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OSSF Exam 2 - Questions With Verified Solutions
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OSSF Exam 2 - Questions With Verified Solutions
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OSSF Exam 2 - Questions With Verified SolutionsExplain the difference between serum and plasma and how the role of
albumin in maintaining blood osmolarity and the clinical consequences of
having a deceased concentration of plasma albumin. Right Ans - Peripheral
blood volume makes up about 9% of an animals body weight. Its general
function is to carry oxygen, nutrients and hormones as well as helping
eliminate CO2 and other wastes. The peripheral blood also plays a role in the
immune system as WBCs use the bloodstream as a simple transport system
(only present for a few hours to a few days).
Plasma is the liquid in unclotted blood and makes up about 55% of animals
peripheral blood. It is about 90% water and in most species it is
colorless/faint yellow. The other 10% is made from low molecular weight
molecules (glucose, electrolytes (salts) and urea) and high molecular weight
molecules (albumin, clotting factors, immunoglobulins (antibodies), enzymes
and lipoproteins). These low molecular weight molecules are in equilibrium
with the interstitial fluid. Albumin mainly stays in the blood vessel lumen and
is used to carry steroid and thyroid hormones as well as Ca2+ so that they do
not slip into cells. It is also used to maintain oncotic pressure which is
important for keeping the fluid in the vascular space (decreased albumin
would result in low oncotic pressure and edema/ascites (swelling caused by
excess fluid trapped in your body's tissues)). Plasma is often collected in a
purple top tube that has an anticoagulant (EDTA) in order to stop the clotting.
Serum is very similar to plasma but lacks the clotting factors (it is the liquid
left after clotting occurs). It has a lower total protein level than plasma as well.
This is usually the top layer of liquid in a red top collection tube (no
anticoagulant).
Explain the function of RBCs and the role of hemoglobin in carrying oxygen
Right Ans - Erythrocytes (RBCs) are the most common cell type in blood and
are important for carrying oxygen to the tissues through the hemoglobin
protein in their cytosol. Hemoglobin (globin=alpha and beta chains, heme
contains iron) causes the homogenous orange to pink color of RBCs in
histology preparations. The main influence on hemoglobin binding affinity is
the concentration of oxygen in the environment. At higher concentrations, the
hemoglobin is more likely to grab O2 (lungs) but at lower concentrations, the
hemoglobin is more likely to release the O2 (tissues). Hemoglobin experiences
cooperative binding, meaning that as O2 binds, the affinity for O2 increases.
,The biconcave disk shape (seen in some species) provides a high surface area
to volume ratio that is optimal for the RBC gas exchange and allows for
deformability (flexibility) during circulation. This is especially important
when navigating the capillaries.
RBC's circulate for several months. When they are worn out or damaged
(senescent RBCs), they will be eliminated by macrophages in the spleen and
bone marrow.
Describe the big species differences in RBC morphologic features Right Ans
- Dogs have the most pronounced biconcave disk shape. Goats have the
smallest RBCs. Camelids have oval shaped RBCS without nuclei. Birds, reptiles
and amphibians have oval shaped RBCS with nuclei.
(in the image A=Elephant, B=Goat, C=Flamingo, D=Alpaca, E=Dog, stained with
Wright stain)
Recognize neutrophils, lymphocytes, eosinophils, monocytes, and basophils in
a mammalian blood smear and be aware of species differences in eosinophil
and basophil appearance. Right Ans - Neutrophils have a multilobed
nucleus (segs), and tightly clumped chromatin, and their second-degree
granules are indistinct (colorless) or they are pale pink/lilac. Some species
have heterophils (rabbits and birds) which function like a neutrophil but have
a more eosinophilic appearance.
Eosinophils have a ribbon-shaped nucleus and their secondary granules are
very eosinophilic (orange to pink in color).
Basophils have either dark purple or pale lavender color (metachromatic,
similar to the nucleus color) secondary granules. Their nucleus is often ribbon
or horse-shoe-shaped and can be diluted by the secondary granules because
of their similarity in color. In dogs and cats, the granules may be more difficult
to identify. In canines, the cytoplasm may be lavender with few granules and
in felines, the cytoplasm can be purple or gray (not blue). These may be
confused with a mast cell that has similar metachromatic granules and
functions. The main difference is that in mast cells, the nucleus is round to
oval and in basophils, the nucleus is bilobed to ribbon-shaped. Also, basophils
leave the bone marrow already mature, while mast cells mature in the tissue
(if in tissue=mast cell, if in blood=basophil).
Lymphocytes are often smaller than a neutrophil (although they vary in size
with some large lymphocytes being bigger) and have a round, usually cleaved
,nucleus. They have a high nucleus: cytoplasm ratio with only a small amount
of smooth, light blue cytoplasm. The chromatin is often, smooth, slightly
clumped and has a pinkish purple color. These cells are unique in that they
can change appearance when stimulated and produce more euchromatin and
a more royal blue cytoplasm.
Monocytes are in the blood and are variable in size, but are often the largest
WBC. Their nucleus is round to lobulated with loose stretched-out chr
Compare the primary functions of each type of WBC and explain some of the
clinical consequences of decreased circulating numbers of the specific WBCs
(e.g. clinical consequence of having decreased numbers of neutrophils)
Right Ans - Leukocytes, or white blood cells (WBCs), take a lot of bone marrow
to produce and are far less numerous than RBCs in the blood (when the
animal is healthy). These are motile cells that function in connective tissue to
provide defense against infection. During an infection, a huge number will be
produced, however, they will quickly move out of the bloodstream and into
the tissues. There are two types of leukocytes, granulocytes (neutrophils,
eosinophils, and basophils --> most of bone marrow time is spent making
these) which have secondary granules and agranulocytes (lymphocytes
[primarily made in the periphery tissues] and monocytes) which do not have
secondary granules (do have lysosomes).
Neutrophils have "neutral" staining granules that are almost colorless or pale
pink/lilac. They are the most numerous WBC and the first to show up at the
site of damage (inflammatory reaction) to defend the body against bacterial
infection (bacteria destroying factory: have myeloperoxidase, lysozymes
(phagocytize) respiratory burst of free radicals and low pH all to destroy the
bacteria). They often last 6-10 hours in the blood or 1-2 days in the tissue.
Eosinophils have distinct orange/pink secondary granules (round except for
cats) and are the defense against parasites. They are not able to phagocytize
the parasite because they are too small in comparison, so they instead dump
their granule contents (ex eosinophil peroxidase) onto the parasite to kill
them. They are also involved in the regulation of allergic reactions and will be
found in the blood and liver more in animals who have allergies. These cells
survive for several weeks in tissues and are often bigger than the neutrophils
(horses have the biggest eosinophils and cats have the smallest). Basophils are
the least common leukocyte and are not easily found in tissues (thes
, Understand the process of Hematopoiesis (or Hemopoiesis) and how all cell
blood cell types are derived from a pluripotent stem cell Right Ans -
Hematopoiesis is the production of all blood cell lineages. This primarily
occurs in the adult bone marrow (found in the medullary cavities of bones,
cells are sitting between the fingers of spongy bone). Some extramedullary
hematopoiesis is found in the spleen (especially in the mouse, ferret and
hedgehog). For example, if a dog becomes anemic, the spleen may also join in
to help produce blood cells BUT this does not happen when the dog is healthy.
The active bone marrow is called red marrow (stains blue because of all the
nuclei) which can be found at the proximal end of long bones (in spongy bone)
and in flat bones (vertebra, sternum, ribs, skull, hip). There is an increase of
red marrow in young growing animals and at time of increased demand. This
marrow is organized into cords of cells separated by sinusoidal capillaries
(sinuses) and supported by reticular connective tissue. The megakaryocytes
sit next to these sinuses and release platelets into the blood while other
mature cells pass through endothelial cells, of the sinuses, into the
bloodstream. The precursors of white cells are often near the fingers of the
spongy bone while the red cell precursors are more central. The medullary
cavity of in diaphysis usually contains the inactive yellow marrow.
Pluripotential stem cells can produce all other blood types. They can make
more (regenerate) themselves or commit to a lineage to produce a specific
cell. Hematopoiesis involves both amplification (through mitosis) and
differentiation of cells. Erythropoiesis is the production of red blood cells
(RBCs) where the RBC sees its nucleus shut down and condense while its
cytoplasm becomes more eosinophilic from the increase in hemoglobin
(polychromatophils because there are two colors present). Eventually, the
RBC will lose its nucleus and become an orange/pink color wi
Recognize platelets in a blood smear and explain platelet function and the
clinical consequences of decreased circulating numbers of platelets (i.e. what
happens when you have a low platelet count) Right Ans - Platelets are a
piece of cytoplasm broken off from a megakaryocyte so it has no nucleus. They
are small cytoplasmic fragments with a lightly stained periphery and a central
zone with pink-stained granules. Platelets can survive for 8-10 days. These
platelets can be seen as a stream as they break off from the megakaryocytes.
The main function of platelets is their clot formation. They break off from the
megakaryocyte and aggregate at the damage in order to patch over the
damaged endothelium. This impedes the blood flow in order to avoid excess
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