pathology (wk 2) Flashcards
what are haematogenous pigments?
pigments that are derived from the haemoglobin molecule within erythrocytes (includes haemoglobin, haemosiderin, bilirubin, and haematoidin, haematin, porphyrin)
what is the haemoglobin molecule composed of?
four subunits of the protein “globin, each of which is folded about a molecule of “haeme” (a tetraphyrrolic ring with a central atom of iron)
what is the main organ in charge of removing old or damaged red blood cells?
the spleen - it has splenic macrophages that are able to recognise old and damaged red blood cells and remove them from the circulation via phagocytosis
haemolysis is a pathological process - what does it mean?
the destruction of red blood cells before they reach the end of their lifespan (eg haemolytic diseases - where large numbers of red blood cells are damaged)
what is extravascular haemolysis?
the same as normal RBC removal (takes place in the spleen, macrophages involved etc) but with excessive levels of red blood cells being taken out
what is the globin from haemoglobin used for after haemolysis?
the globin is converted into amino acids in the macrophage which can be reused for protein synthesis
what two components do does haemoglobin break down into in the splenic macrophage?
heme and globin
how is haemosiderin formed?
golden brown granules formed from the iron from heme binding with ferritin
how is bilirubin formed?
a yellow pigment made from the non-iron part of the heme from the haemoglobin (this then goes to the liver)
what is intravascular haemolysis?
the red blood cells rupture within the circulatory system, releasing haemoglobin directly into the plasma
what is haemoglobinaemia?
a symptom of intravascular haemolysis - the haemoglobin from the ruptured RBC’s stains the plasma pink
what is haemoglobinuria?
pink pee due to haemoglobin released from intravascular haemolysis passing through the kidneys and staining the urine
What are the pigmented breakdown products formed during extravascular haemolysis?
haemosiderin and bilirubin
If you measure the PCV (packed cell volume) from an animal with marked extravascular haemolysis, what would the reading show?
a. Increased PCV
b. Normal PCV
c. Decreased PCV
c. Decreased PCV - with extravascular haemolysis there is destruction of large numbers of RBC’s, leading to haemolytic anaemia
What is the main pigmented substance released during intravascular haemolysis?
haemoglobin
The consequence of massive intravascular haemolysis is visible discoloration of the plasma and leakage of haemoglobin in the urine - what are the terms for these conditions?
- haemoglobinaemia (pink plasma)
- haemoglobinurea (pink urine)
What condition will be present in an animal with massive intravascular haemolysis?
a. Muscle atrophy
b. Anaemia
c. Diarrhoea
d. Bruising
b. Anaemia - too much RBC spontaneous explosion
the accumulation of large amounts of haemosiderin in macrophages is known as ____ and may be seen when there is a systemic overload of iron - is it….?
a. haemosiderosis
b. haemotoidin
c. hematin
a. haemosiderosis (iron deposits in tissues overload)
the bright yellow pigment derived from haemosiderin that is mostly deposited in tissues with haemorrhages (but doesn’t contain Fe itself)… is it:
a. haemosiderosis
b. haemotoidin
c. hematin
b. haemotoidin
a brown - black pigment formed by oxidation of haemoglobin (contain iron in the ferric state). this pigment can be found in formalin fixed tissues when the formalin solution was not prepared properly and in tissues affected with certain parasites…. is it:
a. haemosiderosis
b. haemotoidin
c. hematin
c. hematin
what happens to bilirubin once it’s made in the macrophage?
it’s released into the blood in unconjugated form and couples with albumin - then goes to liver where it’s detached from albumin and conjugated. from there to the bile duct to the small intestine, where it’s now colourless and called urobilinogen (most goes out in faeces, some gets reabsorbed into the urine and makes it yellow)
what is jaundice (otherwise known as icterus?)
where the tissues of the body are abnormally yellow due to a high concentration of bilirubin in the blood and tissues
what are the different colours around a bruise due to?
the presence of haemoglobin and it’s breakdown products - haemosiderin and bilirubin
is bilirubin conjugated in…
a. the macrophage
b. the hepatocyte
b. the hepatocyte (initially unconjugated)
what are the three decreased formation of melanin conditions?
albinism, vitiligo, acquired hypopigmentation
what is albinism?
a genetically induced condition where no melanin is produced by melanocytes within the whole body - commonly due to an inherited deficiency of the the enzyme tyrosinase
what is vitiligo?
an immune - mediated attack to melanocytes or keratinocytes leading to depigmented areas in the skin and hair
what is acquired hypopigmentation?
can be associated with hormone imbalances, a local loss of melanocytes due to physical trauma or chemical injury e.g freeze branding, or due to dietary copper deficiency producing generalised hypopigmentation
the three increased formation of melanin conditions?
acquired melanosis, congenital melanosis, melanocytic neoplasia
what is acquired melanosis?
eg suntan - ultraviolet light stimulates an increase in melanin production in exposed skin
what is congenital melanosis?
(think birthmarks, black marks on dogs gums etc) occurs when melanocytes don’t distribute evenly during embryonic development leading to discrete focal areas of hypopigmentation - these hypopigmented lesions have no clinical significance
what is anthracosis?
accumulation of carbon particles (and other dusts) in the lungs and lymph nodes - common in animals living in heavily polluted urban areas (peppered looking lungs, grey/black lymph nodes)
what’s wrong with cow no. 4?
nothing - it has carotenoid pigmentation of the subcutaneous fat tissue (Carotenoid pigments are present in plants (especially leafy green plants) and can give a yellow orange discolouration to plasma and adipose tissue especially in horses and Jersey dairy cattle. This colour change needs to be differentiated from jaundice.)
what is fatty change?
abnormal accumulation of triglycerides in parenchymal (functional) cells of organs
excessive fat accumulation in the liver (fatty liver) is caused by what three mechanisms?
- increased fat mobilisation (occurs after starvation etc)
- decreased metabolism of fat within hepatocytes
- reduced transport of fat out of hepatocytes
*basically when the lipid metabolism pathway in the picture stops working
which fatty liver mechanism occurs after starvation (particularly in obese individuals), with pregnancy toxaemia/ketosis in last gestation ewes carrying twins (“twin lamb disease; sleepy sickness”), with ketosis in high producing dairy cows in early lactation, and in animals with diabetes mellitus (due to increased carbohydrate metabolism due to lack of insulin)?
1. increased fat mobilisation
2. decreased metabolism of fat
3. reduced transport of fat
- increased fat mobilisation - occurs after starvation
fatty liver - numerous small globules of fat around a central nucleus. is it?
a. acute (recent) fatty change
b. chronic (long standing) fatty change
a. acute (recent) fatty change
fatty liver - the globules coalesce into one or more globules, which may displace the liver towards the of the cell. is it?
a. acute (recent) fatty change
b. chronic (long standing) fatty change
b. chronic (long standing) fatty change - often diseased
which mechanism is most likely to lead to fatty liver with ketosis/pregancy toxaemia, starvation of obese animal, diabetes mellitus, high fat diet?
a. increased input to liver
b. decreased output of liver
a. increased input to liver
which mechanism is most likely to lead to fatty liver with toxins damaging the liver and protein malnutrition?
a. increased input to liver
b. decreased output of liver
b. decreased output of liver
which substance accumulation can occur with certain metabolic abnormalities in skeletal muscle, with ___ storage diseases in various organs and in the liver with diabetes mellitus or in dogs with an endocrine disease called hyperadrenocortisism?
1. glycogen
2. proteins
3. amyloid
- glycogen
which substance accumulation can occur in the proximal renal tubular epithelial cells in animals with severe, chronic kidney disease?
1. glycogen
2. proteins
3. amyloid
- proteins
which abnormal substance accumulation can occur due to misfolded proteins and that can accumulate locally or throughout the body - in animals the latter results from chronic inflammatory diseases, some cancers etc?
1. glycogen
2. proteins
3. amyloid
- amyloid
