Draft 2 Systems Physiology Exam 2

What are the three primary categories of functions performed by blood?

Transport, regulation, and protection.

Which substances are transported by blood to body tissues for energy and metabolism?

Oxygen (O2) and nutrients.

To which two major organs does blood transport metabolic waste products for elimination?

Lungs and kidneys.

How does blood contribute to body temperature regulation?

By absorbing and distributing heat throughout the body.

Which blood component initiates blood clot formation to prevent blood loss?

Platelets

Which two immune elements in blood protect the body against infection?

Antibodies and white blood cells (leukocytes).

In a standard centrifuged blood sample, what percentage of total volume is occupied by plasma?

Approximately 55%

In a centrifuged blood sample shown below: What components make up the narrow middle layer known as the 'buffy coat'?

White blood cells (leukocytes) and platelets.

What normal percentage of total blood volume is comprised of red blood cells (hematocrit)?

Approximately 45%

In hemodynamics, how is blood pressure defined and measured?

The force exerted by blood against vessel walls, measured in millimeters of mercury (mmHg).

In terms of pressure gradient, blood always flows from a region of _____ pressure to a region of _____ pressure.

higher; lower

How is blood flow (Q) defined and measured?

The volume of blood moved per unit time, measured in mL/min.

What is vascular resistance (R)?

A measure of the friction that impedes blood flow between two points at a given pressure difference.

What are the three main physical factors that determine vascular resistance?

1. Blood viscosity 2. Total blood vessel length 3. Blood vessel radius

Which two variables directly alter blood viscosity?

Water volume (plasma hydration) and the number of red blood cells (erythrocytes).

Why is blood vessel radius considered the most important determinant of physiological changes in vascular resistance?

Because vessel length remains constant and viscosity is relatively stable; dynamic changes in vessel radius (constriction and dilation) exert a dramatic effect on resistance.

How does vessel constriction affect vascular resistance and blood flow?

Vessel constriction decreases the radius, which increases resistance and decreases blood flow.

What protein inside erythrocytes binds oxygen and carbon dioxide reversibly?

Hemoglobin

What is the polypeptide chain composition of a standard adult hemoglobin molecule?

Four polypeptide chains: two alpha (α) chains and two beta (β) chains.

As shown in the hemoglobin model below: What chemical ion is located at the center of each heme group to bind oxygen?

Iron ion (Fe2+)

What stem cell gives rise to all formed elements in blood during hematopoiesis?

Hematopoietic stem cell (Hemocytoblast)

How long does the process of erythropoiesis take from stem cell to mature erythrocyte?

Approximately 15 days

What is the committed cell stage in the erythropoiesis developmental pathway?

Proerythroblast

What cellular event occurs during Phase 1 of erythroblast development?

Ribosome synthesis (occurring in basophilic erythroblasts).

What major physiological transition happens to an orthochromatic erythroblast before it enters the bloodstream?

Ejection of the nucleus to become a reticulocyte.

What is a reticulocyte?

An immature red blood cell that has ejected its nucleus but still contains residual ribosomal RNA.

What does a reticulocyte count lower than 0.5% indicate about bone marrow activity?

An abnormally low rate of erythropoiesis.

What does an elevated reticulocyte count greater than 2% indicate?

A high rate of erythropoiesis (active red blood cell production).

What anatomical location is typically used to withdraw red bone marrow for biopsy, as shown below?

Posterior iliac crest

What percentage of the body's total iron is contained within hemoglobin?

Approximately 65%

Where is non-hemoglobin iron stored in the human body?

Liver, spleen, and bone marrow.

Why must intracellular iron ions be stored bound to proteins like ferritin and hemosiderin?

Because free iron ions are toxic to cells.

What plasma transport protein binds to iron to carry it in the bloodstream?

Transferrin

Which dietary vitamin enhances intestinal absorption of iron?

Vitamin C

Why are Vitamin B12 and folic acid required for erythropoiesis?

They are necessary for DNA synthesis in rapidly dividing precursor red blood cells.

Which primary organ secretes erythropoietin (EPO) in response to low oxygen saturation?

The kidney

What are three major physiological causes of tissue hypoxia that trigger EPO production?

1. Decreased RBC count (hemorrhage or destruction) 2. Insufficient hemoglobin per RBC (e.g., iron deficiency) 3. Reduced O2 availability (high altitude or lung disease)

How does testosterone influence red blood cell production?

Testosterone enhances renal EPO production, resulting in higher baseline RBC counts in males.

Why is artificial EPO abuse dangerous for athletes?

It excessively increases hematocrit and blood viscosity, significantly raising the risk of blood clotting, stroke, and heart failure.

What is the average lifespan of a mature erythrocyte?

120 days

Which organ primarily engulfs and breaks down aging, fragile erythrocytes?

The spleen

What are the three main components separated during red blood cell degradation?

Heme, iron, and globin.

How is the protein component (globin) of hemoglobin processed during erythrocyte destruction?

It is metabolized into amino acids and released into circulation for reuse.

What pigment is heme degraded into before secretion by the liver into bile?

Bilirubin (yellow pigment)

In the intestines, bilirubin is degraded into urobilinogen. What compound gives feces its characteristic brown color?

Stercobilin

What derivative of urobilinogen provides the yellow pigment found in urine?

Urobilin

How is clinical anemia defined physiologically?

A condition characterized by abnormally low blood oxygen-carrying capacity that cannot support normal cellular metabolism.

What are four cardinal clinical symptoms of anemia?

1. Fatigue 2. Pallor (pale skin/membranes) 3. Dyspnea (difficulty breathing) 4. Chills

Case Study Clinical Recall: An elderly patient presents with fatigue, dyspnea after walking short distances, pale mucous membranes, and poor dietary intake following bereavement. What anemia condition is indicated?

Iron-deficiency anemia

What underlying pathology causes pernicious anemia?

Autoimmune destruction of the stomach mucosa, preventing the production of intrinsic factor necessary for Vitamin B12 absorption.

How is pernicious anemia standardly treated?

Intramuscular Vitamin B12 injections or nasal gel administration.

What is aplastic anemia, and why does it lead to clotting and immunity defects alongside anemia?

Aplastic anemia is red bone marrow failure (due to toxins or cancer) that destroys precursor stem cells, depressing ALL formed elements (RBCs, WBCs, and platelets).

What internal condition can lead to hemorrhagic anemia via chronic upper gastrointestinal bleeding?

Peptic ulcer disease

What is renal anemia?

Anemia caused by inadequate secretion of erythropoietin (EPO) due to kidney disease.

What defines hemolytic anemia?

Anemia caused by excessive premature lysis (destruction) of circulating erythrocytes (e.g., in sickle-cell disease).

What abdominal organ enlargement (splenomegaly) frequently accompanies severe hemolytic anemia?

Enlargement of the spleen due to hyperactive filtration and clearance of lysed/abnormal RBCs.

What is polycythemia?

An abnormal excess of red blood cells that severely increases blood viscosity.

What is polycythemia vera?

A bone marrow cancer that causes overproduction of RBCs, leading to hematocrit levels exceeding 80%.

What is the primary clinical treatment for polycythemia vera?

Therapeutic phlebotomy (periodic removal of blood volume).

What causes secondary polycythemia?

Chronic low tissue oxygen levels (e.g., high altitude exposure) stimulating increased EPO production.

What is the normal numerical range of leukocytes per microliter (µL) of blood?

4,800 to 10,800 leukocytes per µL

What is leukocytosis, and what does it typically signify?

A white blood cell count over 11,000/µL; it is a normal physiological response to infection.

Which white blood cells are classified as granulocytes?

Neutrophils, eosinophils, and basophils.

Which white blood cells are classified as agranulocytes?

Lymphocytes and monocytes.

What is the primary role of basophil-released histamine during inflammation?

It acts as a vasodilator and attracts leukocytes to inflamed tissue sites.

What are the specific cellular targets of T lymphocytes versus B lymphocytes?

T lymphocytes target virus-infected cells and tumor cells; B lymphocytes give rise to plasma cells that produce antibodies.

What hematological condition is characterized by bone marrow overcrowding with cancerous, nonfunctional WBCs (>150,000/µL)?

Leukemia

Why does leukemia frequently cause severe anemia and bleeding disorders?

Rapidly proliferating cancerous white cells flood red bone marrow, physically crowding out erythrocyte and platelet cell lines.

What is leukopenia?

An abnormally low white blood cell count.

How do glucocorticoids (such as cortisol) induce drug-related leukopenia?

Glucocorticoids act to depress the immune system and inhibit leukocyte production.

What is the operational distinction between a thrombus and an embolus?

A thrombus is a stationary blood clot; an embolus is a detached clot traveling through the circulation.

What are major clinical risk factors for thrombus and embolus formation?

Atherosclerosis, slowly flowing blood, and blood stasis due to immobility.

What platelet count diagnostic threshold defines thrombocytopenia?

A circulating platelet count below 50,000/µL

What characteristic physical skin sign (pictured below) results from spontaneous widespread micro-hemorrhages in thrombocytopenia?

Petechiae

How does liver disease impair blood clotting capabilities?

Impaired liver function reduces synthesis of procoagulants (clotting factors) and impairs bile production needed to absorb fat-soluble Vitamin K.

What electrical event triggers the recurring cardiac cycle of myocardial contractions and relaxations?

Depolarization

How is the cardiac cycle defined?

The complete sequence of blood flow through the heart during one single heartbeat.

What are the two major functional phases of the cardiac cycle?

Systole (contraction and blood ejection) and Diastole (relaxation and ventricular filling).

Which ventricular state occurs simultaneously with atrial systole?

Ventricular diastole

Which ventricular state occurs simultaneously with atrial diastole?

Ventricular systole

What percentage of blood enters the ventricles passively during early-to-mid ventricular filling?

80%

What physiological mechanism delivers the final 20% of blood into the ventricles during filling?

Atrial contraction (atrial systole / "atrial kick")

What is End-Diastolic Volume (EDV)?

The total volume of blood in a ventricle at the end of ventricular diastole, just prior to contraction.

What is the typical resting value for End-Diastolic Volume (EDV) in a healthy adult?

Approximately 120 mL

What is End-Systolic Volume (ESV)?

The amount of blood remaining in a ventricle at the conclusion of ventricular ejection/systole.

What is the typical resting value for End-Systolic Volume (ESV) in a healthy adult?

Approximately 50 mL

What is the formula for calculating Stroke Volume (SV)?

SV = EDV - ESV

Using typical resting values (EDV = 120 mL, ESV = 50 mL), what is the normal resting stroke volume per beat?

70 mL/beat

During the isovolumetric ventricular contraction phase, what are the states of the AV valves and semilunar valves?

Both AV valves and semilunar valves are closed.

During ventricular ejection, what are the states of the AV valves and semilunar valves?

AV valves are closed; semilunar valves are open.

During isovolumetric ventricular relaxation, what are the states of the AV valves and semilunar valves?

Both AV valves and semilunar valves are closed.

During passive ventricular filling, what are the states of the AV valves and semilunar valves?

AV valves are open; semilunar valves are closed.

Examine the image above. Which specific phase of systole occurs when blood actively flows out of the ventricles while AV valves remain closed?

Ventricular ejection

Which specific anatomical valves constitute the Atrioventricular (AV) valves?

Tricuspid valve (right side) and Bicuspid/Mitral valve (left side).

Which specific anatomical valves constitute the Semilunar (SL) valves?

Aortic valve and Pulmonary valve.

What mechanical action directly produces the primary heart sounds (S1 and S2)?

The closure of the heart valves.

Which specific valve closure produces the first heart sound (S1, "Lubb")?

Closure of the Atrioventricular (AV) valves at the onset of ventricular systole.

Which specific valve closure produces the second heart sound (S2, "Dupp")?

Closure of the Semilunar (SL) valves at the onset of ventricular diastole.

What phase of the cardiac cycle is represented by the pause between the "lub-dup" heart sounds?

Ventricular relaxation / Diastole

An abnormal S3 heart sound is clinically associated with what category of cardiac dysfunction?

A fluid volume problem / fluid overload (e.g., Congestive Heart Failure).