The Circulatory System and Internal Transport

Comprehensive vocabulary flashcards covering the components, structure, evolutionary morphology, and hemodynamics of the vertebrate and human cardiovascular and lymphatic systems.

Blood vascular system

The primary circulatory system that distributes nutrients, gases, and hormones to all parts of the body, collects metabolic wastes, and consists of a muscular pump (heart) and a continuum of blood vessels containing blood.

Lymph vascular system

A subdivision of the cardiovascular system consisting of blind-ended lymphatic capillaries, lymphatic vessels, and lymphoid organs that collects tissue fluid from body tissues and returns it to the blood vascular system.

Lymph

The fluid transported within the lymphatic system, which possesses a composition very similar to tissue fluid when found in smaller lymphatic vessels.

Spleen

The largest (biggest) lymphoid organ belonging to the lymph vascular system.

Gastrovascular cavity

A central cavity that serves both digestive and circulatory transport functions in small, thin multicellular organisms such as Hydra and sea anemones.

Closed circulatory system

A circulatory system where blood is confined to continuous channels or vessels and driven by the one-way pumping action of the heart equipped with one-way valves, characteristic of all vertebrates and earthworms.

Open circulatory system

A circulatory system in which true blood vessels are absent or incomplete, allowing the heart to pump hemolymph into large open spaces called sinuses where it directly bathes cells, tissues, and organs, found in most mollusks and all arthropods.

Plasma

The liquid matrix of blood, constituting approximately $55\%$ of total blood volume, composed of $91.5\%$ $H_2O$, $7\%$ proteins, and $1.5\%$ salts, nutrients, and metabolic wastes.

Erythrocytes (Red Blood Cells)

Anucleated formed elements of blood that act as specialized carriers for $O_2$,$CO_2$ , and metabolic wastes, containing the protein hemoglobin which imparts the red color to blood.

Leukocytes (White Blood Cells)

Nucleated cellular components of blood functioning as defenders (soldiers) against foreign invading microorganisms; they include phagocytes that engulf foreign substances, antibody-producing lymphocytes, and granulocytes (neutrophils, eosinophils, and basophils).

Thrombocytes (Platelets)

The smallest formed elements in circulating blood; anucleated cell fragments containing thromboplastin, an essential protein required for blood clotting.

Arteries

elastic, muscular, smooth lining, light colored that carry oxygenated blood away from the heart to peripheral tissue cells.

Conducting Artery

A large-diameter, highly elastic type of artery that receives high-pressure blood pumped directly from the ventricles of the heart.

Distributing Artery

A medium-sized, muscular artery that branches from conducting arteries to deliver blood to specific organs.

Arterioles

Small arterial vessels leading directly to capillary beds that constrict and dilate to regulate systemic blood pressure and blood distribution to tissues.

Veins

Dark-colored vessels with wide lumens and thicker walls that return non-oxygenated blood from tissues toward the heart, functioning as a primary blood reservoir containing $65\% - 70\%$ of total blood volume.

Venules

Small to medium-sized venous vessels homologous to arterioles that collect blood outflow from capillaries and funnel it into veins.

Capillaries

The smallest and most delicate blood vessels, composed of a single cell layer of endothelium, which connect arterial and venous systems (veins) and facilitate substance exchange via diffusion.

Tunica intima

The innermost layer of a blood vessel wall, composed of endothelium (simple squamous epithelium) supported by a basement membrane.

Tunica media

The intermediate layer of a blood vessel wall composed of circularly arranged smooth muscle cells interspersed with elastic and collagen fibers; it is substantially thicker in arteries than in veins.

Tunica adventitia (Tunica externa)

The outermost fibrous layer of a blood vessel consisting of elastic and collagen fibers that blends continuously with the surrounding connective tissue of the organ.

Pericardium

The protective, thin membranous sac that encloses the heart muscle.

Atria

The upper two chambers of the heart (Right Atrium and Left Atrium) that serve as receiving chambers for blood returning from the systemic and pulmonary circuits.

Ventricles

The lower two muscular chambers of the heart (Right Ventricle and Left Ventricle) that serve as pumping chambers to forcefully eject blood into the pulmonary artery and aorta.

Tricuspid valve

An atrioventricular valve located between the right atrium (RA) and right ventricle (RV) that prevents retrograde flow into the atrium during ventricular systole.

Bicuspid valve (Mitral valve)

An atrioventricular valve positioned between the left atrium (LA) and left ventricle (LV) that prevents backflow into the left atrium.

Pulmonary semilunar valve

A pocket-like valve located at the exit of the right ventricle guarding the orifice of the pulmonary artery.

Aortic semilunar valve

A semilunar valve located at the base of the aorta guarding the outflow tract of the left ventricle.

Superior vena cava (SVC)

Also called the anterior vena cava or precaval vein; a great vein that brings deoxygenated blood from the head to arms directly into the right atrium.

Inferior vena cava (IVC)

Also called the posterior vena cava or postcaval vein; the major vein returning deoxygenated blood from the lower parts of the body, and lower extremities to the right atrium.

Pulmonary artery

The blood vessel that carries deoxygenated blood ejected from the right ventricle into the lungs for re-oxygenation.

Pulmonary vein

The vascular vessel that transports oxygen-rich blood collected from the lungs directly into the left atrium of the heart.

Aorta

The largest artery of the human body, arising from the left ventricle to deliver oxygenated blood under high pressure to all systemic organs and body cells.

Systole

The contractile phase of the cardiac cycle during which ventricular contraction generates peak hydrostatic arterial pressure.

Diastole

The relaxation phase of the cardiac cycle during which the heart refills with blood and arterial pressure falls to its baseline minimum.

Blood Pressure (BP)

generation of fluid pressure due to ventricular contraction that forces blood thru pulmonary & systemic cir, quantified as systolic pressure over diastolic pressure with a normal resting value of $120\text{ mmHg} / 80\text{ mmHg}$.

Pulmonary circulation

transport of gases by blood to & from the lungs

Systemic circulation

blood is delivered into tissues & back to the heart

Hepatic portal circulation

circulates nutrient-rich blood through the liver

Renal circulation

blood is delivered into the kidney for adjustment & back to the heart

Coronary circulation

supplies the heart muscle with blood.

Single circulation

A circulatory plan seen in fish possessing a 2-chambered heart (one atrium and one ventricle) where blood flows through the heart only once during a complete circuit through gill and body capillaries.