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
How many antigens
400
What are the 2 ways you can classify blood?
AB system
Rhesus system
What is AB system
-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
AB= Type AB
NONE= Type O
What is the process of the antibodies and antigens in blood groups?
-the plasma of a person carries the antibody (agglutinin) to the antigen that they do not posses
for example if you have antigen A , your blood plasma contains B antibody and vice versa
- Your body contains antibodies to fight antigens to the antigen the rbc doesnt have
What is type AB blood?
universal recipients as you contain no antibodies- so can take anybodies blood - donor and recipient
What is type O blood?
universal donor as it posses neither antigen so therefore can give to anyone
What happens if you are Type A blood
A antigens on rbc - blood plasma cant contain A antibody cause antibody fights antigen
It contains B antibody
What happens if you are Type B blood
Blood plasma contains A antibodies
What happens if you are Type AB blood
Plasma cant contain any antibody
What happens if you are Type O blood
Plasma contains both A and B antibody
What happens if Type A blood is given to type B blood
A antigen in donor blood will react to A antibody in recipient blood = blood clotting and death
Can you give Type A blood to someone who has AB blood
Yes - doesnt contain any A/B antibodies but cant give type A blood to someone who has type O blood
Can you give Type B to Type A
No
Can you give Type B to Type B
Yes
Can you give Type B to Type O
Yes
What was rhesus blood type first described in
Rhesus monkeys - rhesus macque
What does rhesus blood type rely on
The presence of the 6 antigens - C,D,E,c,d,e
what is the significance of C , D, E antigens
Cause immune reaction if an individual has these antigens they are Rh+
Tell you whether antigens are strong enough to cause an immune response
what is the significance of c,d,e antigens
You are Rh-
Are most people Rh+ or Rh-
Rh+ ( 85% )
How is rhesus different from AB
- The body does not usually contain antibodies to these antigens and they take several months to form
- You have to make the antibodies for rhesus and it takes about 100 days to make sufficient quantities and by this time RBC’s are destroyed so can get away with being given wrong Rh once. After that antibodies are around so given wrong group 2nd time is not good. BUT in AB, antibodies are there all the time
What are the 5 types of white blood cell ( leukocytes ) ?
Granulocytes:
. neutrophils ( 40-70% )
. eosinophils ( 1-4% )
. basophils ( 0-1 % )
Agranulocytes:
. lymphocytes ( 20-45 % )
. monocytes ( 4-8% )Other antigens
Have little clinical significance - legal purposes - look at antigens on mother/father/child to see who is biological….
What are the 2 types of leukocytes
Granulocytes
Agranulocytes
They are divided into 2 types depending on whether they have granules in their cytoplasm or not
What is the difference between erythrocytes and leukocytes ?
Leukocytes contain nuclei and are bigger and much less numerous ( 7000 mm-3 of blood ) (far less wbc )
Properties of granulocytes
Weird multilobed nuclei
Visible granules in cytoplasm
Develop in bone barrow
neutrophils , basophils , eosinophils
Properties of agranulocytes
- More regular nuclei
- No granules in cytoplasm
- Lymphocytes , monocytes
- Lymphatic system involved in development
What is main function of WBC’s
The major from of defence against attack by potentially harmful foreign organisms e.g. bacteria, viruses, fungi
Function of granulocytes
Protect body by phagocytosis
as well as monocytes
Function of lymphocytes
Immune response
Produce antibodies - combat invading organism
Structure of neutrophils
- contains granules (granulocyte)
- 10 - 15 um diameter
- nucleus composed of 2-5 -sausage - shaped lobes
- 60-70% of all leukocytes (most common WBC)
- powerful phagocyte
- Main phagocytic cell
- Spherical
How do neutrophils often leave the vascular system and what is it
By diapedesis - the passage of blood cells through the walls of the capillaries, typically accompanying inflammation.
Wbc’s leave capillaries - the vascular system by squeezing through their walls
What happens before diapedesis
Cells adhere/stick to capillary walls - MARGINATION
Where do wbc’s go
Go to infected area in response to inflammation
They live throughout body in connective tissue cause invading organisms to go into body’s tissues 1st. After a while they get into vascular system.
What happens in response to inflammation
All white blood cells go to infected area, both diapedesis and margination increase so WBC can leave the vascular system
How are foreign objects recognised prior to phagocytosis ?
- roughness - foreign objects have rough surface
- difference in charge - foreign objects have positive charge which is wrong. Normal charge is -
- presence of antibodies acting as ‘ flags - neutralise cell
Why do foreign objects have to be recognised
Don’t want to destroy body’s own tissues
What happens when white blood cells encounter foreign objects
Object grows pseudopodia which fuse around invading organism , enclosing/engluf object in a phagocytic vesicle within cell
What is pseudopodia
Long cytoplasmic extensions which fuse around invading organism
What is main function of nucleophiles
Phagocytosis
Explain process of phagocytosis in nucelophiles
- Psuedopodia engulf invading organism until invading organism surrounded in phagocytic vesicle.
- Lysozymes fuse with phagocytic vesicle - release digestive enzymes onto microbe and destroy microbe. ( Hydrogen peroxide also results in production of chlorine). Most waste is discharged
- Extrudes rubbish out of cell/discharge of waste material- , it retains some rubbish, accumulates in cell over time - called LIPOFUSCIN
- After a while, digestive enzymes are released and build up of material destroy nucleophile = hoover of body = ingest foreign particles
- In the end neutrophil itself is destroyed and in turn phagocytosed by monocytes. 10/15 hoovered up.
Summary of phagocytosis
- Adherence of microbe/invading organism to phagocyte
- Ingestion of microbe by phagocyte- in a phagocytic vesicle
- Formation of phagosome
- Fusion of phagosome and lysosome to form a phagolysosome
- Digestion of ingested microbe by enzymes
- Formation of residual body containing indigestible material
- Discharge of waste material
Structure of monocytes
- agranular
- they mature into large macrophages (80 um) only within the extravascular tissue
- they form what is sometimes referred to as the tissue macrophage system
- they need to leave the vascular system and stay in body c.t to mature into strong macrophages- more powerful than neutrophils.
Main function of monocytes
Body’s major phagocyte - neutralise invading organisms and mop up nucleophiles
What’s special about monocytes
When released from bone marrow, they cannot phagocytose things = immature
-They need to leave the vascular system and sit around in bodys connective tissue to grow and mature into strong macrophages ( up to 80 micrometres in diameter )- more powerful than neutrophils.
What are macrophages
Monocytes from vascular system, sitting around in bodys tissues, big powerful phagocytes
Structure of basophils
- 10-15 um diameter
- nucleus often S-shaped - regular
- cytoplasm contains large granules which contain histamine , heparin , serotonin- important in inflammatory response and allergic reactions = makes wbc’s more likely to get out of vascular system = vessels more leaky
- 0.5-2% of all leukocytes
- may form mast cells- which are cells you find in c.t with big granules of histamine and heparin
- weak phagocytes
What is role of histamine
Makes blood vessels more sticky, increases chance of margination
What is role of hepanin
Stops blood coagulating
Structure of eosinophils
- 9 um diameter
- bilobed nucleus
- granulocytes
Function of eosinophils
- detoxify foreign proteins
- possible role in blood clotting
- phagocytosis of antibody-antigen complex
- Weak
Where are eosinophils found
In lung , liver where there is a lot of protein
What are lymphocytes made from
Lymphoid stem cells in bone marrow
What are the two types of lymphocytes ?
T- lymphocytes
B- lymphocytes
where do T-lymphocytes mature, store and release
released from bone marrow and mature in thymus
Stored in secondary lymphatic tissue
where do B-lymphocytes mature and store ?
Bone marrow
Stored in secondary lymphatic tissue
what is the function of T-lymphocytes ?
Mediate cellular immunity in which the whole cell attacks the invader
what is the function of B-lymphocytes ?
Mediate humoral immunity via producing plasma cells which produce antibodies that neutralise invading organisms by binding to antigens and cover toxic area
What is cellular immunity
Whole cell/T lymphocyte goes to invading organism and neutralises it
Structure of thrombocytes
2 um diameter
no nucleus
250,000 - 400,000 mm-3 blood
Fragments of cells = TINY
What is average life span of thrombocyte
5 - 14 days = short lived
what is the function of megakaryocyte?
produce around 4,000 platelets = fragments
what is size of megakaryocyte?
160 um diameter
what is the main function of blood platelets ( thrombocyte )
formation of blood clots to stop bleeding - in unbroken vessel
How is maturation of B lymphocytes in birds different to humans
B lymphocytes released from bone marrow when immature
Go to Burra of Fabricius - mature here BUT humans dont have this
describe the pathway of formation of thrombocytes ?
- hemocytoblast
- megakaryoblast
- promegakaryocyte
- megakaryocyte
- platelets
what is haemostasis?
Prevention of blood loss - STOP BLEEDING
What are phases of haemostasis
- vascular phase
- platelet phase
- coagulation
What happens in the vascular phase of haemostasis ?
endothelial cells produce chemicals causing
. vascular spasm -
. division of endothelial cells , smooth muscles- to repair damage
. endothelial cells become sticky
-smooth muscle of blood vessel contract and close blood vessel down = minimise blood loss
- Contraction of smooth muscle - lasts 30 mins
what happens in the platelet phase of haemostasis ?
- platelets adhere to the damaged endothelium/sticky area of blood vessel and aggregate to form a platelet plug - have accumulated- if damage not too severe this is enough to repair the wound
- However if big injury- need the 3rd phase - coagulatio
What happens if its a small injury
Platelet plug - end of haemostais
How is platelet plug formed
Platelets stick to sticky area of blood vessel = accumulate, they grow themselves and attract more platelets. In end all platelets accumulated
What are two routes of coagulation
Extrinsic route - chemicals released by endothelial cells = EXternal to blood
Intrinsic route - signals initated by blood itself
When does coagulation occur
Big injury
What do both extrinsic and intrinsic route result in
Enzyme cascade - production of prothrombin activator
How is substance X and prothrombin activator produced
Both extrinsic and intrinsic route involve enzyme cascades that form them
Both chemical signals from endothelial cells and blood platelets via enzyme cascade form prothrombin activator
Function of prothrombin activator
Converts plasma protein (prothrombin) into thrombin which converts fibrinogen into fibrin threads
What happens in an enzyme cascade
Where 1 thing - damage to tissue of endothelial cells = release of chemical called tissue factor - converts 1 plasma protein into another plasma protein and so on
What is the function of fibrin threads ?
They stabilise and form a net that makes up the eventual clot
Time span for blood clot formation ?
3 -6 min on average depending on pathway
What is end result of enzyme cascade - how is scab formed
Conversion of fibrinogen into fibrin threads - forms net over wound - other chemicals released - stabilise net - formation of scab
