PBL 7 Flashcards
what is the composition of blood?
55% plasma
- proteins 7% —> albumins, globulins, fibrinogen, prothrombin - water 91% - other solutes 2% —> ions, nutrients, waste products, gases, regulatory substances
45% formed elements
- platelets < 1% - leukocytes < 1% —> neutrophils, lymphocytes, monocytes, eosinophils, basophils - erythrocytes > 99% —> biconcave discs, approx 6-7um
plasma vs. serum
plasma = liquid portion of blood. transports proteins, nutrients, antibodies, hormones etc around the body
serum = plasma - clotting factors (esp. fibrinogen) and blood cells. it is the liquid part of the blood after coagulation
if you want to obtain just plasma, what must be added?
anti-coagulants
why does the spleen rupture easily?
filled will blood therefore like a balloon so ruptures easily
what is yellow bone marrow mainly composed of?
- adipose tissue
- stem cells for cartilage and bone
what is used to diagnose leukaemia?
bone marrow biopsy
where is bone marrow taken from in bone marrow biopsy?
sternum, pelvis
what is TIBC?
- total iron binding capacity
- amount of iron bound to carrier proteins
ferrous vs. ferric iron
ferrous - Fe++
ferric - Fe+++ — cannot be absorbed
serum levels of what can be measured to determine iron?
- ferritin
- transferrin
- iron
what blood group is the universal donor?
O-
what blood group is the universal recipient?
AB+
what is the Rh antigen?
- the +ve or -ve part of the blood type refers to the presence or absence of the Rh antigens on the surface of the red cells
- most people are Rh positive
- the full Rh blood group system includes around 50 different red blood cell antigens, but the most important is RhD protein — if you have RhD, you are Rh positive, if you don’t, you are Rh negative
- a person with Rh-negative blood can donate to a person with or without Rh
- a person with Rh positive blood can only donate to someone with Rh positive blood
- the Rh antigens are transmembrane proteins that appear to be used for the transport of CO2 and/or ammonia across the plasma membrane
how can problems occur in pregnancy to do with Rh antigen?
- problems can occur if the mother has Rh-negative blood and the child has Rh-positive blood
- some RBCs can cross the placenta into the mother’s bloodstream — anti-RhD antibody develops
- these antibodies then go back into a future foetus and attack the foetus’ RBCs
- mother can receive an anti-RhD injection to prevent this immune response
how is blood tpye inherited?
codominance
what blood antigens are dominant?
A and B
what happens to Hb in sickle cell anaemia?
polymerises to form a large Hb chain
- dehydrates
- changes shape
- O2 can’t bind
what is a common cause of microcytic anaemia?
thalassaemia
how is thalassaemia inherited?
autosomal recessive
what are some causes of low Hb levels?
- cancer
- Hodgkin’s lymphoma
- cirrhosis
- chronic kidney disease
is folic acid deficiency anaemia macro/normo/micro cytic?
macrocytic
in what form is iron stored in cells?
Fe+++
what could cause too much iron in the body?
- excessive intake, liver disease, alcohol abuse
- could lead to cirrhosis, heart disease and diabetes
how do you treat iron deficiency anaemia?
- iron supplements — ferrous sulphate tablets
- eat an iron-rich diet — red meat, green veg, fruit
what is glandular fever and how is it diagnosed?
- common in teenagers, young adults and students
- usually stems from an infection with the Epstein-Barr virus (EBV) = a highly contagious herpes virus
- can cause mild inflammation of the liver known as hepatitis
- symptoms: flu-like symptoms, sore throat, swelling of lymph nodes, fatigue, weakness, temperature, nausea
- no cure — rest and sleep, drink lots of fluids, take painkillers, do not drink alcohol
what are some weird symptoms of Fe deficient anaemia?
- strange food cravings eg. ice, hair, paper, chalk
- restless legs
- flat tongue
how long does foetal Hb stay in baby for?
around 6 months
what is rhesus disease?
= a condition where antibodies in a pregnant woman’s blood destroy her baby’s blood cells
- doesn’t harm the mother but can cause the baby to become anaemic and develop jaundice
- occurs when baby is Rh positive and mother is Rh negative
- the antibodies to Rh cannot cross to the placenta in the first pregnancy but can in subsequent pregnancies
what is the anti-D immunoglobulin injection and why is it given?
- given to a mother to prevent causing rhesus disease in the baby
- given at 28 weeks gestation and after childbirth
- injection works by destroying any RhD positives blood cells that may have crossed over from the placenta into the mother’s bloodstream
what is the Kleihauer test?
= a blood test to screen for foetal haemoglobin that may have transferred from a foetus to a mother’s bloodstream
- mainly used to assess the severity of a fetomaternal haemorrhage (FMH) — a condition in which a disruption in the placental barrier allows foetal blood to enter the maternal circulation
- shows if mother needs the anti-D immunoglobulin injection
- the test is based in the fact that foetal Hb is more resistant to acid elation than adult Hb
- 5ml threshold
what is haemolysis?
= the destruction of red blood cells prior to the end of their normal 120 day lifespan
- 2 types: extravascular (more common) and intravascular haemolysis
- extravascular haemolysis occurs primarily in the spleen whereas intravascular is the breakdown of RBCs within the circulation, leading to the release of free Hb into the blood
- the fall in RBC count leads to a reduced oxygen-carrying capacity of the blood and relative hypoxia, which stimulates EPO secretion, up regulating erythropoiesis
what is iron overload and what can it cause?
= too much iron in body
- can be a problem for people who get lots of RBC transfusions
- as red cells break down over time, the iron in the Hb is released
- the body has no natural way to rid itself of excess iron, so extra iron is stored in body tissues
- transferrin carries iron through the blood to organs where it is stored (usually liver, spleen, bone marrow) — excess iron can lead to injury of the organs in which it is deposited
what is Hb electrophoresis?
used to measure different types of Hb in the blood
what is a sign of haemolytic anaemia?
yellow skin
increased destruction of RBC
what are causes of megaloblastic anaemia?
- B12/folate def
- drugs
- impairment of DNA synthesis — grow but can’t divide
is megaloblastic anaemia macro/normo/micro cytic?
macrocytic
what is pernicious anaemia?
autoimmune condition where there is atrophy of the gastric mucosa, with failure of intrinsic factor — decreased Vit B12 absorption
is pernicious anaemia macro/normo/micro cytic?
macrocytic
name a chronic disorder that can cause anaemia
rheumatoid arthritis
how to remember macrocytic anaemias. which are megaloblastic
F - folate def A - alcohol T - thryoid R - reticulocytosis B - B12 def C - cytotoxic drugs
F, B and C are megaloblastic
what is the universal plasma donor?
AB+
what is not included in the mandatory microbiological testing of donated blood?
gonorrhea
- HIV
- HEP B
- HEP C
- SYPHILLIS
what is the primary production site of erythropoietin?
kidneys
why are RBCs broken down in the spleen?
because they are much wider than the trabeculae of the spleen’s red pulp
how wide are normal RBCs?
8um
what conditions are Howell-Jolly bodies seen in? what are they not seen in?
seen in: - following splenectomy - coeliac disease - severe haemolytic anaemia - megaloblastic anaemia (these all affect the spleen_
not seen in:
- Hodgkin lymphoma
what type of anaemia can be caused by excess alcohol?
non-megaloblastic anaemia (macrocytic)
how many mls of blood does an average blood donor donate?
470mls
what are haemolytic anaemias classed as?
anaemia caused by excessive erythrocyte destruction
at 6 months pregnancy, where does the majority of haematopoiesis occur?
bone marrow
