Blood, lymph and immunity Flashcards

Question

Formation of red blood cells

Answer 1

Erythropoiesis: the production of red blood cells from the PPSC in bone marrow Stimulated by erythropoietin, produced mostly by the kidney (~85%) in response to low oxygen levels (hypoxia) in the blood. Initiates differentiation of PPSC into RBC’s Human erythropoietin used to stimulate RBC production in humans and animals, but often animal’s immune system will destroy it. Has been abused in horses in an attempt to increase performance Synthesis of new RBC’s requires iron, folic acid, and vitamin B12 Mature RBCs have no mitochondria, cannot perform Krebs cycle and rely on plasma glucose for energy!!

Answer 2

Important to Vet TEchs because RBCs use glucose after blood is collected Important to separate serum within an hour of collection to prevent errors Falsely low glucose Because RBC use up the serum glucose Falsely high potassium Because most of the body's potassium is intracellular it will shift form inside the RC to the serum

Answer 3

A protein composed of two parts; one globin with 4 heme molecules attached = 1 hemoglobin Heme: each heme molecule has an iron atom portion (Fe++) tha binds to oxygen molecule Almost all oxygen in blood is bound to hemoglobin

Answer 4

Hgb that is carrying oxygen attached to each iron molecule is called oxyhemoglobin and appears bright red Hgb that has no bound oxygen is called deoxyhemoglobin and appears dark red (sometimes purple) Hgb bound to carbon monoxide is called carboxyhemoglobin and appear cherry red

Answer 5

Carrying gasses Ability of Hgb to carry and hold oxygen depends on pH, temperature, and the concentration of oxygen and carbon dioxide gasses in the air and blood (partial pressures) Carbon dioxide transport Some simply dissolves in the plasma Some is bound to proteins and Hgb (not at the oxygen site) The majority is transported as bicarbonate RBCs are very important in bicarbonate formation because they contain an enzyme that catalyzes the formation of carbonic acid CO2 diffuses into RBC, combines with water to make carbonic acid, then dissociates to produce hydrogen ions and bicarbonate At the lungs, the reverse occurs, and CO2 is breathed off

Answer 6

RBC life span varies with species and is typically several months Senescence is the process of aging As RBCs become senescent, they become smaller, rounder, and less flexible More easily damaged in the circulation Old RBCs are removed from circulation and replaced by new ones from bone marrow Billions of RBCs may be destroyed and produced daily in an animal the size of a human

Answer 7

Extravascular hemolysis Intravascular hemolysis

Answer 8

Macrophages remove senescent or abnormal RBCs from circulation and destroy them Much of this occurs in the spleen and liver The main method of removal

Answer 9

Amino acids go to liver to make more proteins Iron is transported by the plasma protein transferrin to the bone marrow to make more RBC

Answer 10

Heme (red) is broken down to biliverdin (green) then bilirubin (yellow). Bilirubin is Carried by albumin to the liver Combined (conjugated) in the liver with glucuronic acid to make it water soluble Excreted as a bile pigment (yellow) Some of this is reabsorbed and eliminated in urine Rest is eliminated in feces Responsible for providing the normal color of stool and urine Iron is carried by a plasma protein called transferrin to bone marrow to make more heme

Answer 11

RBC destruction within the blood vessels due to mechanical stresses and weakening with age Contents are released into plasma Hgb is picked up by a transport protein called haptoglobin and transported to the macrophages in the liver for breakdown If there is excessive hemolysis all the haptoglobins are filled, Hgb remains free in the plasma (hemoglobinemia) and will be eliminated by the kidneys (hemoglobinuria) Hemoglobinemia appears as pink or red plasma Hemoglobinuria appears as red through to pink urine Both are abnormal findings

Answer 12

Hematocrit (Hct) determined by an automated analyzer, calculates volume occupied by RBC’s from their number and shape. PCV = packed cell volume. This is the packed volume of RBCs after centrifugation Hct and PCV should be similar

Answer 13

Decreased ability of the blood to carry oxygen due to decreased number of RBCs

Answer 14

Loss due to hemorrhage, parasitism Increased RBC destruction Hemolysis Decreased RBC production Often due to chronic condition, sometimes to iron deficiency Bone marrow suppression

Answer 15

Total number of RBCs in circulation is increased Polycythemia rubra vera Compensatory polycythemia Relative polycythemia Loss of fluid (dehydration) means concentration of RBCs, not absolute number, is increased Also called hemoconcentration Increases viscosity of blood and can make heart work harder

Answer 16

Fragments of cells specialized to assist in blood clotting Small, irregularly shaped, cellular fragments Do not have a nucleus in mammals Break off from very large, multinucleate cells (called megakaryocytes) in bone marrow Process of platelet production is thrombopoiesis PPSC (Pluripotent stem cell) differentiates into megakaryocyte

Answer 17

Are involved in hemostasis, or the process of blood clotting This process prevents leakage of blood from damaged blood vessels

Answer 18

Maintain vascular integrity Can attach to endothelium and release endothelial growth factor Helps keep endothelium healthy Decreased platelet numbers means leaky capillaries and can lead to petechia (pinpoint hemorrhage) as RBC’s move out through the endothelium into the tissues

Answer 19

Seals small holes in blood vessels Endothelial damage initiates platelet adhesion to exposed connective tissue and to each other Platelets then change shape to form pseudopods Intertwine with each other to form strong plug – platelet aggregation

Answer 20

Play a part in fibrin formation to stabilize the hemostatic plug As platelets squeeze together, they release clotting factors to complete the clotting process There is a complex series of reactions that result in a mature clot 13 clotting factors are involved Activation of one catalyzes the next step The end result in conversion of the plasma protein fibrinogen to insoluble fibrin, which forms strands to bind the clot together Fibrin contracts at the end of this process to assist in pulling the wound edges together Fibrin also provides scaffolding for the repair of damaged vessel wall and for the granulation tissue To prevent the clot from becoming too large, other factors are activated that assist in the dissolution of the clot after repair.

Answer 21

Immediate spasm of the vessels to reduce hemorrhage- this is short duration Platelet plug formation- platelet adhesion followed by platelet aggregation Clot stabilization- platelets release clotting factors that initiates clotting cascade to turn fibrin into fibrinogen

Answer 22

Damaged or infected blood vessels (thromboembolism) leading to blockage of vessel (i.e.: stroke) Anticoagulant rodenticides inhibit Vitamin K, an important factor in the clotting cascade, leading to inability of blood to clot (coagulopathy). Calcium is also required for blood clotting. Lavender top blood collection tubes contain EDTA to bind calcium, this stopping the clotting process

Answer 23

Mobile defenders against infection and foreign invaders Pus is an accumulation of leukocytes - purulent Formed from PPSC’s (pluripotent stem cells) in bone marrow – leukopoiesis Some develop completely in bone marrow Other cell lines develop elsewhere, like spleen and lymph nodes Five kinds, all nucleated in their mature form in circulation: includes monocyte, lymphocyte, neutrophil, eosinophil, and basophil

Answer 24

First, the type of defense function they perform Phagocytosis: cell-eating. The professional blood phagocytes are the neutrophil and the monocyte Immunity: becoming resistant to infections by foreign organisms. Lymphocytes and basophils

Answer 25

Mononuclear: with a single, round nucleus Lymphocytes Polymorphonuclear:multilobed, segmented nucleus Neutrophils, basophils, eosinophils Pleomorphic: varying shapes without segmentation Monocytes

Answer 26

Agranulocytes: Two kinds: Monocytes: large cells that engulf and destroy foreign particles Lymphocytes: smaller and are involved with immune responses Excess of either/both is associated with chronic diseases Granulocytes: Three kinds (differentiated by their affinity for different stains): Neutrophils: pale, purple stain (neutral) Basophils: have very dark-blue staining granules (i.e. they pick up the basic stain) Eosinophils: red-staining granules (i.e. they pick up the acidic stain)

Answer 27

Aka “segs” because they are segmented Most common WBC of horses, dogs and cats Not cows or pigs! Made in the bone marrow in response to infection Contain lightly-staining cytoplasmic granules Immature neutrophils are called “band”, nucleus is not segmented

Answer 28

Professional phagocytes (bacteria, debris) Contain lysosomes (granules) that destroy engulfed material and organisms They are the first responders against microorganisms Respond quickly High numbers in blood are usually associated with infection but can be low numbers if consumed by overwhelming infections!!! Leave circulation within about 10 hours through a process called diapedesis

Answer 29

Granulocyte Named for their red-staining granules Make up 5% or less of the total WBC count Characteristics Segmented with pink-red granules Granule shape can vary, depending on species, they are very large and easy to see in horses.

Answer 30

Common in skin, lungs, and small intestines Important in allergies and defense against parasites

Answer 31

Granulocyte Named for the granule affinity for the basic dye which stains things blue Rarest WBC Characteristics Granules may be washed out during staining, so aren’t always visible Nucleus is segmented

Answer 32

Granules contain histamine and heparin Help initiate inflammation and allergic reactions Maintain blood flow in damaged areas Histamine causes vasodilation Heparin is an anticoagulant

Answer 33

Agranulocytes About 5% of circulating WBC’s Characteristics Migrate into tissues from blood and become macrophages Largest WBC Cytoplasm is blue-gray staining Vacuoles may be present Nucleus pleomorphic – may be round to horse-shoe-shaped (not segmented)

Answer 34

Primary phagocytes Most of their functions occurs in the liver, spleen, lung, and lymph nodes Act as filters to remove microorganisms, cellular debris, and senescent blood cells Some are ‘fixed’ and stay in one location Others are ‘wandering’ and move through the tissues - increase in inflammation

Answer 35

Agranulocytes Major WBC in ruminants and pigs No phagocytic ability Formed in bone marrow then mature in lymphoid tissue Constantly recirculate between tissues and blood Function Make antibodies Kill diseased cells

Answer 36

Magenta round/oval nucleus with scant, blue cytoplasm Can be large or small (compared to neutrophils) Large have more blue cytoplasm and are thought to be younger = lymphoblasts Small have so little cytoplasm it may be difficult to see – can look like just nuclei No granules

Answer 37

Bones Lymph vessels Lymph nodes Spleen Thymus Lymphoid tissue Consists of a series of vessels or ducts and lymph nodes

Answer 38

Lymphatic vessels parallel the routes of veins They carry excess tissue fluid called lymph to the thoracic region where it empties into the vena cava near the heart Lymphatic tissue is scattered throughout the body as lymph nodes, the spleen, thymus, tonsils and gut associated lymph nodes.

Answer 39

Return of extracellular fluid to blood, including waste materials from cellular metabolism Filtration and defense against infection As lymph fluid passes through a lymph node, it filters out microorganisms and cellular debris Protein and lipid transportation: Some proteins and lipids are too large to enter directly into circulation Instead enter by lymphatic vessels

Answer 40

Lymph starts as excess tissue fluid that is not picked up by blood vessels Because the blood pressure forcing fluid out of the vessels is stronger than the osmotic/oncotic pressure drawing fluid back into the vessels Results in an excess accumulation of fluid in the tissues Blind-ended lymph capillaries within the tissue pick up the excess fluid and join together to form larger and larger lymph vessels Eventually terminate in the thoracic duct that empties into the vena cava The lymph vessels have valves within them, preventing back flow As the lymph moves towards the vena cava, lymph passes through the lymph nodes which filter the lymph and are one of the body’s defenses against infection

Answer 41

Are kidney shaped and scattered throughout the body Contain lymphocytes, macrophages and plasma cells

Answer 42

Lymphatic vessels which enter lymph nodes are afferent vessels, those that leave the lymph node are efferent vessels Lymph nodes receive vessels from specific regions of the body so lymph from a specific area always passes through the same lymph nodes The condition of each node reflects the health or disease of that area If Infection is present in a specific area, the lymph nodes in that area tend to increase in size to fight the infection

Answer 43

Because of their significant enlargement in response to some pathogens they are important indicators of infection Cancer cells as well as infections may metastasize or spread throughout the body by way of the lymphatic channels Pathologists examine regional lymph nodes microscopically to determine if the cancer is spreading Meat inspectors study the lymph system for changes in colour or consistency to determine if part of the carcass should be condemned

Answer 44

small dark red or black structures found in cattle and sheep Filter blood instead of lymph and are connected to the vascular system instead of lymphatic channels Located near regular lymph nodes. Do not mistake them for lymph nodes which have taken up blood following local hemorrhage in the area

Answer 45

An organ attached to the stomach and associated with both the circulatory system and the lymphatic system. Body can survive without a spleen- other lymphoid tissue picks up the white pulp functions and other tissue macrophages pick up the red pulp functions. May be some immuno-compromise. Removal of spleen is called splenectomy

Answer 46

As a storage area for blood Part of the macrophages distributed throughout the liver and spleen that “clean up” Phagocytizes fragile worn-out RBCs Removes foreign material from circulating tissue fluids (both lymph and plasma) Contains both red pulp and white pulp White pulp is the localized areas of the lymphoid tissue Red pulp is the blood vessels, sinuses and associated tissue macrophages

Answer 47

Blood storage (remember the spleen has smooth muscle in it that contracts when extra blood is required by the body) Filtration by tissue macrophages Removal of senescent blood cells by macrophages

Answer 48

Lymphoid organ located in the cranial thoracic region lying on each side of the trachea Large in young , progressively gets smaller as animal ages This is because young animals have a developing immune system. The thymus is important in the maturation of T lymphocytes As the animal ages, their immune system becomes fully developed so no longer need the high production of T-lymphocytes.

Answer 49

Found all regions of the body, not just the throat. Are peripheral lymphoid tissue where mature lymphocytes live Differ from lymph nodes because they are found: Close to moist epithelial surfaces (mucosal) At the beginning of the lymph drainage system not along the vessels.

Answer 50

GALT is the lymphoid tissue lining the intestine and makes up over 25% of the intestinal mucosa and submucosa