Mid-Semester Exam

Question 1

What is Extramedullary haematopoiesis?

Answer 1

formation of rbc outside bone marrow in response to haematopoietic stress caused by microbial infections and certain disease or in fetal development

Question 2

What is lifespan of rbc in circulation?

Answer 2

90-130d average

Question 3

How does scavenging happen?

Answer 3

In spleen by macrophages

Rbc get stuck between macrophage slits in red pulp of spleen - membranes become stiffer - This can happen in disease due to
Antibodies/proteins coating membrane -> trapped in spleen by macrophages

Question 4

What are senescence markers?

Answer 4

Old markers presenting on rbc towards end of lifespan to signal phagocytosis by macrophages

Question 5

How is globin, heme and ferritin recycled?

Answer 5

Globin - Recycled into amino acids
Heme - cannot be recycled - contains iron

Ferritin - Holds onto iron in a macrophage then passed to transferin that transports it back to bone marrow. Iron has to be actively exported out of cells like macrophages into circulation to then bind to transferrin

Ferroportin is a membrane protein for this

Question 6

What does hepcidin do?

Answer 6

master iron regulator

When released - smashes ferroportin to stop iron exiting cells - iron can’t travel to bone marrow and we cant make haemoglobin = low iron availability

IL-6 (produced by macrophages during chronic inflammation) major trigger of hepcidin release - Causes anaemia of chronic disease

Question 7

What does haemosiderin do?

Answer 7

Traps iron

Question 8

What is the structure of haemoglobin?

Answer 8

4 globin molecules and heme in the centre of these

Heme has iron bound to it

Question 9

What is the key limiting nutrient to build haemoglobin?

Answer 9

Iron

Question 10

What 2 things do we need to build haemoglobin?

Answer 10

Iron and amino acids

Question 11

What are young rbc called?

Answer 11

Nucleated rbc - with genes to make haemoglobin and heme, lots of ribosomes

Question 12

What happens once nucleated rbc are at capacity with haemoglobin?

Answer 12

The nucleus shrinks down and disappears, then ribosomes leave and cell shrinks to increase concentration -> most of this process in bone marrow

Question 13

What does presence of nucleated rbc mean?

Answer 13

Massive demand for rbc or issue in bone marrow - leaky endothelium letting them out too early or neoplastic change in rbc line

Question 14

What stain do we use to confirm presence of reticulocytes?

Answer 14

new methylene blue

Question 15

What do reticulocytes look like?

Answer 15

Bigger, paler and bluer than normal rbc, ribosomes but no nucleus

Question 16

What does presence of reticulocytes tell us?

Answer 16

Regnerative processes are working -> nursery is okay - dont need to do a bone marrow biopsy

Question 17

Define anaemia

Answer 17

low red blood cell numbers

Question 18

What are the 2 causes of anaemia?

Answer 18

Low production - nonregenerative (low reticulocytes)

Increased loss - regenerative

Question 19

What detects oxygen and what do they do?

Answer 19

Interstitial fibrocytes in the kidneys -> too little oxygen = EPO release

EPO goes to circulation -> bone marrow -> stimulates rbc cell line -> more reticulocytes

Question 20

What does a non-regenerative anaemia look like?

Answer 20

Low reticulocytes = low building blocks (protein/iron) in bone marrow

RBC = pale, small and little haemoglobin

Question 21

5 causes of non-regenerative anaemia

Answer 21

Monocytes and neutrophils (inflammation)
Infections 
Bone marrow neoplastic change
Autoimmune disease
Iron and amino acid deficiency

Question 22

How does inflammation cause non-regenerative anaemia?

Answer 22

IL-6 decreases no. of rbclines to increase neutrophil production (prioritise bone marrow for wbc production)

Question 23

What two things cause regenerative anaemia?

Answer 23

Haemorrhage or haemolysis

Question 24

What does chronic and acute haemorrhage cause?

Answer 24

Chronic -> iron deficiency anaemia, caused by parasitism, GIT ulcers

Acute -> total protein + PCV goes down but comes back up again, reticulocytes come up peak at 1 week and go back down - everything normal 1-2 weeks later

Question 25

What type of anaemia does haemorrhage cause?

Answer 25

Regenerative

Macrocytic and normochromic

Question 26

What are signs of haemolysis?

What are 2 types?

Answer 26

Increased bilirubin
Few rbc, bluish

Extravascular or intravascular haemolysis

Question 27

What is extravascular haemolysis?

Answer 27

Internal haemorrhage leading to haemolysis - occurs in spleen so its enlarged

RBC scavenged before their time - due to things like antibodies -> causes iron and haemosiderin buildup in spleen

Question 28

Characteristics of extravascular haemolysis

Answer 28

Mild anaemia
Lasts days-weeks
Reticulocytosis (increased retic)
Hyperbilirubinaemia/uria

No haemoglobinaemia/uria

Question 29

What is intravascular haemolysis

Answer 29

In blood itself
Rare - associated with snake bites, toxin, drugs, Hg comes out into plasma (red tinge)
Red urine and red plamsa

Red urine only -> caused by myoglobin

Question 30

Characteristics of intravascular haemolysis

Answer 30

Marked rbc damage, hours to days

Mild reticulocytosis
Haemoglobinemia and uria

Question 31

6 types of haemolytic anaemia

Answer 31

Immune mediated
Neonatal isoerhythrolysis (type II hypersensitivity)
Infections
Heinz body anaemia
Hypophosphatemia
Genetic causes

Question 32

Immune mediated haemolytic anaemia - what, test, outcome, prognosis

Answer 32

Primary -> canines
Secondary -> cats due to mycoplasma

Coombs test -> 50% specificity,

• False negatives (incomplete washing on rbc, loose bound IgG or complement)
• False positives - myeloproliferative/lymphoproliferative disease, inflammatory disease

Outcome -> treat with steroids, 50% die from thromboembolism in first 5 days, relapse risk, monitor PCV and platelets

Prognosis -> increased bilirubin, left shift neutrophilia poor prognosis

Question 33

Parasites causing haemolytic anaemia

Answer 33

Mycoplasma -> attached to surface of rbc, IV adn EV haemolysis
Anaplasma -> inside rbc in ruminants
Babesia -> apicomplexa cause IV haemolysis
Theileria -> tick borne protozoa in cattle causing regenerative anaemia, abortion

Question 34

What does heinz body anaemia look like?

Answer 34

pimples on red blood cells

If cats eat paracetamol

Question 35

6 parameters for the diagnosis of anaemia

Answer 35

Use a haemanalyser

Red cell/L

Haemoglobin -> total Hb/L of blood

MCH -> mean cell haemoglobin

Haematocrit -> proportion of blood made up of mostly red blood cells

MCV -> mean cell volume in femtolitres (macro or microcytosis)

MCHC -> Hb concentration (hypochromia = low colour occurs when not enough iron)

Question 36

What is jaundice? what are 2 types?

Answer 36

Too much bilirubin in the blood - either conjugated or not causing yellow mucous membranes

Fetus liver does not conjugate bilirubin -> so cannot excrete it causing jaundice at birth

Post-hepatic -> outflow pathways messed
Hepatic -> hepatocytes not functioning right

Question 37

Excretion of heme

Answer 37

Heme -> biliverdin -> bilirubin (toxic, non-polar) -> goes to blood then liver -> hepatocytes conjugate it to make it polar -> body actively excretes through bile duct -> duodenum -> back to non-conjugated form to prevent digestion of intestine wall (urobilinogen)