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Transcript
Chapter 45:
Anatomy and Physiology of the
Hematological and Immune
Systems
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Functions of the Blood
• Supplies the tissues with
oxygen and nutrients
• Takes away byproducts of
metabolism like CO2 to
organs for excretion
• Maintains acid-base balance
• Fights off infection
• Transports hormones to
target organs
• Prevents hemorrhage by
circulating clotting factors
• Maintains body temperature
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Components of the Blood
• Plasma
• Plasma proteins
–
Liquid portion
–
90% water/10% solutes
–
Contains plasma proteins
–
Immunoglobins
–
Fibrinogen
–
Electrolytes
–
Nutrients
–
Albumin/fibrinogen
produced by liver
• Albumin is carrier
substance and controller
of colloidal osmotic
pressure
• Fibrinogen is a key
component in clotting
–
Immunoglobins produced
by B lymphocytes
• Help prevent infection
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Components of the Blood (cont.)
• All components come from the pluripotent stem cell
• Hematopoiesis is the production of blood cells
• Two-stage process
– Proliferation (cellular or mitotic division)
– Maturation (differentiation into red or white cells or
platelets)
• Controlled by biochemical signals
• Takes place in bone marrow
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Major Maturational Stages of Blood Cells
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Substances that can stimulate red blood cell production in
a patient with anemia include which of the following?
A. Iron, vitamin C, glucose
B. Calcium, potassium, iron
C. Phosphate, potassium, iron
D. Iron, vitamins B6 and B12, folic acid
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
D. Iron, vitamin B6 and B12, folic acid
Rationale: Patients with anemia should be given vitamins
B6 and B12 and folic acid as well as iron.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Erythrocytes: The Red Blood Cells (RBCs)
• Produced in the red bone marrow, primarily in the sternum, ribs,
pelvis, skull, and vertebrae
• Approximately 5 million/mm3
• To prevent anemia, iron, vitamins B6 and B12 plus folic acid are
needed to aid in RBC production
• The immature RBC is called a reticulocyte. Reticulocytes increase in
number when the demand for RBCs increases.
• Mature RBC has no nucleus
• RBCs look like a soft ball compressed between two fingers. Very
flexible with large surface areas.
• RBCs have thin walls that allow them to pass into the
microcirculation. After they release O2, they regain their shape.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Erythrocytes: The Red Blood Cells (RBCs)
(cont.)
• Each RBC contains 12 to 18 g/dL of hemoglobin
• Loosely combines with oxygen, creating oxyhemoglobin
• Life of RBC is around 120 days
• Liver stores heme portion for new RBC formation
• Excess is excreted in the feces and urine as bilirubin
• Major function is respiration
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Leukocytes: White Blood Cells (WBCs)
• Major job is defending the body against invading
organisms
• Usually 5,000 to 10,000/m3
• Two major types: granulocytes and agranulocytes
• Granulocytes have granules that stain a certain color
• Agranulocytes do not have granules
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which of the following represents the largest percentage of
granulocytes?
A. Neutrophils
B. Basophils
C. Lymphocytes
D. Macrophages
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
A. Neutrophils
Rationale: Granulocytes represent 70% of the total white
cell count, and of these, neutrophils represent 57% to
67% of the total. Neutrophils are released as an early
response to inflammation. Basophils are a type of
granulocyte that play an important role in the allergic
response. Lymphocytes and macrophages are
agranulocytes.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Platelets
• Also called thrombocytes
• Not technically cells but fragmented particles from
megakaryocytes
• Their function is to maintain capillary integrity, accelerate the
clotting process, and retract clots
• Live around 10 days
• Produced by the liver under the influence of thrombopoietin
• Normal value is 250,000 to 500,000/mm3
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Blood Coagulation
• Blood coagulation is mediated by platelets
• Platelets secret thromboxane A2, a powerful
vasoconstrictor that slows blood loss
• Platelets also plug small leaks in the endothelium
(intima)
• Collagen exposure from endothelium increases the
stickiness of platelets, leading to a small clot
• Also activation of the intrinsic pathway of the clotting
cascade by release of platelet factor 3
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Intrinsic Factor or Extrinsic?
• Intrinsic factor
– A result of factors released at the site of injury
• Extrinsic factor
– Initiated by injury outside the blood vessel (burn
injury)
• Both pathways converge at factor Xa (prothrombinase or
Stuart-Prower factor)
– Prothrombin is converted to thrombin, and this
results in fibrin formation (clot)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Coagulation Cascade
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Sequence of Thrombus Formation
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Immune System
• Comprises organs (spleen, thymus, lymph node, bone
marrow, appendix, tonsils, and adenoids) and cells (B
and T lymphocytes, eosinophils, basophils, phagocytes)
• Role is to recognize and destroy antigens and microbes,
degrade RBCs, and monitor and destroy cancer cells
• Organs and cells circulate to both blood and lymphatic
system
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
The Immune System (cont.)
• Adds in “self/non-self” recognition, where the body
combats foreign bodies entering it
• Immunocompetency refers to the ability of the body to
mount a defense against non-self cells or foreign bodies
• An antigen is a substance that elicits an attack response
by the body
– Infection and cancers result when body doesn’t
produce antigens
• An antibody combats an antigen
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Immunity
GENERAL (INNATE)
SPECIFIC (ACQUIRED)
• Ability of body to prevent
bacterial invasion
• Patient develops own
antibodies
• Phagocytes and natural
killer cells (NKCs)
• Antibodies against antigens
have memories (quicker
response with second
exposure)
• Nonspecific and has no
memory
• Limits response until
specific response can be
mounted
• Second line of defense
• First line of defense
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of General Immunity
• Physical barriers (skin, mucous membranes, epiglottis,
etc.)
• Chemical barriers (antibodies, acidic solutions)
• Mechanical barriers (urinary flow, tears)
• Biological defenses (colonized flora of gut, skin, etc.)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of General Immunity (cont.)
• Phagocytes and phagocytosis (ingestion of unwanted
bacteria/cells by macrophages and monocytes)
• Inflammatory responses (localized or systemic response to
injury); three stages:
– Vascular stage
– Cellular exudate stage
– Tissue repair and replacement stage
• Cytokines (interleukins are messengers that tell leukocytes
what to do)
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
In the inflammatory response to tissue injury, the most
important result is the collection of neutrophils and
macrophages, resulting in destruction of the causative
organism.
A. True
B. False
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
A. True
Rationale: The first wave of defenders (neutrophils) and
the second wave (macrophages and more long-term
processes) ensure that a swift, sustained resistance is
mounted as part of the normal inflammatory response.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Specific Immunity: Cell-Mediated
• Cell-mediated involves B and T lymphocytes
– T lymphocytes are activated by specific antigens and can
bind to a specific receptor site
– T lymphocytes also produce clones that migrate and attack
antigens and malignant cells
– Macrophages are also stimulated and produce cytokines
– Cytokines liberate and stimulate B cells and phagocytes
– Impaired cellular immunity results in risk for viruses,
fungi, and parasites
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Types of Specific Immunity: Humoral
Immune Response
• The humoral system involves the immunoglobins and
complement, which are serum proteins
• Humoral response occurs outside the cell in the blood
and tissue fluids
• Immunoglobins come from B lymphocytes that
differentiate into memory and plasma cells
• Result in antigen-antibody complexes, which are
phagocytosed
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Question
Which of the following immunoglobins is involved with
secretions of the respiratory and GI tracts?
A. IgA
B. IgM
C. IgD
D. IgE
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins
Answer
A. IgA
Rationale: IgA has two component types that aid body
fluids in destroying microbial invaders.
Copyright © 2009 Wolters Kluwer Health | Lippincott Williams & Wilkins