrhythmia.

Heart blocks

Impaired conduction in the heart's electrical activity, which may result in symptoms like light-headedness, fainting, irregular heartbeat, and chest palpitations.

Premature ventricular contractions

Abnormal action potentials within the AV node or ventricles, resulting from stress, stimulants, or sleep deprivation. They are not detrimental unless they occur in large numbers.

Atrial fibrillation

Chaotic timing of atrial action potentials.

Ventricular fibrillation

Chaotic electrical activity in the ventricles, leading to uncoordinated contraction and pump failure. It can be treated with a paddle electrode defibrillator or automated external defibrillator (AED).

Cardiac cycle

All events in the heart from the start of one heartbeat to the start of the next, including both systole (contraction) and diastole (relaxation).

Ventricular activity

The most important driving force in the cardiac cycle, where ventricular contraction raises ventricular pressure, pushing the AV valves closed and the semilunar valves open.

AV valves

Valves that ensure forward flow of blood by preventing backflow.

Semilunar valves

Valves that open and close to allow blood to be ejected from the ventricles to the arteries and prevent backflow.

Stroke volume (SV)

The amount of blood ejected by the ventricle during ventricular ejection.

End systolic volume (ESV)

The amount of blood remaining in the ventricle after contraction finishes.

End-diastolic volume (EDV)

The volume of blood in the ventricle at the end of diastole, when it is filled to its maximum capacity.1. Isovolumetric relaxation:The phase of the cardiac cycle where the ventricles relax and start to expand, lowering pressure. Blood closes the semilunar valves by sliding back toward the ventricles, while the AV valves remain closed.

Atrial relaxation and ventricular filling

The phase of the cardiac cycle where all heart chambers are relaxed. Atrial blood pressure forces the AV valves open and blood flows into the ventricles, while the semilunar valves remain closed.

Cardiac output

The amount of blood pumped by a single ventricle in one minute. It is measured in liters per minute and is determined by heart rate and stroke volume.