blood Flashcards
What are the functions of blood?
- it transports oxygen from lungs to tissues
- transports carbon dioxide(waste product of respiration) from tissues to lungs
- transports nutrients from digestive organs to cells (which are absorbed from in intestine)
- transports waste products from cells to kidneys, lungs and sweat glands (where they are destroyed)
- transports hormones from endocrine glands
- regulates body pH
- regulates body temp
- regulates water content of cells
- prevents body fluid loss
- protects against toxins and microbes
What is blood?
-it is not a homogenous substance (not made of only one thing)
(It is a transport system
without it our cells wouldn’t survive (it protects))
How is blood tested to not be homogenous?
- Withdraw blood from body
- Add some substance (heporin)
- put in test tube and spin at high speeds in a centrifuge
- heavy bits deposit at bottom of tube and light at top
What are the 2 layers which the blood separates out to?
- Blood plasma (55% of blood)- mostly water
- Red blood cells (Erythrocytes)- 45%
- buffy coat in between 2 layers
What is a haematocrit?
separation of blood
What is the other layer which separates the blood plasma and erythrocytes?
small thin white layer known as a Buffy coat
-made of white blood cells
What is another layer on top of the buffy coat?
Blood platelets (thrombocytes)
What is the composition of blood?
consists of
- blood plasma
- formed elements :
- erythrocytes ( red blood cells )
- leukocytes- white blood cells (buffy coat)
- thrombocytes(blood platelets)
What is blood plasma made of?
90% is water
-suspended within the water is a variety of things such as :
-proteins (8%)
. such as albumin- makes osmotic pressure- which makes sure water does not leak out of the capillaries - help retain water
. globulins- alpha and beta - transport molecules/nutrients, latch onto nutrients and transport them around the body
gamma globulins - they are the antibodies which are proteins produced by body to combat invading organisms
. Clotting proteins- main one is fibrinogen which is responsible of the clotting of blood.- prevent the loss of blood
What else are dissolved in the plasma?
nutrients
oxygen
carbon dioxide - lots
What is the structure of the erythrocytes?
- they are anucleate biconcave disc (big surface area for a small volume which is important for the exchange of substances across surfaces)
- this allows for them to change their shape to ‘squeeze through’ (narrow openings) capillaries due to having no nucleus as it does not restrict the shape.
- no nucleus
- 8um wide 2um thick
What is the average erythrocytes for male and females?
5,200,000 mm-3 of blood male
4,700,000mm-3 of blood female
How does the erythrocytes vary?
- decreases with age
- depends what height you live at
- depends on your health
e. g. anemia - few blood cells - depend on attitude ( higher number of erythrocytes at high attitude
What is the major function of the erythrocytes?
- to transport oxygen from lungs to other tissues
- take waste product of respiration back to the lung
How much does each erythrocyte contain?
280 million molecules of haemoglobin for this purpose
What is haemoglobin made of?
- globin- made of 4 amino acid chains
- each of these amino acid chain linked to a haem group
- the central element of haem group is iron which binds to oxygen
What is the formation of blood cells?
Haemopoiesis
- in the adult this occurs from stem cells in the red bone marrow
- (blood cells forms in RED bone marrow- confined to flat bones (sternum, ribs, vertebrae, skull, pelvis) (red blood cells give the bone marrow its colour)
Is all the blood cells formation from one or more stem cells?
- neither- somewhere in between
There are 2 extreme possibilities - all blood cells types come from one stem cell (monophyletic)
- each type of blood cell has its own stem cell (polyphyletic)
Why is haemoposiesis a limited polyphyletic theory?
It means there are 2 type of stem cells
- one known as lymphoid- which produces lymphocyte
- myeloid stem cells- which produces all the other types of blood cell.
What are the 2 types of leukoemia?
- one is problem with lymphoid stem cells
- problem with myeloid stem cells
What are the 5 phases to the development of every blood cells type? (general haemopoiesis)
- Commitment of the stem cell- decide which blood cell its going to become (commit to a line of differentiation)
- It has to proliferate - make more copies of itself
- Differentiate- make specific types of proteins for that cell e.g red blood cell so therefore make haemoglobin
- Maturation- Protein synthesis wines down
- Release- released from bone marrow
What is erythropoiesis?
formation of RED blood cells
How long do erythrocytes survive for?
- they survive 100-120 days
- Around 2.5x10^8 cells are destroyed every day by the spleen.
- longest living blood cells
How do you manage to produce so many erythrocytes?
- Stem cell-
- Commitment cell- become red blood cell
- Proriferlate- nucleus starts to shrink
- Differentiation- e.g haemoglobin starts to produce and synthesises
- Maturation- filled with haemoglobin and takes out nucleus
- Release- reticulocyte released from bone marrow when they are immature reticuloycyte
- Then a few days later becomes mature and starts carrying oxygen around the body.
Why do you regulate the amount of red blood cell produced?
- the stimulus for producing red blood cells (erythropoiesis) is low oxygen levels.
- So more red blood cells are produced to carry more oxygen around
Why do you have low oxygen levels?
low red blood cells
How do you detect the low oxygen levels?
- detected by kidney
- releases erythropoietin
- travels from kidney to bone marrow
- in red bone marrow it stimulates erythropoiesis
- more blood cells/erythrocytes are released
- increased oxygen levels
What are blood groups?
these rely on antigen (agglutinogens) on the surface of RED BLOOD CELLS
What is an antigen?
markers on cells that enables the body to recognise them as foreign
if detected , the body creates antibodies which neutralises antigen
Prevalence of blood groups?
based on antigens you can classify blood.
- the frequency of these blood groups varies according to race.
What are the 2 ways you can classify blood?
AB system -
Rhesus system
What is ABO blood groups?
-relies on the presence of 2 antigens called A and B.
Our red blood cells potentially have A or B antigen on our red blood cell.
- If you have A antigen= type A
B antigen= Type B
A and B antigen = Type AB
NO antigen = Type O