Blood structure and 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.
Why do you regulate the amount of red blood cell produced?
- the stimulus for producing red blood cells (erthropoiesis) 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 erthropoietin
- travels from kidney to bone marrow
- in red bone marrow it stimulates erthropoiesis
- more blood cells/erthrocytes 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
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
if have antigen AB , have no antigen in blood plasma
If are type o- have no antigen but A and B antibody in blood plasma
What happens if you get a wrong blood transfusion?
get blood clotting and lead to death
What is type 0 blood?
universal donor as it posses neither antigen so therefore can give to anyone
What is type AB blood?
universal recipients as you contain no antibodies- so can take anybodies blood.
what is rhesus blood type?
relies on the presence of 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+
what is Rh- ?
antigens c, d, e
what is different about rhesus blood type ?
the body does not usually contain antibodies to these antigens and they take several months to form , so can get away with being given wrong Rh once ( after antibodies are present)
- You have to make the antibodies
what are the 5 types of white blood cell ( leukocytes ) ?
. neutrophils ( 40-70% ) . eosinophils ( 1-4% ) . basophils ( 0-1 % ) . lymphocytes ( 20-45 % ) . monocytes ( 4-8% )
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 )
what are the two types of leukocytes structures ?
Morphologically they are divided into 2 types depending on whether
they have granules in their cytoplasm or not
1. granulocytes - lobed nuclei, granular cytoplasm, develop in bone barrow
neutrophils, basophils, eosinophils
2. agranulocytes - no granules in cytoplasm, regular nuclei , lymphatic system
lymphocytes, monocytes
what is the main function of most white blood cells ?
- the granulocytes and monocytes protect body by phagocytosis
- while lymphocytes (produce antibodies) are involved in the immune response
describe the 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
what is the main function of neutrophils ?
powerful phagocyte
how do most leukocytes leave the vascular system ?
by the process of diapedesis which is the passage of blood cells through the walls of the capillaries, typically accompanying inflammation.
what happens during inflammation ?
all white blood cells go to infected area, both diapedesis and margination increase so WBC can leave the vascular system
what is margination?
cells adhere to the capillary walls
why do most white blood cells live around body in connective tissue ?
invading organisms go to tissue than vascular system
how are foreign objects recognised prior to phagocytosis ?
- roughness - foreign objects have rough surface
- difference in charge - foreign objects have positive charge
- presence of antibodies acting as ‘ flags - neutralise cell
what happens when white blood cells encounter foreign objects ?
object grows pseudopodia ( long cytoplasmic extensions ) which fuse around invading organism , enclosing/engluf object in a phagocytic vesicle
explain the process of phagocytosis- neutrophils ?
- 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 enzyme- lyzozyme fuse with a vesicle and release the digestive enzymes onto the microbe and destroys it.
- formation of residual body containing indigestible material
- discharge of waste material- retain some waste which accumulates in cell over time- lipofuscin
- eventually neutrophil itself is destroyed and in turn phagocytosed by monocytes
what is the function of proteolytic enzyme released by lysozymes ?
destroys object
what is the main function of monocytes ?
body’s major phagocyte
Describe the 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.
what is the structure of basophil?
- 10-15 um diameter
- nucleus often S-shaped
- cytoplasm contains large granules which contain histamine , heparin , serotonin- important in inflammatory response and allergic reactions-
- 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 the function of basophils ?
important in inflammatory response and allergic reactions
- WBC can leave capillaries by the basophils releasing these chemicals
describe structure of eosinophils ?
- 9 um diameter
- bilobed nucleus
- granulocytes
what is the function of eosinophils ?
- detoxify foreign proteins
- possible role in blood clotting
- phagocytosis of antibody-antigen complex
- found in lung , liver where there is a lot of protein
what are the two types of lymphocytes ?
T- lymphocytes
B- lymphocytes
where do T-lymphocytes mature ?
released from bone marrow and mature in thymus
where do B-lymphocytes mature ?
bone marrow
what is the function of T-lymphocytes ?
T-lymphocytes mediate cellular immunity in which the whole cell attacks the invader
what is the function of B-lymphocytes ?
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 the structure of thrombocyte ( blood platelets )?
2 um diameter
no nucleus
250,000 - 400,000 mm-3 blood
what is the average life span of thrombocytes?
5-14 days
what is the function of megakaryocyte?
produce around 4,000 platelets
what is size of megakaryocyte?
160 um diameter
what is the main function of blood platelets ( thrombocyte )
formation of blood clots to stop bleeding
describe the pathway of formation of thrombocytes ?
- hemocytoblast
- megakaryoblast
- promegakaryocyte
- megakaryocyte
- platelets
what is haemostasis?
prevention of blood loss
what are the three phases of heamostasis ?
- vascular phase
- platelet phase
- coagulation
what happens in the vascular phase of haemostasis ?
endothelial cells produce chemical signals causing
. vascular spasm - smooth muscles contract and close blood vessel and minimises blood loss
. division of endothelial cells , smooth muscles- to try and repair damage
. endothelial cells become sticky ( blood vessel become sticky )
prevent blood loss
what happens in the platelet phase of haemostasis ?
- platelets adhere to the damaged endothelium and aggregate to form a platelet plug - have accumulated- this enough to repair damage if wound not too big
- However if big injury- need the 3rd phase - coagulation
how does coagulation/blood clotting occur?
via extrinsic route and intrinsic route
coagulation occurs to repair big injury
what is the extrinsic route in coagulation ?
chemicals released by endothelial cells
what is the intrinsic route in coagulation ?
signals initiated by blood itself
how is prothrombin formed ?
both chemical signals from endothelial cells and blood platelets via enzyme cascades in the intrinsic and extrinsic route form prothrombin
what is the function prothrombin?
prothrombin activator converts plasma protein (prothrombin) into thrombin which converts fibrinogen into fibrin threads
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 depending on pathway
What are lymphocytes?
-made from lymphoid stem cells in bone marrow
What are alveolar macrophages ?
that sit and reside within our lungs
- deal with all of those bacteria , fungal spores and viruses
- large and able to phagocytose engulf and destroy many bacteria at once
- as long as this can happen we dont have a systemic problem that causes inflammation and needs to recruit neutrophils .
