Blood structure and function Flashcards
What are the functions of blood
-it transports oxygen ( in rbc’s) 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 - wbc’s - protect body - always under attack - immune response
= TRANSPORT SYSTEM AND PROTECTS - WITHOUT IT CELLS WONT SURVIVE
What is an amoeba
Single celled organism, acts independently but as soon as cell becomes part of organ it can’t act independently
What needs blood
Specialised cells part of larger organisms
What is blood not
Homogenous substance = not just one thing = made up of many components
What is the test to seperate blood into its components
- Withdraw blood from body
- Add some substance (heparin)
- put in test tube and spin at high speeds in a centrifuge
- heavy bits deposit at bottom of tube = red and light at top
What are the 2 layers which the blood seperates out to?
- Blood plasma (55% of blood)- mostly water = top layer = lightest in weight and colour
- Red blood cells (Erthrocytes)- 45% - heaviest in weight, has rbc
What is a haematocrit?
- blood is separated out into its components from spinning at high speeds in a centrifuge
What is the layer which seperates the blood plasma and erthrocytes?
small thin white layer known as a Buffy coat
-made of white blood cells
What is layer on top of the buffy coat?
Blood platelets/ thrombocytes
What is most of blood
Blood plasma and suspended within it you have red blood cells of erythrocytes
What is the composition of blood?
- blood plasma
- formed elements :
- erthrocytes ( rbc’s)
- leukocytes- white blood cells (buffy coat)
- thrombocytes(blood platelets)
What are the types and subtypes of leukocytes
- Granulocytes:
- Neutrophils
- Basophils
- Eosinophils - Agranulocytes:
- Monocytes
- Lymphocytes
Blood plasma
- Most blood plasma is water - 90%
- Suspended within the water is a variety of things apart from rbc’s such as :
- mostly proteins (8%) - most common is albumin- regulates and creates osmotic pressure called COLLOID OSMOTIC PRESSURE - makes sure water doesnt leak out of capillaries = retain water in capillaries
- globulins- alpha and beta - alpha and beta transports molecules/nutrients/proteins/antibodies, 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 is most blood plasma
Water - 90%
What proteins does blood plasma contain
- Albumin
- Gobulins - alpha, beta and gamma
- Clotting proteins
What is role of albumin in blood plasma
Regulate osmotic pressure
What is role of alpha and beta and gamma gobulins in blood plasma
Alpha and beta = transport molecules
Gamma = transport antibodies
What is role of clotting proteins in blood plasma
Prevent loss of blood
What else are dissolved in the plasma?
nutrients
Respiratory gases - CO2 and O2
What is the structure of the erthrocytes?
- they are anucleate biconcave disc
- big surface area for a small volume = important for the exchange of substances across surfaces)
- can 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 ( 6/7 l blood )
4,700,000mm-3 of blood female ( 4/5 l blood )
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)
How many red blood cells in body
25 billion
What is the major function of rbc’s
Transport O2
How much does each erthrocyte contain?
280 million molecules of haemoglobin - transports O2
What is haemoglobin made of?
- globin- made of 4 amino acid chains
- each of these amino acid chain linked to a haem group - 4 haem groups in each haemoglobin molecule so each haemoglobin can bind 4 O2 molecules
- the central element of haem group is iron which binds to oxygen - oxygen binds to iron of each haem group
- If 280 million molecules of haemoglobinin rbc - each blood cell can transport 1000 million molecules of 02
What happens when red blood cells get to lungs
O2 diffuses from lungs to blood and O2 binds onto Fe in haemoglobin
What happens to most co2
Transported around body and dissolved in blood plasma
What is Haemopoiesis and where does this occur in adults
Formation of blood cells
In adult it occurs from stems cells in red bone marrow - confined to flat bones (sternum, ribs, vertebrae, skull, pelvis)
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/same stem cell/ one stem cell givees rise to all blood cell types (monophyletic)
- each type of blood cell has its own stem cell (polyphyletic)
Where do blood cells form
In bone marrow
In adults where are blood cells made
Red bone marrow
How does colour of bone marrow change as we get older
Born - bone marrow red
Older - bone marrow yellow
What are the two classes of stem cell
One giving rise of lymphocytes and the other to all other types of blood cell
Why is haemopoiesis described as a limited polyphyletic system
It means there are 2 type of stem cells that produce blood
-one known as lymphoid- which produces lymphocyte
–2nd = myeloid stem cells- which produces all the other types of blood cell.
therefore all red blood cell formation does not arise from 1 stem cell only
What are the 2 types of leukoemia?
- one is problem with lymphoid stem cells
- other is problem with myeloid stem cells = myeloid leukemia
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 when matured/nearly matured
What is erythropoiesis?
Formation of red blood cells
Properties of erythrocytes
- Survive and circulate for about 100 - 120 days
- Around 2.5x108 cells are destroyed everyday by the spleen - about 3000 a second = therefore have to make this many rbc’s every day
- longest living blood cells
- commited cell - proarythroblast - 25micrometres across
How can you figuire out how long rbc’s can survive
Put little radioacitve bag on and inject into bloodstream = follow how long radioactivity stays in blood - 100/120 days
How many days is longest living blood cell
100 - 120 days
How are red blood cells produced
Stem cell has to commit to become rbc
Proriferlate- nucleus starts to shrink and more copies of itself
-Differentiation- e.g haemoglobin starts to produce and synthesises = fills cytoplasm = site of nucleus decreased ( excluded )
-Maturation- filled with haemoglobin and takes out nucleus - not quite matured yet
Immature reticular site released from bone marrow = rbc circulates in system for 2/3 days
-Then a few days later becomes mature and starts carrying oxygen around the body.
What is control of erythropoiesis
Amount of rbc destroyed needs to match rbc produced
Homeostatic mechanisms - whole cycle takes 1 week to work
What is stimulus for producing rbc
Low O2 levels
What happens if O2 levels are low
Make more rbc to carry more O2 around
Hypoxia - due to low number of rbc’s
What is low O2 levels detected by
- detected by kidney
- releases erthropoietin
- travels from kidney to bone marrow
- in red bone marrow it stimulates erthropoiesis
- more blood cells/erthrocytes are released
- increased oxygen levels
What happens when you climb mountains
Have more rbc’s = need to spend 2 weeks climatisng to high altitude t= more haemoglobins = O2 levels are low so you produce more rbc = have more rbc to carry limited O2
How do some athletes cheat
Artificial erythropoietin - inject this = increase rbc’s count so not going up mountains = blood doping = armstrong did this - powerful therapeutic agent - radiation therapy - knocked out stem cells
What are blood groups
These rely on antigen (agglutinogens) on the surface of red blood cells.
What is the most commonly used system
Involves 2 antigens - A and B
What to the blood types mean
Type A - A antigen
Type B - B antigen
Type A B - both antigens
Type O - neither antigen
What causes frequency of blood group to vary
Race
What are antigens
Markers on cells that enables the body to recognise them as foreign
if detected , the body creates antibodies which neutralises antigen
Most cells on their surface have substances which enable other stuff to recognise them as foreign
Substances recognised as foreign by body
What usually happens when someone has someone elses blood
- Blood clotting
- Person with foreign blood dies