Transcript Orientation to the Human Body

Cardiovascular &
Hematological Systems
Chapter 6
Pathology
Circulatory System




circulatory system - the heart, blood vessels and blood
cardiovascular system - the heart and blood vessels
hematology – the study of blood
functions of circulatory system
◦ transport
 O2, CO2, nutrients, wastes, hormones
◦ protection
 limit spread of infection, destroy microorganisms and
cancer cells, and initiates clotting
◦ regulation
 fluid balance, stabilizes pH of ECF, and temperature
control
Transportation
Blood
 Carries oxygen to tissues
 Carries carbon dioxide from tissues
 Transports nutrients and other
substances to cells
 Transports waste products from cells
 Carries hormones to organs
Regulation
Blood

Buffers keep pH of body fluids between
7.35 and 7.45

Substances maintain osmotic pressure to
regulate fluid in tissues (fluid balance)

Transports heat generated in muscles to
aid in regulation of body temperature
Protection
Blood
 Carries cells and antibodies of immune
system
 Carries factors to protect against blood
loss
Components and General Properties of
Blood
adults have 4-6 L of blood
 a liquid connective tissue consisting of
cells and extracellular matrix
◦ plasma – matrix of blood

 a clear, light yellow fluid
◦ formed elements - blood cells and cell
fragments
 red blood cells, white blood cells, and
platelets
Components and General Properties of
Blood

seven kinds of formed elements
◦ erythrocytes - red blood cells (RBCs)
◦ Platelets - thrombocytes
 cell fragments from special cell in bone marrow
◦ leukocytes - white blood cells (WBCs)
 five leukocyte types divided into two categories:
 granulocytes (with granules)
 neutrophils
 eosinophils
 basophils
 agranulocytes (without granules)
 lymphocytes
 monocytes
Formed Elements of Blood
Monocyte
Platelets
Small
lymphocyte
Neutrophil
Eosinophil
Small
lymphocyte
Erythrocyte
Young (band)
neutrophil
Neutrophil
Monocyte
Large
lymphocyte
Neutrophil
Basophil
Separating Plasma From Formed Elements of
Blood

Withdraw
blood
Centrifuge
hematocrit (packed cell vol.)centrifuge blood to separate
components
◦ erythrocytes are heaviest
and settle first
 37% to 52% total volume
(hematocrit)
Plasma
(55% of whole blood)
◦ leukocytes and platelets
 1% total volume; buffy coat
Buffy coat: leukocytes
and platelets
(<1% of whole blood)
Erythrocytes
(45% of whole blood)
Formed
elements
◦ plasma
 the remainder of volume
 47% - 63%
Plasma and Plasma Proteins
plasma – liquid portion of blood
 3 major categories of plasma proteins

◦ albumins – smallest and most abundant
◦ globulins (antibodies)
 provide immune system functions
 alpha, beta and gamma globulins
◦ fibrinogen
 precursor of fibrin threads that help form blood clots
Composition of Whole Blood
Percentages show the relative proportions of the
different components of plasma and formed
elements.
Blood Plasma
Plasma is 55% of blood

91% water

8% protein
•1% other materials
–Glucose
–Amino acids
–Lipids
◦ Albumin
–Electrolytes
◦ Clotting factors
–Vitamins
◦ Antibodies
◦ Complement
–Hormones
–Wastes
–Drugs
–Dissolved gases
Hemopoiesis

adult production of 400 billion platelets, 200 billion
RBCs and 10 billion WBCs every day

hemopoiesis – the production of blood, especially
its formed elements

hemopoietic tissues produce blood cells
◦ yolk sac produces stem cells for first blood cells
 colonize fetal bone marrow, liver, spleen and thymus
◦ liver stops producing blood cells at birth
◦ spleen remains involved with lymphocyte production
◦ red bone marrow produces all seven formed
elements
The Formed Elements

Produced in red bone marrow

Hematopoietic (blood-forming) stem cells
can develop into any blood cell

Short-lived tissue cells
Erythrocytes
Red blood cells (RBCs) most numerous
 Mature cells anuclear
 Contain hemoglobin

◦ Binds to oxygen for transport
◦ Carries hydrogen ions for buffering
◦ Carries carbon dioxide for elimination
Erythrocytes (RBCs)
Erythrocytes (RBCs)
Erythrocytes are an example of the
complementarity of structure and function
 Structural characteristics contribute to its
gas transport function

◦ Biconcave shape has a huge surface area
relative to volume
◦ Erythrocytes are more than 97% hemoglobin
◦ ATP is generated anaerobically, so the
erythrocytes do not consume the oxygen they
transport
Erythrocyte Function

RBCs are dedicated to respiratory gas transport

Hb reversibly binds with oxygen and most oxygen in
the blood is bound to Hb

Hb is composed of the protein globin, made up of
two alpha and two beta chains, each bound to a
heme group

Each heme group bears an atom of iron, which can
bind to one oxygen molecule

Each Hb molecule can transport four molecules of
oxygen
Erythrocytes and Hemoglobin

RBC count and hemoglobin concentration indicate amount of O2 blood
can carry
◦ hematocrit (packed cell volume) – percentage of whole blood
volume composed of red blood cells
 men 42- 52% cells; women 37- 48% cells
◦ hemoglobin concentration of whole blood higher in men
◦ RBC count higher in men

Why values are lower in women
◦ androgens stimulate RBC production
◦ women have periodic menstrual losses
◦ hematocrit is inversely proportional to percentage of body fat
Hemoglobin (Hb)

Oxyhemoglobin – Hb bound to oxygen
◦ Oxygen loading takes place in the lungs

Deoxyhemoglobin – Hb after oxygen
diffuses into tissues (reduced Hb)

Carbaminohemoglobin – Hb bound to
carbon dioxide
◦ Carbon dioxide loading takes place in the
tissues
Production of Erythrocytes

Hematopoiesis – blood cell formation

Hematopoiesis occurs in the red bone
marrow of the:
◦ Axial skeleton and girdles
◦ Epiphyses of the humerus and femur

Hemocytoblasts give rise to all formed
elements
Hormonal Control of Erythropoiesis

Erythropoietin (EPO) release by the kidneys
is triggered by:
◦ Hypoxia due to decreased RBCs
◦ Decreased oxygen availability
◦ Increased tissue demand for oxygen

Enhanced erythropoiesis increases the:
◦ RBC count in circulating blood
◦ Oxygen carrying ability of the blood
Erythropoietin Mechanism
Start
Homeostasis: Normal blood oxygen levels
Stimulus: Hypoxia due to
decreased RBC count,
decreased amount of
hemoglobin, or decreased
availability of O2
Increases
O2-carrying
ability of blood
Reduces O2 levels
in blood
Enhanced
erythropoiesis
increases
RBC count
Erythropoietin
stimulates red
bone marrow
Kidney (and liver to a smaller
extent) releases erythropoietin
Erythrocyte Homeostasis


negative feedback control
◦ drop in RBC count causes kidney hypoxia
◦ kidney production of EPO stimulates
bone marrow
◦ RBC count increases in 3 - 4 days
stimuli for increasing erythropoiesis
◦ low levels O2 (hypoxemia)
◦ high altitude
◦ increase in exercise
◦ loss of lung tissue in emphysema
Hypoxemia
(inadequate O2 transport)
Increased
O2 transport
Sensed by liver and kidneys
leaves
Increased
RBC count
Accelerated
erythropoiesis
Secretion of
erythropoietin
Stimulation of
red bone marrow
Erythrocyte Disorders

polycythemia - an excess of RBCs
◦ primary polycythemia (polycythemia vera)
 cancer of erythropoietic cell line in red bone marrow
 RBC count as high as 11 million/L; hematocrit 80%
◦ secondary polycythemia
 from dehydration, emphysema, high altitude, or physical
conditioning
 RBC count up to 8 million/L

dangers of polycythemia
◦ increased blood volume, pressure, viscosity
 can lead to embolism, stroke or heart failure
Anemia

causes of anemia fall into three categories:
◦ inadequate erythropoiesis or hemoglobin synthesis
 kidney failure and insufficient erythropoietin
 iron-deficiency anemia
 inadequate vitamin B12 from poor nutrition or lack of
intrinsic factor (pernicious anemia)
 hypoplastic anemia – slowing of erythropoiesis
 aplastic anemia - complete cessation of
erythropoiesis
◦ hemorrhagic anemias from bleeding
◦ hemolytic anemias from RBC destruction
Anemia

anemia has three potential consequences:
◦ tissue hypoxia and necrosis
 patient is lethargic
 shortness of breath upon exertion
 life threatening necrosis of brain, heart, or kidney
◦ blood osmolarity is reduced producing tissue
edema
◦ blood viscosity is low
 heart races and pressure drops
 cardiac failure may ensue
Blood Types

blood types and transfusion compatibility
are a matter of interactions between
plasma proteins and erythrocytes

blood types are based on interactions
between antigens and antibodies
Blood Antigens and Antibodies

antigens
◦ complex molecules on surface of cell membrane
that are unique to the individual
 used to distinguish self from foreign
 foreign antigens generate an immune response
 agglutinogens – antigens on the surface of the
RBC that is the basis for blood typing
Blood Antigens and Antibodies

antibodies
◦ proteins (gamma globulins) secreted by plasma
cells
 part of immune response to foreign matter
 bind to antigens and mark them for destruction
 forms antigen-antibody complexes
 agglutinins – antibodies in the plasma that bring
about transfusion mismatch
ABO Group

your ABO blood type is determined by
presence or absence of antigens
(agglutinogens) on RBCs
◦ blood type A person has A antigens
◦ blood type B person has B antigens
◦ blood type AB has both A and B antigens
◦ blood type O person has neither antigen
 most common - type O
 rarest - type AB
Universal Donors and Recipients
Safest transfusion is same blood type
 universal donor

◦ Type O – most common blood type
◦ lacks RBC antigens
◦ donor’s plasma may have both antibodies against
recipient’s RBCs (anti-A and anti-B)
 may give packed cells (minimal plasma)

universal recipient
◦ Type AB – rarest blood type
◦ lacks plasma antibodies; no anti- A or B
Blood Typing
Labels on the bottles denote the
kind of antiserum (antibodies)
added to the blood samples.
Anti-A serum agglutinates (causes
to clump) red cells in type A
blood, but anti-B serum does not.
Type A
Type B
Type AB
Type O
Anti-B serum agglutinates red cells
in type B blood, but anti-A serum
does not. Both sera agglutinate
type AB blood cells, and neither
serum agglutinates type O blood
Leukocytes

White blood cells (WBCs) colorless, round
◦ Granulocytes
 Neutrophils (polymorphs)
 Eosinophils
 Basophils
◦ Agranulocytes
 Lymphocytes
 Monocytes


Prominent nuclei
Clear body of foreign material, cellular debris,
pathogens
Hemostasis
Prevents blood loss when blood vessel
ruptures
 Contraction of smooth muscles in blood
vessel wall (vasoconstriction)
 Formation of platelet plug
 Formation of blood clot
Uses of Blood and Blood
Components

Blood stored in blood banks up to 35
days
◦ Anti-clotting solution added
◦ Expiration date added

Blood donated before elective surgery
(autologous blood)
Whole Blood Transfusions
Used for loss of large volume of blood

Massive hemorrhage from serious injuries

During internal bleeding

During or after an operation

Blood replacement in treatment of HDN
Use of Plasma

Replace blood volume

Treat circulatory failure (shock)

Treat plasma protein deficiency

Replace clotting factors

Provide needed antibodies
Blood Disorders
Blood abnormalities
 Anemia (low level of hemoglobin or red
cells)
 Leukemia (increase in white cells)
 Clotting disorders (abnormal tendency to
bleed)
Anemia
Anemia causes
 Excessive loss or destruction of red cells
◦ Hemorrhagic anemia
◦ Hemolytic anemia
◦ Sickle cell anemia

Impaired production of red cells or
hemoglobin
◦ Deficiency anemia
◦ Thalassemia
◦ Bone marrow suppression
Leukemia
Leukemia is characterized by enormous
increase in white cells
 Myelogenous leukemia from bone
marrow
 Lymphocytic leukemia from lymphoid
tissue
 Bone marrow transplants sometimes
successful in restoring blood-producing
stem cells lost after leukemia treatment
Clotting Disorders
Abnormal bleeding through disruption of
coagulation process
 Hemophilia
 Von Willebrand disease
 Thrombocytopenia
 Disseminated intravascular coagulation
(DIC)
The Blood Slide (Smear)
Complete blood count (CBC) performed
on drop stained blood slide

Red cells examined

Platelets examined

Parasites may be found

Differential white count performed