Human Anatomy & Physiology II - Topic 2

Pericardial cavity

cavity surrounding the heart is filled with a lubricating serous fluid that reduces friction as the heart contracts

Cardiac notch

depression in the medial surface of the superior lobe of the left lung where the apex of the heart is located

Hypertrophic cardiomyopathy

pathological enlargement of the heart, generally for no known reason

Atrium

upper or receiving chamber of the heart that pumps blood into the lower chambers just prior to their contraction

Right atrium

receives blood from the systemic circuit that flows into the right ventricle

Left atrium

receives blood from the pulmonary circuit that flows into the left ventricle

Ventricle

one of the primary pumping chambers of the heart located in the lower portion of the heart

Left ventricle

the major pumping chamber on the lower left side of the heart that ejects blood into the systemic circuit via the aorta and receives blood from the left atrium

Right ventricle

the major pumping chamber on the lower right side of the heart that ejects blood into the pulmonary circuit via the pulmonary trunk and receives blood from the right atrium

Pulmonary circuit

blood flows to and from the lungs

Systemic circuit

blood flow to and from virtually all of the tissues of the body

Thoracic Cavity

the space within the chest that houses the heart, lungs, and other vital organs

Sternum

the breastbone, a flat bone located in the center of the chest, to which the ribs are attached

Pericardial sac

membrane that separates the heart from other mediastinal structures (Pericardium)

Epicardium

innermost layer of the serous pericardium and the outermost layer of the heart wall

Myocardium

thickest layer of the heart is composed of cardiac muscle cells built upon a framework of primarily collagenous fibers and blood vessels that supply it and the nervous fibers that help to regulate it

Endocardium

the innermost layer of the heart's lining, consisting of endothelial cells that provide a smooth surface for blood flow

Auricle

extension of an atrium visible on the superior surface of the heart

Sulcus

fat-filled groove visible on the surface of the heart; coronary vessels are also located in these areas

Coronary sulcus

sulcus that marks the boundary between the atria and ventricles

Anterior interventricular sulcus

sulcus located between the left and right ventricles on the anterior surface of the heart

Posterior interventricular sulcus

sulcus located between the left and right ventricles on the posterior surface of the heart

Squamous Epithelium

a type of tissue consisting of flat, scale-like cells found in various body structures

Serous Fluid

a thin, watery fluid that lubricates the layers of serous membranes, reducing friction between organs

Septum

walls or partitions that divide the heart into chambers

Interatrial septum

cardiac septum located between the two atria; contains the fossa ovalis after birth

Foramen ovale

opening in the fetal heart that allows blood to flow directly from the right atrium to the left atrium, bypassing the fetal pulmonary circuit

Interventricular septum

cardiac septum located between the two ventricles

Atrioventricular septum

cardiac septum located between the atria and ventricles; atrioventricular valves are located here

Atrioventricular valves

one-way valves are located between the atria and ventricles

Tricuspid valve

valve located between the right atrium and ventricle; consists of three flaps of tissue

Bicuspid valve

valve located between the left atrium and ventricle; consists of two flaps of tissue

Semilunar valves

valves located at the base of the pulmonary trunk and at the base of the aorta

Cardiac skeleton

reinforced connective tissue located within the atrioventricular septum; includes four rings that surround the openings between the atria and ventricles, and the openings to the pulmonary trunk and aorta; the point of attachment for the heart valves

Pulmonary capillaries

capillaries surrounding the alveoli of the lungs where gas exchange occurs: carbon dioxide exits the blood and oxygen enters

Aorta

the largest artery in the human body, originating from the left ventricle of the heart and distributing oxygenated blood to the systemic circulation

Chordae tendineae

string-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles

Pulmonary valve

valve at the base of the pulmonary trunk that prevents backflow of blood into the right ventricle; consists of three flaps

Aortic valve

valve located at the base of the aorta

Transverse Section

a horizontal cut across a structure, revealing its cross-sectional anatomy and organization

Epicardial coronary arteries

surface arteries of the heart that generally follow the sulci

Anastomosis

area where vessels unite to allow blood to circulate even if there may be a partial blockage in another branch

Marginal arteries

branches of the right coronary artery that supply blood to the superficial portions of the right ventricle

Great cardiac vein

vessel that follows the interventricular sulcus on the anterior surface of the heart and flows along the coronary sulcus into the coronary sinus on the posterior surface

Posterior cardiac vein

vessel that parallels and drains the areas supplied by the marginal artery branch of the circumflex artery; drains into the great cardiac vein

Middle cardiac vein

vessel that parallels and drains the areas supplied by the posterior interventricular artery; drains into the great cardiac vein

Small cardiac vein

parallels the right coronary artery and drains blood from the posterior surfaces of the right atrium and ventricle; drains into the coronary sinus, middle cardiac vein, or right atrium

Anterior cardiac veins

vessels that parallel the small cardiac arteries and drain the anterior surface of the right ventricle; bypass the coronary sinus and drain directly into the right atrium

Interventricular Septum

the muscular wall that separates the left and right ventricles of the heart

Coronary Sulcus

the groove on the heart's surface that separates the atria from the ventricles and encircles the heart, housing coronary vessels

Cardiac cycle

period of time between the onset of atrial contraction (atrial systole) and ventricular relaxation (ventricular diastole)

Systole

period of time when the heart muscle is contracting

Diastole

period of time when the heart muscle is relaxed and the chambers fill with blood

Phases of the Cardiac Cycle

Ventricular Systole

Phase 1: Isovolumic Contraction

Phase 2: Ventricular Ejection

Ventricular Diastole

Phase 1: Isovolumic Ventricular Relaxation

Phase 2: Late Ventricular Diastole

Action Potential

a brief electrical impulse or change in voltage across a cell membrane that propagates nerve or muscle cell signaling

Depolarization

the change in electrical charge across a cell membrane, making it less negative and more positive, often associated with cell excitation

Mitral Valves

heart valves that separate the left atrium from the left ventricle and prevent the backflow of blood

Isovolumic contraction

initial phase of ventricular contraction in which tension and pressure in the ventricle increase, but no blood is pumped or ejected from the heart

S1 (Lub)

sound created by the closing of the atrioventricular valves during ventricular contraction; first heart sound

S2 (Dub)

sound of the closing of the semilunar valves during ventricular diastole; second heart sound

S3

rarely heard in healthy individuals; third heart sound "Kentucky gallop"

S4

results from the contraction of the atria pushing blood into a stiff or hypertrophic ventricle, indicating failure of the left ventricle; fourth heart sound "Tennessee gallop"

Murmur

used to describe an unusual sound coming from the heart caused by the turbulent flow of blood

Chordae Tendineae

string-like extensions of tough connective tissue that extend from the flaps of the atrioventricular valves to the papillary muscles

Semilunar Valves

valves located at the base of the pulmonary trunk and at the base of the aorta

Atrioventricular Septum

the cardiac structure that separates the atria from the ventricles, preventing direct communication between these chambers

Autorhythmicity

ability of cardiac muscle to initiate its own electrical impulse that triggers the mechanical contraction that pumps blood at a fixed pace without nervous or endocrine control

Cardiac output (CO)

amount of blood pumped by each ventricle during one minute; equals HR multiplied by SV

Echocardiogram

a medical imaging technique that uses ultrasound to create images of the heart's structure and function

Catheter

a thin, flexible tube used in various medical procedures to introduce fluids, access vessels, or measure pressure

Stroke volume (SV)

amount of blood pumped by each ventricle per contraction; also, the difference between EDV and ESV

Cardiac plexus

paired complex network of nerve fibers near the base of the heart that receive sympathetic and parasympathetic stimulations to regulate HR

Proprioceptors Reflex

signal the need for higher blood flow, prompting the cardiac centers to reduce parasympathetic stimulation and increase sympathetic stimulation

Baroreceptor reflex

autonomic reflex in which the cardiac centers monitor signals from the baroreceptor stretch receptors and regulate heart function based on blood flow

Atrial reflex

autonomic reflex that responds to stretch receptors in the atria that send impulses to the cardioaccelerator area to increase HR when venous flow into the atria increases

Chemoreceptors

provide feedback to the cardiovascular centers, influencing the blood flow based on the levels of these substances

Emotional Impact on HR

stressful situations often lead to increased heart rates, sometimes accompanied by elevated cortisol levels; extreme anxiety can mimic heart attack symptoms but is usually temporary and treatable

Glossopharyngeal

cranial nerve; detect metabolic byproducts like carbon dioxide, hydrogen ions, lactic acid, and declining oxygen levels

Medulla Oblongata

the part of the brainstem responsible for vital functions like breathing, heart rate, and blood pressure regulation

Hypertension

a medical term for high blood pressure, a condition where the force of blood against artery walls is consistently too high

Cardioaccelerator nerves

release of norepinephrine by cardioaccelerator nerves

Limbic system

anticipation of physical exercise or strong emotions by the limbic system

Catecholamines

decreased epinephrine and norepinephrine release by the adrenal glands

Factors Decreasing Heart Rate

Electrolytes, pH Levels, Body Temperature

Hyponatremia

lower-than-normal levels of sodium in the blood

Hypernatremia

abnormal increase in blood sodium levels

Hypokalemia

abnormally decreased blood levels of potassium

Hyperkalemia

higher-than-normal blood potassium levels

Acidosis

a condition in which excess hydrogen ions are present, and the patient's blood expresses a low pH value

Alkalosis

a condition in which there are too few hydrogen ions, and the patient's blood has an elevated pH

Cardiovascular Center

a medullary control center within the brain that regulates heart rate, stroke volume, and vascular resistance

Adrenal Medulla

the inner portion of the adrenal gland that is responsible for secreting epinephrine (adrenaline) and norepinephrine during the fight-or-flight response

Genome

the complete set of an organism's genes or genetic material, including all of its DNA sequences

Arrhythmias

abnormal heart rhythms, which can cause the heart to beat too fast (tachycardia), too slowly (bradycardia), or irregularly

Preload

amount of blood in the ventricles at the end of atrial systole just prior to ventricular contraction

Afterload

force the ventricles must develop to effectively pump blood against the resistance in the vessels

End diastolic volume (EDV)

the amount of blood in the ventricles at the end of atrial systole just prior to ventricular contraction

Frank-Starling mechanism

relationship between ventricular stretch and contraction in which the force of heart contraction is directly proportional to the initial length of the muscle fiber

Contractility

the strength of the heart's contraction is a key determinant of stroke volume (SV) and end-systolic volume (ESV)

Positive inotropic factors

factors that positively impact or increase heart contractility