Circulatory System Human Biology Quiz

Hemostasis is the physiological process that stops bleeding after vascular injury. It involves vasoconstriction, platelet plug formation, and clotting mechanisms. Without hemostasis, even minor injuries could lead to excessive blood loss, making this process essential for survival.

Viscosity measures a fluid’s resistance to flow. Blood’s viscosity depends on plasma composition and cellular content. Higher viscosity means greater resistance, affecting circulation and workload on the heart.

Blood is approximately five times more viscous than water due to suspended cells and plasma proteins. This increased thickness affects flow rate and pressure within vessels.

Blood is slightly denser than water because it contains cells and dissolved proteins. Density refers to mass per volume, not thickness or weight perception.

Blood pH is tightly regulated between 7.35 and 7.45. Deviations outside this range can disrupt enzyme activity, oxygen transport, and cellular function.

Plasma is the liquid component of blood, consisting mostly of water along with proteins, nutrients, and waste products. It serves as the transport medium for blood components.

Formed elements include red blood cells, white blood cells, and platelets. These components originate in bone marrow and perform oxygen transport, immune defense, and clotting functions.

Plasma makes up about 55% of blood volume, while formed elements account for about 45%. This balance supports efficient transport and cellular function.

Albumin maintains osmotic pressure, globulins support immunity, and fibrinogen is essential for clot formation. These proteins are critical for blood stability and defense.

Erythrocytes are red blood cells responsible for oxygen transport via hemoglobin. Their biconcave shape increases surface area for gas exchange.

Red blood cells make up about 99% of formed elements, emphasizing their primary role in oxygen delivery throughout the body.

Platelets are cell fragments that initiate clot formation. They aggregate at injury sites to prevent blood loss.

Leukocytes and platelets together form only about 1% of blood’s formed elements, yet play crucial immune and clotting roles.

About 50% of whole blood is water, calculated by multiplying plasma percentage by plasma water content.

Elevated white blood cell counts usually indicate infection or inflammation, reflecting immune system activation.

Hemoglobin is a protein–iron complex that binds oxygen, enabling efficient oxygen transport to tissues.

Anucleate cells lack a nucleus. Mammalian red blood cells are anucleate to maximize space for hemoglobin.

Anemia results from insufficient hemoglobin or red blood cells, reducing oxygen delivery and causing fatigue.

Hematocrit measures the percentage of red blood cells in blood, aiding diagnosis of anemia or dehydration.

Adult males typically have higher RBC percentages than females due to hormonal and physiological differences.

Diapedesis allows white blood cells to exit blood vessels and enter tissues during immune responses.

Chemotaxis directs cell movement toward chemical signals, guiding immune cells to infection sites.

Leukocytes are divided into granulocytes and agranulocytes based on cytoplasmic granule presence.

Neutrophils, basophils, and eosinophils are granulocytes involved in immune defense and inflammation.

Eosinophils have red-staining granules and two-lobed nuclei. They help regulate allergic responses and inflammation.

Heparin is an anticoagulant that prevents local blood clot formation by inhibiting clotting factors.