Chapter 20: Blood

Vocabulary flashcards covering the components, formed elements, plasma proteins, cell types, and developmental processes of human blood from Chapter 20.

Blood

A specialized connective tissue with an average volume of $5\,L$ in the human body, composed of formed elements (cells) and a fluid matrix (plasma) that transports materials, maintains homeostasis, and defends tissues.

Formed Elements

The cellular components of blood, which include erythrocytes, leukocytes, and platelets suspended in plasma.

Blood Plasma

The liquid matrix of blood making up $55\%$ of total blood volume, composed of $92\%$ water, metabolic wastes, electrolytes, organic nutrients, hormones, and plasma proteins.

Albumin

The smallest and most abundant plasma protein ($60\%$ of plasma proteins) that transports fatty materials such as bilirubin, steroids, thyroid hormones, and lipids in the blood.

Globulins

Plasma proteins constituting $35\%$ of all plasma proteins, consisting of immunoglobulins (Y-shaped antibodies that bind foreign compounds) and transport globulins (which bind ions and hormones to prevent renal filtration).

Fibrinogen

A plasma protein accounting for $4\%$ of plasma proteins that acts as an essential precursor protein for blood clotting.

Erythrocytes

Anucleate, biconcave red blood cells with a collapsed center and no mitochondria, ER, or ribosomes; they make up of blood cells and formed elements and circulate for about $120\,\text{days}$.

• Very flexible and can stack in rouleaux

Rouleaux

Stacks of flexible red blood cells aligned in a roll that allow them to squeeze through narrow capillaries.

Hemoglobin

A four-chained protein molecule constituting $95\%$ of a red blood cell's protein, where each subunit contains a heme molecule and an iron ion that reversibly binds oxygen. (makes blood red)

Oxyhemoglobin

Hemoglobin that is bound to oxygen, resulting in a bright red color.

Deoxyhemoglobin

Hemoglobin devoid of oxygen, which exhibits a dark-red or maroon appearance.

Carbaminohemoglobin

Hemoglobin molecules bound to carbon dioxide ($CO_2$), which display a dark-red or maroon color.

Leukocytes

White blood cells that function to defend the body against pathogens, as well as eliminate toxins, cellular wastes, and damaged tissue.

Diapedesis

The migration process by which circulating leukocytes squeeze through blood vessel walls to enter surrounding tissues.

Granulocytes

A classification of leukocytes featuring visible, dark-staining secretory granules; includes neutrophils, eosinophils, and basophils.

Neutrophils

The most common and highly mobile white blood cells, featuring neutral pink-staining granules, which are the first responders to an injury site where they phagocytize bacteria and die.

Eosinophils

Granulocytes with bi-lobed nuclei and red-staining granules that attack antibody-bound cells and increase in quantity during allergic responses.

Basophils

The rarest type of leukocytes, characterized by blue-staining granules that secrete histamine at infection sites.

Agranulocytes

A class of white blood cells lacking visible cytoplasmic granules, comprising monocytes and lymphocytes.

Monocytes

The largest type of leukocyte; agranulocytes that leave circulation to mature into macrophages in connective tissues, where they engulf pathogens and cellular debris.

Lymphocytes

Moderately common agranulocytes that migrate out of the bloodstream to populate the lymphatic system, where they exist in high abundance.

Platelets

Small, anucleate cell fragments filled with proteins and enzymes that survive for $10\text{--}12\,\text{days}$ and function in blood clotting.

Megakaryocyte

A large bone marrow stem cell containing a large nucleus that sheds cytoplasmic fragments to produce functional platelets.

Hemostasis

The physiological process of stopping bleeding, during which platelets clump and convert soluble fibrinogen into insoluble fibrin to mesh and seal wounds.

Hemopoiesis

The comprehensive biological process responsible for the formation and development of all formed elements of blood.

Erythropoiesis

The specific developmental pathway leading to mature erythrocytes, stimulated by the hormone erythropoietin (EPO).

Leukopoiesis

The developmental pathway responsible for generating leukocytes, stimulated by colony-stimulating factors released in the red marrow.

Myeloid Tissue

The tissue where blood cells originate, restricted to red bone marrow in adult humans but found in embryonic liver, spleen, and blood vessels.

Hematopoietic Stem Cells

Precursor cells residing within myeloid tissue that undergo differentiation to produce all blood cell types.