Blood And Lymphatics Flashcards
True or false
Blood is a type of connective tissue
True
Give examples of bloods transportation functions
Hemoglobin in RBCs carry oxygen
Nutrients and other compounds are carried dissolved in plasma
Waste removal (CO2 and urea) carried to the lungs, liver and kidneys
Transporting hormones to target organs
carries WBCs to sites of infection
Carries platelets to locations of blood vessel damage
Give examples of regulatory functions of blood
Body temperature
Tissue fluid content (reservoir for fluids during over hydration and dehydration)
pH (acidic waste products are buffered with bicarbonate and phosphate buffers)
What is the normal pH range of blood
7.4 +/- 0.05
Give examples of defence functions of blood
WBCs provide immunity functions (ex. Phagocytosis)
Clotting factors and platelets protect against blood loss
Blood is composed of cells suspended in plasma, these cells include
Erythrocytes (RBCs)
Leukocytes (WBCs)
Platelets (cell fragments)
What is plasma, what is it composed of
Clear fluid in which cells are suspended
Has clotting factors such as fibrinogen
Clotting factors + serum
If blood is clotted, or if blood has been collected in a red top tube, what fluid portion is left
Serum -NO clotting factors (used in clot)
If blood is spun down, or collected in a tube with anticoagulant (Heparin or EDTA) what fluid portion is left
Plasma -HAS clotting factors
Define peripheral blood
Blood in blood vessels around the body
Define whole blood
Blood as it is drawn from a blood vessel
What can you estimate blood volume based on, what is the rule of thumb?
Lean body weight
Rule of thumb, 6-8% of lean body weight is blood volume (varies with fitness/muscling)
1kg=1000ml
True or false
Fit, muscular or hyper animals have a greater volume of blood
True
In general a >___% of total volume of blood loss is life threatening
> 30%
During rest, the need for circulating blood is lower, so the body stores RBCs in the
Spleen
What stimulates the spleen to release blood into circulation
Exercise and hemorrhage causes the spleen to contract
Usually, 45-78% of a blood sample is
Plasma
How much plasma is in a blood sample depends on
Species
Exercise
Hydration
Main component of plasma is
Water (93%)
The other 7% of plasma is composed of
Dissolved substances
What are some of the dissolved substances found in plasma
Proteins (70%)
Gases
Electrolytes
Others
Describe the proteins found in plasma
Primarily albumin, globulins and clotting factors such as fibrinogen and prothrombin
All proteins create much of the oncotic pressure important in maintaining vascular volume
What is oncotic pressure
Pressure due to large molecules which cannot move out of the vessels so water is drawn into the vessels (albumin is the main contributor)
What is a osmotic pressure
Pressure that draws water into an area with higher concentration of solutes (these solutes can move in and out of membranes)
True or false
The proteins in blood are nutritional proteins
FALSE
they are functional proteins
What are some of the gases found in blood? Which is the most abundant but has no function?
Oxygen
Carbon dioxide
Nitrogen (most abundant/no function)
Due to hemoglobin, O2 has a ____ concentration in the body than in the air
Higher
What are some electrolytes found in blood
Sodium
Potassium
Calcium
Magnesium
Chloride
Bicarbonate buffers
Phosphate buffers
True or false
Electrolytes conduct an electrical charge in water
True
What are some other things found in blood
Nutrients: glucose, lipids
Wastes: urea, creatinine, bilirubin
Hormones
Medications/drugs
Describe the normal appearance of plasma
Clear to pale yellow
What does white, cloudy appearance of plasma indicate
High lipid content, potentially from a recent fatty meal or disease
What does a yellow-orange color of plasma indicate
Indicates the presence of bilirubin (a breakdown product of hemoglobin)
Hemolytic anemia or liver disease can show this (become icteric)
Why is it normal for herbivores to have a pale yellow hue in their plasma
Due to plant carotenoids
When would it be normal to see a moderately yellow color in plasma in horses
During fasting due to increased bilirubin
Define hematopoiesis
Production of blood cells
Blood production is continuous due to
Continuous loss, use and replacement
Sites of hematopoiesis in the fetus
Liver and spleen
Sites of hematopoiesis in the newborn
Red bone marrow
Sites of hematopoiesis in older animals
Most red bone marrow in medullary cavities is replaced by yellow bone marrow (mostly fat) with age, so hematopoiesis continues in ends of long bones and in flat bones
Very little production continues in liver and spleen
Blood cells all differentiate from a common cell type called the ______. What is it?
Pluripotent stem cell (PPSC)
A primitive/stem cell that can develop into whatever the body needs
Describe stimulation of pluripotent stem cells
Various stimuli trigger PPSC to develop into what type of blood cell is needed
Most are hormonal triggers
If they are not stimulated by anything they will not develop
Ex. Erythropoietin from the kidneys stimulate erythrocytes to form
Cytology of bone marrow shows populations of cells in various stages of development, why is this?
What do the numbers of each cell depend on?
What can this be used for?
Because most blood cell types complete development within bone marrow
Depends on the cell type and the stimuli the bone marrow received to produce it
Used to diagnose disease
What is the exception to the fact that most blood cell types complete development in bone marrow
Lymphocytes - these mature in lymphatic tissue (thymus, lymph nodes, spleen)
What would hemorrhage stimulate the release of? Infection?
Hemorrhage: RBCs
Infection: neutrophils
If there is a very serious and sudden problem, _____ cells may be released in attempt to get as much of the cell type into circulation as possible, even though they may not be as effective
Immature cells
Describe erythrocytes
Biconcave discs with no nucleus or mitochondria
Contain hemoglobin to carry oxygen to tissues (and CO2 to lungs)
Define erythropoiesis
The production of erythrocytes (RBCs) from the PPSC in bone marrow
Where does erythropoiesis occur? What is it stimulated by
In bone marrow, stimulated by erythropoietin released by the kidneys in response to low oxygen levels in Blood
Initiates PPSC differentiation into RBCs
Synthesis of new RBCs requires
Iron
Folic acid
Vitamin B12
Since RBCs do not have mitochondria, where do they receive their energy?
Rely on plasma glucose for energy
Describe what must be done in order to get a reliable blood glucose level test?
Since RBCs use glucose for energy, when a blood sample is taken the serum needs to be separated from the blood ASAP to give a accurate reading of glucose
Can result in a incorrect reading of low glucose and high potassium
Describe hemoglobin
A protein
Each molecule contains 1 globin attached to 4 heme molecules
Each heme portion contains an iron ion and an bind to an O2 molecule
Almost all oxygen in blood is bound to hemoglobin
Describe the difference in fetal hemoglobin
Fetal hemoglobin has a higher affinity for O2 than normal adult hemoglobin and can steal O2 from mother through the placenta
What is oxyhemoglobin
Hemoglobin that is carrying O2 attached to each iron molecule and appears bright red
What is deoxyhemoglobin
Hemoglobin with no bound O2 (empty) and appears dark red to purple
What is carboxyhemoglobin
During carbon monoxide poisoning, carbon monoxide may bind to hemoglobin
This appears cherry red
Ability of hemoglobin to carry and hold O2 depends on
pH
Temperature
Concentrations of O2 and CO2 in air and blood
What are the 3 ways in which blood carries CO2
Dissolved in plasma
Some transported on another site on hemoglobin
Majority is transported by bicarbonate
Why are RBCs important in bicarbonate formation
Because RBCs contain an enzyme that catalyses formation of carbonic acid.
CO2 diffuses into RBC where the enzyme catalyses the combination of CO2 with water into carbonic acid which then dissociates into hydrogen ions and bicarbonate
What is the equation that represents carbonic acid formation and dissociation that occurs in tissues and lungs?
in which direction does the equation run in the tissues? The lungs?
H2O+CO2<> H2CO3<>H+HCO3
> in tissues
< in lungs
How long is a RBC’s life span? What does it depend on?
Depending on species, it is typically several months long
As RBCs become older, they become
Smaller, rounder and less flexible and are more easily damaged
Billions of RBCs may be destroyed and replaced from bone marrow, how are the majority removed?
Extravascular hemolysis (eaten my macrophages) occurring mainly in the spleen and liver
How are the components of RBCS recycled (amino acids, iron, heme)
Amino acids are used to make proteins in the liver
Irons is transferred via plasma protein transferrin and used to make more RBCs in the bone marrow
Heme is broken down to biliverdin (green) then broken down to bilirubin (yellow) and carried by albumin to the liver where it is combined with glucuronic acid to make it water soluble and is then secreted as bile pigment (yellow) (some is reabsorbed and excreted in urine or feces -responsible for color of stool and urine)
How are the minority of RBCs removed?
Intravascular hemolysis
RBC destruction within blood vessels due to mechanical stresses and weakening due to age
Describe what happens to contents after intravascular hemolysis
Contents are released into plasma
hemoglobin is picked up by transport protein called haptoglobin and taken to macrophages in the liver for break down seen with extravascular hemolysis
What happens if hemolysis is excessive and all the haptoglobin used in the intravascular hemolysis process is filled
Hemoglobin will remain free in plasma (hemoglobinemia) and will be eliminated by the kidneys (hemoglobinuria)
Hemoglobinemia appears as
Pink or red plasma
Hemoglobinuria appears as
Pink or red urine
True or false
Hemoglobinemia and hemoglobinuria are both normal findings
True
What is anemia
A condition that decreases the ability of the blood to carry oxygen caused by decreased numbers of RBCs
Can be loss due to hemorrhage, parasitism, increased hemolysis or decreased RBC production (bone marrow depression) Often due to chronic disease or iron deficiency
What is polycythemia
A primary disease causing An increased number of RBCs
Relative polycythemia, fluid loss results in RBCs being more concentrated but the total number is unchanged
In both cases, it increases viscosity of blood which can cause the heart to work harder
Describe PCV and hematocrit results with polycythemia
Values are increased
Described as hemoconcentrated
What do hematocrit tube results determine
Calculates volume occupied by RBCs from their number and shape
Describe thrombocytes (platelets)
Fragments of cells specialized to assist in blood clotting
Small and irregularly shaped
Do not have a nucleus in mammals
Break off from large multinucleate cells (megakaryocytes) in bone marrow
Involved in Hemostasis (clotting)
Process of platelet production is called ___, it is when PPSC differentiate into
Thrombopoiesis
PPSC differentiate into megakaryocytes
What are the 3 specific functions in clotting that platelets are responsible for
Maintaining vascular integrity
Platelet plug formation
Play a part in fibrin formation to stabilize hemostatic plug
Describe how platelet me maintain vascular integrity
Platelets attach to epithelium and release endothelial growth factors to keep endothelium healthy
Decreased platelet numbers result in
Leaky capillaries which lead to petechia as RBCs move out through the endothelium into the tissues
Describe platelet plug formation
Platelet plugs seal small holes
Endothelial damage initiates platelet adhesion to exposed connective tissue and to each other
After adhesion the platelet changes shape to form pseudopods
These intertwine to form a strong plug
This is called platelet aggregation
How do platelets play a part in fibrin formation in order to stabilize the hemostatic plug
As platelets squeeze together, they release 13 clotting factors, activation of one clotting factor catalyses the next
Prothrombin turns into thrombin and forms on the surface of the platelet aggregation (cluster) which causes the conversion of plasma protein fibrinogen to the insoluble fibrin, which forms strands to bind the clot together
What does fibrin do
Fibrin contracts at the end of the process to assist in pulling the wound edges together
Provides scaffolding for the repair of damaged vessel walls and for the granulation tissue
Give a brief summary of the clotting process
Vascular spasm (doesn’t last long and only effective in small vessels) which allows short period of plug formation
Platelet plug formation activated by collagen (platelets become sticky when exposed to connective tissue)
Blood coagulation (conversion of plasma into a solid gel composed of a mass of fibrin fibers)
What is thrombophlebitis
When a damage or infected blood vessels become inflamed and blood clots on their inner surface
What is embolism
If a clot dislodges and travels through circulation which can potentially block an artery
Can be very serious in the brain
The clotting process of dependent on the process of
Calcium
If an animal is hypocalcemic, how will the animal most likely die, due to damage of the nervous or muscular system or through lack of clotting
Nervous and muscular systems are first affected and the animal will die before clotting is affected
Purple top tube contains ___ which binds calcium and prevents clotting
EDTA
Green top tubes contain ____ which inactivated several blood clotting enzymes
Heparin
Describe what happens with rodenticide poisoning
Clotting requires Vit K for synthesis of clotting factors.
Coumarin/Coumarol type of rodenticide block the action of Vit K and the pest does from blood loss
Animals can be treated by giving high doses of Vit K
May contain warfarin (diccoumarol) which blocks Vit K
Describe leukocytes
Mobile defenders against infection and foreign invaders
Formed from PPSC in bone marrow -called leukopoiesis
Some develop completely in bone marrow, others develop elsewhere such as the spleen or lymph nodes
Pus is an accumulation of (purulent)
Leukocytes
What are the 5 types of leukocytes
Monocytes Lymphocytes Neutrophils Eosinophils Basophils
What are the 3 different classifications of leukocytes
Type of defence they perform
Shape of nucleus
Presence or absence of cytoplasmic granules
Describe the types of defences leukocytes have
Leukocytes are either phagocytic or not
Phagocytosis: ingestion of foreign particles/bacteria
Includes: neutrophils and monocytes are professionals (other may have minor roles in phagocytosis)
Describe the shapes of nuclei of leukocytes
Mononuclear: single round nucleus
Includes: lymphocytes
Polymorphonuclear: multilobed, segmented nucleus
Includes: neutrophils, basophils, eosinophils
Pleomorphic: varying shapes without segmentation
Includes: monocytes
which leukocytes are agranular
Monocytes and lymphocytes
Excess of either or both monocytes and leukocytes is associated with
Chronic disease
What leukocytes are granulocytes? How do they stain?
Neutrophils: pale purple stain (not intense)
Basophils: have very dark blue staining granules (pick up basic dye)
Eosinophils: red staining granules (pick up acidic stain)
Describe neutrophils
AKA: PMN, Neuts, segs, band cells
Granulocyte
Most common WBC in horses, dogs and cats
Made in bone marrow in response to infection
Granules stain lightly (why they are called neutral)
Nucleus is segmented (polymorphonuclear) typically with 2-5 lobes
Immature neutrophils have a horseshoe shape nucleus called a band cell
Will see many neutrophils with severe infection
What are the functions of neutrophils
Professional phagocytes (mainly small bacteria and debris)
Contain lysosomes (granules) that destroy engulfed material and organisms
Found in all tissues but Mainly in lung and intestinal tissue (constantly exposed to microorganisms)
Describe how neutrophils respond to microorganisms
Very quickly, can be found in Hugh numbers during infection or low numbers if the infection overwhelms them
Neutrophils typically leave circulation within 10 hours through Diapedesis
Attracted to areas of infection by chemicals released during inflammation (this is called chemotaxis)
At the site, neutrophils phagocytize invaders either directly or after they have been covered in antibodies to help identify them
Neutrophils use hydrogen peroxide in their lysosomes to help destroy microorganisms
When neutrophils are aged or destroyed, they are phagocytize by
Macrophages
How can you tell neutrophils are old?
Hypersegmentation
Nucleus becomes more segmented
This can happen in a blood collection tube (why it is important to make a smear shortly after collecting blood)
Describe eosinophils
Polymorphonuclear: segmented usually with 2 lobes
Granulocyte: Named for red staining granules. Granules can vary depending on species, in horses they are very large and round and bright staining
Make up 5% or less of total WBC count
Function: important in allergies and defence against parasites
Generally found in large numbers in skin, lungs and small intestine
Describe basophils
Granulocyte
Named for granule’s affinity for the basic dye which stains granules very dark blue (may be washed out and cannot see)
Polymorphonuclear: 2-3 segmented lobes
Rarest WBC: 1% or less
Function: granules contain histamine and heparin (anticoagulants) to help initiate inflammation and allergic reaction and maintain blood flow in damaged areas (histamine)
Describe monocytes
Makes up about 5% of circulating WBCs
Pleomorphic: may be round to horseshoe shaped -not segmented
Agranulocyte
Largest WBC
Cytoplasms is blue-grey staining
Vacuoles may be present: may look like
Granules but they are white
Migrate into tissues from blood and become macrophages
Functions of monocytes
Primary phagocytes
Most of their functions occur in the liver, spleen, lung and lymph nodes
Act as filters to remove microorganisms, debris and old blood cells
Some are fixed and stay in one location, others are wandering and move throughout tissue to increase inflammation
Describe lymphocytes
Mononuclear: round or oval (no segmentation
Agranulocyte
Major WBC in ruminants and pigs
No phagocytic abilities
Function: to make antibodies (1 type) or kills diseased cells (other 2 types)
Primarily in lymphoid tissue (spleen/thymus/lymph nodes)
Constantly recirculate between tissue and blood
Formation: arise from PPSC in bone marrow and then move to lymphoid tissue to mature
Large ones: more blue cytoplasms and are often younger
Smaller: little cytoplasm visible
What does the lymphatic system consist of
Bone, lymph vessels and nodes, spleen, thymus, and lymphoid tissue
Vessels, ducts and lymph tissue
Lymphatic tissue is scattered throughout the body as lymph nodes, the spleen, thymus, tonsils and gut associated lymph tissue
Lymphatic vessels ____ the routes of veins
Parallel
They carry excess tissue fluid called lymph to the thoracic region where it empties into the vena cava near the heart
What are the 3 major functions of the lymphatic system
Return of extracellular fluid to blood
Filtration and defence against infection
Protein and lipid transportation (big molecules) since these molecules are too big to enter circulation they get carried in the lymphatic system
Describe lymph formation
Lymph starts as excess fluid that is not picked up by blood vessels. This is because blood pressure forcing fluid out of the vessels is stronger that the osmotic/oncotic pressure pulling fluid back in. Results in an accumulation of fluid in the tissues
lymph capillaries within the tissue pick up the excess fluid and join to form larger and larger vessels.
These larger vessels terminate in the thoracic duct that empties into the vena cava
The lymph vessels have valves to prevent back flow
As lymph moved toward the vena cava, lymph passes through lymph nodes which filter the lymph (one of the body’s defence mechanisms)
Describe lymph nodes
Kidney shaped and scattered throughout the body
Contain lymphocytes, macrophages and plasma cells
Lymphatic vessels entering the lymph node is deemed Afferent and those exiting are deemed Efferent
Each lymph nodes receives vessels from a specific region of the body (useful In Localizing pathology)
Condition of lymph nodes reflect health of that area -infections in the area cause lymph node to increase in size
If the first lymph node is unable to filter out/stop the infection, where does it go
The infection will pass to the next lymph node and it will respond as well
Why are lymph nodes clinically important
Significant enlargement in response to pathogens are important indicators of infection
Cancer cells and infections can metastasize throughout the body via the lymphatic system
Pathologists examine lymph ones to determine if cancer is spreading
Meat inspectors study lymph system to determine if parts of the carcass can be eaten or not
What are hemal nodes
Small dark red or black structures found in cattle and sheep
These filter blood instead of lump and are connected to the vascular system instead of the lymphatic system
Located near regular lymph nodes
Can be mistaken for lymph nodes that have taken up blood Following a local hemorrhage
Carnivores and ruminants typically have ____ lymph nodes at each side
1-2
Porcine and equine normally have ___ lymph nodes per site
Many
How many lymph nodes are in equine, bovine and canine?
Equine: 8000
Bovine: 300
Canine: 60
What is the thymus
Lymphoid organ located in the cranial thoracic region lying on each side of the trachea
Very large in young animals and regress as the animal ages This is because young animals are still developing their immune system
The thymus is important for maturation of T cells , as the animal ages their immune system because fully functional so they do not need the high production of T-lymphocytes
What is the spleen
An organ attached to the stomach and associated with both circulatory and immune systems
What are the functions of the spleen
Storage area for blood
Part of reticuloendothelial (macrophage) system
Phagocytize fragile worn out RBCs
Removes foreign material from circulating tissue fluids (lymph and plasma)
What is the white and red pulp in the spleen
White pulp: localized areas of lymphoid tissue in the spleen
Red pulp: blood vessels and sinuses and associated tissue macrophages in the spleen
Serves in:
Blood storage
Filtration by tissue macrophages
Removal of old blood cells by macrophages
What happens if the body loses the spleen
The body can survive because other lymphoid tissue will pick up the white pulp functions and other tissue macrophages will pick up red pulp functions
May cause some immunosuppression
Define Splenectomy
Removal of the spleen
What are the tonsils
Found in all regions of the body (not just throat)
Are the peripheral lymphoid tissue where lymphocytes live
How do tonsils differ from lymph nodes
Tonsils are close to moist epithelial surfaces (mucosa) and are found at the beginning of the lymph drainage system not along the vessels
What is the Gut Associated Lymph Tissue (GALT)
Lymphoid tissue lining the intestines and makes up over 25% of the intestinal mucosa and Sub-mucosa
