THE BLOOD
PNUR 101
ANATOMY & PHYSIOLOGY
BLOOD IS…

a liquid connective tissue with cells
moving in a fluid matrix (plasma)

bright red when oxygenated

dark red/bluish when deoxygenated

8% of total body weight or approx. 5 litres of
blood in the body
FUN FACTS


Historically blood was thought to be the “essence of
life” because if we loose too much we die
It also was thought to define our character and
emotion:
• Noble bloodline = blueblood
• Criminals = bad blood
• Anger = blood boils
• Fear = blood curdles
FUNCTION OF BLOOD

Transportation
gases (O2 and CO2) nutrients, wastes
• regulatory molecules – hormones, enzymes
•

Regulation
•
pH (7.35 – 7.45)
water content
• body temperature
•

Protection
foreign substances/pathogens
• clot formation
•
BLOOD CONSTITUENTS
BLOOD PLASMA

91% water (serum)

7% plasma proteins
albumin – maintain osmotic pressure
• globulins – act as antibodies, transports substances
• fibrinogen & prothrombin - formation of blood clots
•

2% other
•
gases, glucose, amino acids, lipids, electrolytes,
hormones, vitamins, urea, other wastes, drugs
FORMED ELEMENTS
Erythrocytes (RBC), Leukocytes
(WBC), Thrombocytes (platelets)
 produced by a process called
HEMATOPOIESIS – occurs in red bone
marrow and lymphatic tissue
 derived from STEM CELLS that
differentiate into specific blood cells

ERYTHROCYTES (RBC)
Most abundant cell in the blood
 Life span 80-120 days – no nucleus
or cellular organelles (no cell division)
 Hemoglobin - iron-containing protein
that binds to O2 (oxyhemoglobin)
and CO2 (carbaminohemoglobin)
 Erythropoietin - hormone released from kidney in response to
decreased O2 - stimulates RBC production
 Erythropoiesis – manufacturing RBC in red bone marrow

LEUKOCYTES (WBC)
Round, prominent nucleus, irregular shapes
 Produced in red bone marrow and mature in lymph
tissue
 Travel out of blood vessels and into tissues by
amoeboid movement
 Provide immunity against micro-organisms
 Remove dead cells, micro-organisms and debris by
phagocytosis
 Differentiated by appearance when stained

TYPES OF LEUKOCYTES
Granulocytes
Agranulocytes
 Neutrophils (60-70%)
 Monocytes (3-8%)
phagocytize foreign
matter
 Basophils (0.5-1%)
• inflammatory response
• release histamine (vasodilation)
and heparin (anticoagulant)
 Eosinophils (2-4%)
• allergic reactions
•
•
mature into macrophages
and phagocytize foreign
matter (bacteria, viruses)
 Lymphocytes (20-25%)
• immune response
• produce antibodies (B cells)
• attack infected cells (T cells)
Video
Neutrophil Phagocytosis
White Blood Cell Eats Bacteria
THROMBOCYTES
(PLATELETS)
Smallest formed elements
 Fragments of
megakaryocyte cells
 Essential for preventing
blood loss (clotting)

COAGULATION/CLOTTING
Hemorrhage - excessive bleeding
Hemostasis - stop bleeding
Preventing Blood Loss
• vasoconstriction of blood vessel 
arrival of platelets  platelet plug
- if damage is significant a larger blood clot is
necessary
CLOT FORMATION
A series of reactions involving numerous clotting factors
(plasma proteins)
1.
tissue damage (platelet plug)  releases an enzyme
2.
enzyme reaction turns prothrombin (plasma protein) into
thrombin (enzyme)
3.
thrombin + fibrinogen (plasma protein)  fibrin
4.
fibrin threads form a mesh network that traps RBC’s,
platelets, plasma = clot
Video
How Blood Clots Form
`
DID YOU KNOW?
Aspirin inhibits platelet plug formation:

In heart attack or stroke victims platelet plugs can be lifethreatening
•

Small amounts of aspirin everyday can reduce the likelihood
of clot formation or another heart attack
If an expectant mother takes aspirin near the end of the
pregnancy
Mom can experience excessive bleeding after delivery
• Baby can exhibit localized hemorrhages on body
•
Video
Why We Have Different Blood Types
BLOOD TYPES
4 blood groups: A, B, AB, O
 Named for the presence or absence of antigens
(protein or sugars) on the surface of RBC
 Antibodies - proteins circulating in plasma
 Antibodies react with specific RBC antigens
causing agglutination (clumping)

A antibody agglutinates with A antigens
• B antibody agglutinates with B antigens
•
ABO Blood Typing
Type A
• A antigens on the surface of red blood cells and B antibodies in
blood plasma
 Type B
• B antigens on the surface of red blood cells and A antibodies in
blood plasma.
 Type AB
• both A and B antigens on the surface of red blood cells and no A or
B antibodies in blood plasma.
 Type 0
• neither A or B antigens on the surface of red blood cells but has both
A and B antibodies in blood plasma.

Blood Type Compatibility Chart
Rhesus (Rh) Factor
Rh+ have Rh antigen on RBC and no antibodies in
plasma
 Rh- no Rh antigen

if Rh- receives Rh+ blood can produce Rh antibodies
• with 2nd transfusion of Rh+ blood the antibodies will
clump with Rh antigen
•

Both blood type and Rh factor needed for safe
transfusion
Erythroblastosis Fatalis
DID YOU KNOW?
DIAGNOSTIC BLOOD TESTS
Hematocrit -volume percentage of RBC in whole
blood (men 42-54%, women 36-46%)
 Hemoglobin - men 140-174 g/L, women 123157g/L
 Red Blood cell count
 White Blood cell counts
 CBC - counts all blood cells present on a slide
 Chemistry - tests amounts of numerous chemicals in
the blood plasma
 GTT (Glucose Tolerance Test) - hyperglycemia
 Clotting tests (INR/PT, PTT)
