Blood Anatomy and Physiology

A set of practice question-and-answer flashcards covering blood components, formed elements, leukocyte types, blood disorders, and ABO/Rh blood grouping.

What type of tissue is blood, and what are its main components?

Blood is a type of connective tissue consisting of a nonliving fluid matrix called plasma and living cells called formed elements (erythrocytes, leukocytes, and platelets).

What accounts for the variation in the color of blood?

Color varies with oxygen ($\text{O}_2$) content: high oxygen levels show a scarlet red color, whereas low oxygen levels show a dark red de-oxygenated color.

What three layers are obtained after centrifuging a tube of whole blood?

Erythrocytes at the bottom (about $45\%$ of whole blood), a thin whitish buffy coat of leukocytes and platelets in the middle (less than $1\%$), and plasma on top (about $55\%$).

What is hematocrit, and what are the normal reference ranges for males and females?

Hematocrit is the percentage of total blood volume composed of red blood cells. Normal values are $47\% \pm 5\%$ for males and $42\% \pm 5\%$ for females.

What are the major plasma proteins and their primary functions?

Albumin maintains osmotic balance; Fibrinogen is involved in the clotting of blood; Globulins function in defense (antibodies) and lipid transport.

Why are leukocytes the only formed elements considered complete cells?

Leukocytes are complete cells containing nuclei and organelles, whereas erythrocytes lack nuclei or organelles and platelets are cell fragments.

What are the normal cell counts per $\text{mm}^3$ (or $\mu\text{l}$) of blood for erythrocytes, leukocytes, and platelets?

Erythrocytes: $4-6\text{ million}$; Leukocytes: $4800-10,800$; Platelets: $150,000-400,000$.

What are the dimensions and structural characteristics of a human erythrocyte?

A biconcave, anucleate disc with an orange-pink color, a diameter of $7.5\,\mu\text{m}$ ($7-8\,\mu\text{m}$), and a thickness of $2.5\,\mu\text{m}$.

What is the structural composition of a hemoglobin molecule?

Hemoglobin consists of globin (two alpha polypeptide chains and two beta polypeptide chains) and four heme groups.

What molecular mutation causes sickle-cell anemia, and how does it alter red blood cell function?

A single amino acid mutation (valine substituted for glutamic acid at position $6$ in the $146$-amino-acid beta globin chain) produces Hemoglobin S, causing RBCs to become crescent-shaped under low $\text{O}_2$ levels, rupture easily, and block small vessels.

What mnemonic helps recall the relative abundance of leukocytes in blood from most to least abundant?

'Never let monkeys eat bananas' standing for Neutrophils ($50-70\%$), Lymphocytes ($25-45\%$), Monocytes ($3-8\%$), Eosinophils ($2-4\%$), and Basophils ($<1\%$).

How do leukocytes exit blood vessels and navigate through tissue spaces?

They exit capillaries via diapedesis and move through tissue spaces using amoeboid motion and positive chemotaxis.

What leukocyte is shown in this micrograph, and what are its identifying characteristics?

Neutrophil; characterized by a multilobed nucleus ($3-6$ lobes) and pale red and blue cytoplasmic granules. It functions to phagocytize pathogens or debris.

What leukocyte is depicted here, and what are its key features and functions?

Eosinophil; characterized by a bilobed nucleus and coarse red cytoplasmic granules. It kills parasitic worms and plays a complex role in allergy and asthma.

What type of white blood cell is shown here, and what does it release?

Basophil; characterized by a lobed nucleus and large purplish-black cytoplasmic granules. It releases histamine and contains the anticoagulant heparin.

Which cell type is pictured in this slide, and what does it become in tissues?

Monocyte; characterized by a U- or kidney-shaped nucleus and abundant gray-blue cytoplasm. In tissues, it develops into macrophages that phagocytize pathogens or debris.

What clinical features and cell abnormalities define Acute Lymphoblastic Leukemia (ALL)?

In ALL, too many immature lymphocytes continuously multiply and are overproduced by bone marrow, leading to fatigue, anemia, fever, and bone pain.

What RBC antigens and plasma antibodies are associated with each ABO blood group?

Group AB: A and B antigens, no plasma antibodies; Group B: B antigen, Anti-A antibody; Group A: A antigen, Anti-B antibody; Group O: no antigens, Anti-A and Anti-B antibodies.

What does an $\text{Rh}^+$ status mean, and under what conditions do anti-Rh antibodies form?

$\text{Rh}^+$ indicates the presence of the D antigen ($85\%$ of population). Anti-Rh antibodies are not formed spontaneously in $\text{Rh}^-$ individuals; they form after exposure to $\text{Rh}^+$ blood via transfusion or pregnancy with an $\text{Rh}^+$ fetus.

How do blood typing agglutination reactions indicate the ABO blood type of a sample?

Blood is mixed with anti-A and anti-B sera. Agglutination (clumping) occurs when the corresponding antigen is present on the RBCs: Type AB agglutinates with both, Type A with anti-A, Type B with anti-B, and Type O with neither.