Lecture 3 Flashcards
Where are RBC’s made?
Bone marrow
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
What stimulates erythropoiesis?
Erythropoetin and iron travel to the bone marrow
What are the 3 major pools the erythron contains?
erythrocyte precursors
blood erythrocytes
splenic erythrocytes
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
Where are RBC’s stored?
Spleen
How and where are RBC’s destroyed
the spleen and liver by macrophages
What are the functions of RBC’s?
Transport oxygen to the tissues
Carry C02 away from tissues
buffering of hydrogen ions
What increases the 02 carrying capacity of blood to 70x that of plasma
hemoglobin
what are the 3 things that affect the oxygen content in the blood
Hemoglobin content
partial pressure of 02
hemoglobin oxygen affinity (p50)
How do erythrocytes get rid of C02?
carbonic anhydrase
What is the normal morphology for erythrocytes in dogs?
biconcave disc with prominent central pallor
minimal anisocytosis with only a few polychromatophils
what is anisocytosis
differences in cell size
What do normal erythrocytes look like in cats?
slightly smaller than dogs with less central pallor
exhibit rouleaux
What is rouleax
RBC’s look like stacks of coins
non- specific binding of RBC’s due to protein coating
What do normal RBC’s look like in horses?
same size as cats also exhibit rouleaux
What do camelid RBC’s look like?
oval shaped
What is different about Bird/reptile RBC’s?
they are nucleated
True/False
we can use analyzers for non-mammal species
False - analyzer does not recognize the nucleated RBC’s
What do we use a microcentrifuge and refractometer for?
Microcentrifuge - PCV
refractometer - total protein concentration (TP)
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)
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
What does the PCV measure
RBC mass
What type of blood is used for PCV
Well-mixed/ anti-coagulated blood
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)
