Description
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LEARNING OBJECTIVES
At the completion of this exercise, you will be able to:
- Analyze components of whole blood by examining a blood smear and differentiating the formed elements.
- Comprehend the structure of cardiac muscle tissue by observing and drawing a diagram of cardiac muscle tissue from a prepared slide.
- Comprehend structures of the heart, by identifying various anatomical features on diagrams and models, and describing the function of each.
- Analyze movement of blood through the heart, by diagramming the sequence of blood flow through the heart.
- Analyze the structures of the heart by virtually dissecting, observing, and relating the structures of the heart with its function.
- Comprehend the structure of the major blood vessels of the body, by identifying the blood vessels on diagrams and models.
INTRODUCTION
In complex multicellular organisms, such as humans, trillions of cells must work together to support the whole organism. Each cell type takes on a different job (function), and the survival of each cell type depends on the proper functioning of all other cell types that make up the organism. To obtain energy to complete work, cells use oxygen from the air and produce wastes, such as carbon dioxide gas. Some multicellular organisms, many insects and amphibians for example, may exchange oxygen and carbon dioxide directly with the surrounding air, through their moist skin. However, humans use lungs to acquire oxygen and expel carbon dioxide waste through respiration (inhalation/exhalation), to allow cellular respiration. During cellular respiration, cells use oxygen, water, and glucose sugar to produce adenosine triphosphate (ATP), a form of chemical energy that cells use to do work. While the lungs gathers oxygen, the circulatory system is responsible for distribution of gaseous oxygen to cells. Carbon dioxide and other wastes are distributed to the lungs and kidneys for processing and excretion.
The circulatory system is composed of the heart, blood, and the blood vessels. Whole blood is comprised of plasma (the liquid portion) and formed elements (the cellular portion). Amongst the cell types that make up formed elements are erythrocytes (red blood cells), leukocytes (white blood cells), and platelets (cell fragments important for blood clotting). Each component of blood contributes a particular function important for survival. For example, erythrocytes bind and transport oxygen and carbon dioxide. Leukocytes are immune cells that kill bacteria, parasites, and fungi that invade the body.
Cardiac muscle tissue, a specialized muscle tissue, functions to produce regular contractions of the two atria and two ventricles of the heart. The left atrium and ventricle pump blood through the pulmonary circuit, which serves the lungs, so that erythrocytes may pick up oxygen and drop off carbon dioxide. The right atrium and ventricle pump blood through the systemic circuit, where erythrocytes distribute oxygen to cells and tissues and gather carbon dioxide.
Arteries, capillaries, venules, and veins are the elements through which blood travels in the pulmonary and systemic circuits. When viewing a cross section of these elements and comparing them side-by-side, functional differences are clear. Compared to veins, arteries contain a thick, smooth muscle layer (tunica media) that provides structural support. Arteries are closer to the heart and are under greater pressure. In contrast, the tunica intima of veins form valves that prevent backward flow of deoxygenated blood at the distal extremities.
In the following laboratory exercises, you will explore the structure and function of the circulatory system.
DEFINE THE TERMS
- Formed elements
- Wright-Geisma stain
- Capillary
- Vein
- Pulmonary circuit
- Systemic circuit
LABORATORY PROCEDURES
- In Activity 1, you will watch a video on how to prepare a Wright-stained blood smear, observe formed elements, and use distinguishing characteristics to differentiate various cell types.
- In Activity 2, you will observe a cardiac muscle tissue specimen and draw a diagram, identify anatomical features of the heart on diagrams and models, and virtually dissect a sheep heart to relate structure/function to blood flow through the heart.
- In Activity 3, you will identify the major blood vessels on diagrams and models.
ACTIVITY 1 – INTERPRET A BLOOD SMEAR
Part 1A. Preparing and Staining a Blood Smear
Instructions: Watch the video below, which shows you how a blood smear is prepared. List the steps of how a blood smear is prepared.
Part 1B. Interpret a Blood Smear
Instructions:
- Navigate to the virtual microscope by clicking on the following link. Click Here to Access the Virtual MicroscopeLinks to an external site.
- Click on “Explore”
- Click on the microscope slide storage box on the right hand side of the virtual microscope.
- Select “Sample Slides”, “Human”, then select “Blood”.
- Toggle the coarse focus first then the fine focus to perfect the image. You may also toggle the light to adjust the brightness. You can change the magnification by clicking on 4X, 10X, 40X or 100X. These are the magnifications of the objective lenses, not the total magnification. Click the image of the letter e on the virtual microscope and use the mouse to move it around to see different parts of the slide.
- Observe the blood slide at 400X and 1000X total magnification, where you will clearly see erythrocytes, leukocytes, and platelets. Complete the table below by illustrating your observations from the virtual microscope, lab atlas, or textbook.
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Cell type |
Illustration |
Physical Description When Stained With Wright-Geisma |
Number of Cells Per μL of Whole Blood |
Function |
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Erythrocytes (red blood cells or RBCs) |
Biconcave, anucleate disc; salmon-colored; diameter 7-8 mm |
4-6 million |
Binds and transports oxygen and carbon dioxide |
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Leukocytes (white blood cells, WBCs) |
Granulocytes |
Neutrophil |
10-12 mm · · · |
3000-7000 |
Kill bacteria by phagocytosis |
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Eosinophil |
10-14 mm · · · |
100-400 |
Kill parasitic worms; destroy antigen-antibody complexes; inactivate some inflammatory chemicals of allergy |
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Basophil |
20-25 mm · · · |
20-50 |
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Agranulocytes |
Lymphocyte |
1500-3000 mm · · · |
1500-3000 |
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Monocyte |
100-700 mm · · · |
100-700 |
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Platelets |
150,000-400,000 mm · · · |
150,000-400,000 |
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Instructions: Answer the questions below using your observations.
- What is the most abundant formed element of blood?
- What is the physical difference between a granulocyte and an agranulocyte?
- Under a microscope, how is it possible to distinguish an eosinophil from a neutrophil?
- Hypothesize what would happen if an immunocompromised person with abnormally low lymphocytes were exposed to the common cold (flu) virus.
ACTIVITY 2 – RELATE STRUCTURE AND FUNCTION OF THE HEART
Part 2A. Observe and Diagram Cardiac Muscle Tissue
Instructions: Using the photo of cardiac muscle tissue below, which was taken using a compound light microscope, sketch a rough diagram of the tissue. Label ALL the following features:
- Intercalated discs
- Nucleus
- Sarcolemma
- Cardiac muscle cells
Part 2B. Identifying Anatomical Features of the Heart on Diagrams and Models
Instructions: Using your textbook, identify the structures listed below in diagrams of the heart. Use the file below to identify the structures in models of the heart. List the function of each structure in the table provided.
Click Here for Models of the HeartDownload Click Here for Models of the Heart
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Select Anatomical Features of the Heart |
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Anatomical Feature |
Function |
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Structures External to the Heart |
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Contains the pericardium and heart. |
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Tough, dense CT layer that protects the heart, anchors it, and prevents it from overfilling with blood. |
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Line the pericardial cavity, which is filled with serous fluid that lubricates the serous layers to allow friction-free movement of the heart. |
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Layers of the Heart |
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Middle layer of cardiac muscle, forming the bulk of the heart. |
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Innermost layer of white squamous endothelium continuous with tissue endothelial linings of the blood vessels leaving and entering the heart. |
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Chambers of the Heart |
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Receives deoxygenated blood from the sup/inf vena cava. Pumps the blood into the R ventricle. |
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Internal Structure of the Heart |
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Valves of the Heart |
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Valve Structures |
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Part 2C. Sheep Heart Dissection: Relating Structure and Function
Instructions: Watch the sheep heart dissection video, which points out structures of the sheep heart.
Instructions: Using the sheep heart dissection video and your lab atlas, identify the structures of the heart listed below on a dissection specimen.
Click Here for Sheep Heart Dissection PhotosDownload Click Here for Sheep Heart Dissection Photos
- External Features of the Sheep Heart
- Fibrous pericardium
- Anterior interventricular sulcus
- Anterior interventricular artery.
- Left and right auricles
- Pulmonary trunk
- Aorta
- Ligamentum arteriosum
- Left and right pulmonary veins
- Posterior interventricular sulcus
- Posterior interventricular artery
- Internal Features of the Sheep Heart
- Interventricular septum
- Interatrial septum
- Superior vena cava
- Inferior vena cava
- tricuspid valve (right atrioventricular valve)
- Chordae tendineae.
- Papillary muscle
- Pulmonary valve
- Aortic valve
- Mitral valve (left atrioventricular valve)
Instructions: Create a flow chart showing how blood moves through the heart, pulmonary circuit, and systemic circuit. Be sure to write-in all of the valves as well as the chambers.
ACTIVITY 3. IDENTIFY THE MAJOR HUMAN BLOOD VESSELS
Part 3A. Identify the Major Blood Vessels of the Cardiovascular System on Diagrams and Models
Instructions: Using your textbook, identify the blood vessels listed below in diagrams. Using the models of blood vessels in your lab atlas and in the file provided below, identify the blood vessels listed below.
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Select Blood Vessels of the Heart |
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¨ Superior vena cava |
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¨ Inferior vena cava |
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¨ Pulmonary trunk |
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¨ Right pulmonary artery |
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¨ Left pulmonary artery |
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¨ Right pulmonary veins |
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¨ Left pulmonary veins |
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¨ Aorta |
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¨ Coronary arteries |
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¨ Right coronary artery |
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¨ Left coronary artery |
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¨ Circumflex artery |
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¨ Anterior interventricular artery |
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¨ Coronary sinus |
Instructions: Identify the blood vessels in the list below using models.
Click Here for Blood Vessel ModelsDownload Click Here for Blood Vessel Models
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Select Arteries |
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¨ Aorta |
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¨ Ascending aorta |
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¨ Aortic arch |
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¨ Descending aorta (thoracic & abdominal portions) |
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¨ Brachiocephalic trunk |
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¨ Common carotid arteries (right & left) |
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¨ Subclavian artery (right & left) |
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¨ Axillary artery |
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¨ Brachial artery (radial & ulnar) |
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¨ Celiac trunk |
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¨ Superior and inferior mesenteric artery |
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¨ Renal artery |
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¨ Common iliac |
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¨ Internal iliac artery |
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¨ External iliac artery |
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¨ Femoral artery |
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Select Veins |
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¨ Superior vena cava |
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¨ Brachiocephalic vein |
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¨ Internal jugular vein |
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¨ External jugular vein |
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¨ Subclavian vein |
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¨ Inferior vena cava |
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¨ Renal vein |
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¨ Common iliac vein |
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¨ Internal iliac vein |
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¨ External iliac vein |
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¨ Superior and inferior mesenteric artery |
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¨ Hepatic portal vein |
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¨ Femoral vein |
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¨ Great saphenous vein |
