Lecture 3 Flashcards by kaley bullock

Where are RBC’s made?

Bone marrow

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What organs are important in the production of RBC’s

Kidney produces erythropoetin
Liver - iron
other hormones support too: from gonads, adrenal cortex, pituitary, thyroid

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What stimulates erythropoiesis?

Erythropoetin and iron travel to the bone marrow

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What are the 3 major pools the erythron contains?

erythrocyte precursors
blood erythrocytes
splenic erythrocytes

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How are erythrocytes made in the bone marrow?

EPO stimulates colony forming unit erythroid cells (CFU-E) to differentiate into rubriblasts (Rb), the Rb’s then undergo mitosis and pyramidal maturation (one Rb makes 16 eventual mature erythrocytes) that are released into the bloodstream

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Where are RBC’s stored?

Spleen

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How and where are RBC’s destroyed

the spleen and liver by macrophages

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What are the functions of RBC’s?

Transport oxygen to the tissues
Carry C02 away from tissues
buffering of hydrogen ions

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What increases the 02 carrying capacity of blood to 70x that of plasma

hemoglobin

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what are the 3 things that affect the oxygen content in the blood

Hemoglobin content
partial pressure of 02
hemoglobin oxygen affinity (p50)

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How do erythrocytes get rid of C02?

carbonic anhydrase

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What is the normal morphology for erythrocytes in dogs?

biconcave disc with prominent central pallor

minimal anisocytosis with only a few polychromatophils

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what is anisocytosis

differences in cell size

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What do normal erythrocytes look like in cats?

slightly smaller than dogs with less central pallor

exhibit rouleaux

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What is rouleax

RBC’s look like stacks of coins

non- specific binding of RBC’s due to protein coating

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What do normal RBC’s look like in horses?

same size as cats also exhibit rouleaux

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What do camelid RBC’s look like?

oval shaped

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What is different about Bird/reptile RBC’s?

they are nucleated

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True/False

we can use analyzers for non-mammal species

False - analyzer does not recognize the nucleated RBC’s

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What do we use a microcentrifuge and refractometer for?

Microcentrifuge - PCV

refractometer - total protein concentration (TP)

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What is the automated hematology analyzer used for?

RBC count
HgB concentration
Calculated hematocrit 
Mean Cell volume (MCV)
Red cell distribution width (RDW)
Mean cell hemoglobin concentration (MCHC)

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Why do we evaluate peripheral blood films?

Red blood cell density
Microscopy: size, shape, color and inclusions
Ex: parasites, RBC/WBC morphology, platelet clumping, inclusions, toxic changes
bone marrow evaluation

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What does the PCV measure

RBC mass

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What type of blood is used for PCV

Well-mixed/ anti-coagulated blood

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What information do you get from spinning the microhematocrit tube?

plasma color and plasma protein concentration

True/False | there is species variation in PCV %

True

True/ False | Age may affect PCV% and Plasma protein

true

Why would plasma protein concentrations be lower in juveniles

Haven't been exposed to as many pathogens as adults have been so not as many globulins

What is anemia of neonates

Low PCV in neonates because they have fetal RBC's but need to start making their own

what is a normal PCV% for mammals

Roughly 30-50%

What is a normal plasma protein (TP)

Roughly 6-8 g/dl

What does normal plasma color look like?

Dogs/cats - colorless | horses and ruminants - colorless to pale yellow depending on what they eat

How does the hematology analyzer evaluate quantity of RBC's

RBC - RBC count per microliter (measured) Hgb - hemoglobin concentration per deciliter (measured) HCT - hematocrit % calculated version of the spun PCV

How does the hematology analyzer evaluate the quality of RBC's

MCV - mean cell volume (size of RBC's) Measured RDW - Red cell distribution width (size variation among RBC's) measured MCHC - Mean cell hemoglobin concentration (hemoglobin within RBC's) Calculated

Which is more accurate measured or calculated values?q

MEASURED

What 3 values should always go together if one is high all three should be high

PCV, RBC, and Hgb

What is the Mean cell hemoglobin concentration

the ratio of hemoglobin to the number of RBC's | expressed as grams of hemoglobin per 100ml of RBC's

what 2 types of anemia do you see with decreased MCHC (hypochromasia)

Anemia with a marked response by the marrow to regenerate new RBC's (new RBC's are lighter colored) Anemia that is due to severe iron deficiency with very low hemoglobin in RBC's (central pallor will be increased)

What does increased MCHC mean?

usually always an artifact hemolysis in vivo or in vitro interference with hemoglobin measurement (Ex: lipemia)

How does exercise affect PCV and TP in horses

During exercise, horses sweat so you will get hemoconcentration because the fluid component of blood has been reduced. PCV and TP may appear falsely high and can mask anemia

What is the hallmark of dehydration?

Increased PCV and total protein

What is anemia

Low RBC's for the species, breed, gender, and age of the animal

How do you base your diagnosis of anemia?

History Physical Exam Clinical signs Diagnostics

What are the clinical signs of anemia due to?

Decreased 02 delivery to the tissues

What are the clinical signs of anemia influenced by?

Rate and severity of decrease in RBC number Cardiopulmonary function Age and activity of the animal Cause of the anemia

What are some things to ask about when taking a history in a possible anemic patient?

``` Recent illness drug or vaccine administration exposure to toxice chemicals or plants family or herd occurrence recent transfusion or colostrum ingestion age of onset of anemia severity of anemia ```

What are the clinical signs of anemia?

``` Weakness, lethargy, exercise intolerance Poor peripheral perfusion - pale mucous membranes - pale sclera Cardiovascular - tachycardia - weak pulses - systolic murmur Pulmonary - tachypnea, dyspnea ```

What body systems are involved in the response to anemia?

Kidney, liver, thyroid, adrenal gland, sex hormones from gonads

IF the body systems required for hematopoiesis are healthy, what should happen in response to the anemia?

3-4 days bone marrow should start making new RBC's | Could take a week before you see regenerative changes

What is an immature RBC called?

Polychromatophil

What is an immature RBC stained with New methylene blue stain called?

Reticulocyte

The more severe the anemia, the higher the what?

reticulocyte count

how long do reticulocytes hang out in circulation before they are mature?

24-48 hours

Why do we have to do a manual reticulocyte count in cats?

cats have aggregate reticulocytes that only stay in circulation for 12 hr. These become punctate reticulocytes which remain in circulation for 10-12 days. The analyzer does not pick up punctate reticulocytes and will greatly underestimate the response to anemia the body is having

What are some hallmarks of a regenerative response to anemia?

``` increased polychromasia increased anisocytosis increased nucleated RBC's increased Howell-Jolly bodies basophilic stippling ```

What is a normal finding in cats because their spleen does not remove them?

Howell- jolly bodies

What is a normal feature of immature ruminant erythrocytes?

Basophilic stippling

What is indicative of polychromasia in our lab results?

Increased MCV - polychromatophils are larger than mature RBC's Lower MCHC - polychromatophils contain less hemoglobin than mature RBC's Increase RDW will be greater variation in red cell size

What lab findings indicate anemia?

Low PCV, Low Hgb, Low RBC

What does increased polychromasia or reticulocytosis tell us?

Regenerative anemia

What can cause a regenerative anemia?

Hemorrhage | Hemolysis

What can appear as a non-regenerative anemia?

less than 4 days duration hemorrhage or hemolysis extramarrow disease intramarrow disease

How do we describe mean cell volume in RBC's

macrocytic, normocytic, microcytic

How do we describe MCHC in RBC's?

Hypochromic, normochromic, hyperchromic

What are the pathophysiologic mechanisms of anemia?

Hemorrhage or blood loss Increased erythrocyte destruction decreased or defective erythropoiesis hemodilution (not true anemia)