The Cardiovascular System: Blood and The Heart (Seeley's Anatomy and Physiology)

A comprehensive set of practice flashcards covering the main concepts from Seeley's The Cardiovascular System: Blood and The Heart, including blood composition and function, hematopoiesis, formed elements, hemostasis, coagulation, blood groups, diagnostic testing, cardiac anatomy, coronary circulation, systemic circulation, and vascular structure and function.

What is the cardiovascular system?

The body's circulatory system (circulatory system) that moves blood through the heart, vessels, and blood; functions include transport, regulation, and protection.

What are the main components of the cardiovascular system?

The heart, blood vessels (arteries, veins, capillaries), and blood.

List the primary functions of the cardiovascular system.

1) Transport of gases, nutrients, hormones, and wastes; 2) Regulation of body temperature, pH, and fluid balance; 3) Protection via immune components and clotting.

What role does the heart play in the circulatory system?

The pump that propels blood through vessels to distribute it to all body tissues.

What are the three major components of blood composition?

Plasma (55% of blood volume) and formed elements (45%: RBCs, WBCs, platelets). Blood volume averages 4–6 L depending on sex and body size.

What is plasma, and what percentage of blood volume is it?

The liquid matrix of blood; about 55% of total blood volume, composed of 91% water and 9% other substances.

What are the major plasma proteins and their general functions?

Albumin (osmotic pressure and transport), Globulins (transport and immunity, includes antibodies), Fibrinogen (clot formation).

What is serum?

Plasma without clotting factors.

From what cells do all formed elements originate?

Hemocytoblasts (stem cells in red bone marrow).

What are the two intermediate stem cells in hematopoiesis and what do they give rise to?

Myeloid stem cells and lymphoid stem cells; myeloid gives rise to RBCs, platelets, and most WBCs, while lymphoid gives rise to lymphocytes.

What hormone drives erythropoiesis and where is it produced?

Erythropoietin (EPO), produced primarily by the kidneys.

What triggers the release of erythropoietin?

Hypoxia—low blood oxygen levels.

What are the normal RBC count ranges for males and females?

Males: 4.7–6.1 million RBCs/μL; Females: 4.2–5.4 million RBCs/μL.

What is the typical diameter and shape of an RBC?

7.5 μm in diameter; biconcave disc shape.

What is the main protein inside RBCs and what proportion of the cell volume does it occupy?

Hemoglobin; occupies about 1/3 of the cell volume.

How many hemoglobin molecules does an RBC typically carry?

About 280 million hemoglobin molecules per RBC.

How is oxygen carried by hemoglobin?

98.5% is bound to hemoglobin as oxyhemoglobin; 1.5% is dissolved in plasma.

How is carbon dioxide transported in the blood?

CO₂ is carried as 7% dissolved in plasma, 23% bound to hemoglobin, and 70% as bicarbonate (HCO₃⁻) in plasma.

What enzyme catalyzes the conversion of CO₂ and water to carbonic acid, which dissociates to bicarbonate?

Carbonic anhydrase.

Describe the lifespan of a typical RBC and its demographic differences.

About 120 days in males and about 110 days in females.

What is erythropoiesis and what is its typical duration for a single RBC?

The production of new red blood cells; about 4 days from stem cell to mature RBC.

Where does erythropoiesis occur after birth?

Primarily in red bone marrow (sites include ribs, sternum, vertebrae, pelvis, proximal femur, proximal humerus). Yellow marrow replaces red marrow elsewhere.

How is bilirubin processed and excreted after hemoglobin is broken down?

Iron is freed from heme; heme is converted to biliverdin, then bilirubin, which is transported to the liver, conjugated, secreted in bile, and eventually excreted in feces (stercobilin) and urine (urobilin).

What stimulates RBC production and what is the feedback mechanism?

EPO stimulates RBC production; high O₂ lowers EPO production (negative feedback).

What are the major formed elements of blood and their percentages?

RBCs ~45% of blood, WBCs and platelets make up the remaining formed elements.

What is the purpose of platelets in hemostasis?

Platelets form a temporary platelet plug and participate in clot formation and wound repair.

From what cells are platelets derived, and what regulates their production?

Megakaryocytes in the red bone marrow; regulated by thrombopoietin.

How long do platelets circulate, and where are they removed?

About 5–9 days; removed by spleen and liver.

What triggers vascular spasm in hemostasis?

Nervous system reflexes and chemical mediators such as endothelin and thromboxanes released by platelets.

What is a platelet plug and why is it important?

An accumulation of platelets that seals small vessel breaks; it serves as a precursor to a stable clot.

What is the cooperative relationship between platelets and coagulation factors in forming a clot?

Platelets form plug and release factors; coagulation factors (involving Ca²⁺ and phospholipids) stabilize the plug with a fibrin mesh.

What are the two main clotting pathways and where do they converge?

Extrinsic pathway (tissue factor/thromboplastin) and intrinsic pathway (exposed collagen) converge on the common pathway.

What initiates the extrinsic clotting pathway?

Tissue damage exposing tissue factor (thromboplastin, factor III) which, with Ca²⁺, activates factor VII.

What initiates the intrinsic clotting pathway?

Exposure of blood to collagen activates factor XII, leading to a cascade via factors XI and IX in concert with VIII and Ca²⁺.

What is prothrombinase and what does it do?

A complex of activated Xa and Va that converts prothrombin (II) to thrombin.

What is the role of thrombin in coagulation?

Thrombin converts fibrinogen to fibrin, forming the clot mesh; also activates other clotting factors.

What is factor XIII’s role in coagulation?

Fibrin-stabilizing factor; crosslinks fibrin to stabilize the clot.

Why is calcium important in coagulation pathways?

Calcium ions are required at multiple steps across intrinsic and extrinsic pathways.

What anticoagulants regulate clot formation and name a few examples?

Antithrombin, heparin, and prostacyclin regulate clotting; EDTA and sodium citrate are used to prevent clotting in stored blood by binding Ca²⁺.

What is fibrinolysis and which enzyme dissolves clots?

The dissolution of a clot; plasmin hydrolyzes fibrin to dissolve the clot. Plasmin is activated from plasminogen by t-PA, urokinase, streptokinase, and others.

What is agglutination in transfusion medicine?

Clumping of RBCs caused by antibodies binding to foreign antigens; can cause transfusion reactions.

What is the ABO blood group system based on?

Presence or absence of A and B antigens on RBCs; types A, B, AB, and O.

Which antibodies are present in Type A and Type B plasma?

Type A plasma has anti-B antibodies; Type B plasma has anti-A antibodies.

Who can donate universal blood type and why?

Type O is the universal donor because it lacks A and B antigens, though it contains anti-A and anti-B antibodies.

What is the Rh factor and how does it affect transfusion safety?

Rh factor is the presence (Rh+) or absence (Rh−) of the D antigen; anti-Rh antibodies develop upon exposure in Rh− individuals; important for pregnancy and transfusions.

What is a crossmatch test used for in transfusions?

A compatibility test that mixes donor red cells with recipient serum (and vice versa) to detect agglutination beyond ABO/Rh typing.

What does a complete blood count (CBC) measure?

RBC count, hemoglobin, hematocrit, WBC count, and differential WBC count.

What is leukopenia and leukocytosis?

Leukopenia: abnormally low WBC count; leukocytosis: abnormally high WBC count.

What is prothrombin time (PT) and INR used for?

PT measures time to clot; INR standardizes this across labs to monitor coagulation status and anticoagulant therapy.

What are the two major functions of the heart’s atrioventricular (AV) valves?

Prevent backflow from ventricles into atria; tricuspid (Right) and mitral (Left) valves.

What are the two semilunar valves and their locations?

Aortic semilunar valve (between left ventricle and aorta) and pulmonary semilunar valve (between right ventricle and pulmonary trunk).

What is the role of the papillary muscles and chordae tendineae?

Prevent valve inversion during ventricular contraction by pulling on the valve cusps via chordae tendineae.

What are the layers of the heart wall and their primary components?

Epicardium (visceral pericardium), Myocardium (cardiac muscle), Endocardium (thin, smooth lining of chambers and valves).

What are the three layers of the pericardium?

Fibrous pericardium (tough outer layer), Serous pericardium (parietal and visceral/epicardium), with the pericardial cavity containing serous fluid.

Where is the heart located in the thorax and what are its apex and base?

In the mediastinum; apex directed anteriorly and left, base directed posteriorly; base located behind the left sternum near the second intercostal space.

What are the three layers of blood vessel walls?

Tunica intima (endothelium and sublayers), tunica media (smooth muscle and elastic fibers), tunica adventitia (connective tissue).

Which arteries are elastic (conducting) arteries and give examples?

Largest arteries near the heart with thick elastic layers; examples: aorta and pulmonary arteries.

What are muscular (distributing) arteries and give examples?

Medium-sized arteries with thick tunica media; examples: radial and femoral arteries.

What are capillaries and their main types?

Small-diameter vessels enabling exchange; types: continuous, fenestrated, and sinusoidal capillaries.

What occurs in capillary exchange and what mechanisms are involved?

Diffusion of lipid-soluble substances (O₂, CO₂) and water-soluble substances (glucose); sometimes pinocytosis; capillary networks include arterioles, metarterioles, thoroughfare channels, and precapillary sphincters.

What is the hepatic portal system?

A special venous system that carries nutrient-rich blood from abdominal viscera to the liver for processing before entering general circulation via hepatic veins and the IVC.

What vessels form the hepatic portal vein?

Union of the superior mesenteric vein and the splenic vein; also receives gastric veins before entering the liver.

What is the primary purpose of the hepatic sinusoids?

Process nutrients and substances in blood brought by the hepatic portal vein and perform detoxification/modification.

Name the major veins returning blood to the right atrium from the heart itself and from the body.

Coronary sinus returns blood from the heart walls; superior and inferior vena cava return blood from the body to the right atrium.

Describe the major venous drainage of the head and neck.

External jugular (superficial) drains posterior head/neck into subclavian; internal jugular (deep) drains cranial cavity and face and drains into brachiocephalic veins.

What are the superficial veins of the upper limb and their drainage paths?

Cephalic (lateral; drains into axillary vein), Basilic (medial; becomes axillary), Median cubital (connects cephalic and basilic in the cubital fossa).

Which major veins drain the lower limb and return blood to the heart?

Deep veins (radial/ulnar, brachial, axillary, subclavian, internal and external iliac, femoral, popliteal, tibial) and superficial veins (great saphenous, small saphenous) with common iliac and IVC drainage.

What is the Circle of Willis and its significance?

A vascular ring formed by cerebral arteries that supplies the brain; protects against compromised blood flow by collateral circulation.

What are the major arteries arising from the aortic arch?

Brachiocephalic trunk (branches into right common carotid and right subclavian), left common carotid, and left subclavian arteries.

What are the three primary sections of the aorta and their general roles?

Ascending aorta (originates from left ventricle), aortic arch (gives off major branches), descending aorta (thoracic and abdominal portions supplying thorax and abdomen).

Name the major arteries of the upper limb and their progression from the subclavian artery.

Subclavian becomes axillary as it passes the first rib, then brachial in the arm; brachial divides into radial and ulnar arteries.

What are the palmar arches and their significance?

Superficial palmar arch (mainly from ulnar) and deep palmar arch (mainly from radial); they form the vascular network in the hand and give off digital arteries.

What are the major arteries of the thoracic and abdominal aorta viscerally and parietally?

Thoracic visceral branches supply thoracic organs; thoracic parietal branches include intercostals and superior phrenic arteries; abdominal visceral branches include celiac trunk, superior and inferior mesenteric arteries, and paired visceral arteries (renal, suprarenal, gonadal); parietal branches include inferior phrenic, lumbar, and median sacral arteries.

What are the major venous sinuses of the cranium?

Superior and inferior petrosal, cavernous sinus, transverse sinus, straight sinus, superior sagittal sinus, inferior sagittal sinus, sigmoid sinus, etc., forming the venous drainage network of the brain into the internal jugular veins.

What is the function of the coronary arteries and which branches supply the heart?

Supply oxygenated blood to the heart muscle; right coronary artery (RCA) and left coronary artery (LCA) with branches such as the right marginal artery, posterior interventricular (interventricular) artery, left anterior descending (anterior interventricular) artery, obtuse marginal arteries, and circumflex artery.

What is the function of the coronary veins and where do they drain?

Drain deoxygenated blood from the heart muscle into the coronary sinus, which empties into the right atrium.

Explain the concept of oxygen extraction in coronary circulation at rest vs during exercise.

At rest, coronary blood provides about 70% O₂ extraction; during exercise, cardiac muscle already extracts near maximum O₂, so increased blood flow is required to meet demand.

What is the pericardial cavity and its function?

A fluid-filled space between the visceral and parietal serous pericardium that reduces friction during heart movement.

Describe the layers of the heart wall from outer to inner.

Epicardium (visceral pericardium), Myocardium (muscle), Endocardium (inner lining and valve surfaces).

What are pectinate muscles and the crista terminalis?

Muscular ridges in the atrial walls; crista terminalis separates the pectinate muscles from smooth parts of the atrial wall.

What is the role of trabeculae carneae?

Muscular ridges in ventricular walls that help forceful ejection of blood.

What are the heart valves and their primary function?

Atrioventricular valves (tricuspid and mitral) prevent backflow into atria; semilunar valves (aortic and pulmonary) prevent backflow into ventricles.

What fetal heart structure allows blood to bypass the lungs and what closes after birth?

Foramen ovale allows right-to-left shunt; it closes after birth to separate the atria.

What is the order of blood flow on the right side of the heart from body to lungs?

Right atrium → right ventricle → pulmonary trunk → lungs (gas exchange) → left atrium.

What is the order of blood flow on the left side of the heart from lungs to body?

Left atrium → left ventricle → aorta → systemic circulation → back to right atrium.

What is the function of the visceral pericardium?

Also called the epicardium; part of the serous pericardium that covers the heart surface.

What is the function of the parietal pericardium?

Lines the fibrous pericardium; part of the serous pericardium.

What is the role of the mediastinum in heart location?

The heart sits in the mediastinum, the central compartment of the thoracic cavity.

What is the apex of the heart and where is it located?

The blunt, pointed end; located left of the midline, near the fifth intercostal space.

Name the major arteries that branch from the aortic arch.

Brachiocephalic trunk (→ right carotid and right subclavian), left common carotid, left subclavian.

What is the function of the azygos system?

drains the posterior thoracic wall and other thoracic structures; empties into the superior vena cava.

What is a venous sinus and where is it found?

A venous space not a true vein; found in the cranial cavity and heart (e.g., dural venous sinuses).

What is the role of the hepatic portal vein in metabolism?

Carries nutrient-rich blood from the GI tract to the liver for processing before entering systemic circulation.

What is the difference between arteries and veins in wall structure?

Arteries have thicker walls and more smooth muscle; veins have thinner walls, thinner tunica media, and valves to prevent backflow.

What are the calf arteries that supply the lower leg and foot?

Anterior and posterior tibial arteries; fibular (peroneal) artery; dorsalis pedis and plantar arteries.

What are arteriovenous anastomoses and their function?

Direct connections between arterioles and veins that bypass capillaries; regulate heat loss in extremities.

What is the purpose of the glomera in AV shunts?

Arteriovenous anastomoses in glomera regulate heat transfer by adjusting blood flow to skin.

What are the differences between continuous, fenestrated, and sinusoidal capillaries?

Continuous capillaries have no gaps; fenestrated capillaries have pores (fenestrae) for higher permeability; sinusoidal capillaries have large gaps and leaky walls for transfer of larger molecules and even cells.

What is the primary function of capillaries?

Facilitate exchange of gases, nutrients, and wastes between blood and tissues.

What is the essential role of the lymphatic system in relation to blood vessels?

Not explicitly in notes; however, blood vessels work with lymphatics to return interstitial fluid and immune cells; not required here.