Anatomy and Physiology Chapter 10: Blood Reviewer

Flashcards testing knowledge on blood composition, plasma, formed elements, hematopoiesis, hemostasis, blood groups, and fetal blood development from Chapter 10.

What are the physical characteristics of blood regarding pH, temperature, and total volume in adults?

Blood is slightly alkaline with a pH of 7.35–7.45, has a temperature of 38°C (100.4°F), and accounts for a volume of 5–6 L (about 6 quarts) in a healthy adult.

What percentage of whole blood is made up of plasma, formed elements, and the buffy coat?

Plasma makes up approximately 55%, formed elements make up about 45% (measured as hematocrit), and the buffy coat makes up less than 1% of whole blood.

Why does a decrease in plasma proteins lead to a reduction in plasma volume?

Lower plasma protein concentration reduces blood osmotic pressure, which prevents fluid from being retained or drawn back into circulation.

How many hemoglobin molecules are present in a single erythrocyte, and how many oxygen molecules can each hemoglobin bind?

One RBC contains about 250 million hemoglobin molecules, and each hemoglobin molecule can bind 4 oxygen molecules.

Why do mature erythrocytes generate ATP anaerobically without consuming the oxygen they carry?

Mature RBCs are anucleate and lack mitochondria, so they produce ATP through anaerobic mechanisms and do not consume the oxygen they transport.

What is the specific cause of pernicious anemia?

Pernicious anemia is caused by a Vitamin B12 deficiency, typically resulting from a lack of intrinsic factor needed for B12 absorption.

What genetic molecular alteration leads to sickle cell anemia?

Sickle cell anemia is caused by a change in a single amino acid in two of hemoglobin's four polypeptide chains.

What is polycythemia and what is its main primary danger?

Polycythemia is an excessive or abnormal increase in RBC count, which dangerously increases blood viscosity and causes sluggish flow and impaired circulation.

How do diapedesis, positive chemotaxis, and amoeboid motion assist leukocyte function?

Diapedesis allows WBCs to slip into and out of blood vessels; positive chemotaxis guides them toward damaged or infected tissue chemicals; amoeboid motion allows them to move through tissues using cytoplasmic extensions.

What mnemonic represents the relative abundance of the five white blood cell types from most to least abundant?

Never Let Monkeys Eat Bananas (Neutrophils [40–70%], Lymphocytes [20–45%], Monocytes [4–8%], Eosinophils [1–4%], Basophils [0–1%]).

Which white blood cell type is the most abundant and serves as an active phagocyte during acute bacterial or fungal infections?

Neutrophils (3,000–7,000 per mm³; 40–70% of WBCs).

What is the primary role of eosinophils?

Eosinophils attack parasitic worms using digestive enzymes and play a complex role in allergic reactions.

From what parent cell line do blood platelets originate?

Platelets are anucleate cell fragments pinched off from giant, multinucleate cells called megakaryocytes.

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

The hemocytoblast.

What is a reticulocyte, and how long does it take to become a fully functional RBC after entering circulation?

A reticulocyte is a young RBC that still contains some rough ER; it enters the bloodstream and becomes a fully functional RBC within about 2 days.

How are heme breakdown products excreted after phagocytes break down old RBCs?

Heme is degraded to bilirubin, secreted into the intestine, converted into stercobilin (a brown pigment), and eliminated in feces.

Which organ produces the majority of erythropoietin (EPO), and what mechanism regulates its production?

The kidneys produce most EPO via a negative feedback loop triggered by low oxygen-carrying ability in the blood.

What are the three major sequential phases of hemostasis?

1) Vascular spasms (vasoconstriction), 2) Platelet plug formation, and 3) Coagulation (blood clotting).

What interaction during coagulation leads to the formation of thrombin?

Tissue factor (TF) interacts with platelet factor 3 (PF3), other clotting factors, and calcium ions (Ca²⁺) to form an activator that converts prothrombin to thrombin.

What is the function of thrombin during the final step of blood coagulation?

Thrombin converts soluble fibrinogen into long, insoluble fibrin threads that form a mesh trapping RBCs and platelets.

What is the normal human blood clotting time?

3 to 6 minutes.

How does a thrombus differ from an embolus?

A thrombus is a clot that develops and persists in an unbroken blood vessel, whereas an embolus is a thrombus that breaks away and travels through the vascular system.

What physical symptom and underlying platelet defect characterize thrombocytopenia?

Thrombocytopenia is characterized by an abnormally low platelet count leading to spontaneous bleeding and petechiae (small purplish skin blotches).

At what temperature and for how long can donated whole blood be stored in blood banks?

Donor blood mixed with an anticoagulant is refrigerated at about 4°C (39.2°F) for up to approximately 35 days.

What antigens and antibodies are associated with Type O blood?

Type O blood has no A or B surface antigens on its RBCs, and its plasma contains both Anti-A and Anti-B antibodies.

Why is Type AB blood considered the universal recipient in ABO blood compatibility?

Type AB plasma lacks both Anti-A and Anti-B antibodies, so it will not cause agglutination of donor RBCs carrying A or B antigens.

How does anti-Rh antibody formation differ from ABO antibody formation?

Rh- individuals do not naturally possess anti-Rh antibodies; anti-Rh antibodies are produced only after an Rh- person is sensitized by exposure to Rh+ blood.

What treatment prevents maternal sensitization to Rh+ fetal blood, and when is it administered?

RhoGAM (an immune serum) is administered around the 28th week of pregnancy and again shortly after birth to prevent sensitization.

How does fetal hemoglobin (HbF) differ functionally from adult hemoglobin (HbA)?

HbF has a higher affinity for oxygen, enabling it to pick up oxygen more readily from maternal blood in the placenta.

What causes physiologic jaundice in newborn infants?

Physiologic jaundice occurs when rapid post-birth destruction of fetal RBCs produces bilirubin faster than the newborn's immature liver can clear it.