Block 4 Flashcards
what are the functions of blood? (2)
- transportation - supplies O2 and nutrients to tissues
- regulation - body temp, maintain pH and osmotic pressure
how much blood does an average adult have?
- 5 litres
what are the components of blood? (2)
- 55% liquid - plasma
- 45% formed elements - RBCs, WBCs and platelets
what are the components of plasma? (3)
- 92% water
- 7% proteins
- 1% other
what are the components of formed elements?
- 99% RBCs
- 1% WBCs and platelets
what is haematopoiesis?
blood cell formation
where does haematopoiesis start?
- yolk sac
- bone marrow in adults
where does haematopoiesis occur in adults?
- long bones
- flat bones in later life
what does a long term haematopoietic stem cell differentiate into?
short term haematopoietic stem cell
what does a short term haematopoietic stem cell differentiate into?
- multipotent progenitor
what can a multipotent progenitor cell differentiate into? (2)
- common myeloid progenitor
- common lymphoid progenitor
what can a common myeloid progenitor cell differentiate into? (3)
- megakaryote
- erythrocytes
- granulocyte/macrophage
what can a granulocyte/macrophage cell differentiate into? (5)
- mast cell
- basophil
- neutrophil
- eosphil
- monocyte
what does a megakaryocytic differentiate into?
- thrombocytes
what can a common lymphoid progenitor cell differentiate into? (4)
- dendritic cell
- natural killer cell
- B-cells
- T-cells
what does a B-cell differentiate into?
plasma cell
what does a monocyte differentiate into? (2)
- macrophage
- dendritic cell
what are the 7 stages of erythropoiesis?
- hemocytoblast
- proerythroblast
- early erythroblast
- late erythroblast
- normoblast
- reticulocyte
- erythrocyte
what is erythropoiesis?
- red blood cell formation
- occurs in bone marrow
- regulated by EPO binding to erythropoietin receptors on progenitor cells
what is the role of haemoglobin?
- O2 binding
- transport
how long do RBCs live for?
120 days
what removes RBCs?
spleen macrophages
what is iron transported by?
transferrin
where is iron transported to for new RBCs ?
bone marrow
what is the role of platelets? (3)
- maintaining blood volume
- bind to endothelial cells in blood vessels to prevent blood loss
- become activated during tissue damage
what % of platelets are stored?
30%
where are platelets stored?
spleen
how long do platelets live for?
7-10 days
what is the role of leucocytes (WBCs)?
mediate protective effects of blood through regeneration of the inflammatory process
what are the 5 signs of inflammation?
- pain
- redness
- heat
- swelling
- loss of function
what % of neutrophils make up WBCs?
60-70%
what % of eosinophils make up WBCs?
2-5%
what % of basophils make up WBCs?
0.2%
what % of monocytes make up WBCs?
2-10%
what % of natural killer cells make up WBCs?
15%
what % of lymphocytes make up WBCs?
20%-40%
what is the lifespan of neutrophils?
18hrs
what is the lifespan of eosinophils?
2-5 days
what is the lifespan of basophils?
1-2 days
what is the lifespan of monocytes?
1-7 days
what is the lifespan of natural killer cells?
14 days
what is the lifespan of lymphocytes?
weeks-years
what role do neutrophils play in the immune system?
phagocytosis
what role do eosinophils play in the immune system?
phagocytosis
what role do basophils play in the immune system?
allergic reaction
what role do monocytes play in the immune system?
- phagocytosis
- differentiate to become macrophages in tissue
what role do natural killer cells play in the immune system?
killing virally infected cells
what is anaemia?
- reduction of RBCs
or - decreased amount of haemoglobin in RBCs
what is the consequence of anaemia?
- reduced level of O2 delivered to tissues
- causing weakness, tiredness, inability to exercise and SOB
what are the signs of anaemia? (5)
- pallor
- tachycardia (100bpm+)
- glossitis (swollen tongue)
- koilonchia (spoon nails)
- dark urine
how does EPO regulate erythrocytes? (3)
- juxtatubular intestinal cells of the renal cortex produce 90% of the EPO
- sense O2 levels through oxygen-dependant prolyl-hydroxylase
- regulates transcription factor for EPO HIF-1 (alpha).
describe the negative feedback system of EPO (5)
- hypoxia (low o2)
- increased HIF detected and increases EPO production
- this increases erythrocyte production
- decrease in hypoxia
- decrease HIF therefore decreased EPO production
name two types of conditions that affect erythropoiesis
- Pure Red Cell Aplasia (PRCA) - only affects erythropoiesis
- Pancytopenia - affects RBC and other cell types (WBC, platelets)
name an example of PRCA
- diamond-blackfan anemia
what is haemolytic anaemia?
premature destruction of erythrocytes either by extrinsic or intrinsic mechanisms
what causes haemolytic anaemia?
bone marrow is unable to match production to the destruction of new RBCs
what are the two causes of haemolytic anaemia?
- RBCs destroyed by external processes e.g. drugs, toxins, infection
- something is intrinsically wrong e.g. damage, abnormal haem, destruction
what is an extrinsic cause of haemolytic anaemia?
- Auto-immune Haemolytic Anemia (AIHA)
what is Auto-immune Haemolytic Anemia (AIHA)?
patients own immune system recognises own erythrocytes as foreign and destroy them
what can cause Auto-immune Haemolytic Anemia (AIHA)?
- lymphoproliferative disorders
- drug induced - bind to the surface of RBCs to act as antigen
how is Auto-immune Haemolytic Anemia (AIHA) diagnosed?
on a blood film
- schisocytes - fragments of RBCs
- polychromatic - blue tint of RBCs
- spherocytes - different sizes
what is haemoglobinpathies?
- autosomal co-dominant genetic defects
- causing abnormal structure of the global chains of the haem molecule
give two examples of haemoglobinpathies
- sickle cell anaemia
- sideroblastic anaemia
what happens in iron deficiency anaemia?
absence of iron means not enough o2 is absorbed
what can be two causes of iron deficiency anaemia?
- malnutrition
- malabsorption
how is iron deficiency anaemia diagnosed?
on a blood film
- hypochromic - pale
- microcytes - small
what is sideroblastic anaemia?
this is not from a lack of iron, but failure to be incorporated into haem in erythrocyte precursor cells
what forms in sideroblastic anaemia?
- failure of incorporation of iron forms iron-rich mitochondria that surrounds the nucleus as granules
- called sideroblasts
what is the type of anaemia as a result of a low MCV?
microcytic
what is the type of anaemia as a result of a normal MCV?
normocytic
what is the type of anaemia as a result of a high MCV?
macrocytic
what can cause anaemia with low MCV and a low RBC level?
- iron-deficiency
- lead poisoning
- sideroblastic
- chronic inflammation
what can cause anaemia with low MCV and a high RBC level?
thalassemias
what can cause anaemia with a normal MCV level?
- haemolytic anaemias
- bone marrow disorders
- acute blood loss
what can cause anaemia with a high MCV level? (4)
- vit B12 deficiency
- folate acid deficiency
- liver disease
- hypothyroidism
what are the 4 blood groups?
- A
- AB
- B
- O
what are A and B antigens?
carbohydrates present on red cell membranes
how are blood groups determined?
- by one gene on chromosome 9
- three variants can be inherited from out parents
- Ia, Ib or I
which blood groups are dominant and recessive?
- Ia, Ib are co-dominant
- I is recessive to both Ia and Ib
what type of antibodies does a person with blood group A possess?
anti-B
what type of antibodies does a person with blood group B possess?
anti-A
what type of antibodies does a person with blood group AB possess?
no antibodies
what type of antibodies does a person with blood group O possess?
- anti-A
- anti-B
what is the process of Rhesus disease? (4)
- Father is Rh+ and mother is Rh-. Mother is carrying a Rh+ baby.
- When pregnant with the first child the Rh antigens from foetus enters the mothers blood during delivery
- mother produces Rh antibodies in response to the fetal Rh antigens (sensitisation)
- when mother becomes pregnant again with Rh+ foetus, antibodies will cross the placenta and damage fetal red blood cells
what % of the population are RhD-?
15%
what are the symptoms of rhesus disease?
range from mild anaemia to miscarriage
what are the treatments for rhesus disease?
- prophylaxis anti-D therapy - bind and neutralise any Rh+ cells preventing development of maternal antibodies
what DNA changes occurs in sickle cell anaemia?
GAG to GTG
changes DNA base to Valine
what affect does sickle cell anaemia have?
alters Hb affinity for o2
Describe the genetic make up of sickle cell disease/ traits/ no disease?(3)
HbAA = no disease
HbAS = SC trait
HbSS = SC disease
what are the chances of inheriting sickle cell anaemia?
- both parents are carrying the gene - 25% will have and 25% will NOT have and 50% they would be a carrier
Which ethnicity is sickle cell anaemia most present?
African/Caribbean
Why is sickle cell anaemia most present in African/Caribbeans?
- sickle cell correlates with malaria
- HbAS provides protection from dying of malaria (selective advantage)
- HbSS gains worse outcome for malaria
what are the treatments of sickle cell anaemia?(6)
- prophylaxis
- bone marrow/stem cell transplants
- prevention
- education
- management
- NHS services
how has immunology been important? (4)
- vaccinations for infectious diseases
- transplantation
- cancer vaccines
- immunotherapies
where is the site of haematopoiesis?
- foetal life - week 4 of development in the Yolk sac
- before birth - liver
- adult life - bone marrow in pelvis, sternum, vertebrae
what are the types of lymphoid tissue?
- primary
- secondary
what is a primary lymphoid tissue?
- sites where lymphocytes differentiate to express antigen receptors
- e.g. thymus (T-cells) and bone marrow (B-cells)
what is a secondary lymphoid tissue?
specialised sites for turning on the acquired immune response
- e.g. lymph nodes, speen, MALT, GALT, NALT
what is the lymphatic system?
a drainage system in fluid balance, returning to the blood
how much lymphatic fluid is lost per day?
3L/day
what are lymph capillaries?
- ‘closed tubes’
- walls contain overlapping endothelial cells that respond to fluid pressure
what are the two types of lymphatics?
- superficial lymphatics - follows superficial veins e.g. axillary, inguinal, neck where they drain into deep lymphatics
- deep lymphatics - follows main vessels e.g. pre-aortic and post-aortic
what are lymph nodes?
- meeting place for cells of the immune system to expose the antigen
- filters lymphatics
what is the role of the spleen?
- directs immune responses to antigens in the blood
- clearance of RBCs
what are the two pulps in the spleen?
- red-pulp - clearing RBCs
- white pulp - ‘lymph nodes’
why do we have innate immunity? (4)
- prevent pathogen establishment
- limit pathogen multiplication
- provides protection from early death
- instructs nature of acquired immune response after infection
what are the three pathways in the complement system?
- classical
- lectin
- alternative
what do all three complement pathways produce?
C3
what does C3 split into?
- C3a
- C3b
what is the role of C3a?
- enhances inflammation
what is the role of C3b?
- opsonisation
- lysis of cell membrane (attack complex)
how does the classical pathway work?
- activated when antibodies bind to antigen of pathogen
- C1q, C1s, C1r binds to antibody
- forms C4b2a - C3 convertase
how does the lectin pathway work?
- activated when proteins bind to carbohydrates
- mannose binds to MASP-1 and MASP-2
- forms C4b2a - C3 convertase
what does C4b2a activate?
C3 protein
what does the C3 do?
split to form C3a and C3b
how does the alternative pathway work?
- C3b binds on the surface of the pathogen
- forms C3Bb - C3 convertase
- enhances classical and lectin pathway
describe the common pathway?
- C3 convertase activates C3
- C3 splits to C3a and C3b
- C3b binds to C4b2a complex to form C4b2a3b - C5 convertase
- C5 convertase activates C5 to split into C5a and C5b
- C5a - enhances inflammation
- C5b - iniaties membrane attack complex which causes the cell to self destruct
how are pathogens identified?
Pattern recognition receptors identify pathogens by recognising “pathogen associated molecular patterns” (PAMPs)
what do PAMPs trigger?
phagocytosis
how do PAMPs trigger phagocytosis? (4)
- attachment by PAMPs
- forms phagosome
- granule fusion and killing
- release of microbial products
what do phagocytes release during phagocytosis?
- activates NADPH oxidase during respiratory burst
- releases toxic oxygen radicals
- these directly damage microbial membranes and activate microbial enzymes
what is the role of the phagocytes in adaptive immunity? (4)
- antigen degradation
- antigen processing
- antigen presentation - MHCII
- antigen presentation - MHCI
what is the role of the phagocytes in innate immunity? (3)
- pathogen killing
- pathogen processing
- pathogen presentation
what do neutrophils contain? (3)
- chromatin
- granule proteins
- pathogen presentation
what are the features of HSC-derived monocytes and macrophages? (3)
- varied differentiation pathways
- long-lived
- host cells for pathogens
what are macrophages in the liver called?
kupfer cells
what is the role of kupfer cells? (3)
- respond to environment
- transcription factors
- forms and functions in different tissue