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