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Laboratory Techniques and Procedures
Objective 4.01: Implement proper techniques for collection and analysis of laboratory samples
Circulatory System FunctionsHeart, blood, vessels, and lymphaticsFunctions:
◦Respiratory – O2 and CO2 exchange
◦Excretory – removes waste from body cells◦Protection – clotting and transporting white
blood cells to infections◦Nutrition – carries energy and food
throughout the body◦Regulatory – maintain pH and temperature◦Hormonal – transfers hormones to organs
Circulatory System ComponentsHeart – muscular, four-
chambered pump that drives the circulatory system
Pericardium – fibrous sac that encloses the heart
Artery – elastic vessel with thick walls to maintain high pressure while carrying blood away from the heart
Vein – thin-walled vessel that carries deoxygenated blood to the heart
Capillary – microscopic vessel that forms a network between arteries, veins, and body tissues
Lymph system – consists of lymphatic vessels & tissues (tonsils, thymus, spleen, lymph nodes) that play an important role in immunity and disease prevention
Lymph node – bean-shaped structures located throughout the body that produce lymphocytes and monocytes, and filters bacteria, foreign bodies, and malignant cells
Spleen – largest lymph organ, produces lymphocytes and monocytes, stores red blood cells and iron, and destroys old red blood cells
Blood Circulation Through the HeartProblems in the right side of the heart will
cause the abdomen to fill with fluid (ascites)
Problems in the left side of the heart will cause lung congestion
Flow of blood through heart in this order:
right atrium right ventricle pulmonary arteries lungs pulmonary veins left atrium left atrium left ventricle aorta
Cardiac Cycle Videohttps://www.youtube.com/watch?
v=5tUWOF6wEnk
Major Arteries & VeinsAorta – largest artery that sends
blood from the heart to the bodyBrachiocephalic – branches
from the aorta to send blood to the head and right side of the body
Common carotid arteries – (left & right) run up both side of the neck and supply blood to the head
Coronary arteries – wraps around the exterior of the heart and supply blood to the heart muscle
Facial artery – wraps under lower jaw and is used to take the pulse on a horse or cow
Femoral artery – runs down the inside hind leg; used to take the pulse on a cat or dog
Mesenteric – supplies blood to the intestines
Renal artery – supplies blood to the kidney
Pulmonary arteries – carry deoxygenated blood to the lungs
Pulmonary veins – carry oxygenated blood to the left atrium
Cranial vena cava – returns blood to the heart from the head, neck, and forelegs
Caudal vena cava – returns blood to the heart from the thorax, abdomen, and hind legs
Cephalic vein – runs along the front of the foreleg
Jugular vein – runs down the neck and returns blood from the head
Renal vein – returns blood from the kidney to the caudal vena cava
Femoral vein – runs along the inside of the hind leg
Saphenous vein – an extension of the femoral vein
Heart
Major Veins
Major Arteries
Structure of BloodComposed of cells and plasma
(liquid portion of blood)◦40% cells
Erythrocytes (red blood cells) Leukocytes (white blood cells) Platelets
◦60% plasmaTypically blood volume comprises
6% - 8% of the animal’s total body weight
Blood Cells
Hematopoiesis
blood
formation & development
The formation and development of blood cells
Blood CellsAll blood cells develop in the
bone marrow from one type of cell called a hemocytoblast
In young animals blood is produced in all bones
In adult animals blood is produced in the pelvis, ribs, vertebrae, femur, and humerus
Erythrocytes (Red Blood Cells)Most abundant blood cellFunction: to transport O2
throughout the bodyContains: hemoglobin (a pigment
that contains iron and gives blood its red color when combined with O2)
In mammals the red blood cell is non-nucleated
In reptiles and birds the red blood cell is nucleated
• Red cell’s life span in dogs and humans is 120 days, but it varies among different species
Leukocytes (White Blood Cells)
Colorless, nucleated cells capable of moving throughout the body
Function: body defenseDivided into two categories:
◦Granulocytes ◦Agranulocytes
GranulocytesProduced in the bone marrowHave lobed nuclei and granules
in their cytoplasmNeutrophils, basophils, and
eosinophils
NeutrophilHas red and blue granules in cytoplasmFunction: stop or slow down foreign
organismsHow they work –
1. Phagocytosis: to eat bacteria and dead cells
2. Bactericidal: kill bacteria How they get to infection site –
1. Sticky and can migrate through vessel walls
2. Release chemicals to attract other neutrophils to the infection site
BasophilHas dark purple granules in
cytoplasmFunction: phagocytosis, mediate
allergic reactions, and produce heparin and histamine
EosinophilHas orangish-red granules in the
cytoplasmFunction: moderate the
inflammatory response and phagocytosis
AgranulocytesProduced in lymphatic organsHave rounded nuclei, and no
granules in the cytoplasmLymphocytes and monocytes
LymphocytesHas a round nucleus and plays a
vita role in immunityTwo categories:
1. T-cells (memory cells) – long-lived; once they are sensitized to an antigen, they remember it so that next time they can fight off that antigen
2. B-cells – encounter an antigen and divide to form many cells that all produce the same antibodies to fight the antigen
MonocyteHas an irregular shaped nucleusLargest cell in the bloodFunction: phagocytosis
Thrombocytes (platelets)Main function: hemostasis
(clotting)Platelets are 1/3 the size of a red
blood cellStop bleeding by adhering to
damaged vessels and clumping together and releasing proteins that help form a clot
Average life span: 10 days
HematologyStudy of the structure of blood
and the tissues that produce blood
Lab tests most commonly performed in vet medicine: ◦PCV or hematocrit◦White cell count◦TPP (total plasma protein)◦Blood film evaluation
PCV – Packed Cell VolumeMeasures percentage of red blood cells
in the total blood volume
Capillary tube is filled with fresh anticoagulated blood, sealed with clay, and centrifuged for five minutes
Results read using special scale
Animal with PCV below normal is said to have anemia
Normal PCV values: Dog: 37 – 55Cat: 30 – 45Horse: 32 – 48Bovine: 24 – 46
TPP – Total Plasma ProteinMeasurement of proteins produced mainly
by the liver
Measured using a capillary tube of blood, broken at the plasma layer, plasma placed on a refractometer
Elevated TPP is a sign of inflammation, infection, or dehydration
Decreased TPP occurs normally in newborns and pregnant animals
Blood Film EvaluationUsed to determine size, color,
and shape of cells and abnormalities in their formation
Used to look for blood parasites such as microfilaria of the heartworm
Prepared by spreading a drop of blood on a slide, drying the slide, staining with Wright’s stain
Evaluated by scanning under high power for abnormalities
Abnormalities appear in the RBC as color changes in the cell, abnormal cell shape and size, and foreign bodies within the cell
Blood Chemistry ProceduresVacutainer tubes have a vacuum
created to place a needle and syringe into a rubber plunger
Different tubes for specific requirements – different colors to identify
Red Top – sterile or no anticoagulant that contains a gel separator
Tiger Stripe – contains no silicone, gel separators, anticoagulants, or additives of any kind
Lavender Top – sterile, contains EDTA as the anticoagulant
Green Top – sterile, contains lithium heparin as the anticoagulant
Light Blue Top – sterile, contains sodium citrate as the anticoagulant
Gray Top – sterile, contains potassium oxalate and sodium fluoride as the anticoagulant
Each test requires a specific amount of blood, serum, or plasma to run the sample
Allow the samples that require centrifuging at least 30 minutes to clot prior to spinning but not more than 60 minutes
Specific Procedures
Complete Blood Count – evaluates the different types of WBCs
Blood Smear – evaluates blood cell morphology
Specific ProceduresPCV – measurement of the
percentage of RBCs in whole or unclotted blood (also a hematocrit)
Plasma Protein (total protein) – measures the ratio of protein within the blood and checks the hydration of the patient
VideosVeterinary Blood Testing:
https://www.youtube.com/watch?v=o00eU2sqRtU
Vet Tech Training-Basic Blood Collection: https://www.youtube.com/watch?v=uYyh3DIQ91c
Urinary System Major organs:
◦Kidneys ◦Ureters ◦Urinary bladder ◦Urethra
Function: to extract and remove waste from the blood
KidneysResponsible for extracting and
collecting wastePaired organs located on both
sides of the spinal column Bean-shaped in most species of
animalsKidneys of cattle have several
lobes
Parts of the kidneyCortexMedullaRenal pelvisNephrons
◦Located throughout the cortex and medulla
◦Functioning units of the kidneys◦Responsible for filtering and collection
of waste from the blood◦Collecting ducts run through medulla
and drain into renal pelvis
UretersUrine then passes into the
ureters and proceeds to the bladder
Smooth muscled tubes that extend from each kidney
Use peristalsis to move urine to the bladder
Urine is pushed into the bladder every 10-30 seconds depending on the species
Flows in spurts rather than continuously
BladderSmooth muscle, extremely
elastic sac Capable of holding large volumes
of urineHas three openings
◦Two that receive urine from ureters◦One used to excrete urine to the
urethra
UrethraCarries urine from the bladder to
the exteriorVaries in length and
circumference in males and females◦Female urethra is shorter in length
and runs directly from bladder to the exterior
◦Males have narrower urethra that is longer to extend through the accessory sex glands and exit through the penis
3 Phases of Urine Production1. Filtration2. Reabsorption3. Secretion
Occur in the nephrons
FiltrationBlood enters the glomerulus
through the afferent arteriole
Under various pressures, water, salt, and small molecules move out of the glomerulus and into Bowman’s capsule
Reabsorption Occurs in the proximal
convoluted tubule and the loop of Henle
Substances needed by the body such as water and electrolytes will be reabsorbed by the body from the loop of Henle
SecretionSubstances are secreted into the
collecting tubules and transported to the renal pelvis
Urine Production: https://www.youtube.com/watch?v=oCQ-5iwTQvM
Urinalysis Provides information about how
the kidneys are functioning and if wastes are being properly filtered from the body
Specimen Collection ◦Free Catch◦Manual Expression◦Catheterization◦Cystocentesis
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