The BloodThe Blood
Discuss the composition of blood including the functions of the various components
Explain the anatomy and functions of the red blood cells, including a description of blood typing
Discuss the types of white blood cells found in the blood and give the functions of each
Give a brief accounting of the platelets
Review hemopoiesis, including RBC and leukocyte formation
what’s in
red blood cells white blood cells
platelets
plasma
carbon dioxide
digested food
waste (urea)
hormones
oxygen
The Blood
plasma
red blood cell white blood cell
platelets
Functions of Blood
Distribution - nutrients, wastes, hormones, gases, etc.
Self-sealing – hemostasis
Disease/ infection fighting
Blood = connective tissue
extracellularmatrix:Plasma
specialized cells:
(= Formed elements)
RBCs
WBCs
Plateletscolor ?volume ?
Plasma CompositionPlasma Composition
Water 92%
Plasma proteins 7% Other solutes
1%
Transports organic and inorganic molecules, formed elements, and heat
Plasma ProteinsPlasma Proteins
There are some proteins that are essential which swims in the blood:
example
Fibrinogen (4%) Essential component of clotting system (conversion to insoluble fibrin)
Plasma
A straw-coloured liquid that carries the cells and the platelets which help blood clot.
• carbon dioxide
• glucose
• amino acids
• proteins
• minerals
• vitamins
• hormones
• waste materials like urea.
It also contains useful things like;
BLOOD CELLS BLOOD CELLS
Red and White Blood Cells
Platelets
Platelets WBCs
RBCs
.1%
99.9%
..Why whitewhite blood cells
RBCs = Erythrocytes
Measured by hematocrit or PCV
Most abundant blood cell: 1000 RBCs/1 WBC
Contain hemoglobin, carry O2
Very regular shape - biconcave discs
NO Nucleus: Lifespan ~ 120 days replacement rate ~ 3 mio RBCs / sec
Red Blood Cells
contain haemoglobin, a molecule specially designed to hold oxygen and carry it to cells that need it.
can change shape to an amazing extent, without breaking, as it squeezes single file through the capillaries.
a biconcave disc that is round and flat without a nucleus
Structure of Hemoglobin (Hb)Structure of Hemoglobin (Hb)
Fe ion in heme group reversibly binds O2
How many oxygen
molecules can 1
Hb molecule
carry?
Acclimatization• People living at high altitudes usually have
large number of RBCs.• Compensate for low oxygen concentration at
high altitudes
Clinical Brief
Anemia:Reduced oxygen carrying ability of blood.
Causes
One cause of anemia is iron deficiency anemia as iron is essential to make hemoglobin which is needed to transport oxygen
WBCs = LeukocytesWBCs = Leukocytes
Quantity and type determined by differential WBC count
Circulating WBCs are only a small fraction of total WBCs. Most are located in BETWEEN CELLS
There are many types of WBC
White Blood Cells
there are many different types and all contain a big nucleus.
the two main ones are the lymphocytes and the PHAGOCYTES .
some lymphocytes fight disease by making antibodies to destroy invaders by dissolving them.
other lymphocytes make antitoxins to break down poisons.
PHOGOCYTES engulf and digest micro-organisms .
Phagocytic cell
Other phagocytes Other phagocytes
LymphocytesLymphocytes
~ 20% - 30% of circulating WBCs Relatively small (slightly larger than RBCs) Large round nucleus
Antibodies Pathogens contain antigens (chemicals) on
their sufaces These antigens stimulate lymphocytes to
produce specific antibodies Antibodies can:
» kill bacteria » neutralize toxins» Cause bacteria to clump together (agglutination)
Specificity
• Antibodies specific for bacteria A (eg. measles) will not attack bacteria B (eg. chicken pox)
Immunity
After an illness (e.g. chicken pox), antibodies against chicken pox persist and remain in the blood
Thus, the person is said to be immune to chickenpox
Memory cells
Special type of lymphocytes (WBCs) Formed after an infection / illness Remain in the blood stream for life Able to be activated very quickly if person
encounters the same antigen again Person is said to be immune to that
infection/ illness
Vaccines
Dead or harmless form of the pathogen (BCG vaccine against tuberculosis)
Toxoid – the inactivated toxin from the pathogen (tetanus vaccines)
Organ transplant and tissue rejection
Replacement of diseased organ with healthy one
BUT new organ must not be rejected by body
(Body detects new organ as foreign particle Defence system kicks in)
Prevention of tissue rejection
Donor and recipient must be close relatives Suppress immune system
» Use of drugs called immuno-supressive drugs» X-ray of bone marrow to reduce blood production
Platelets = ThrombocytesPlatelets = Thrombocytes
Cell fragments of Megakaryocytes
(~ 4,000 thrombocytes per Megakaryocyte)
~ 160 m
Lifespan ~ 12 days
involved in blood clotting
Platelets
Platelets are bits of cell broken off larger cells.
Platelets produce tiny fibrinogen fibres to form a net. This net traps other blood cells to form a blood clot.
Blood clotting Clotting of blood seals the wound Prevents excessive blood loss Prevents foreign particles from entering blood
Blood ClottingInjury/ Ruptured blood vessel
Thrombokinase(enzyme)
Prothrombin(inactive)
Thrombin(active)
Fibrinogen(soluble)
Fibrin(insoluble)
Blood Clot
Activates platelets to release
catalyses
(Ca2+, Vit K)
catalyses
Forms meshwork
Why doesn’t blood clot in undamaged blood vessels?
Anticlotting substance called heparin Produced in liver Thrombokinase able to neutralize the action
of heparin
Abnormal Blood Cell Counts
Leukopenia < 2,500/ L (normal 6000 – 9000)
Leukocytosis > 30,000/ L
Thrombocytopenia: < 80,000/ L (normal ~ 350,000)
Thrombocytosis: > 1,000,000/ L
Also
Lymphopenia vs. _____________
_________vs. Neutrophilia
Hemopoiesis = Blood Cell FormationHemopoiesis = Blood Cell Formation
Hemocytoblasts: One type of stem cell for all blood cells
In red bone marrowIn red bone marrow
. . . then differentiation into 4 types of progenitor stem cells:
Erythroblast
Myeloblast
Monoblast
Lymphoblast
Fig 20.8