Cardiovascular System

LABORATORY INSTRUCTION: THE CARDIOVASCULAR SYSTEM

I. HISTOLOGY: Use the microscope to observe the following prepared slides.

A. Cardiac muscle: notice striations, branched fibers, intercalated disks, central nuclei. Picture

B. Artery/vein cross-section: Walls of an artery typically contain elastic and/or smooth muscle to the extent that the wall appears thick, compact, and very rounded or oval in cross-section. Walls of a vein are thinner, contain little smooth muscle, and tend to collapse during slide preparation into various folded shapes in cross-section. Identify the lumen of each vessel, the tunica externa (adventitia), composed of connective tissue; the tunica media, composed of smooth muscle and elastin; and the tunica interna or intima (endothelium), composed of simple squamous epithelium. Picture 1, Picture 2

II. GROSS ANATOMY OF THE HEART AND GREAT VESSELS: Use all available plastic models, torsos, charts, and preserved specimen to find the structures named below. Refer to the labeled diagrams and photographs in your text and lab atlas. The keys which go to the numbered models are not helpful as they contain more information than is required. Heart Diagrams: model 1, model 2, model 3, model 4, model 5, model 6, model 7,model 8, model 9 and model 10

base

apex

B. Layers of heart walls
     1. epicardium (visceral pericardium)
     2. myocardium
     3. endocardium

C. Chambers
     1. atria (right and left separated by the interatrial septum and made of pectinate muscle)
     2. ventricles (right and left separated by the interventricular septum and made of trabeculae carneae)
     3. auricles (external flaps associated with atria)

4. fossa ovalis (depression in the interatrial septum)

D. Valves
     1. atrio-ventricular valves (notice the cusps, chordae tendineae, and papillary muscles)
         a. bicuspid (between left atrium and left ventricle)
         b. tricuspid (between right atrium and right ventricle)
     2. semilunar valves (3 flaps)
         a. pulmonary (at base of pulmonary trunk within the right ventricle)
         b. aortic (at base of systemic aorta within the left ventricle)

E. Great vessels
       1. pulmonary trunk (exits right ventricle and branches to form the right and left pulmonary arteries)
       2. systemic aorta (exits left ventricle and curves to form the aortic arch followed by the descending thoracic aorta)
       3. superior vena cava (enters right atrium from above and is formed by the merging of the right and left brachiocephalic veins)
       4. inferior vena cava (enters right atrium from below)

F. Coronary circulation:
      1. Arterial circulation:

            a. left coronary artery
                   (1) anterior interventricular (anterior descending) artery
                   (2) circumflex artery
            b. right coronary artery
                   (1) marginal artery
                   (2) posterior interventricular artery

      2. Venous circulation

            a. coronary sinus, drains myocardium into right atrium

            b. great cardiac vein (parallel to the anterior interventricular artery)

            c. small cardiac vein (parallel to the marginal artery)

            d. middle cardiac vein (parallel to the posterior interventricular artery)

III. GROSS ANATOMY OF THE MAJOR BLOOD VESSELS: Use the available models to find examples of the following blood vessels. Use the labeled sketches and photographs of the text or lab atlas to guide your study. Blood Vessel Models: model 1, model 2, model 3, model 4, model 5, model 6, model 7, model 8, model 9, model 10, model 11 and model 12

          A. Great vessels
                1. superior vena cava
                2. inferior vena cava
                3. pulmonary veins
                4. pulmonary trunk
                5. systemic aorta

B. Major arteries
        1. aortic arch
        2. brachiocephalic artery
        3. right and left common carotid arteries

            a. right and left facial artery
            b. right and left superficial temporal artery
        4. right and left subclavian arteries
            a. right and left axillary artery
            b. right and left brachial artery
            c. right and left ulnar artery
            d. right and left radial artery
            e. right and left humeral circumflex artery
            f. right and left superficial and deep palmar arch
            g. right and left digitals
        5. from descending thoracic aorta
                  -intercostal arteries
        6. from descending abdominal aorta
           a. celiac trunk
                  -splenic artery
                  -gastric artery
                  -hepatic artery
           b. superior mesenteric artery
           c. right and left renal arteries
           d. right and left gonadal arteries
           e. right and left lumbar arteries
           f. right and left adrenal (suprarenal) arteries

g. inferior mesenteric artery
h. median sacral artery

           i. right and left common iliac arteries
                  -right and left internal iliac arteries
                  -right and left external iliac arteries
                  -right and left femoral arteries
                  -right and left femoral circumflex artery

-right and left popliteal arteries

-left anterior tibial arteries

-left posterior tibial arteries

-left dorsalis pedis arteries

-right arcuate arteries

-right metatarsal arteries

     C. Major veins
         1. coronary circulation: see previous coronary lists
         2. pulmonary circulation: pulmonary veins
         3. hepatic portal circulation: hepatic portal vein
         4. systemic circulation:
             a. superior vena cava
                  -right and left superficial temporal veins

-right and left facial veins

-azygos vein

                  -intercostal veins
                  -right and left brachiocephalic veins
                  -right and left jugular veins
                  -right and left subclavian veins

                  -right and left axillary veins
                  -right and left brachial veins
                  -right and left cephalic veins (superficial)
                  -right and left basilic veins

-right and left median cubital vein

-right and left radial vein

-right and left ulnar vein

                  -right and left digital veins
             b. inferior vena cava
                 -phrenic veins
                 -hepatic vein
                 -splenic vein

-gastric vein

-paired renal veins
-adrenal vein (suprarenal)

-right and left gonadal veins

                 -right and left lumbar veins
                 -right and left common iliac veins
                 -right and left internal iliac veins
                 -right and left external iliac veins
                 -right and left femoral circumflex vein

-right and left femoral veins
-right and left great saphenous veins

                 -right and left popliteal vein
               -right dorsalis pedis vein
                 -right dorsal venous arch

D. Lymphatic System: Observe the green lymph vessels and associated lymph nodes on available models.

FOR THE LAB PRACTICAL, BE ABLE TO RECOGNIZE AND NAME THE VESSELS ABOVE ON APPROPRIATE CHARTS, MODELS, AND PRESERVED CATS.

IV. CARDIOVASCULAR PHYSIOLOGY

A. Blood Pressure: The typical device used clinically for measurement of blood pressure is the sphygmomanometer which consists of an inflatable cuff attached to a pressure measuring device (gauge). The artery most typically selected for use in measuring blood pressure is the brachial artery. On occasion, the femoral artery may be preferred. Diagram 1, Diagram 2

systolic

diastolic

Another instrument required to obtain a measurement of blood pressure is a stethoscope. This device is useful for several clinical observations: listening to breathing sounds for evaluation of airway obstruction, listening to heart sounds for evaluation of valvular function, and listening for resumption of blood flow in response to external pressure changes induced by the sphygmomanometer.

1. In preparation for measuring the blood pressure, wipe the earpieces of a stethoscope with disinfectant swabs and air dry. Place the earpieces of the stethoscope at the opening of your outer ear canal. (The supports for the earpieces curve forward for best results).

2. In order to measure blood pressure in the brachial artery, the cuff is wrapped around the upper arm and secured with hooks or Velcro depending upon the design of the particular cuff.

3. Place the diaphragm (flat part) of the stethoscope over the brachial artery as it crosses anterior and slightly superior to the elbow joint.

4. A bulb is attached by a rubber tube to the cuff. Upon squeezing the bulb, the cuff inflates, (If inflation does not occur, try tightening the screw-valve or rotating between the thumb and forefinger as you continue to squeeze the bulb.) It should take 4 or 5 squeezes to inflate the cuff to the appropriate level.

5. While inflating, watch the pressure measuring device attached. This may be a mercury column that rises within a calibrated scale, or it may be a needle moving around a dial. The pressure should read above 200 but less than 250 mm Hg when inflation is completed. DO NOT GO HIGHER. Immediately turn the screw-valve to release pressure slowly as you watch the mercury column or the needle drop to lower pressures. YOU HAVE COMPLETELY BLOCKED BLOOD FLOW AT THIS POINT. NEVER LEAVE THE PRESSURE THIS HIGH, IMMEDIATELY ALLOW RELEASE OF THE VALVE.

6. As the pressure drops, listen for a rhythmic tapping sound (Korotkoff Sounds) which is a result of blood being forced through the brachial artery. Make a notation of the pressure reading when the first sound is heard. This value corresponds to the level of blood pressure which is able to overcome the external pressure of the cuff and force blood through the artery. Known as the "systolic" pressure, this pressure is the maximum pressure of the blood against the walls of the brachial artery and corresponds to the surge of blood sent through the system with ventricular systole.

7. Continue slowly releasing air from the cuff and listening to the "tapping" sounds. If you hear the sounds become suddenly muffled, or if the sounds stop altogether, note the pressure reading immediately, as this corresponds to the pressure at which blood can flow through the artery without impedance; that is, the minimum pressure of blood in the brachial artery, the "diastolic" pressure which is the pressure maintained even when the ventricles are in diastole.

8. The two values are written as a fraction: systolic/diastolic

9. CAUTION: Immediately begin to lower the pressure in the cuff after exceeding 200 mm Hg. DO NOT leave the cuff inflated--you have cut off the blood supply to your friend's lower arm and hand--have mercy! Do not re-inflate the cuff until it has been completely deflated and normal circulation restored in the arm for a few minutes. ALLOW YOUR PARTNER TO REST AND RECOVER BETWEEN MEASUREMENTS. AFTER THREE TRIES, CHANGE ROLES. (ALLOW AT LEAST TWO MINUTES BETWEEN ATTEMPTS.)

10. After you have practiced taking your lab partner's blood pressure, getting similar readings two times, then try various conditions: lying down, sitting, standing, after stepping in place for 3 minutes, after a rest period of five minutes after stepping. Compare results with other classmates.

B. Pulse Rate and Pulse Points: Pulse rate can easily be measured by lightly pressing the radial artery across the styloid process of the radius and counting the pulsations while watching a second hand. If you count for 15 seconds, multiply by four to get pulse/min. If you count for 30 seconds, multiply by two. Another place pulsations can be counted easily is at the bifurcation of the common carotid artery, inferior and medial to the angle of the mandible. Care should be taken not to press too hard in this location since pressure receptors are located within the artery wall at this point, and blood pressure will change in response to the external pressure. Diagram

Lying down: __________ rt. arm _____________
lt. arm _____________

(now choose either rt. or lt. and stay consistent)

Sitting ___________ _____________

Standing ___________ _____________

After short ___________ _____________
exercise

After rest ___________ _____________
five min.

C. Heart Sounds: Use the stethoscope to listen to heart sounds. Try several positions on the anterior chest wall. Choose a location which gives you the clearest sound (usually nearest the apex). Listen to the heart sounds of several classmates and try to compare the "lubb-dupp" patterns. Diagram

D. Electrocardiogram: (also known as an ECG or EKG: Although we will not perform an actual ECG, use strips obtained previously to identify the waves typical of an ECG. Also observe abnormal ECG strips to identify which waves are absent. Diagram

V. DISSECTION:

Sheep Heart Dissection

Apex and base

Epicardium (also known as the visceral serous pericardium)

Endocardium

Right and left auricle

Right and left atria

Right and left ventricle

Tricuspid and bicuspid

Chordae tendineae

Trabeculae carnae and papillary muscle

Aortic semilunar (and sometimes the pulmonary semilunar is visible)

Interventricular septum

Pulmonary trunk

Aorta

Cat Vessel Dissection

Aortic arch

Descending thoracic aorta

Brachiocephalic artery

Right and left brachiocephalic vein

Superior and inferior vena cava

Right and left common carotid artery

Right and left jugular vein

Right and left subclavian artery and vein

Right and left axillary artery and vein

Right and left brachial artery and vein

Azygos vein

Intercostal artery and vein

Descending abdominal aorta

Celiac trunk

Splenic artery

Gastric artery

Hepatic artery

Superior mesenteric artery

Right and left renal artery and vein

Right and left gonadal artery and vein

Inferior mesenteric artery

Right and left lumbar artery and vein

Right and left common iliac vein

Right and left external iliac vein

Right and left internal iliac vein

Right and left external iliac artery

Internal iliac artery

Right and left femoral artery and vein

Right and left great saphenous artery and vein

Right and left popliteal artery and vein

VI. WEBSITES: Click on the following link for websites that will be useful: Cardiovascular System