Cardio 01 & 02: Blood Flashcards
Lectures 01 and 02
The pulmonary and systemic circulations are arranged in _______, but systemic circulation to different organ systems is in _______.
The pulmonary and systemic circulations are arranged in series, but systemic circulation to different organ systems is in parallel.
In general blood passes through ___ set(s) of capillaries before returning to the heart.
Portal systems involve ____ capillary bed(s).
In general blood passes through one set of capillaries before returning to the heart.
Portal systems involve two capillary beds.
What is transported by the blood through the cardiovascular system (list six)?
- O2
- CO2
- Nutrients
- Hormones
- Waste products
- Heat
During CPR how should chest compressions be performed?
Depress sternum 4-5 cm at a rate of 100/minute
What is the difference between primary and secondary cardiovascular disturbances?
Primary are direct CVS problems that can be wither congenital or acquired. CV disorders effect ~11% of small animals in a hospital population.
Secondary disturbanced of the CVS occur as a consequence of non-cardiovascular disorders or disease
List some examples of congenital primary CV disorders/diseases
- Cardiac defects e.g.
- valve defects
- defects of the heart wall
- Defects of the major vessels
- Clotting disorders
Image shows congenital aortic stenosis
List some examples of acquired primary CVD
- Haemorrhage – eg. due to trauma
- Acquired clotting disorders (e.g. warfarin poisoning)
- Primary cardiac disease, eg. Myocarditis, myopathy, acquired valvular disease (e.g. from ageing), infection of valves
- Parasitic infections (eg. heartworm)
Image shows heartworm (Dirofilaria immitis)
(1) What is the name of the organism commonly called ‘heartworm’ in pets and (2) what kind of organism is it? (3) How is it commonly spread?
- Dirofilaria immitis
- It belongs to the filarioidea, a superfamily of highly specialised parasitic nematodes (roundworms)
- Spread through bites from mosquitoes (intermediate host)
(1) What is the name of the horse parasites commonly known as “bloodworms”?
(2) What is the life cycle and some of the clinical issues and signs?
(3) What are two of the most common treatments?
- Strongylus vulgaris (large strongyles)
- Usually acquired through faeces (from eating grass etc contaminated)
- Life cycle: adults lay eggs in cecum and colon which lass out in faeces. These hatch into larvae and are consumed e.g. on grass. Consumed larvae migrates to the small intestine where they enter the intestinal mucosa and develop further to a stage that can enter the blood vessels. Here they continue their migration throughout the body to various organs causing damage to the blood vessels along the way, for a period of up to six months. They then return to the intestinal wall to copulate and lay their eggs and the cycle begins again.
- Clinical signs: Weight loss, dull goat, impaired performance, diarrhea, weakness, anorexia, anemia, severe colic, rupture of the intestines, and death. Diagnosis through fecal culture.
- Ivermectin and Moxidectin
What are some examples of secondary CV dysfunction (arise as a restult of diesase/disorder elsewhere)?
- Severe vomiting or diarrhoea can lead to loss of water & electrolytes (e.g. Na+, Cl-, K+, Ca2+). This can lead to cardiac arrhythmias & heart failure
- Septic shock/endotoxaemia - bacterial infection (bacteraemia) in the bloodstream
- Anaesthetic overdose - most depress the CNS, barbiturates also depress hearts ability to pump
List the three main cellular components of blood (poper names)
- Red blood cells (erythrocytes) 4.8 - 5.4 million/μL
- White blood cells (leucocytes) 5000 - 10,000/μL
- Neutrophils 60-70%
- Lymphocytes 20-25%
- Monocytes 3-8%
- Eosinophils 2-4%
- Basophils 0.5-1.0%
- Platelets (thrombocytes) 150,000 - 400,000/μL
What are two other functions of blood besides its respiratory and transport roles?
- Homeostasis/regulation
- Body temperature & pH
- Protection
- Immunity & clotting
What is the matrix of blood tissue and what is it composed of?
Blood plasma forms usually about 55% of blood. Of this:
- water makes up 91.5%,
- proteins (albumins (helps maintain fluid balance), globulins (important in immune responses), fibrinogen (important in blood clotting & inflammation), and others) make up about 7%,
- other solutes (e.g. electrolytes, nutrients, gasses, regulatory substances, vitamins, and waste products) make up about 1.5%
What is one way to separate out different components of the blood?
Centrifuge
Approximately what % of body mass is comprised of blood volume?
Differs between species: approx 5.5 - 11% of body mass
What is the usual size range of erythrocytes?
4 - 9μm
Erythrocytes form as biconcave discs in most species eg. dogs, cats,
horses, humans and flexible (as move through capillaries etc).
What difference in appearance do ruminant, pig, and camelid RBCs display?
They are flatter (less concavity), and some species are ovoid.
See attached slide of ovoid alpaca erythrocytes.
What kind of lifespan do most erythrocytes/RBCs have?
2 (e.g. cats) - 6 (e.g. cattle) months
Older erythrocytes bbecome less flexible and more prone to damage
What kind of animal might this slide of erythrocytes/RBCs belong to? Why?
Some kind of non-mammal (e.g. bird, lizard, fish, frog) as these all have nuclei, while mammalian erythrocytes lack nuclei and organelles.
The slide in fact shows reptilian RBCs.
What is the term for variation in RBC/erythrocyte shape?
In what mammalian species does this commonly occur natirally (non-clinical)?
- Poikilocytosis (from from poikilos (ποικίλος) meaning “varied” in Ancient Greek)
- Mostly goats and cattle (image is bovine blood)
- Can indicate clinically relevant issues in other species
What is the term for variation in erythrocyte/RBC size in some animals?
What species are you likely to encounter that display this?
- Anisocytosis (from Ancient Greek: an- ‘without’ or ‘negative quality’ + iso- ‘equal’ + cyt- ‘cell’ + -osis ‘condition’)
- Commonly found in normal cattle
- It can be a clinical sign in other species (e.g. indicating anaemia)
What are the main functions of erythrocytes/RBCs?
Transport of O2 and CO2
- O2 transported via haemoglobin (Oxyhaemoglobin)
- CO2 may be transported:
- in solution
- as bicarbonate
- bound to protein(carbamino compounds)
What is the type of step cell that produces both erythrocytes and leukocytes?
Where are they found?
- Multipotential hematopoietic stem cell (hemocytoblast)
- Bone marrow
RBCs have no nucleus so are incapable of cell division.
Where are they produces from nucleated stem cells (–> erythroblasts) in (1) the fetus and (2) in adults?
- In the fetus RBCs are primarily produced in the liver & spleen
- In adults, production occurs within bone marrow.
Rate of erythropoiesis is under endocrine control. What is the hormone involved and where is this hormone produced?
Erythropoietin (EPO) is formed in the kidneys in response to a decreased partial pressure of arterial O2.
Slow response (2 - 3 days).
Activity of erythropoietic cells is greatly affected by nutritional status.
What are some specific nutritional defecits that can affect Hb (haemoglobin) content and erythropoiesis?
Hb content will be affected by deficiencies of:
- Protein
- Iron
- Copper
- B vitamins (B2, B6, B9 (folic acid) & B12)
What are some of the reasons that erythrocytes are removed after 2-6 months?
- Metabolic machinery declines with age since no DNA or RNA (required for protein synthesis).
- Cell membrane becomes more fragile & rupture as they pass through capillaries (especially in the spleen).
(1) What type of cells remove damaged erythrocytes in the liver, spleen, and bone marrow?
(2) What are the fates of the heme and iron after erythrocyte degradition?
- macrophages
- Heme is degraded to bilirubin and iron is reused.
What is the anticoagulant usually used for haematological examinations that require liquid blood and is found in purple-topped blood tube?
Ethylenediamine tetraacetic acid (EDTA)
Evert tube a couple of times gently (do not shake) to thoroughly mix blood with anticoagulant.
What is the normal range of hematocrit (packed cell volume) (%) for canines? What does this measure?
35 - 57%
Proportion of RBC within the blood
Can also be written fractionally e.g, 55% = 0.55
What is the normal range of red blood cell, white blood cell, and platelet counts in canine blood (x103/μl)?
- RBC: 5000 - 7900 x103/μl
- WBC: 5 - 14 x103/μl
- Platelets: 210 - 620 x103/μl
What is the normal range of canine blood hemoglobin levels (g/dL)?
12 - 19 g/dL
What are MCH and MCHC? How is this calculated?
Ware the normal ranges of MCH (mean corpuscular hemoglobin, pg) and MCHC (mean corpuscular hemoglobin concentration, g/dL) for canines?
MCH: 21 - 26 pg: [Hb] (x10g/L)/RBC (x1012/L)
Mean cell Haemoglobin [MCH] is the average amount of haemoglobin in red blood cells expressed in picograms [pg]. It is calculated by dividing the haemoglobin by the red blood cell count and is used to differentiate some anaemia.
MCHC: 32 - 36 g/dL: [Hb]/Hct
Mean Corpuscular Haemoglobin Concentration [MCHC] indicates the average concentration of haemoglobin in red blood cells, expressed grams per dL and is calculated by dividing the haemoglobin by the haematocrit
What is hematocrit (Htc) and what instruments are used to measure it?
- Aka packed cell volume (PCV).
- = fraction of total volume represented by erythrocytes.
- Species differences.
- PCV may vary due to changes in total number of cells or size of cells.
- Measured using microhematocrit or automated analyser
Hematocrit (Hct) afficts the ability of blood to carry O2. It also effects blood viscosity.
(1) What do we call low Hct (usually <30%)?
(2) What sorts of conditions can cause this (list 6)?
- Anaemia
- Haemorrhage
Haemolysis
Iron deficiency (human)
Bone marrow disorder
Chronic renal disease
Over hydration
Hematocrit (Hct) afficts the ability of blood to carry O2. It also effects blood viscosity.
(1) What do we call high Hct (usually >50%)?
(2) What sorts of conditions can cause this (list 4)?
-
Polycythaemia
- Latin poly- (“many”) + cyt- (“cells”) + -emia (“condition in the blood”)
- Dehydration
Splenic contraction
Response to living at altitude
Blood doping & EPO administration
How is Mean Corpuscular Volume [or Mean Red Blood Cell volume] (MCV) calculated?
MCV is the average volume of the red cells expressed in femtolitres [fL] and is calculated by dividing the haematocrit (Hct or PCV) by the red blood cell count. Anaemia is classified as microcytic or macrocytic based on whether this value is above or below the expected normal range.
Where are RBD/erythrocytes stored in the body? What can happen here in some species (e.g. horses) during extercise?
- Spleen
- Splenic contraction to release RBCs when extra O2 needed
What are three different types of anemia?
-
Normochromic normocytic anemia
- decreased RBC count (PCV)
- normal colour = normal amt of Hb/cell (MCH)
- normal mean cell volume (MCV) = normal sized cells
-
Microcytic hypochromic anemia
- Decreased RBC count (PCV)
- Smaller than usual cells (reduced MCV)
- Hypochromic (decresed Hb/cell) decreased MCH and MCHC
-
Macrocytic normochromic anemia
- Decreased RBC count (PCV)
- normochromic
- Macrocytic = increased MCV so increased MCH because more Hb in each as a result of increased size, but normal MCHC
What is used to measure total plasma proteins in a blood sample?
Centrifuge sample then use refractometer 5-9g/dL
What may high total plasma protein levels indicate?
- Haemoconcentration eg. dehydration
- Increased globulin production eg. inflammation or infection
What may low total plasma protein measurement readings indicate?
- Loss of protein via the kidneys (protein losing nephropathy)
- Loss of protein via the gastrointestinal system (protein losing enteropathy)
- Loss of lymph
- Chronic or severe blood loss
- Lack of plasma protein production by liver
What determines the different blood groupings?
alloantigens on
the surface of erythrocytes
What are some erythrocyte alloantigens of
importance in a verterinary context (dogs, cats, horses)?
- Aa1 & Aa2 (dogs)
- AB (cats)
- Aa & Qa (horses)
What is the term for antibodies that cause lysing of the RBCs in the serum of mismatched donor and recipient animals?
haemolysing antibodies
What is the term for antibodies that cause acclutination of the RBCs in the serum of mismatched donor and recipient animals?
haemagglutinating antibodies
What are the two possible outcomes demonstrating an inappropriate match in a blood cross-match test?
haemolysis and heamagglutination
What is the difference between the two tests in which the suspensions of washed cells are mixed with serum samples to determine whether two samples are compatible - the major cross-match and the minor cross-match?
- Major cross-match = donor RBCs + recipient plasma
- Minor cross-match = donor plasma + recipient RBCs
What is the technical name for White Blood Cells (WBC)?
Leukocytes
What are the main features of leukocytes that distincuish them from erythrocytes?
- Leukocytes are larger than erythrocytes
- Leukocytes contain a nucleus, organelles & cytoplasmic vesicles
- Leukocytes primarily perform immune functions
- Directed to sites of inflammation to combat invading organisms
- Emigration from cardiovascular system
- Leukocytes only make up ~1% of blood volume
Leukocyte types are differentiated based on size, granularity, nucleus (lobes).
What are the two main category types?
- Agranulocytes
- Granulocytes (polymorphonuclear)
What are the three main types of granulocyte leukocytes and what proportion/percentage of total leukocytes is comprised of each of these types?
- Neutrophils (50-70% of total)
- Eosinophils (2-10% of total)
- Basophils (0-3% of total)
What type of granulocyte is depicted here?
neutrophil
What type of granulocytes are depicted here?
neutrophils
What kind of granulocyte is depitected here? Why is it named this?
eosinophil
They stain pink/orange/red - named after the pink eosin stain
What kind of granulocytes are depitected here?
eosinophils
What kind of granulocytes are depicted here?
basophils
What kind of granulocyte is depicted here?
basophil
What are some of the primary identifying features of neutrophils?
- most common granulocyte
- Irregular, knobbly nucleus
- Small granules that stain pale lilac
- 9-15μm (2x the size of erythrocytes)
- Motile (move using pseudopodia)
- non-dividing
The bottom example in the attached image shows a band neutrophil, which has been released early and is immature and still developing
What is the function of neutrophils?
Part of innate immune system
- 1st line of defence against bacteria and some fungi
- Follow chemical signals
- ingests bacteria in phagosomes - these combine with lysosomes that kill and digest the bacteria
- Then autolyses and remnants consumed by other cells
With severe inflammation or toxaemia, neutrophils develop morphologic changes. List some of these.
Image shows normal (left A & C) and toxic (right B & D) neutrophils.
- Cytoplasmic basophilia (more blue)
- Cytoplasmic vacuolation - white ‘bubbles’ in attached image
- Dohle bodies (shown with arrow in image) - thought to be remnants of rough ER
- Bizarre nuclear configuration
Describe some of the defining features of eosinophils
- Make up 2-10% of total WBCs
- Large, uniform granules that stain red-orange in most species (greyhounds have paler staining granules and can look a bit like neutrophils)
- Bilobed nucleus
What are some of the main functions of eosinophils?
- Unlike neutrophils they cannon phagocytose
- They kill parasitic worms (granules contain chemicals toxic to such parasites)
- Modulate inflammatory responses, especially from allergic reactions
List some comon identifying features of the granulocytes known as basophils.
- Rare in cats & dogs, 0-3% in horses & ruminants
- U or S-shaped nucleus
- Stains blue - dark purple
- Granules:
- Fewer in number
- Larger in size
- Contain histamine & heparin
What roles do basophils play in immune responses?
Important role in immediate hypersensitivity reactions (granules contain histamine and heparin):
- urticaria (hives)
- anaphylaxis
- acute allergy
What are the two main types of agranulacytes?
- Lyphocytes
- Monocytes
What type of agranulocyte is depicted here?
lymphocyte
What type of leukocytes are depicted here?
lymphocytes
What are some distinguishing features of lymphocytes?
- 12-30% of WBCs (in dog)
- Nucleus is large, spherical, slightly indented, and stains dark purple
- Vary in size:
- Large – 10-14μm
- Small – 6-9μm
- Circulate between blood & lymphoid tissues
- Long lived cells (mths – yrs)
How do lymphocytes function as part of the immune system?
- part of specific (adaptive) immune response:
-
Cell-mediated immunity: T-lymphocytes (approx 90%)
- T-helper cells
- Cytotoxic T-cells
- Mempry cells
-
Humoral (antibody) immunity: B-lymphocytes
- Give rise to plasma cells which produce antibodies
- Memory cells
-
Cell-mediated immunity: T-lymphocytes (approx 90%)
What kind of agranulocyte is depicted here?
Monocyte
Describe some of the identifying features of monocytes?
- 3-10% WBCs; 12-18μm
- Variable in appearance
- Variable shaped nucleus; Kidney or horseshoe shaped nucleus – may resemble band neutrophils (but bigger)
- Contain lysosomes
- blue-grey staining cytoplasm
What roles do monocytes play in the immune response?
- Phagocytosis
- Become macrophages after leaving capillaries
To which (non-mammalian) animal class to these leukocytes belong?
What type of cells are those labelled heterophils in the attached diagram and what is their primary role?
Avian (birds)
Heterophils: predominant phagocytic leukocyte in birds (role analagous to neutrophils in mammals)
What two components does quantitative analysis of WBCs (leukocytes) include?
- Total WBC count
- Differential white cell count (%)
Increased WBC count is known as _______. A decrease is called _______.
Increased WBC count is known as leucocytosis. A decrease is called leucopaenia.
What are the three steps involved in preparing a blood film?
- A small drop of blood is placed near the end of a slide
- A spreader slide is drawn back into the blood drop at at 30-degree angle
- The the spreader slide is pushed away from the blood drop, creating a uniform film across the slide
(1) what are platelets, (2) how are they formed, and (3) what is their function?
- Small (1-5μ), variable shape
- non-nucleated - not whole cells
- Lifespan 5-10d
- Formed in bone marrow from megakaryocytes
- Central role in haemostasis & clotting
What is the normal range for a platelet count?
It is species-specific, but normal platelet count varies ~ 100 x 103/μl – 800 x103/μl
(1) What is the term for a low platelet count and (2) what can it indicate?
- Thrombocytopenia (Greek thrombos ‘clot’ + Latin cyta, from Ancient Greek κύτος kútos ‘vessel, jar’ (used for ‘cell’) + Ancient Greek πενία penía ‘poverty, lack’)
- Abnormal production, accelerated removal, or abnormal distribution
(1) What are the terms for increased platelet count and (2) what can this indicate?
- (a) Thrombocytosis (Ancient Greek θρόμβος thrómbos, “lump”, “piece”, “blood clot”, “milk curd” + cyto- borrowed from Ancient Greek κύτος kútos, ‘container, receptacle’ + Ancient Greek -ωσις -ōsis, ‘state, abnormal condition, or action’)
(b) Thrombocythemia (Ancient Greek θρόμβος thrómbos, “lump”, “piece”, “blood clot”, “milk curd” + cyto- borrowed from Ancient Greek κύτος kútos, ‘container, receptacle’ + New Latin combining form of Ancient Greek αἷμᾰ haîma/ αἵμᾰτος haímatos, “blood”) - Primary thrombocythemia due to bone marrow disorder; secondary cytothrombosis due to disease. Can also be physiologic/reactive - in response to inflammation.
What is the term for the mechanisms that minimise or prevent blood loss?
Haemostasis
What are the three components of Haemostasis?
- Contraction of injured blood vessel (I° Hemostasis)
- Formation of platelet plug (I° Hemostasis)
- Coagulation of the blood (2° Hemostasis)
Describe (1) the Vascular Phase of Primary Haemostasis
Reflex vasoconstriction temporarily restricts blood flow.
- Due to direct mechanical input on smooth muscle of vessel wall & release of vasoactive substances
- Most extensive if blunt trauma
- Lasts up to 30 min
Describe (2) the Platelet Phase of Primary Haemostasis
Damage to endothelium stimulates platelet adhesion & plug formation
What comprises (3) the coagulation of the blood (seconsary haemostasis)?
- Occurs simultaneously with primary haemostasis but takes longer
- Causes consolidation of temporary platelet plug to form a blood clot
- A ‘coagulation cascade’ of enzymatic processes involves intrinsic, extrinsic & common pathways
Compare the extrinsic and intrinsic pathways of the clotting cascade with respect to:
- Triggers
- Initiation
- Series of reactions involving several clotting factors and calcium ions lead to the production of…
- Prothrombin activator and calcium ions cause conversion of…
- Thrombin causes fragmentation, then joining of ____ to ____
Describe what ahppens at the missing step of the coagulation pathway
Describe what happens at the missing step of the coagulation pathway
What comprises the major event in coagulation (blood clot formation)?
Major event = conversion of soluble plasma protein fibrinogen into insoluble threads of fibrin
- trap RBCs and form a gelatinous clot
What are the stimulus for and effect of the haemostatic vasospasm mechanism?
Stimulus: Direct stimulus to vessel wall or to pain receptors; platelets release serotonin (a vasoconstrictor)
Effect: Reflex contraction of smooth muscle in vessel wall; Vasoconstriction helps maintain prolonged bl vessel spasm
What are the stimulus for and effect of the haemostatic platelet plug formation mechanism?
Stimulus: Exposure of platelets to rough surface or collagen
Effect: Platelets adhere to rough surfaces and each other, forming a plug
What are the stimulus for and effect of the haemostatic blood coagulation mechanism?
Stimulus: Cellular damage & blood contact with foreign surfaces activate factors that favour coagulation
Effect: Blood clot forms as a result of a series of reactions, terminating in the conversion of fibrinogen to fibrin
What are three tests for evaluating haemostasis?
- Buccal mucosal bleeding time (BMBT)
- Crude test of platelet function
- Activated clotting time (ACT)
- Evaluates intrinsic & common coagulation pathways
- Prothrombin time (PT) test
- Evaluates extrinsic & common pathways
What is the term for a blood clot that abnormally forms
within a vessel?
Thrombus
What is the clinical term for a clot that dislodges or a fragment of a clot that breaks loose and is carried away by the blood flow?
Embolus
When a dislodged embolus reaches a narrow place in a vessel where it may lodge and block blood flow, it forms a(n) _______.
When a dislodged embolus reaches a narrow place in a vessel where it may lodge and block blood flow, it forms an embolism.
Where a thromubs blocks blood flow such that this causes tissue death (necrosis) due to inadequate blood supply to the affected area, this is known as ________.
Where an embolism blocks blood flow such that this causes tissue death (necrosis) due to inadequate blood supply to the affected area, this is known as infarction.
What are two classes of what are colloquially known as clot preventing and clot buster drugs that are used in both human and veterinary medicine? What is the difference between them?
Anticoagulant drugs are used to prevent abnormal clot formation and Thrombolytic drugs are used to break down abnormal clots once they have formed.
What is the Prothrombin Time Test (PTT) and what does it measure? What may abnormal results signify?
- TPTT used to detect disorders in blood coagulation
- PTT measures the integrity of the extrinsic and common pathways of coagulation [factors II, V, VII, X and fibrinogen as well as its inhibitors].
- If a deficiency exists within the extrinsic pathway, the time required for clot formation will be prolonged depending on the severity of the deficiency.
- It is also prolonged in Vitamin K deficiency and liver disease
