Andrew Chapter 15: Circulation of Blood

Comprehensive practice vocabulary flashcards covering the circulation of blood, including vessel structure, systemic, pulmonary, hepatic portal, and fetal circuits, hemodynamics, blood pressure regulation, pulse points, hypertension stages, and circulatory shock.

Arteries

Large distribution blood vessels that carry oxygen-rich blood under high pressure away from the heart and toward capillaries, with the aorta being the largest in the body.

Arterioles

Microscopic arterial branches that receive blood from larger arteries and control the flow of blood into capillary beds by constricting or dilating.

Capillaries

Microscopic exchange vessels whose walls consist solely of a single layer of flat endothelial cells, permitting the exchange of gases, nutrients, and cellular wastes between blood and interstitial fluid.

Venules

Small vessels that collect blood exiting capillary beds and unite to form progressively larger veins.

Veins

Low-pressure vessels that carry blood back toward the heart from capillaries and act as expandable blood reservoirs.

Lumen

The hollow interior space bounded by a vessel wall through which blood flows.

Tunica Externa (Tunica Adventitia)

The outermost layer of a blood vessel wall, composed of connective tissue fibers that reinforce the vessel to resist stretching and prevent bursting under pressure.

Tunica Media

The middle layer of a blood vessel wall, composed of smooth muscle and elastic connective tissue; it is thicker in arteries to withstand systolic blood pressure and regulates vessel diameter under autonomic nervous control.

Tunica Intima

The innermost lining of arteries and veins made of a single layer of endothelial cells; it is the sole structural layer present in capillaries and forms one-way valves in veins.

Precapillary Sphincters

Smooth muscle fibers encircling the origin of a capillary from an arteriole that contract or relax to regulate blood flow into the capillary bed.

Venous Valves

Flaplike, one-way extensions of the tunica intima inside veins that prevent the backflow of blood, keeping it moving toward the heart.

Respiratory Pump

A mechanism that promotes venous return through alternating pressure changes in the thoracic and abdominal cavities during breathing.

Capillary Exchange

The dynamic movement of fluids and solutes between blood and tissue spaces driven by hydrostatic pressure (filtration) pushing fluid out at the arterial end and osmotic pressure pulling fluid in at the venous end, returning approximately $90\%$ of fluid to the capillary and $10\%$ to the lymphatic system.

Arteriosclerosis

A vascular disease characterized by the initial thickening and eventual calcification (hardening) of arterial walls, impairing blood flow and weakening vessel structures.

Ischemia

A condition of reduced or inadequate blood supply to a tissue, which can deprive cells of oxygen and lead to necrosis.

Gangrene

Tissue decay that develops following severe tissue necrosis caused by extensive loss of blood flow.

Atherosclerosis

A common form of arteriosclerosis characterized by the buildup of fatty deposits (such as cholesterol and triglycerides) along with fibrous material to form plaques that narrow the arterial lumen.

Vasodilators

Pharmacological agents that induce relaxation of smooth muscle in arterial walls, causing lumen widening (dilation) to decrease blood pressure.

Balloon Angioplasty

A mechanical procedure in which a catheter with a deflatable balloon is passed into an occluded artery and inflated to compress plaque and restore luminal diameter.

Stents

Permanent metal mesh tubes or coils inserted into opened arteries to maintain vessel patency and prevent reocclusion.

Aneurysm

An abnormal saclike widening or ballooning of an arterial section resulting from a weakened vessel wall that carries risks of thrombus formation or catastrophic rupture.

Cerebrovascular Accident (CVA)

A medical term for a stroke, resulting from brain tissue ischemia caused by either an embolus blocking a cerebral vessel or a ruptured intracranial aneurysm.

Varicose Veins (Varices)

Swollen, dilated superficial veins—commonly occurring in the legs—caused by weakened vessel walls and incompetent (leaky) valves that permit venous blood pooling.

Hemorrhoids (Piles)

Varicosities located in the rectum or anus, typically triggered by increased venous pressure from excessive straining during defecation or from pregnancy.

Phlebitis

Inflammation of a vein, often precipitated by local mechanical trauma such as intravenous catheterization.

Thrombophlebitis

Acute vein inflammation that is accompanied by blood clot (thrombus) formation, producing localized pain and tissue discoloration.

Pulmonary Embolism

A potentially fatal complication occurring when a venous thrombus detaches, travels through the circulation as an embolus, and lodges in the pulmonary vascular bed.

Systemic Circulation

The pathway of blood flow carrying oxygenated blood from the left ventricle through the aorta and systemic vessels to body tissues and returning deoxygenated blood through the venae cavae to the right atrium.

Pulmonary Circulation

The vascular route that conveys deoxygenated blood from the right ventricle via the pulmonary trunk and arteries to lung alveoli for oxygenation, returning oxygenated blood through pulmonary veins to the left atrium.

Hepatic Portal Circulation

A specialized circulatory detour where venous blood from abdominal digestive organs and the spleen is routed via the hepatic portal vein to liver capillary beds for glucose management and detoxification before reaching the inferior vena cava.

Placenta

The temporary vascular organ facilitating exchange of oxygen, nutrients, and metabolic wastes between the maternal blood and the fetal circulation.

Umbilical Vein

The single, large vessel within the umbilical cord that carries oxygenated, nutrient-rich blood from the placenta to the fetus.

Umbilical Arteries

The two small vessels arising from the internal iliac arteries that transport oxygen-poor blood and metabolic wastes from the fetus back to the placenta.

Ductus Venosus

A fetal vascular shunt that continues from the umbilical vein, allowing most umbilical blood to bypass the immature liver and drain directly into the inferior vena cava.

Foramen Ovale

An interatrial opening present before birth that shunts blood directly from the right atrium to the left atrium, bypassing the unexpanded fetal lungs.

Ductus Arteriosus

A fetal vascular shunt that connects the pulmonary artery directly to the aortic arch, diverting blood away from the nonfunctional pulmonary circuit.

Cyanosis

A bluish tint observable in lightly pigmented skin, caused by elevated levels of dark, oxygen-depleted hemoglobin in systemic circulation.

Hemodynamics

The study and collection of mechanical and physiological forces that govern blood flow through the cardiovascular system.

Blood Pressure Gradient

The difference in pressure between two points in the circulatory loop (such as $100\text{ mm Hg}$ in the aorta down to $0\text{ mm Hg}$ in the venae cavae) that provides the physical driving force for blood flow.

Diuretics

Therapeutic medications that promote urinary fluid excretion, lowering circulating blood volume and reducing arterial blood pressure.

Stroke Volume (SV)

The specific volume of blood ejected by a ventricle during a single contraction (approximately $70\text{ mL}$ at rest), directly influencing cardiac output and arterial blood pressure.

Cardiac Output (CO)

The volume of blood pumped into the arterial system each minute, equal to the product of stroke volume and heart rate ($\text{CO} = \text{SV} \times \text{HR}$).

Blood Viscosity

The physical thickness of blood determined primarily by erythrocyte concentration; elevated viscosity increases vascular resistance and elevates arterial pressure.

Polycythemia

An abnormal hematological state characterized by an elevated red blood cell count, which raises blood viscosity and increases blood pressure.

Peripheral Resistance (PR)

The frictional force resisting blood movement within blood vessels, determined largely by blood viscosity and the caliber of arterioles.

Vasomotor Mechanism

The physiological regulation of arteriole diameter by smooth muscle contraction or relaxation, causing dramatic shifts in peripheral resistance and blood flow.

Central Venous Pressure

The venous blood pressure measured where the venae cavae empty into the right atrium, representing the lower boundary of the systemic pressure gradient.

Pulse

The rhythmic wave of alternate expansion and recoil palpated along an elastic arterial wall generated by ventricular systole and diastole.

Pulse Points

Specific superficial anatomical sites where an artery crosses over a bony foundation, allowing pulse assessment and point pressure application to slow hemorrhage.

Radial Artery Pulse

The most frequently monitored and easily accessible pulse point in the body, located at the wrist on the radial side.

Sphygmomanometer

A clinical device comprising an inflatable limb cuff and a pressure manometer used to quantify systolic and diastolic blood pressure.

Korotkoff Sounds

Vascular tapping sounds heard through a stethoscope during cuff deflation that delineate systolic pressure (first sound heard) and diastolic pressure (point of disappearance).

Hypertension (HTN)

A clinical condition where arterial pressure chronically exceeds $140/90\text{ mm Hg}$, creating mechanical strain on blood vessel walls and myocardium.

Primary (Essential) Hypertension

Idiopathic elevated blood pressure lacking an identifiable underlying pathological cause, accounting for roughly $90\%$ of all clinical hypertension cases.

Secondary Hypertension

Elevated blood pressure resulting from a specific, diagnosable medical cause such as renal parenchymal disease, endocrine disorder, pregnancy, or medication use.

Circulatory Shock

A systemic failure of the circulatory apparatus to deliver adequate oxygen and nutrients to tissues, impairing cellular homeostasis throughout the body.

Cardiogenic Shock

Circulatory shock caused by primary myocardial pump failure, such as massive myocardial infarction or severe cardiac infections.

Hypovolemic Shock

Circulatory failure resulting from substantial loss of blood volume (hemorrhage) or fluid volume (severe dehydration, extensive burns, vomiting, or diarrhea).

Neurogenic Shock

Circulatory shock resulting from massive systemic vasodilation due to disrupted sympathetic vasomotor tone, commonly triggered by spinal cord or medulla damage.

Anaphylactic Shock

An acute, systemic allergic collapse marked by widespread vascular dilation and precipitous blood pressure reduction.

Septic Shock

Severe shock resulting from septicemia, wherein infectious micro-organisms and their toxins prompt extensive systemic vasodilation combined with high cellular metabolic demand.

William Harvey

The English physician ($1578\text{--}1657$) who first deduced and demonstrated through logical experiments that blood circulates along a continuous, closed circular route powered by the heart.

Raynaud Phenomenon

A clinical syndrome characterized by sudden paroxysmal ischemia of the digits in response to cold exposure or stress, presenting with digital blanching, cyanosis, and pain upon reperfusion.