Chapter 18: The Cardiovascular System: Blood

erythrocyte clumps

As the ________ are degraded, in a process called hemolysis, their hemoglobin is released into the bloodstream.

Hemolytic disease

________ of the newborn (HDN) or erythroblastosis fetalis, may cause anemia in mild cases, but the agglutination and hemolysis can be so severe that without treatment the fetus may die in the womb or shortly after birth.

development of megakaryocytes

It triggers the ________ into platelets.

flexible cell membrane

They have a thin, ________ that encloses a small amount of cytoplasm and a single nucleus.

extrinsic pathway

Once factor X has been activated by either the intrinsic or ________, the enzyme prothrombinase converts factor II, the inactive enzyme prothrombin, into the active enzyme thrombin.

**platelets**

cell fragments called

 **red blood cells (RBCs), white blood cells (WBCs),platelets**

**formed elements** include

**hematocrit**

measures the percentage of RBCs, clinically known as erythrocytes, in a blood sample.

agranular leukocytes

While granules are not totally lacking in ________, they are far fewer and less obvious.

 **buffy coat**

because of its color; it normally constitutes less than 1 percent of a blood sample.

The process by which this replacement occurs is called hemopoiesis, or hematopoiesis (from the Greek root haima

= "blood"; -poiesis = "production")

Myeloid stem cells give rise to all the other formed elements, including the erythrocytes; megakaryocytes that produce platelets; and a myeloblast lineage that gives rise to monocytes and three forms of granular leukocytes

neutrophils, eosinophils, and basophils

The erythrocyte, commonly known as a red blood cell (or RBC), is by far the most common formed element

A single drop of blood contains millions of erythrocytes and just thousands of leukocytes

They can be divided into two main categories

granulocytes and agranulocytes

**packed cell volume (PCV)**

The volume of erythrocytes after centrifugation

**Viscosity**

is a measure of a fluid’s thickness or resistance to flow, and is influenced by the presence of the plasma proteins and formed elements within the blood.

**Blood Plasma**

is the liquid component of blood that carries red and white blood cells, platelets, and other substances throughout the body.

**Albumin**

is the most abundant of the plasma proteins.

**globulins**

The second most common plasma proteins are the

**fibrinogen**

The least abundant plasma protein is

**Sites of Hemopoiesis**

 are the places in the body where blood cells are produced.

 **pluripotent stem cell**

which gives rise to multiple types of cells of the body and some of the supporting fetal membranes.

**hemopoietic stem cell**, or **hemocytoblast**

One step lower on the hierarchy of stem cells is the

**hemopoietic growth factor**

Hemopoiesis begins when the hemopoietic stem cell is exposed to appropriate chemical stimuli collectively

**Lymphoid stem cells**

give rise to a class of leukocytes known as lymphocytes, which include the various T cells, B cells, and natural killer (NK) cells, all of which function in immunity.

**Myeloid stem cells**

give rise to all the other formed elements, including the erythrocytes; megakaryocytes that produce platelets; and a myeloblast lineage that gives rise to monocytes and three forms of granular leukocytes: neutrophils, eosinophils, and basophils.

**Erythropoietin (EPO**)

is a glycoprotein hormone secreted by the interstitial fibroblast cells of the kidneys in response to low oxygen levels.

**Thrombopoietin**

another glycoprotein hormone, is produced by the liver and kidneys. It triggers the development of megakaryocytes into platelets.

**Cytokines**

are glycoproteins secreted by a wide variety of cells, including red bone marrow, leukocytes, macrophages, fibroblasts, and endothelial cells.

**Colony-stimulating factors (CSFs)**

are glycoproteins that act locally, as autocrine or paracrine factors.

**Interleukins**

are another class of cytokine signaling molecules important in hemopoiesis.

 **bone marrow transplant**

a treatment in which a donor’s healthy bone marrow—and its stem cells—replaces the faulty bone marrow of a patient.

**bone marrow biopsy**

a diagnostic test of a sample of red bone marrow

 **erythrocyte**

commonly known as a red blood cell (or RBC), is by far the most common formed element:

**Hemoglobin**

is a large molecule made up of proteins and iron

**globin**

 It consists of four folded chains of a protein

**heme**

Each of these globin molecules is bound to a red pigment molecule

**oxyhemoglobin**

In the lungs, hemoglobin picks up oxygen, which binds to the iron ions, forming

 **carbaminohemoglobin**

About 23–24 percent of it binds to the amino acids in hemoglobin, forming a molecule

**hypoxemia**

 low blood oxygen

**Iron**

We have said that each heme group in a hemoglobin molecule contains an ion of the trace mineral iron.

**Copper**

is a component of two plasma proteins, hephaestin and ceruloplasmin.

**Zinc**

The trace mineral zinc functions as a co-enzyme that facilitates the synthesis of the heme portion of hemoglobin.

**B vitamins**

The B vitamins folate and vitamin B12 function as co-enzymes that facilitate DNA synthesis.

 **anemia**

The size, shape, and number of erythrocytes, and the number of hemoglobin molecules can have a major impact on a person’s health. When the number of RBCs or hemoglobin is deficient

**sickle cell disease**

A characteristic change in the shape of erythrocytes is seen in

**Thalassemia**

is an inherited condition typically occurring in individuals from the Middle East, the Mediterranean, African, and Southeast Asia, in which maturation of the RBCs does not proceed normally.

**polycythemia**

In contrast to anemia, an elevated RBC count is called

 **leukocyte**

commonly known as a white blood cell (or WBC), is a major component of the body’s defenses against disease.

**Granular leukocytes**

contain abundant granules within the cytoplasm.

**Agranular leukocytes**

include monocytes, which mature into macrophages that are phagocytic, and lymphocytes, which arise from the lymphoid stem cell line.

**Leukopenia**

is a condition in which too few leukocytes are produced.

**Leukemia**

is a cancer involving an abundance of leukocytes.

**Lymphoma**

is a form of cancer in which masses of malignant T and/or B lymphocytes collect in lymph nodes, the spleen, the liver, and other tissues.

**megakaryocyte**

A platelet is not a cell but rather a fragment of the cytoplasm of a cell

**Thrombocytosis**

is a condition in which there are too many platelets

 **thrombocytopenia**

 an insufficient number of platelet

**Hemostasis**

the process by which the body seals a ruptured blood vessel and prevents further loss of blood.

**Vascular Spasm**

 the smooth muscle in the walls of the vessel contracts dramatically.

**Coagulation**

Those more sophisticated and more durable repairs are collectively

**clotting factors**

In the coagulation cascade, chemicals called

 **extrinsic pathway**

which normally is triggered by trauma.

 **intrinsic pathway**

which begins in the bloodstream and is triggered by internal damage to the wall of the vessel.

**Common Pathway**

Both the intrinsic and extrinsic pathways lead to the common pathway, in which fibrin is produced to seal off the vessel.

**Fibrinolysis**

is the gradual degradation of the clot.

**plasmin**

which gradually breaks down the fibrin of the clot.

**anticoagulant**

is any substance that opposes coagulation.

**Antithrombin**

inactivates factor X and opposes the conversion of prothrombin (factor II) to thrombin in the common pathway.

**agglutination**

Because the arms of the Y-shaped antibodies attach randomly to more than one nonself erythrocyte surface, they form clumps of erythrocytes.

**Rh Blood Groups**

 is classified according to the presence or absence of a second erythrocyte antigen identified as Rh.

**Hemolytic disease of the newborn (HDN)**

or erythroblastosis fetalis, may cause anemia in mild cases, but the agglutination and hemolysis can be so severe that without treatment the fetus may die in the womb or shortly after birth.