Blood Cells, Hematopoiesis, and Clotting: Key Concepts for Biology

What are formed elements?

Cellular components of blood—RBCs, WBCs, platelets

List the three formed elements by name.

Erythrocytes, leukocytes, thrombocytes

Define hematopoiesis.

Formation of blood cells

Where do blood cells originate?

Red bone marrow from hematopoietic stem cells

Scientific name for RBCs?

Erythrocytes

Shape and characteristics of RBCs?

Biconcave, no nucleus, flexible, contain hemoglobin

Function of hemoglobin?

Transports oxygen and some carbon dioxide

Hormone that stimulates RBC production?

Erythropoietin (EPO)

What triggers erythropoietin release?

Low blood oxygen (hypoxia)

Life span of RBCs?

~120 days

Nutrients needed for RBC production?

Iron, vitamin B12, folic acid, protein

Define anemia.

Reduced oxygen-carrying ability (low RBCs or hemoglobin)

Categories of WBCs?

Granulocytes and agranulocytes

Granulocytes include:

Neutrophils, eosinophils, basophils

Agranulocytes include:

Lymphocytes, monocytes

Define diapedesis.

WBCs squeeze through capillary walls into tissues

Define chemotaxis.

WBCs move toward chemical signals

Define phagocytosis.

Engulfing and digesting pathogens/debris

Neutrophil appearance?

Light purple granules, multi-lobed nucleus

Eosinophil appearance?

Red-orange granules, bi-lobed nucleus

Basophil appearance?

Dark blue-purple granules, obscured nucleus

Lymphocyte appearance?

Large nucleus, thin rim of cytoplasm

Monocyte appearance?

Largest WBC, kidney-shaped nucleus

Function of neutrophils?

Phagocytosis of bacteria (first responders)

Function of eosinophils?

Fight parasites, allergy response

Function of basophils?

Release histamine and heparin (inflammation)

Function of lymphocytes?

Immunity (T cells & B cells)

Function of monocytes?

Become macrophages; strong phagocytes

Most abundant WBC?

Neutrophils

Least abundant WBC?

Basophils

Two types of lymphocytes?

T cells and B cells

Define leukocytosis.

High WBC count

Define leukopenia.

Low WBC count

Define differential WBC count.

Percent of each type of WBC in blood

Define leukemia.

Cancer of blood-forming tissues → many abnormal WBCs

Platelets come from:

Megakaryocytes

Appearance of platelets:

Small cell fragments, no nucleus

Function of platelets:

Clot formation and vessel repair

Define thrombocytosis.

High platelet count

Define thrombocytopenia.

Low platelet count

Components of plasma:

Water, proteins, nutrients, gases, wastes, electrolytes

Function of plasma:

Transport substances

Define electrolytes & examples in plasma.

Ions; Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl⁻, HCO₃⁻

Define hemostasis.

Process that stops bleeding

Role of platelets in hemostasis:

Form platelet plug, release clotting chemicals

Overall purpose of clotting cascade:

Convert fibrinogen to fibrin (blood clot)

What are clotting factors?

Proteins needed for clotting

Role of vitamin K?

Required to produce many clotting factors

Major event in clotting?

Fibrinogen → fibrin

Type of feedback in clotting?

Positive feedback

Difference between serum and plasma?

Serum = plasma without clotting factors

What determines blood type?

Antigens on RBC surface

Blood type A antigens and antibodies:

A antigen; Anti-B antibody

Blood type B antigens and antibodies:

B antigen; Anti-A antibody

Blood type AB antigens and antibodies:

A & B antigens; No antibodies

Blood type O antigens and antibodies:

No antigens; Anti-A & Anti-B antibodies

Universal donor and why?

O- ; no antigens

Universal recipient and why?

AB+ ; has all antigens

Rh-positive vs Rh-negative:

Rh+ has D antigen; Rh- lacks D antigen