L5 - blood cells Flashcards
learning outcomes
- main composition of blood: cells/plasma/serum
- how blood cells are made from bone marrow (erythrocytes, leucocytes, platelets)
- function of blood components
how much blood does the average human have?
5 litres
4 main components of blood
- blood cells
- plasma
- human plasma proteome/ proteins
- serum
how much of our blood consists of blood cells?
45-55%
what is plasma?
everything besides the blood cells / cell components
what is the human plasma proteome?
proteins inside plasma including albumin, immunoglobulins + clotting factors
what is the serum?
plasma without the clotting factors and fibrinogen
what happens if you centrifuge blood?
it will separate out into the erythrocytes (hematocrit) on the bottom and plasma components on the top. between the 2 there is a thin layer of WBCs and platelets
what are leukocytes?
white blood cells
what is the hematocrit?
% of blood volume composed of red blood cells
what does the separation of blood in leukaemia look like?
paler section in the middle (excessive production of white blood cells which aren’t functioning properly)
why do we separate out plasma from the blood?
- plasma = blood substitute to increase blood VOLUME during surgery/ after trauma. controls bleeding + helps wounds heals
- some drugs bind to plasma proteins at therapeutic concentrations
why do we separate out serum from the blood?
- serum can be used to measure the concentrations of substances inside it
- serum used in cosmetics
- serum used as a growth media for cell culture
3 main types of blood cells?
- erythrocytes
- leucocytes
- platelets
use of RBCs?
- transport oxygen to body cells
- pH buffer (keeps blood pH at 7.2-7.4)
types of leucocytes?
- agranulocytes
- granulocytes
- lympocytes
where are platelets derived from?
megakaryocytes (note: platelets are cell fragments)
what are platelets important in?
blood clotting
what is the bone marrow?
soft, spongy tissue in the centre of bones
2 types of bone marrow?
- red marrow
- yellow marrow
what is red marrow responsible for?
generating RBCs and leucocytes (blood cells)
what is yellow marrow for?
source of cartilage, fat and bone cells
what other things does bone marrow contain?
- collagen
- glucosamine
which is important for healthy bones and joints
in children which bone marrow generates blood cells?
bone marrow of most bones
in adults which bone marrow generates blood cells?
bones of chest, base of skull, spinal vertebrae and upper sections of limb is where most blood cells are made
what type of stem cells are blood cells derived from?
hematopoietic stem cells (undifferentiated cells that can produce precursors of different blood cells)
how long does a RBC last?
about 120 days
how long do some neutrophils last for?
about 6 hours
what symptoms do you get if bone marrow becomes damaged?
- fatigued - anaemia, not enough RBCs to carry oxygen around
- most susceptible to infections
- bleeding disorders - can’t clot
what might damage bone marrow?
- radiation
- chemotherapy
- certain drugs
2 types of bone marrow transplants?
- autologous
- allogeneic
autologous transplants
your own bone marrow before it turned bad
allogeneic transplants?
bone marrow from other patients
3 key functions of blood?
- transport of oxygen, co2, nutrients, excretory products around body
- regulation via delivery of hormones to target sites and diversion of blood in body via homeostasis and temp regulation
- protection via leukocytes and clotting mechanisms
describe rbcs
- transport o2 and co2
- no nucleus, can’t grow, divide, express proteins
- contains hb
- biconcave disc shaoe to increase SA:VOL for oxygen
- membrane polysaccharides and proteins on surface which decides you blood group
- can squeeze through small capillaries
what is erythropoiesis?
production of RBCs.
describe erythropoiesis (EPO)
- controlled by hormone erythropoietin
- secreted in small amounts by kidney
- some by liver
what triggers EPO production?
decreased oxygen
things that cause decreased oxygen levels?
- high altitude (less oxygen in air to be taken into body)
- lung disease
- insufficient pumping of the heart
- anaemia
what is anaemia?
decrease in total number of erythrocytes and/or decreased conc of Hb per RBC
what is anaemia often caused by?
- iron or vitamin B12 deficiency
- failure in bone marrow production - called aplastic anaemia
- genetic disorders, e.g sickle cells anaemia
what are leucocytes involved in?
host immunity - protecting against pathogens
what is the innate immune system?
first line of defence against pathogens mediated by myeloid cells / granulocytes
what is the adaptive immune system?
- highly specific to certain pathogens (so antigen specific)
- longer lasting protection
- mediated by lymphocytes
what are myeloid cells?
- monocytes/macrophages or neutrophils
- eosinophils
- basophils / mast cells
describe monocytes/macrophages and neutrophils?
- phagocytic cells
- called monocytes in blood
- these differentiate into macrophages when they migrate out into tissues
- neutrophils: cells that engluf pathogens etc
- apart of innate immunity
describe eosinophils?
- important in defence to parasites
- key mediators in asthma
describe basophils and mast cells
- immune cells that contain histamine, pathogensis of allergic reactions
- involved in inflammation
what are agranulocytes?
monocytes and macrophages
what are macrophages?
- phagocytic cells that ENGULF bacteria + cell debris
- release inflammatory mediators called cytokines
- antigen presenting cells to T cells
what are granulocytes?
- neutrophils
- basophils
- eosinophils
they are densely stained granules in cytoplasm. can be called polymorphonuclear leukocytes due to nucleus shape
what do lymphocytes contain?
- have large nucleus
- contain lysosomal enzymes
examples of lymphocytes?
- b cell and plasma cell
- t helper cells
- natural killer (NK) cells/ cytotoxic T cells
what are b cell and plasma cells involved in?
antibody production
what do t helper cells do?
provide activation stimulus to other immune cells
what are natural killer cells aka cytotoxic t cells?
kill virally infected + cancer cells
why may someone have too little leucocytes?
HIV or chemotherapy
what happens to someone when they have too few leucocytes?
become immunosuppressed/ immunocompromised and susceptible to opportunistic infections
what happens if you have too much leucocyte activation?
- the immune system is actively inappropriately
- need immunosuppressive drugs
examples of excessive leucocyte activation
- allergies
- inflammatory conditions
- autoimmunity
give examples of medical conditions where the manipulation of immune systems is needed
cancer, transplants, vaccinations
another name for platelets
thrombocytes
describe platelets
- no nucleus
- cell fragment
- for clotting
- produced from bone marrow from the progenitor cells leading to megakaryocytes
what are megakaryocytes?
cells with multi lobed nucleus
what is platelet production regulated by?
thrombopoietin, TPO (hormone produced by liver that stimulates the production)
what does TPO do?
TPO binds to platelets in circulation.
if platelet counts are normal the free TPO level is low.
if platelet count is low then free TPO level in serum is high so platelet production is stimulated
what is thromobocytopenic purpura?
low platelet counts that lead to excessive bleeding
what can reduce the risk of blood clots in thromboembolic diseases?
anti platelet drugs (aspirin + clopidogrel)
what are anti platelet drugs used to treat?
- myocardial infarction
- deep vein thrombosis
- ischaemic stroke