Physiology of Blood

Question 1

list and describe the critical cellular components of blood plus site of production

Answer 1

white blood cells: originate in bone marrow; include neutrophils, eosinophils, basophils, lymphocytes, and monocytes (large role in innate immunity)

platelets: originate from megakaryocytes in bone marrow; have hemostatic and non-hemostatic functions

red blood cells: originate in bone marrow, transport oxygen

Question 2

list and describe the critical noncellular components of blood (plasma) plus site of production

Answer 2

plasma: 90% water; also contains solids including
proteins: most important are fibrinogen (blood clotting), albumin (transport protein), globulins (inflammation and immunity)

electrolytes (salts): Na+, K+, Cl-, bicarbonate; important in water homeostasis regulation, acid-base balance, support muscle and nerve function, and support movement of waste and nutrients in and out of cells

minerals: calcium, phosphate, magnesium; concentration tightly regulated by hormones, required for bone formation, cell functions, water balance, hormone and enzyme component

enzymes, vitamins, hormones, and other nutrients

Question 3

how are electrolytes absorbed?

Answer 3

through the GI tract and kidney

Question 4

describe what often moves with sodium

Answer 4

sodium and chloride are best buddies so they often move together; water often moves with sodium also (osmosis)

Question 5

predict how various cellular and noncellular components of blood might change in response to various physiological conditions

Answer 5

noncellular:
secretion/loss of electrolytes occurs in the GI tract and kidneys, through sweat (big for horses) and saliva (big for ruminants), often during vomiting and diarrhea

absorption/deposition/excretion of minerals takes place in bone, intestinal tract, and kidneys

Question 6

list the major functions of circulating blood (11)

Answer 6

1. water homeostasis
2. maintenance of oncotic pressure
3. maintain blood pressure and circulation
4. coagulation
5. immune defense
6. nutrition
7. respiration
8. excretion
9. hormones
10. regulation of acid-base balance
11. regulation of body temperature

Question 7

what is hematopoiesis and where does it occur?

Answer 7

the making of blood cells from pluripotent stem cells; three lines (erythrocytes, leukocytes, platelets/thrombocytes); occurs in the yolk sac prenatally; the bone marrow of long bones in neonates and juveniles; in the bone marrow of flat bone and ends of long bones in adults; the spleen and liver also contribute to extramedullary hematopoiesis, increasing activity during high demand leading to organ enlargement or nodule formation

Question 8

what is myelopoeisis?

Answer 8

production of granulocytes (neutrophils, eosinophils, and basophils) and monocytes

Question 9

list and describe the 5 leukocyte categories

Answer 9

granulocytes:
neutrophils: predominant in most species, antimicrobial, inflammation, phagocytosis, appear as heterophils in some species
eosinophils: hypersensitivity and parasites
basophils: rare, hypersensitivity

mononuclear cells:
lymphocytes: second most common cell type, part of acquired immune response
monocytes: called macrophages in tissues, monocytes in blood; phagocytosis, APC, cytokine secretion

Question 10

what is a neutrophil storage pool? describe

Answer 10

bone marrow reserve of neutrophils

Question 11

describe species differences of bone marrow storage pool of neutrophils

Answer 11

dogs: have the largest pool; a five day supply so they tend to not display neutropenia unless shits real fucked
ruminants: small storage pool so frequently develop neutropenia in times of high demand like inflammation
cats and horses: intermediate storage pool

Question 12

describe blood pools of neutrophils

Answer 12

there is a total storage pool of blood which is made up of a circulating neutrophil pool (free-flowing in the bloodstream) and a marginating neutrophil pool (stuck to endothelial cells)

Question 13

which neutrophil blood pools are and are not sampled with phlebotomy? why is this okay and give a species difference

Answer 13

circulating pools ARE sampled; marginal pool is NOT; this is okay because the marginal pool is usually equal to the circulating pool except in cats where the marginal pool is 3x the circulating pool

Question 14

what affects the numbers of neutrophils in peripheral blood? (4)

Answer 14

1. shifts between circulating and marginal pools; epinephrine and glucocorticoids cause shift from marginating to circulating; bacterial endotoxins can increase adhesion so can shift from circulating to marginal
2. rate of production in bone marrow
3. rate of release from bone marrow to blood
4. rate of migration into tissue

Question 15

what does a left shift of neutrophils mean and indicate?

Answer 15

many immature banded neutrophils in peripheral blood; indicates infection or inflammation

Question 16

Describe the size, lifespan, and major functional intracellular components of eosinophils

Answer 16

production similar to neutrophil; blood transit time is very short, with a half life of about half an hour in dogs, granules are different in each species; functions are parasite killing, hypersensitivity reactions, and prinflammatory

Question 17

Describe the size, lifespan, and major functional intracellular components of basophils

Answer 17

production similar to neutrophils; very rare in most species except rabbits, turtles and tortoises, and birds; functions similar to eosinophils and mast cells via hypersensitivity reactions, hemostasis, and parasite rejection

Question 18

Describe the size, lifespan, and major functional intracellular components of monocytes

Answer 18

largest of blood leukocytes; highly variable nucleus but generally large, kidney bean shaped, with blue-gray vacuolated cytoplasm;
rapid maturation in bone marrow (24-36hours) and are immediately released upon production (no storage pool); transit approximately 1 day in blood; develop into macrophages and APCs for phagocytosis and cytokine secretion

Question 19

Describe the size, lifespan, and major functional intracellular components of lymphocytes

Answer 19

maturation in lymphoid organs; can persist for a long time and can transit BOTH ways between tissue and blood!!; predominant WBC in most species and can be large and small

Question 20

Describe the size, lifespan, and major functional intracellular components of platelets

Answer 20

1. mammalian platelets are anuclear
2. cytoplasmic fragments of megakaryocytes
3. hella tiny (except in cats!)
4. non-mammalian platelets are called thrombocytes and are nucleated, can be phagocytic
5. megakaryocytes are the larges cells in bone marrow, mature for 4-5 days until platelet release directly into bloodstream, where they live for 5-10 days (can also be produced in spleen, liver, lungs)

Question 21

describe thrombopoeitin

Answer 21

stimulates platelet production; is a main growth factor produced by hepatocytes (enhanced by inflammation); is produced constantly and bound and cleared by megakaryocytes in an inverse relationship to platelet mass

Question 22

where does most of platelet mass reside?

Answer 22

in the spleen
splenic contraction: thrombocytosis; induced by epinephrine
splenic congestion: thrombocytopenia: platelets sequestered, induced by anesthesia and splenic cancer, often mild

Question 23

list and describe the 2 major functions of platelets

Answer 23

hemostatic: prevent hemorrhage by forming a primary hemostatic plug, facilitates assembly of coagulation factors to form secondary hemostatic plugs, repair vascular damage
non-hemostatic: interact with WBCs to promote inflammation and wound healing

Question 24

Describe the size, lifespan, and major functional intracellular components of erythrocytes

Answer 24

1. mature RBC is anucleated in mammals with red-orange cytoplasm; about 7um in dogs
2. primary function is oxygen transport thanks to hemoglobin binding and releasing O2
3. hemoglobin is oxygen-carrying part; heme is porphyrin rings that hold iron and globin is a protein
4. perform anaerobic glycolysis to produce ATP and NADPH to maintain cell and convert MetHgb (irreversibly bind O2=bad) to Hgb (reversibly bind O2)
5. lifespan correlates with body size; approx 120 days in dogs

Question 25

describe the process of erythropoiesis

Answer 25

1. in response to eyrthropoietin
2. as RBCs mature, they decrease in size and basophilia as they increase in hemoglobin formation
3. iron is essential for hemoglobin synthesis
4. vitamin B12 (cobalamin) and folic acid are required for nucleic acid synthesis

Question 26

Describe the size, lifespan, and major functional intracellular components of neutrophils

Answer 26

nucleus: 2-5 segments
cytoplasm: colorless
granules: contain multiple microbial and chemotactic agents
maturation has three pools
proliferation pool: dividing cells, lasts 2.5 days
maturation pool: maturation only, 2.5 days
storage pool: bone marrow reserve
lifespan is 5-6 days, or 7 days in cattle

Question 27

explain how an aged erythrocyte and its contents are destroyed and metabolized in the normal body

Answer 27

RBCs are called senescent when they age, as enzyme activity and deformability decrease; these RBCs are phagocytized by macrophages mostly in the spleen; the iron and globin are recycled and the heme is metabolized to unconjugated bilirubin that is exported from the macrophage, bound to albumin, and taken up be hepatocytes, where the bilirubin is conjugated and excreted into bile

Question 28

define anemia and explain its effects on the function of the circulatory system

Answer 28

1. reduction in oxygen-carrying capacity of the blood
2. clinical signs are due to decreased oxygen: lethargy, exercise intolerance, tachycardia, pale MM, increased resp effort, heart murmur
3. is a clinical syndrome!!! not a disease or diagnose so you MUST find the underlying cause and treat that!

Question 29

define polycythemia and explain its effects on the function of the circulatory system

Answer 29

1. also called erythrocytosis; increase in RBC mass
2. increase in blood viscosity leads to sludging of RBCs in vessels
3. impaired blood flow decreases tissue oxygenation, causes congested MM, dilated retinal vessels, and seizures