Hematology Review Questions

• Blood functions and features encompass volume, percentage composition, pH, formed elements, and other cellular components.

Functions of Blood

• Transports oxygen, carbon dioxide, nutrients, waste products, and hormones.
• Regulates pH balance (7.35-7.45), temperature, and fluid balance.
• Provides protection against infections and facilitates clot formation to prevent bleeding.

Features of Blood

• Volume in males is 5-6 liters, and in females, it is 4-5 liters.
• Plasma constitutes 55% of blood, carrying nutrients, waste, and proteins.
• Formed elements make up 45% of blood; red blood cells (RBCs) transport oxygen, white blood cells (WBCs) aid in fighting infections, and platelets assist in blood clotting, with spectrin providing flexibility.
• Hematocrit levels are 42-47% for males and 37-42% for females.

Plasma Proteins

• Albumin helps maintain the correct amount of water in the blood.
• Globulin aids the immune system.
• Fibrinogen facilitates blood clotting.
• Electrolytes like sodium, potassium, and calcium are essential for muscle and nerve function.
• Nutrients, including glucose, fats, and vitamins, supply cells with energy and support growth.
• Waste products like urea are transported for kidney filtration.

Erythrocytes (RBCs) Life Cycle

• Erythropoiesis, or red blood cell production, takes place in the red bone marrow and is stimulated by erythropoietin.
• The stages of erythropoiesis are stem cells (hemocytoblasts) to proerythroblast to erythroblast, then reticulocyte (immature RBC) and finally mature erythrocyte, taking 1-2 days.
• Circulation and function involve RBCs transporting oxygen from the lungs to tissues and carbon dioxide from tissues to the lungs, with a lifespan of about 120 days.
• Destruction and recycling occur in the spleen and liver, where aged RBCs are removed.
• Hemoglobin is broken down; heme converts to bilirubin, iron is reused for new RBCs, and globin breaks down into amino acids.
• Anatomical structures involved include bone marrow for RBC production, kidneys for erythropoietin release, and the spleen and liver for breaking down old RBCs.

White Blood Cells (WBCs)

• Neutrophils are elevated in bacterial infections.
• Lymphocytes are elevated in viral infections.
• Monocytes are elevated in chronic infections and inflammations.
• Eosinophils are elevated in parasitic and allergic reactions.
• Basophils are elevated in allergic reactions and inflammations.

Factors Influencing Hematocrit

• Dehydration increases hematocrit, reducing plasma and concentrating RBCs.
• Overhydration (hyperhydration) lowers hematocrit by diluting RBCs with more plasma.
• Blood loss initially shows normal hematocrit, which decreases as fluid is replaced.
• Anemia lowers hematocrit due to fewer RBCs.
• High altitude increases hematocrit.
• Polycythemia increases hematocrit due to excessive RBC production.

Steps of Blood Clotting

• Step 1, Vascular Spasm: Blood vessel constriction reduces blood loss.
• Step 2, Platelet Plug Formation: Platelets adhere to damaged vessels and release chemicals to recruit more platelets.
• Step 3, Coagulation: A series of chemical reactions converts fibrinogen (soluble) into fibrin (insoluble), forming a clot.
• Platelet Deficiency (Thrombocytopenia) leads to impaired clot formation and excessive bleeding.
• Vitamin K Deficiency impairs the production of clotting factors, causing prolonged bleeding.
• Hemophilia involves missing clotting factors, resulting in uncontrolled bleeding and is a genetic disorder.
• Liver disease leads to reduced production of clotting factors, causing bleeding disorders.

Blood Disorders

• Clotting Disorders:
• Thrombosis: Formation of an abnormal blood clot in an unbroken vessel.
• Embolism: A clot that breaks loose and travels in the bloodstream.
• Bleeding Disorders:
• Hemophilia: Genetic disorder causing a lack of clotting factors that leads to uncontrolled bleeding.
• Thrombocytopenia: Low platelet count causing excessive bleeding.
• Liver Disease: Reduced clotting factor production, leading to increased bleeding.
• Disseminated Intravascular Coagulation (DIC): Causes widespread clotting followed by excessive bleeding due to clotting factor depletion.

Blood Type

• Blood groups are based on ABO and Rh antigens on RBCs and antibodies in plasma.
• Type A has A antigens on RBCs and anti-B antibodies in plasma.
• Type B has B antigens on RBCs and anti-A antibodies in plasma.
• Type AB has both A and B antigens and no antibodies (universal recipient).
• Type O has no antigens and both anti-A and anti-B antibodies (universal donor).

Rh Factor

• Rh-positive (Rh+) has Rh antigens on RBCs and no anti-Rh antibodies.
• Rh-negative (Rh-) has no Rh antigen but can develop anti-Rh antibodies if exposed to Rh+.
• If an Rh-negative mother carries an Rh-positive fetus, she may produce anti-Rh antibodies.

Blood Flow Through the Heart

• Deoxygenated Blood:
• Superior & Inferior Vena Cava -> Right Atrium -Right Atrium -> Tricuspid Valve -> Right Ventricle -Right Ventricle -> Pulmonary Semilunar Valve -> Pulmonary Arteries -Pulmonary Arteries -> Lungs (CO2 out, O2 in)
• Oxygenated Blood: -Lungs -> Pulmonary Veins -> Left Atrium -Left Atrium -> Bicuspid Valve -> Left Ventricle -Left Ventricle -> Aortic Semilunar Valve -> Aorta -> Body
• Pulmonary circuit; right side pumps deoxygenated blood to lungs
• Systemic circuit; the left side pumps oxygenated blood to the body

Heart Valves

• Valves ensure one-way flow
• Atrioventricular valves: Tricuspid and bicuspid valves
• Semilunar valves: Pulmonary and aortic valves

Heart Pressures

• AV valves open when atrial pressure is higher than ventricular pressure
• AV valves close when ventricles close (preventing backflow)
• Semilunar valves open when ventricular pressure is higher than artery pressure
• Semilunar valves close when ventricles relax (preventing backflow)

ECG (Electrocardiogram) Components

• P Wave: Atrial depolarization (atria contracting)
• QRS Complex: Ventricular depolarization (ventricles contracting)
• T Wave: Ventricular repolarization (ventricles relaxing)

ECG Condidtions

• Bradycardia: Slow heart rate (long R-R interval)
• Tachycardia: Fast heart rate (short R-R interval)
• Atrial Fibrillation: No clear P waves, irregular rhythm
• Ventricular Fibrillation: No organized QRS complex, life-threatening
• Heart Block: Delayed or blocked signal between atria & ventricle (long PR interval)
• Enlarged R waves: Bigger heart
• Elevated or depressed S-T segment: Cardiac ischemia, lack of blood flow
• Prolonged Q-T interval: Ventricles unable to repolarize

Cardiac Values

• EDV (end-diastolic volume): Max blood in the ventricle before contraction
• ESV (end-systolic volume): Blood left after contraction
• HR (heart rate): Beats per minute
• SV (stroke volume): mL per beat
• SBP (systolic blood pressure)
• DBP (diastolic blood pressure)

Cardiac Equations

• Stroke Volume (SV) = EDV - ESV
• Cardiac Output (CO) = HR x SV
• Ejection Fraction (EF) = SV/EDV x 100 (as a %)
• Mean Arterial Pressure (MAP) = ⅓ (SBP - DBP) + DBP

Nervous System Receptors in the Heart

• Neurotransmitter: Norepinephrine (NE)
• Receptor Types: -B1 (Beta-1): Increase HR & contractility -a1 (Alpha-1): Vasoconstriction
• Effects on Heart: -Increased HR (chronotropic effect) -Increase contractility (inotropic effect) -Increased conduction speed (dromotropic effect)
• Neurotransmitter: Acetylcholine (ACH)
• Receptor Type: Muscarinic (M2)
• Effects on Heart: -Decreased HR (via vagus nerve) -Decreased conduction speed

Heart Rate

• Sympathetic: Norepinephrine (NE) on B1, a1 increases HR & contractility
• Parasympathetic: Acetylcholine (ACh) on M2 decreases HR & conduction speed

Blood Vessel Layers

• Vessels have 3 layers of tunics (except capillaries):
• Tunica Intima: Inner most layer
• Tunica Media: Middle layer made of smooth muscle
• Tunica Externa: Outermost layer plus nerve fiber & lymphatic vessels
• Other Things in Vessels:
• Endothelium; simple squamous layer that lines lumen of all vessels
• Vasa Vasorum; system of micro-vessels found in larger blood vessels, nourish outermost layers w/ blood supply
• Lumen; central blood-containing space surrounded by a cell wall

Artery Information

• Thick walls and a smaller lumen which maintains high blood pressure
• Away From Heart
• Pulmonary circuit -> deoxygenated blood from heart to lungs
• Systemic circuit -> oxygenated blood from heart to tissues
• Muscular arteries adjust diameter through vasoconstriction/dialation

Arterioles Information

• Smaller branches of arteries
• Thick tunica media w/ high smooth muscle content
• Acts as resistance vessels, controlling flow to capillaries
• Primary site of vasodilation/constriction

Capillaries Information

• Small vessels help w/ direct contact with tissues
• Directly serves cellular needs
• Small epithelial layer w/ basal lamina surrounding cells
• Site of gas & nutrient exchange between blood and tissues
• BP drops significantly to allow for diffusion and prevent damage to vessels

Venules information

• Thin walls with some smooth muscle
• Collects deoxygenated blood from capillaries & begin return flow to heart
• Constrictions can happen to push blood forward

Veins Information

• Thin walls, less smooth muscle, but larger lumen
• Contains valves to prevent backflow
• Relies on skeletal muscle contraction and respiratory movements to aid blood return to heart
• Towards The Heart
• Systemic circuit -> deoxygenated blood to body
• Pulmonary circuit -> oxygenated blood to the heart
• Serves as a blood reservoir

Blood Pressure Information

• Volume of blood moving through vessel per unit time (mL/min)
• Directly proportional to pressure difference
• Increases with higher cardiac output & vasodilation
• Decreases with vasoconstriction & increased blood viscosity

Blood Flow Information

• The force exerted by blood on vessel walls (mmHg)
• Created by the heart's pumping action
• Highest in aorta (120mmHg) lowest in veins (5mmHg)
• Regulated by cardiac output, blood volume, vessel diameter

Resistance Information

• Opposition to blood flow, caused by friction between blood and vessel walls
• Smaller diameter of vessels means higher resistance
• Thicker blood means higher resistance
• Longer vessels means higher resistance
• If BP increases, BF increases, unless resistance increases
• If resistance increases, BF decreases, unless BP also increases
• Arterioles play a huge regulatory role
• Vasoconstriction/dilation

Responses of ↓ BP

• Baroreceptors:↑↑ HR, vasoconstriction
• Chemorecepetors: ↑BP to increase oxygen
• RAAS System: ↑ BP & volume
• ADH (vasopressin): ↑ water retention & vasoconstriction

Responses of ↑ BP

• Baroreceptors: ↓HR, vasodilation
• Chemoreceptors: Weak effect
• RAAS System: N/A
• ADH (vasopressin): N/A

Regulation Types & Effects on BP

• Short-Term (Neural & Hormonal)

• Baroreceptor - seconds to minutes

• Adjust HR, vasocontriction to stabalize

• Long-Term (Kidneys -Renal - Hours to Days

• Regulates Blood Volume to control overtime

Test your knowledge of hematology concepts with these questions. Topics covered include white blood cell types, plasma proteins, erythropoiesis, liver function, hematocrit regulation, hemostasis, carbon dioxide transport and thrombocytopenia.