Chapter 19: Nursing Assessment: Hematologic Function
The Hematologic System
Anatomic and Physiologic Overview
Consists of the blood and the sites where blood is produced, including the
bone marrow and the reticuloendothelial system (RES)
Blood is a specialized organ that exists in a fluid state
Blood is composed of plasma and various types of cells:
Approximately 55% of blood volume is plasma, and 45% consists of
various cellular components
Blood
Three primary cell types:
Erythrocytes (red blood cells [RBCs])
Leukocytes (white blood cells [WBCs])
Thrombocytes (platelets)
Life of Cells
RBS’s generally 120 days
WBC’s live from days to years depending on the type
Platelets live 7 – 10 days
Hematopoiesis: formation and production of RBS’s; the process of replenishing
blood cells
Primary site is the bone marrow
Within it are primitive cells called stem cells
Stem cells can begin a process of differentiation into either myeloid
or lymphoid stem cells
Normal bone marrow produces 175 billion erythrocytes, 70 billion neutrophils
(a mature type WBC), and 175 billion platelets DAILY
Blood makes up 7% - 10% of the normal body weight and mounts to 5 - - L of
volume
, Bone Marrow
The site for hematopoiesis or blood formation
In children: blood formation involves ALL skeletal bones BUT with aging,
marrow cavity is limited to the pelvis, ribs, vertebrae, and sternum.
Marrow = 4% - 5% of total body weight, consists of cellular components
(red marrow) separated by fat (yellow marrow)
Adults w/ disease causes marrow destruction, fibrosis, or scarring, the
liver and spleen resume production of blood cells (extramedullary
hematopoiesis)
Marrow is HIGHLY vascular with stem cells in it (ability to self-replicate)
Lymphoid stem cells produce T or B lymphocytes, where myeloid stem
cells have three broad cell types:
o Erythrocytes, leukocytes, and platelets
o With exception to lymphocytes, ALL blood cells are derived from
myeloid stem cells
, Erythrocytes (Red Blood Cells)
Mature erythrocytes consist primarily of hemoglobin, which contains iron and
makes up 95% of the cell mass
Oxygen readily binds to hemoglobin in the lungs and is carried as
oxyhemoglobin in arterial blood
Erythropoiesis
Erythroblasts arise from the primitive myeloid stem cells in bone marrow
Differentiation is stimulated by erythropoietin from the kidneys
Depends on adequate supplies of folic acid, vitamin B12, and iron
Old RBCs are removed from the blood by the reticuloendothelial cells,
particularly in the liver and the spleen
Question
Which of the following situations would most likely prompt an increase in
erythropoietin synthesis?
A woman is admitted to the hospital with anemia.
A man with atrial fibrillation has begun taking anticoagulants to prevent a stroke.
A child fractures his ulna and radius in a playground accident.
A woman develops an infection in an arterial ulcer.
Rationale: If the kidney detects low levels of oxygen (as would occur in anemia, in which
fewer red cells are available to bind oxygen, or with people living at high altitudes), the
release of erythropoietin is increased. Anticoagulants, infections, and injury without
blood loss do not increase erythropoiesis.
Leukocytes (White Blood Cells)
• Two general categories:
1. Granulocytes:
Eosinophils
Basophils
Neutrophils
2. Agranulocytes:
Monocytes
Lymphocytes
Question: Is the following statement true or false?
An individual with an active infection is likely to experience an increase in neutrophil
production.
, Rationale: Infection is the condition in which neutrophil production most sharply
increases.
Platelets (Thrombocytes)
Play an essential role in the control of bleeding
Circulate freely in the blood in an inactive state
When vascular injury occurs, platelets collect at the site and are activated,
forming a platelet plug
Plasma and Plasma Proteins
More than 90% water
Remainder consists primarily of plasma proteins and clotting factors
(particularly fibrinogen
Plasma proteins consist primarily of albumin and the globulins
Hemostasis
Involves primary and secondary phases
Can be activated by the intrinsic or the extrinsic pathway
Many factors are involved in the reaction cascade that forms fibrin
Question
An individual’s body is responding to a minor cut. What event will take place during
primary hemostasis?
• The severed blood vessels will constrict.
• Thrombopoietin will be synthesized.
• Platelets will begin to circulate.
• Plasma volume will increase.
Rationale: Primary hemostasis involves the severed vessel constricting and platelets
collecting at the injury site. Thrombopoietin is not synthesized in the immediate
response to an injury, and platelets are in constant circulation. Plasma volume does not
increase in response to bleeding.
Complete Blood Count With Differential
WBC: 5,000–10,000/µL
Absolute neutrophil count: >1,800/µL
Segments: 38%–71% of total WBC
Bands: 0%–10% of total
Monocytes: 2%–15% of total
Basophils: 0%–1% of total
Eosinophils: 0%–5% of total
The Hematologic System
Anatomic and Physiologic Overview
Consists of the blood and the sites where blood is produced, including the
bone marrow and the reticuloendothelial system (RES)
Blood is a specialized organ that exists in a fluid state
Blood is composed of plasma and various types of cells:
Approximately 55% of blood volume is plasma, and 45% consists of
various cellular components
Blood
Three primary cell types:
Erythrocytes (red blood cells [RBCs])
Leukocytes (white blood cells [WBCs])
Thrombocytes (platelets)
Life of Cells
RBS’s generally 120 days
WBC’s live from days to years depending on the type
Platelets live 7 – 10 days
Hematopoiesis: formation and production of RBS’s; the process of replenishing
blood cells
Primary site is the bone marrow
Within it are primitive cells called stem cells
Stem cells can begin a process of differentiation into either myeloid
or lymphoid stem cells
Normal bone marrow produces 175 billion erythrocytes, 70 billion neutrophils
(a mature type WBC), and 175 billion platelets DAILY
Blood makes up 7% - 10% of the normal body weight and mounts to 5 - - L of
volume
, Bone Marrow
The site for hematopoiesis or blood formation
In children: blood formation involves ALL skeletal bones BUT with aging,
marrow cavity is limited to the pelvis, ribs, vertebrae, and sternum.
Marrow = 4% - 5% of total body weight, consists of cellular components
(red marrow) separated by fat (yellow marrow)
Adults w/ disease causes marrow destruction, fibrosis, or scarring, the
liver and spleen resume production of blood cells (extramedullary
hematopoiesis)
Marrow is HIGHLY vascular with stem cells in it (ability to self-replicate)
Lymphoid stem cells produce T or B lymphocytes, where myeloid stem
cells have three broad cell types:
o Erythrocytes, leukocytes, and platelets
o With exception to lymphocytes, ALL blood cells are derived from
myeloid stem cells
, Erythrocytes (Red Blood Cells)
Mature erythrocytes consist primarily of hemoglobin, which contains iron and
makes up 95% of the cell mass
Oxygen readily binds to hemoglobin in the lungs and is carried as
oxyhemoglobin in arterial blood
Erythropoiesis
Erythroblasts arise from the primitive myeloid stem cells in bone marrow
Differentiation is stimulated by erythropoietin from the kidneys
Depends on adequate supplies of folic acid, vitamin B12, and iron
Old RBCs are removed from the blood by the reticuloendothelial cells,
particularly in the liver and the spleen
Question
Which of the following situations would most likely prompt an increase in
erythropoietin synthesis?
A woman is admitted to the hospital with anemia.
A man with atrial fibrillation has begun taking anticoagulants to prevent a stroke.
A child fractures his ulna and radius in a playground accident.
A woman develops an infection in an arterial ulcer.
Rationale: If the kidney detects low levels of oxygen (as would occur in anemia, in which
fewer red cells are available to bind oxygen, or with people living at high altitudes), the
release of erythropoietin is increased. Anticoagulants, infections, and injury without
blood loss do not increase erythropoiesis.
Leukocytes (White Blood Cells)
• Two general categories:
1. Granulocytes:
Eosinophils
Basophils
Neutrophils
2. Agranulocytes:
Monocytes
Lymphocytes
Question: Is the following statement true or false?
An individual with an active infection is likely to experience an increase in neutrophil
production.
, Rationale: Infection is the condition in which neutrophil production most sharply
increases.
Platelets (Thrombocytes)
Play an essential role in the control of bleeding
Circulate freely in the blood in an inactive state
When vascular injury occurs, platelets collect at the site and are activated,
forming a platelet plug
Plasma and Plasma Proteins
More than 90% water
Remainder consists primarily of plasma proteins and clotting factors
(particularly fibrinogen
Plasma proteins consist primarily of albumin and the globulins
Hemostasis
Involves primary and secondary phases
Can be activated by the intrinsic or the extrinsic pathway
Many factors are involved in the reaction cascade that forms fibrin
Question
An individual’s body is responding to a minor cut. What event will take place during
primary hemostasis?
• The severed blood vessels will constrict.
• Thrombopoietin will be synthesized.
• Platelets will begin to circulate.
• Plasma volume will increase.
Rationale: Primary hemostasis involves the severed vessel constricting and platelets
collecting at the injury site. Thrombopoietin is not synthesized in the immediate
response to an injury, and platelets are in constant circulation. Plasma volume does not
increase in response to bleeding.
Complete Blood Count With Differential
WBC: 5,000–10,000/µL
Absolute neutrophil count: >1,800/µL
Segments: 38%–71% of total WBC
Bands: 0%–10% of total
Monocytes: 2%–15% of total
Basophils: 0%–1% of total
Eosinophils: 0%–5% of total
