Transcript The Blood - MYP5BIOLOGY

The 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
digested food
red blood cells
white blood cells
oxygen
waste (urea)
platelets
carbon dioxide
plasma
hormones
The Blood
red blood cell
platelets
white blood cell
plasma
Functions of Blood

Distribution - nutrients, wastes,
hormones, gases, etc.

Self-sealing – hemostasis

Disease/ infection fighting
Blood = connective tissue
extracellular
matrix:
Plasma
specialized cells:
(= Formed elements)
RBCs
WBCs
color ?
volume ?
Platelets
Plasma Composition
Transports organic and
inorganic molecules,
formed elements, and heat



Water
92%
Plasma proteins 7%
Other solutes
1%
Plasma 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
It also contains useful
things like;
• carbon dioxide
A strawcoloured
liquid that
carries the
cells and the
platelets
which help
blood clot.
• glucose
• amino acids
• proteins
• minerals
• vitamins
• hormones
• waste materials
like urea.
BLOOD CELLS
Red and White
Blood Cells
Platelets
Platelets
 WBCs


RBCs
.1%
99.9%
.
Why white 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
a biconcave disc that is round
and flat without a nucleus
can change shape to an
amazing extent, without
breaking, as it squeezes
single file through the
capillaries.
contain haemoglobin, a
molecule specially designed
to hold oxygen and carry it to
cells that need it.
Structure of Hemoglobin (Hb)
b
Fe ion
in heme
group
reversibly
binds O2
How many oxygen
molecules can 1
Hb molecule
carry?
a
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 = 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
.
PHOGOCYTES engulf and digest
micro-organisms .
some lymphocytes fight disease by making antibodies to destroy
invaders by dissolving them.
other lymphocytes make antitoxins to break down poisons.
Phagocytic cell
Other phagocytes
Lymphocytes



~ 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 = 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 Clotting
Injury/ Ruptured blood vessel
Activates platelets to release
Thrombokinase
(enzyme)
catalyses
Prothrombin
(inactive)
(Ca2+, Vit K)
Thrombin
(active)
catalyses
Fibrinogen
(soluble)
Fibrin
(insoluble)
Forms
meshwork
Blood Clot
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 Formation
Hemocytoblasts: One type of stem cell for all blood cells
. . . then differentiation
into 4 types of
progenitor stem cells:
Erythroblast
Myeloblast
Monoblast
Lymphoblast
In red bone marrow
Fig 20.8