Blood Function 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) - e.g amine groups with nitrogen which turn into ammonia which is toxic which then converts to urea which is safe and filtered by kidney and excrete as urine.
- 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))
-transport system for waste products as well.
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 seperates out to?
Blood plasma (55% of blood)- mostly water -Red blood cells (Erthrocytes)- 45%
What is a haematocrit?
- blood is separated out into its components from spinning at high speeds in a centrifuge
What is the other layer which seperates the blood plasma and erthrocytes?
small thin white layer known as a Buffy coat
-made of white blood cells
What is another layer ontop of the buffy coat?
Blood platelets (thrombocytes)
Overall, What is the composition of blood?
consists of
- blood plasma
- formed elements :
- erthrocytes
- 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 erthrocytes?
- 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 erthrocytes for male and females?
5,200,000 mm-3 of blood male
4,700,000mm-3 of blood female
How does the erthrocytes vary?
- decreases with age
- depends what height you live at
- depends on your health (anemic- less blood cells and polycythemia- too many blood cells)
What is the major function of the erthrocytes?
-to transport oxygen
How much does each erthrocyte contain?
280 million molecules of haemoglobin for this purpose
What is haemoglobin made of?
- globin- made of 4 aa chains
- each of these aa 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 inbetween
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 erthrocytes 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 erthrocytes?
- 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.