Blood cell production Flashcards
What is blood?
- One of the main components of the cardiovascular system
- Responsible for carrying material from one part of the body to another
- It is a connective tissue made up of cellular elements, suspended in a fluid matrix (plasma- component of ECF)
- Acts as a buffer between cells and the external environment
Plasma Proteins
- Albumins are the most abundant (~60%) :
* Liver is the main source of production
* Their presence is important in the cardiovascular system to promote movement of fluid into and out of capillaries - Globulins e.g. immunoglobulins
primary proteins to synthesise antibodies in your immune system - Fibrinogen
the plasma protein that’s responsible for blood clotting - Transferrin
essential for red blood cell production
Cellular component of blood
3 main type of cells: RBC, WBC and platelets
- RBC : also known as Erythrocytes, erthyos = red
* O2 and CO2 transport
* No nuclei - WBC : are also known as leukocytes
role : facilitate an immune response.
=> broken down further into five different phenotypes of white blood cells.
lymphocytes, monocytes, neutrophils, eosinophils and basophils. - platelets : Thrombocytes/ thrombo = clotting
* are formed by splitting off their mother cells , Megakaryocytes
* initiate blood clotting process with fibrinogens
Blood cell production - Haematopoiesis
features :
* Begins early in embryonic development and continues through life
* makes 25% RBC, 75% WBC because WBC lifespan is shorter : in order to maintain a homeostatic balance to be contributing more to the white blood cell production.
=> if you’re sick, this ratio can change and produce more WBC
* production controlled by cytokines
- Colony-stimulating factors
- Interleukins
- Stem cell factor
- Erythropoietin : tell your hematopoietic stem cells to go down this pathway to lead to the production of RBC.
- Thrombopoietin : will lead to the production of platelets.
Erythropoiesis
- Controlled by glycoprotein erythropoietin (EPO) + some cytokines
Kidney controlls how much RBC is made
- Organ has reduced oxygen capacity and releases factor into blood
- Kidney senses there is a distant organ that is hypoxic and releases EPO
- EPO will then travel through your blood.
- It’ll reach your blood cell production factory in your bone marrow, which will then trigger those stem cells to now start producing more red blood cells.
- more red blood cells circulating your blood, thereby increasing the oxygen carrying capacity to serve those oxygen needs of that of that organ.
- Target for blood doping :
= doping blood with EPO causing the body to produce more red blood cells
–> thus increasing oxygen carrying capacity
–> increase cardiac output and the muscular output that one can produce when exercising
Blood Diagnostics
function: look at the proportion of RBC that you have in your blood to indicate a variety of different clinical presentations that you’ll see in the hospital.
Features:
hematocrit : the percentage of total blood volume that
is occupied by these red blood cells in centrifuge sample
buffy coat : the layer in the sample that contains WBC, less than 1% of blood
Results meaning:
–> optimal percentage of RBC in blood is between 42-45% (depends on gender)
–> lower than 30% : means you have a smaller proportion of red blood cells that are circulating in your blood, meaning that you can’t carry enough oxygen to your tissue.
–> more than 70% : having too many blood cells => causing your blood to be too viscous and having too much oxygen carrying capacity.
Red Blood Cells (Erythrocytes)
structure/ function
* No nucleus, organelles, or ribosomes : form biconcave disc structure promotes O2 transport in blood
–> Large surface area may expedite diffusion of O2 across
membrane
* Flexible membrane ==> Allows RBCs to travel through narrow capillaries without rupturing in the process
haemoglobin structure
Large complex protein with 4 globular protein chains
- Most adult Hb has two α chains and two β chains
- Each wrapped around an iron-containing heme group
heme group : heme groups are consists of these porphyrin rings
–> centre of these rings has one single iron atom
–> these iron atoms are responsible for conjugating a single molecule of oxygen.
4 heme groups per Hb so 4 oxygen molecules
!! there’s up to 200 million of these hemoglobins in a single red blood cell!!
The importance of iron
- 70% of the body’s total iron is found in Hb
- Synthesis requires adequate iron from your diet
steps of iron absorption
1. iron from diet is absorbed by active transport
2. transferrin protein transports the Fe in plasma and will carry it throughout your blood into your bone marrow.
3. bone marrow uses Fe to make Hb as part of RBC synthesis
4. when lifespan is up, spleen destroys old RBC and converts Hb to bilirubin
5. bilirubin and metabolites are excreted in urine (by the kidney) and (the liver excretes it into bile) feces
6. excess iron in liver will then be stored as ferritin
7. ferritin can act you need more or less red blood cell production.
8. if not enough iron, the liver will draw from its iron stores
RBC disorders
- If RBC levels are low (low haemocrit), anameia arises
==> Blood cannot transport enough O2 to the tissues - Sickle Cell Disease
- Abnormal Hb molecules
there is a genetic defect where 6th amino acid (glutamate) in β chain is replaced with valine
- different amino acid causes a different confirmation or that protein structure to change in shape ==> Hb polymerising (forms sickle shape) when it gives up O 2
- sickled RBC causes blockages in small blood vessels, and
rupturing of RBCs
ABO blood groups
the types of the antibodies that are circulating within your plasma depend on our blood type
O : no A/B antigens on your RBC == anti-A & anti-B antigens
A : A antigens on your RBC == anti-B antigens
B : B antigens on your RBC == anti-A antigens
AB : both A/B antigens on your RBC == no antigens
–> therefore, antibodies must not be specific to our OWN RBCs
==> So if you’re blood A, you have A antigens on your RBC, so anti A will attack your own cells
INSTEAD: you’ll have anti-B antigens
Blood Group O : Universal RBC donors
- No “A” or “B” antigens on RBC
- RBC will not be “attacked” by either anti-A or anti-B antibodies
Blood Group AB : Universal RBC recipients
- Lack both anti-A and anti-B antibodies won’t attack other RBCs
- Can accept donor blood of any type
Rhesus blood groups
Rh D antigen is what determines if our blood type is + or - (Positive means Rh D antigen present)
- If you are Rh negative (no antigen present on RBC) and exposed to Rh-positive blood (has antigens on RBC), then you will produce Rh-positive antibodies against the D antigen
- Significant in pregnancy is a Rh-negative mother is pregnant with a Rh-positive foetus
- Mother produces Rh-positive antibodies that cross placenta and react with the foetus’ RBCs and destroys them
- Haemolytic disease of the newborn
