Blood
Blood Functions
• Transport
Gases
Nutrients
metabolic wastes
hormones
• Regulate
pH
temperature
fluid
• Defense
blood loss
infectious agents
•
•
•
•
O2 and CO2
Carbs, proteins, fats
urea and uric acid
Estrogen, testosterone, ADH, insulin
• Between 7.45 to 7.48
• Acts as a heat resevoir to distribute it
• tissues get fluid from blood
• Has ability to stop blood loss
• Defend against foreign invaders
Blood Composition
Cells = Formed Elements
(not all are technically cells)
Erythrocytes
aka RED blood cells
count ~ 5.0
million/drop
Leukocytes
aka White blood cells
count ~ 4,000 –
11,000/drop
Platelets
aka Thrombocytes
count 250,000 –
500,000/drp
Blood Composition
Matrix = Plasma
90% Water
8% Proteins
albumin
globulins
fibrinogen
2% Other
gases
nitrogenous wastes
nutrients
electrolytes
ERYTHROCYTES
• Biconcave discs
• Lack nucleus
• Lack mitochondria
• Contain hemoglobin
• Carry oxygen and some
carbon dioxide
HEMOGLOBIN
• HEME PORTION
Has central Fe atom that
carries one oxygen
molecule
Each Hemoglobin is like a
4 passenger TAXI
HEMOGLOBIN
• GLOBIN PORTION
4 protein chains
*each chain has one heme
*each RBC carries 250
million hemoglobin
molecule
*Therefore each RBC
carries ONE BILLION O2
HEMOGLOBIN
• When oxygen is bound to hemoglobin it is
called oxyhemoglobin.
• When oxygen is NOT bound to
hemoglobin it is called deoxyhemoglobin
• 20% of CO2 is transported
in hemoglobin, but does not
compete with oxygen site of heme
CO
So how can we get rid of CO?
Skiing the Rockies
Hematopoiesis
Formation of blood
Erythropoiesis:
formation of
erythrocytes
•Starts with hemocytoblasts
•Occurs in red bone marrow
Hemocytoblast
Stem cell
Proerythroblast
Committed cell
Early erythroblast
Ribosome production
Late erythroblast
Hemoglobin production
Normoblast
Reticulocyte
Erythrocyte
When hemoglobin content
reaches ~35%, organelles get
ejected. Eventually nucleus gets
ejected.
Gets released into blood stream
Mature cell
Time it takes for erythropoiesis
Hemocytoblasts
3 to 5
days
Reticulocytes
2 days
more
Erythrocytes
Total time to
replace RBCs is
about ONE week
Erythropoietin (EPO)
• Regulates RBC production
–Normal rates 2 million/sec
• Kidneys control production of EPO
mechanism for regulating erythropoiesis
Homeostasis: Normal blood oxygen levels
1
Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
2
Kidney (and liver to
a smaller extent)
releases
erythropoietin.
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
2 Kidney (and liver to
Erythropoietin
stimulates red
bone marrow.
3
a smaller extent)
releases
erythropoietin.
Homeostasis: Normal blood oxygen levels
1 Stimulus:
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
Enhanced
erythropoiesis
increases RBC
count.
4
2 Kidney (and liver to
3 Erythropoietin
stimulates red
bone marrow.
a smaller extent)
releases
erythropoietin.
Homeostasis: Normal blood oxygen levels
1 Stimulus:
O2- carrying
ability of blood
increases.
5
Hypoxia (low blood
O2- carrying ability)
due to
• Decreased
RBC count
• Decreased amount
of hemoglobin
• Decreased
availability of O2
4 Enhanced
erythropoiesis
increases RBC
count.
2 Kidney (and liver to
3 Erythropoietin
stimulates red
bone marrow.
a smaller extent)
releases
erythropoietin.
Induced Polycythemia
Increasing the number of red blood cells in
circulation
- Training at higher altitudes
- Blood doping
Who is he?
WHY DO BRUISES TURN
YELLOW
Fate and destruction of RBCs
Hemoglobin
Aged and damaged red
blood cells are engulfed by
Heme Globin
macrophages of liver,
Bilirubin Iron stored Amino
spleen, and bone
acids
In liver
marrow; the
Iron is released to
hemoglobin is
blood from liver as
broken down.
needed for
erythropoiesis.
Urine gets
its color
from
urochrome
(comes from
bilirubin)
Bilirubin is picked up from blood
by liver, secreted into intestine in
bile, metabolized by bacteria,
and excreted in feces.
Circulation
Food nutrients are
absorbed from
intestine and enter
blood.
Raw materials are
made available in blood
for erythrocyte synthesis.
Fate and destruction of RBCs
Circulation
Erythrocyte disorders
Anemias = abnormally LOW oxygen carrying capacity
•
low RBCs – blood loss, RBC destruction,
defective bone marrow
•
low Hemoglobin content – low iron, B12
deficiency
•
abnormal hemoglobin – sickle cell
Polycythemia = abnormal excess of RBCs
•
increases blood viscosity
•
increases blood pressure
Can be due to disease, high altitude or blood
doping
Leukocytes
• Granulocytes = have cytoplasmic granules
– Basophils – release histamine (inflammation);
contain heparin (anticoagulant)
– Neutrophils – phagocytize bacteria
– Eosinophils –role in allergies and asthma
•Agranulocytes = lack cytoplasmic granules
•Monocytes – phagocytize foreign invaders
•Lymphocytes – involved in immune response
Leukopoiesis – formation of
WBCs
Leukemia – abnormally high
WBC count of abnormal
WBCs
Leukopenia – low WBC count
Thrombocytes aka
Platelets
•Responsible for
Blood Clotting
Hemostasis
Stoppage of
blood flow
Step 1 Vascular spasm
• Smooth muscle contracts,
causing vasoconstriction.
Step 1 Vascular spasm
• Smooth muscle contracts,
causing vasoconstriction.
Collagen
fibers
Step 2 Platelet plug
formation
• Injury to lining of vessel
exposes collagen fibers;
platelets adhere.
Step 1 Vascular spasm
• Smooth muscle contracts,
causing vasoconstriction.
Collagen
fibers
Platelets
Step 2 Platelet plug
formation
• Injury to lining of vessel
exposes collagen fibers;
platelets adhere.
• Platelets release chemicals
that make nearby platelets
sticky; platelet plug forms.
Chemicals that aid platelet plug
formation
• Serotonin
– Enhances vasoconstriction
• Thromboxane
– Enhances vasoconstriction
– Attracts platelets to the wound
What is aspirin, and how does it work?
Inhibits thromboxane
increases bleeding time
Step 1: Vascular spasm
• Smooth muscle contracts,
causing vasoconstriction.
Collagen
fibers
Platelets
Fibrin
Step 2: Platelet plug
formation
• Injury to lining of vessel
exposes collagen fibers;
platelets adhere.
• Platelets release chemicals
that make nearby platelets
sticky; platelet plug forms.
Step 3: Coagulation
• Fibrin forms a mesh that
traps
red blood cells and
platelets,
forming the clot.
Inactive Clotting
Factors
Collagen
exposure
Becomes
The
catalyst
Ca+2
Active Clotting
Factors
Prothrombin
Activator
Prothrombin
Becomes
The
catalyst
Thrombin
Fibrinogen
Fibrin
Fibrin
Platelets
RBC
Figure 17.15
Clot Retraction
•Platelets contract within
30–60 minutes
•Platelets pull on the fibrin
strands pulling ends of
wound together
Fibrinolysis
•Clot dissolving
–Takes several days to occur