Human Anatomy Exam IV (Blood, Heart, Vessels, Lymphatic System)

Comprehensive practice flashcards covering blood histology, vascular hemodynamics, lymphatic filtration, adaptive immunity, and cardiovascular physiology.

Reason blood is classified as a connective tissue

Blood contains all three classical connective tissue components: living cells, a liquid ground matrix (plasma), and dissolved protein fibers (such as fibrin).

Normal pH range of human blood

Blood is slightly alkaline with a normal pH range between $7.35$ and $7.45$.

Normal temperature of human blood

Human blood maintains an internal temperature of approximately $100.4^\circ\text{F}$ ($38^\circ\text{C}$).

Percentage of body weight accounted for by blood

Blood accounts for approximately $8\%$ of total human body weight.

Average adult human blood volume

Adult males average $5-6\,\text{L}$ and adult females average $4-5\,\text{L}$.

Hematocrit

The percentage of total blood volume composed of erythrocytes (red blood cells).

Buffy coat

The thin, whitish intermediate layer composed of leukocytes and platelets that forms between erythrocytes and plasma during blood centrifugation.

Percentage of total blood volume made up of plasma

Plasma constitutes approximately $55\%$ of total blood volume.

Primary functions of albumin

Constitutes $60\%$ of plasma proteins, generates osmotic pressure to regulate tissue water balance, and buffers blood pH.

Primary functions of alpha and beta globulins

Transport proteins synthesized by the liver that bind and carry lipids, metal ions, and fat-soluble vitamins through circulation.

Primary function of gamma globulins

Serve as circulating antibodies secreted by plasma cells during immune responses.

Primary function of fibrinogen

Soluble clotting protein that is enzymatically converted into insoluble fibrin strands during blood coagulation.

Quaternary structure of a hemoglobin molecule

Composed of the protein globin (two alpha and two beta polypeptide chains) bound to four iron-bearing heme groups.

Maximum oxygen-carrying capacity of one hemoglobin molecule

$4$ oxygen molecules, with one oxygen molecule binding to each iron atom in its four heme groups.

Cellular progression of erythropoiesis

Hemocytoblast (stem cell) develops into myeloid stem cell, proerythroblast, erythroblast, normoblast, reticulocyte, and mature erythrocyte.

Primary organ of erythropoietin (EPO) production

The kidneys produce the vast majority of erythropoietin, with minor production occurring in the liver.

Primary stimulus for erythropoietin (EPO) secretion

Tissue hypoxia (decreased oxygen availability to cells).

Metabolic fate of globin during erythrocyte recycling

Globin is degraded by macrophages into free amino acids that re-enter circulation for future protein synthesis.

Metabolic fate of non-iron heme during erythrocyte recycling

The non-iron remainder of heme is converted into bilirubin, secreted into bile by the liver, and excreted via feces.

Nuclear morphology of neutrophils

Possesses a multilobed nucleus with $3$ to $6$ connected lobes.

Primary immune role of neutrophils

Migrate to acute inflammation sites to phagocytize bacteria and fungi using defensins and hydrogen peroxide.

Physiological role of histamine in basophil granules

Acts as a potent vasodilator to increase capillary permeability and attracts circulating leukocytes to inflamed sites.

Physiological role of heparin in basophil granules

Functions as an anticoagulant that inhibits unwanted blood clotting.

Vascular spasm phase of hemostasis

Immediate contraction of vascular smooth muscle in damaged vessels to constrict the lumen and reduce blood loss.

Platelet plug formation phase of hemostasis

Adhesion and aggregation of platelets to exposed underlying collagen fibers, creating a temporary mechanical seal.

Coagulation phase of hemostasis

Multistep enzymatic cascade converting soluble plasma fibrinogen into an insoluble meshwork of fibrin threads.

Universal red blood cell donor blood type

Type O, because its red blood cells lack both A and B surface agglutinogens (antigens).

Universal red blood cell recipient blood type

Type AB, because its plasma produces neither anti-A nor anti-B agglutinins (antibodies).

Etiology of hemolytic disease of the newborn (erythroblastosis fetalis)

Maternal anti-Rh antibodies from an Rh-negative mother cross the placenta in a subsequent pregnancy to destroy Rh-positive fetal red blood cells.

Tunica interna (intima)

Innermost vascular layer composed of simple squamous endothelium that provides a smooth, low-friction surface for blood flow.

Tunica media

Middle vascular layer composed of smooth muscle and elastic fibers that mediates vasoconstriction and vasodilation.

Tunica externa (adventitia)

Outermost vascular tunic composed of collagen and elastic connective fibers that anchors vessels and houses vasa vasorum.

Vascular vessels known as resistance arteries

Arterioles, because alterations in their lumen diameter regulate local tissue perfusion and systemic resistance.

Carotid sinuses

Baroreceptors located in the internal carotid arteries that detect changes in systemic arterial blood pressure.

Carotid bodies

Chemoreceptors situated near the carotid bifurcation that monitor arterial blood gas concentrations and pH.

Aortic bodies

Receptors in the aortic arch that monitor blood pressure and systemic blood chemistry.

Continuous capillaries

Capillaries with an unbroken, continuous endothelial tube joined by tight junctions and supported by pericytes.

Fenestrated capillaries

Capillaries characterized by endothelial pores (fenestrations) that permit rapid filtration, common in the kidneys and endocrine glands.

Sinusoidal capillaries

Wide, highly permeable capillaries with large intercellular clefts found in the liver, spleen, and red bone marrow.

Venous valves function in venous return

Folds formed by the tunica interna that prevent backflow of blood under low pressure and against gravity.

Respiratory pump function in venous return

Pressure shifts in the thoracic and abdominal cavities during breathing that draw venous blood upward toward the heart.

Skeletal muscle pump function in venous return

Contractions of skeletal muscle that physically squeeze deep veins, propelling blood past one-way venous valves toward the heart.

Hepatic portal vein

Vascular vessel delivering nutrient-laden, deoxygenated blood from the digestive tract directly into hepatic sinusoids.

Kupffer cells

Hepatic macrophages lining liver sinusoids that engulf bacteria, foreign particulates, and cellular debris from portal blood.

Ascending aorta anatomical boundaries

Aortic segment extending superiorly from the left ventricle to the sternal angle.

Aortic arch anatomical boundaries

Curved portion of the aorta that both begins and terminates at the level of the sternal angle.

Descending (thoracic) aorta anatomical boundaries

Portion of the aorta traversing the posterior mediastinum alongside the spine from vertebral level $\text{T5}$ to $\text{T12}$.

Abdominal aorta anatomical boundaries

Aortic segment originating at the diaphragm ($\text{T12}$) and terminating at vertebral level $\text{L4}$ where it bifurcates into common iliac arteries.

Foramen ovale

Interatrial opening in the fetal heart that routes blood directly from the right atrium to the left atrium, bypassing the pulmonary circuit.

Ductus arteriosus

Fetal vascular conduit connecting the pulmonary trunk/artery directly to the aortic arch to bypass nonfunctioning lungs.

Arteriosclerosis

General degenerative loss of elasticity, stiffening, and thickening of arterial walls, frequently exacerbated by free radicals.

Atherosclerosis

Specific vascular disease characterized by lipid-rich plaque buildup within the tunica intima that calcifies and obstructs arterial blood flow.

Fluid recovery role of the lymphatic system

Reabsorbs excess interstitial fluid and filtered proteins from tissue spaces and returns them to the systemic venous circulation.

Lacteals

Specialized lymphatic capillaries within intestinal villi that absorb digested fats and lipid-soluble vitamins, transporting them as chyle.

Minivalve mechanism of lymphatic capillaries

Loose overlapping endothelial edges swing inward to admit interstitial fluid during high external pressure and seal shut when internal pressure rises.

Right lymphatic duct drainage region

Drains lymph exclusively from the right upper limb, right side of the thorax, and the right side of the head and neck.

Thoracic duct drainage region

Drains lymph from the entire lower body, left upper limb, and left side of the head and thorax into the left subclavian vein.

Cause of reduced lymph flow velocity in lymph nodes

Fewer efferent lymphatic vessels leave the hilus than afferent vessels enter the capsule, creating a filtration bottleneck for immune surveillance.

White pulp of the spleen

Splenic lymphoid tissue containing clusters of lymphocytes and macrophages organized around central arteries to execute immune surveillance.

Red pulp of the spleen

Splenic tissue composed of splenic cords and sinusoids filled with macrophages that dismantle worn-out erythrocytes and blood platelets.

Endocrine secretions of the thymus gland

Secretes thymosin and thymopoietin, peptide hormones that stimulate T lymphocyte maturation and immunocompetence.

Tonsillar crypts

Deep invaginations lined with epithelium that trap airborne and food-borne pathogens, presenting them to lymphoid follicles.

Antiviral mechanism of interferons

Proteins secreted by virus-infected cells that bind uninfected neighbor cells, inducing the synthesis of antiviral proteins that inhibit viral replication.

Active humoral immunity

Adaptive immunity acquired when host B cells encounter antigens, driving endogenously generated antibodies and long-lived memory cells.

Passive humoral immunity

Short-term adaptive immunity mediated by administering preformed exogenous antibodies, offering temporary defense without immunological memory.

Fibrous pericardium

Tough, dense connective tissue exterior bag that anchors the heart within the mediastinum and prevents acute overfilling.

Serous pericardium

Two-layered serous membrane composed of an outer parietal layer lining the fibrous pericardium and an inner visceral layer (epicardium) covering the heart.

Cardiac tamponade

Pathological condition where excessive fluid in the pericardial cavity compresses cardiac chambers and impairs ventricular filling and stroke volume.

Chordae tendineae and papillary muscles

Tendinous cords and muscular projections that anchor atrioventricular valve cusps, preventing eversion into the atria during ventricular contraction.

Pulmonary circulation circuit pathway

Right ventricle to pulmonary semilunar valve, pulmonary trunk/arteries, alveolar capillaries of lungs, pulmonary veins, and left atrium.

Anterior interventricular artery ('Widow Maker')

Branch of the left coronary artery supplying the interventricular septum and anterior ventricular walls whose sudden occlusion induces massive myocardial infarction.

Sinoatrial (SA) node

Crescent-shaped cluster of autorhythmic cells in the right atrial wall that generates spontaneous impulses to serve as the heart's primary pacemaker.

Physiological purpose of the atrioventricular (AV) node delay

Delays electrical impulse transmission for approximately $0.1\,\text{s}$ to allow atria to complete contraction before ventricles contract.

Atrioventricular (AV) bundle (Bundle of His)

Specialized muscle conduction pathway providing the sole electrical route linking atrial myocardium to ventricular myocardium.

Electrocardiogram (ECG) P wave

Deflection wave corresponding to atrial depolarization, immediately preceding atrial contraction.

Electrocardiogram (ECG) QRS complex

Ventricular depolarization wave representing ventricular electrical excitation immediately preceding ventricular contraction.

Electrocardiogram (ECG) T wave

Deflection wave representing ventricular repolarization, occurring during ventricular relaxation (diastole).

First heart sound ('Lubb')

Acoustic sound generated by turbulence following the closure of atrioventricular (tricuspid and bicuspid/mitral) valves during early ventricular systole.

Second heart sound ('Dubb')

Acoustic sound generated by turbulence following the closure of semilunar (aortic and pulmonary) valves at the onset of ventricular diastole.

Sympathetic stimulation of heart rate

Sympathetic cardiac nerves trigger norepinephrine and epinephrine release, accelerating sinoatrial (SA) node firing and elevating heart rate.

Parasympathetic stimulation of heart rate

Vagal nerve stimulation acts on the sinoatrial (SA) node to decrease firing frequency and reduce resting heart rate.

Tachycardia

An abnormally elevated resting heart rate exceeding $100\,\text{beats/min}$.

Bradycardia

An abnormally low resting heart rate falling below $60\,\text{beats/min}$.