Now we will discuss the basics of blood.
Blood has a lot of functions.
It's responsible in assisting
in respiration, nutrition
thermoregulation which is
temperature control in your body,
immunity, hemostasis because it's gonna control
of the control the ability to clot or stop bleeding,
What's the recipe for blood?
Well, it's composed of two things: (1) plasma which is
a yellowish fluid that contains nutrients, proteins,
hormones and waste,
and (2) blood cells.
In the blood cells we see white blood
cells, red blood cells and platelets.
Plasma. This is the
liquid portion of the blood
and it's a complex solution
containing more than 90% water.
The water can move between the plasma
and the body cells and other extracellular fluid
and it's available to maintain
hydration to the tissues.
Every living cell within
the body relies on this water.
Plasma is a very protein-rich solution
compared to the extracellular fluid
and about 7% of the
plasma is made of proteins.
These plasma proteins can exert the
osmotic effect to control the water movement
from the extracellular fluid to the plasma.
The major plasma protein is called albumin and it
is responsible for keeping water in the bloodstream
by its osmotic effect.
Another type of protein found in
the plasma are the immunoglobulins.
These are your antibodies and these are produced in
response to a specific foreign substance or an antigen.
There are other solutes in the plasma including lipids, and
this is the phospholipids, triglycerides and cholesterol.
Glucose is also present
and this is your blood sugar.
It's absorbed from the GI tract and can
be released into the blood from the liver.
This provides a constant source
of energy for your tissue cells
and is the only source for some
cells including the red blood cells.
If glucose is not needed immediately, it
can be conserved and stored for later.
Amino acids. These are transported in the plasma and are
required for all protein synthesis throughout the body.
Nitrogenous wastes. The plasma is also
responsible for handling the waste products.
This includes uric acid,
creatinine and urea.
This is an end product of the protein
metabolism and these are all removed.
Electrolytes are present including sodium,
potassium, chloride, calcium, magnesium and phosphate.
Hormones. The hormones of the
endocrine glands are secreted into the plasma
and transported to their target organs,
the organs on which they exert their effects.
You'll also see gases and this
includes oxygen and carbon dioxide.
Now let's look at the blood cells.
The blood cells contain red blood cells which are
our erythrocytes, platelets which are thrombocytes
and white blood cells
which ae your leukocytes.
And within the leukocytes,
we see lymphocytes
and phagocytes -and these
are granulocytes and monocytes.
These are parts of the components
of the complete blood count or CBC.
First, we're gonna talk
about red blood cells.
These are highly
specialised and these are the most abundant cells in the blood.
They account for approximately
40 to 45% of the blood.
They're used to transport oxygen.
They also are used to transport carbon
dioxide from the tissues to the lungs.
These are shaped as biconcave discs
and this increases the surface to volume ratio.
Oxygen from the lungs binds with
hemoglobin molecules on the red blood cell
and then it's transported
and released to the tissues.
Red blood cells can squeeze through small
vessels and they can change shape without breaking.
Once they squeeze through a
tiny vessel and they're compressed,
they can pop right back into their
original shape because they're squishy.
They can be broken if they're stretched
or swell and this can destroy the cell.
The membrane is freely permeable to water, oxygen, carbon
dioxide, glucose, urea and certain other substances.
It is impermeable to hemoglobin.
Red blood cells are
subjective to osmotic effects
when they are suspended in very dilute
or hypotonic solutions of sodium chloride.
They're gonna take in the water in this will
cause them to swell, this can destroy the cell.
In a concentrated salt solution, the red
cells will lose their water and will shrink.
The membrane of a red blood cell has a group of
molecules that confer the blood group specificity,
and this is type A,B, AB or O.
95% of the dry weight of a
red blood cell is the hemoglobin.
Let's talk about hemoglobin.
We abbreviate this as Hb or Hgb.
This is the iron-containing oxygen
transport protein on a red blood cell.
It carries oxygen from
lungs to the rest of the body.
Now anemia is defined as a patient who has a less than
5th percentile normal hemoglobin level based on age.
Most anemic children are asymptomatic.
How are red blood cells made? Well
this is a process called erythropoeisis.
Red blood cells cannot repair themselves
so they have to be constantly generated.
These are produced
continuously in the bone marrow,
and certain nutrients such as riboflavin, vitamin
B12 and folic acid are necessary for this process.
The rate of production is controlled by
erythropoeitin which is produced in the kidneys.
So you'll see up top this
is done for two reasons:
First there can be a decrease in the number of
cells, and a decreased level of oxygen in the cells
Now look over on the chart, the decreased oxygen in the
tissues is going to stimulate the release of erythropoietin.
this is going to increase the erythropoeitin in the
blood and that's gonna stimulate the bone marrow
to churn out more red blood cells.
This in turn will increase the oxygen to the tissues and that
feedback is going to inhibit further eryrthopoeitin release.
This helps maintain homeostasis
which is the steady-state.
Red blood cells are also destroyed.
They live about 120 days.
The wear and tear is going to lead
to the loss of proteins and enzymes
and their function's going to decrease.
Also as they age, their
chemical reactions are impaired.
Water is going to pass in and they're
gonna swell and become sluggish
and eventually they'll be
engulfed by phagocytes.
The proteins are gonna
be broken down and reused
and the iron is gonna go back
to the bone marrow for reuse.
Bilirubin is released and it's gonna be transported
to the liver for processing and removal from the body.