Download Blood and its function

Cardiovascular System (CVS)
L-1: Blood and Its Function
Dr Than Kyaw
6 February 2012
Blood vascular system
• Closed system
• Blood Vessels – through which blood travels
• Heart – pumps or pushes blood through body
• Blood – mainly transport important substances
through body
The Blood
• Constitute
1. Cells: Erythrocytes (red blood cells; RBC)
Leukocytes (white blood cells; WBC)
Platelets (Thrombocytes)
2. Plasma
Colloides (proteins)
Electrolytes (Ca, Na, K, etc)
Other substances (hormones,
vitamins, etc)
Formed
elements
Functions of Blood
• Transport
- Nutrients absorbed from GI tract
- O2 – from lungs to cells of whole body
- CO2 - – from metabolized cells to lungs
- Wastes - from metabolized cells to kidney
- Hormones – from endocrine glands to target cells
• Body temperature control
• Maintenance of body fluid pH (Buffering action)
• Prevent blood loss (coagulation)
• Prevent diseases (phagocytosis and antibody production)
Blood volume
• Total amount of blood in an animal’s body including
formed elements and plasma
• Usually 8 – 10% of the body weight
What will be the different percentages of
- lean, muscular, or athletic animals and
- fat animals
Can blood volume be measured by bleeding?
The Hematocrit
– Percent of packed cell volume (PCV) in whole blood
– Measured as
- Blood + anicoagulant in hematocrit tube
- Centrifuge
(11,000 rpm; 5 min)
- Usually buffy coat
not counted
The Hematocrit values of animals
– Percent of packed cell volume (PCV) in whole blood
•
•
•
•
•
•
•
•
•
Human - 45% in males; 42% in females
Cow – 35%
Horse – 41%
Sheep – 35%
Pig – 42%
Dog – 45
Chicken – 30%
White whale - 53% in females; 52% in males
Pekin duck - 45% at seal level; 56% at high altitude
Why is hematocrit value of animals higher at high altitude?
Blood pH
Average pH value
Arterial blood = 7.4
Venous blood = 7.36
Blood pH should not be changed too much
from normal.
Why is pH of venous blood lower than arterial
blood?
Erythrocytes
– Oblong oval or biconcaved flattened discs
– Flexible
– Contain no nucleus, orgennelles, or ribosomes
– Contain plasma and hemoglobin
RBCs of Birds and Fishes have nuclei
Erythrocytes
• Transport O2 and CO2
• Color: due to O2 carrying pigment: hemoglobin
• Oxygen-rich blood is scarlet red
• Contains oxyhemoglobin
• Oxygen-poor blood is bluish
• Contains deoxyhemoglobin
Does not use the oxygen that they carry!
RBC Lifespan
•
•
•
•
•
•
Horse
Cattle, Sheep, Goat
Pig
Dog
Cat
Chicken
140 – 150
125 – 160
75 – 95
100 – 120
70 – 80
20 - 30
Hemoglobin
• Hemoglobin reversibly binds with O2 and most O2
in the blood is bound to hemoglobin
• Composition of hemoglobin
– A protein called globin
• made up of two alpha and two beta chains
– A heme molecule
• Each heme group bears an atom of iron, which can bind to
one oxygen molecule
• Each hemoglobin molecule thus can transport four molecules
of oxygen
Hemoglobin
• Oxyhemoglobin – hemoglobin bound to oxygen
– Oxygen loading takes place in the lungs
• Deoxyhemoglobin – hemoglobin after oxygen diffuses
into tissues (reduced Hb)
• Carbaminohemoglobin – hemoglobin bound to CO2
– CO2 loading takes place in the tissues
Hemoglobin
 Iron-containing protein
(Hb + globin)
Molecular weight of Hb = 67,000
 Binds reversibly to oxygen
 Each molecule has four oxygen binding sites
 Each erythrocyte can carry 250 million hemoglobin
molecules
Fate of Erythrocytes
 Unable to divide, grow, or synthesize proteins
 Wear out in 100 to 120 days
 Removed by
Monocyte-macrophage system
(Also k/s RE-System=Reticulo-endothelial system or
MPS = Mononuclear phagocytic system)
After leaving the blood stream, the monocytes
become fixed-macrophages in the sinusoids of
liver, spleen, bone marrow and lymph nodes.
Senescent RBCs
Hemolysed* RBCs
In MPS cells
releasing HB
*What are hemolytic
Fate of
Erythrocytes
agents?
(bacterial toxins,
snake venoms,
blood parasites,
hypotonic solutions)
Leukocytes (White Blood Cells)
Properties
 Play a role in immune response
 Typical cells with nucleus, organelles
 Able to move into & out of blood vessels by
Diapedesis: Gr. “leaping through”
Leukocytes (White Blood Cells)
Properties
 Move by ameboid motion
 Respond to chemicals released by damaged
tissues
 “chemotaxis” – chemical attraction
 Allows for immune response
Types of Leukocytes




Leucocytes: brightly colored in stained preparations,
have a nuclei and are generally larger in size than
RBC’s.
Two categories – 1. Granulocytes &
2. Agranulocytes
All together 5 cell types
Classified by the +/- of granules and the staining
characteristics of their cytoplasm.
Agranulocytes
Granulocytes
Granulocytes
have large granules in their cytoplasm
Three types
 Neutrophils
 Eosinophils
 Basophils
Neutrophils







Stain light purple with neutral dyes
Granules are small and numerous—course
appearance
Several lobes in nucleus
65% of WBC count
Highly mobile/very active
Diapedesis—Can leave blood vessels and enter
tissue space
Phagocytotic - contain several lysosomes
1. Neutrophils
2. RBCs
Eosinophils or Acidophils






Large, numerous granules
Nuclei with two lobes
2-5% of WBC count
Found in lining of respiratory and digestive tracts
Important functions involve protections against infections
caused by parasitic worms and involvement in allergic
reactions
Secrete anti-inflammatory substances in allergic reactions
Basophils



Least numerous -- 0.5-1%
Diapedesis — Can leave blood vessels and
enter tissue space
Contain histamine, serotonin, heparin—
inflammatory chemical
Agranulocytes
do not have granules in their cytoplasm
Lymphocytes
 Monocytes

Lymphocytes




Smallest WBC
Large nuclei/small amount of cytoplasm
Account for 25% of WBC count
Two types—T lymphocytes—attack an infect or
cancerous cell
B lymphocytes—produce antibodies against
specific antigens (foreign body)
Monocytes





Largest of WBCs
Dark kidney bean shaped nuclei
Highly phagocytic
Longer life span
Found in chronic infection (long term defence)
White Blood Cells
– Fight and kill germs
that may enter
blood stream
Lifespan of White Cells
• Granulocytes – 6 – 20 h in blood
2 – 3 d in tissues
- Once they leave blood, they normally do not return
•
Monocytes – 24 h in blood
- several months in tissues
- become fixed macrophages in sinusoids of
liver, spleen, bone marrow and lymph nodes
• Lymphocytes - T cells: 100 – 200 d
B cells: 2 – 4 d
Memory T and B cells (years)
- lymphocytes repeatedly circulate from blood
to tissues, to lymph and back to blood
Platelets
(Thrombocytes)
Platelets
• Platelets are fragments of megakaryocytes
• Their granules contain serotonin, Ca2+,
enzymes, ADP, and platelet-derived growth
factor (PDGF)
• Platelets function in the clotting mechanism
by forming a temporary plug that helps seal
breaks in blood vessels
• Platelets not involved in clotting are kept
inactive by Nitric Oxide (NO) and
prostaglandins
Hematopoiesis
Formation of Blood Elements
Erythropoiesis
Hematopoiesis
Leukopoiesis
●
●
Formed in the red marrow of many bones.
Also can be formed in lymphatic tissues.
Hematopoiesis
• All blood cells originate from pluripotent stem cell
hemocytoblasts
– The mother of all blood stem cells
• Hemocytoblasts differentiate into myeloid stem cells and
lymphoid stem cells
– Myeloid stem cells become myeloblasts or monoblasts
• Granulocytes form from myeloblasts
• Monoblasts enlarge and form monocytes
– Lymphoid stem cells become lymphoblasts
• Lymphoblasts develop into lymphocytes
All blood cells originate from pluripotent stem cell hemocytoblasts
Pluripotent stem cells
(Hemocytoblasts)
Myeloid
stem cells
Rubriblast
Erythrocytes
Lymphoid
stem cells
Megakaryoblasts
Myeloblast
Monoblast
Lymphoblast
Thrombocytes
Granulocytes
(Neutrophils,
Eosinophils,
Basophils
Monocytes
Lymphocytes
Hormonal control of erythropoiesis
Hypoxia (decreased RBCs)
Decreased O2 availability
Increased tissue demand for O2
Stimulate
Erythropoietin
(glycoprotein
produced by kidney)
Bone marrow
Adequate supplies of
iron, amino acids, and
B vitamins
Erythropoiesis
Erythropoiesis
Dietary Requirements
• Erythropoiesis requires:
– Proteins, lipids, and carbohydrates
– Iron, vitamin B12, and folic acid
• The body stores iron in Hb (65%), the liver, spleen,
and bone marrow
• Intracellular iron is stored in protein-iron
complexes such as ferritin and hemosiderin
• Circulating iron is loosely bound to the transport
protein transferrin
Blood Groups and Transfusions
• Large losses of blood have serious
consequences
• Loss of 15 to 30 % causes weakness
• Loss of over 30 % causes shock, fatal
• Seldom practiced in animal
Blood Groups and Transfusions
 Transfusions are the only way to replace blood
quickly
 Transfused blood must be of the same blood
group
 Wrong group: dead patient
 First done: William Harvey, England (1600’s?)
Blood Groups and Transfusions
• RBCs carry genetically determined proteins
• Called antigens (Ag)
• Proteins embedded in cell membrane
• A foreign protein (Ag) may be attacked by the
immune system
Blood groups in animals and man
• Animals have a variety of different blood
types
• Human 4 groups
Blood Groups of some animals
Animal spp
Blood groups
Cattle
A, B, C, F, J, L, M, R, S, T, Z
11
Goats
A, B, C, M, J
5
Sheep
A, B, C, D, M, R and X
7
Horse
8 major groups (A, C, D, K, P, Q, U, T)
Over 30
Cat
A, B, AB
3
Dog
DEA 1.1, 1.2, 4, 5, 6,7, 8
8
Human
A, B, AB, O
4
DEA=Dog Erythrocyte Antigen
Blood Typing
• Blood antigens
– Type A
– Type B
• Agglutininins (Ab)
– Act in blood typing
– Antigen-antibody
reaction
ABO Blood Groups
 Based on the presence or absence of two
antigens
- Type A
- Type B
 The lack of both these antigens is called type O
ABO Blood Groups
 The presence of A is called type A
 The presence B is called type B
 The presence of both A and B is called type AB
Blood Groups
• Blood Types and
their corresponding
Abs
–
–
–
–
Type A, anti-B
Type B, Anti-A
Type AB, neither
Type O, both
Rh Blood Groups
 Depends on presence or absence of Rh
antigens (agglutinogen D)
 Most Americans are Rh+ (85%)
 Rest are Rh Problems can occur in mixing Rh+ blood into a
body with Rh– blood
Rh Dangers During Pregnancy
 Called hemolytic disease of the newborn or
Erythroblostosis fetalis
 Danger is only when
 the mother is Rh–
 the father is Rh+
 the child inherits the Rh+ factor
Rh Dangers During Pregnancy
 Problem in an Rh– mother carrying an Rh+ baby:
 The first pregnancy usually proceeds without
problems
 At birth, mother may receive some of baby’s
RBCs
Rh Dangers During Pregnancy
 Mom’s immune system is sensitized
 Makes antibodies against Rh
 In a subsequent pregnancy:
 Mother’s blood carries antibodies
 Anti-Rh antibodies cross placenta
 Attack the Rh+ blood in the fetus
Rh Dangers During Pregnancy
 Erythroblostosis fetalis, or

Hemolytic disease of the newborn
Fig. 11.13
Blood Groups and Transfusions
 Large losses of blood have serious
consequences
 Loss of 15 to 30 percent causes weakness
 Loss of over 30 percent causes shock, which
can be fatal
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 10.25
Blood Groups and Transfusions
 Transfusions are the only way to replace blood
quickly
 Transfused blood must be of the same blood
group
 Wrong group: dead patient
 First done: William Harvey, England (1600’s?)
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 10.25
Human Blood Groups
 RBCs carry genetically determined proteins
 Called antigens (Ag)
 Proteins embedded in cell membrane
 A foreign protein (Ag) may be attacked by the
immune system
Human Blood Groups
 How blood is “typed”:
 Uses antibodies (Ab)
 Made by body against foreign proteins
 cause “different” blood to clump (agglutination)
Blood Typing
Blood Typing
 Typing for Rh factors is done in the same
manner
 Cross matching
 testing for agglutination of donor RBCs
by the recipient’s serum
 testing for agglutination of recipient
RBCs by the donor’s serum
Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings
Slide 10.30
Blood Typing
 Blood samples are mixed with anti-serum
 anti-A: “against” A antigens
 anti-B: “against” B antigens
 Presence/absence of agglutination
determines blood type