Circulatory system observation experiment
Circulatory system observation experiment
1. Observe the location, shape and gross anatomy of the heart. Understand the connection between the atria and ventricles and the large blood vessels that enter and exit the heart.
2. Observe the branches and genera of the major arteries and veins of the body. Compare the distribution pattern and structural characteristics of arteries and veins.
3. Observe the microstructure of the large arteries, middle arteries and middle veins, and understand their structural characteristics in relation to their functions.
4. Understand the scope of lymphatic conduits for collecting lymph.
Operation method
Circulatory system observation experiment
Materials and Instruments
Thoracic cavity anatomical specimen Heart anatomical specimen and model Pig heart anatomical specimen Sheep or cow heart anatomical specimen Human whole body artery and vein anatomical specimen and model Lymphatic conduit anatomical specimen. Transverse section of aorta Transverse section of mesenteric vessels Electron microscopic picture of capillaries Move I. Location and external form of the heart For more product details, please visit Aladdin Scientific website.
Dissecting apparatus Anatomy Microscope.
Anatomical specimens of human thoracic cavity and isolated heart specimens were taken for observation. The external shape of the heart is like a slightly flattened conical shape, wrapped with the pericardium, located in the thoracic mediastinum, above the diaphragm, adjacent to the pleural cavity and the lungs on both sides, behind the esophagus and the thoracic aorta. The whole heart is 2/3 on the left side of the body midline and 1/3 on the right side of the body midline. Its shape is divided into the base of the heart, the apex, the thoracic rib surface, and the septal surface. The base of the heart is oriented to the upper right posteriorly, and near the base of the heart there is a circular groove, the coronary sulcus, which divides the surface of the atria from the ventricles. The apex of the heart consists of the left ventricle, facing anteriorly downward to the left, and the thoracic rib surface faces anteriorly upward to the left. The diaphragmatic surface faces downward posteriorly, and the septal pericardium is adjacent to the septum. The anterior and posterior interventricular grooves, which run from the coronal sulcus to the right of the apex, are found on the thoracic-ribbed and septal surfaces of the ventricles, respectively, and are the division between the left and right ventricles on the surface of the heart.
Second, the general anatomy of the heart
If the laboratory of the human heart specimen is insufficient, ding take fresh pig heart or sheep heart to do anatomical observation. Observe the external morphological structure of the heart, and distinguish the aorta, pulmonary artery, superior and inferior vena cava and pulmonary vein. A scalpel is used to make an incision along the pulmonary vein, the left atrium to the left ventricle so that the aortic valve in the aorta will not be cut. (Then cut along the pulmonary artery to the right ventricle so as not to disrupt the right atrioventricular valve). The structures of the heart chambers and valves can then be visualized against the specimen.
(i) Cardiac chambers
The heart has four chambers. The two atria and the two ventricles are separated by the atrial septum and the interventricular septum. The ipsilateral atria and ventricles are connected by atrioventricular orifices.
The right atrium has a thin wall and a large cavity, and its anterior part is tapered and protrudes to the right of the aortic root, which is the right auricle. The right atrium has a superior vena cava port in the upper part and an inferior vena cava port in the lower part. There is a coronary sinus opening between the inferior vena cava opening and the right atrioventricular opening. There is a slightly ovoid ovoid fossa on the atrial septum, where the septum is thinnest and easily visible when viewed in the light.
The right ventricle The right atrioventricular orifice has three valves, called the right atrioventricular valve (tricuspid valve). The right atrioventricular valve hangs down into the right ventricle and is attached to the papillary muscle by a tendon cable. The bundles of muscle in the right ventricular wall form longitudinal and transverse elevations called sarcomeres, of which three tapered sarcomeres are particularly well developed, with their tips facing the ventricular cavity, called papillary muscles. The right ventricle also has a bundle of muscles that runs from the septum to the root of the anterior papillary muscle in the anterior wall, called the septal meatus. The portion of the right ventricular cavity that protrudes superiorly to the left is called the arterial cone. The arterial cone has an opening to the left superiorly that leads to the pulmonary artery. The opening has three half-moon shaped pulmonary valves.
The left atrium is a small, conical protrusion forward of the left atrium, which is located to the left of the pulmonary artery. There are two pulmonary vein openings on each side of the posterior left atrium.
4. The left ventricle has the thickest wall, a conical cavity, and two orifices at the bottom, the left atrioventricular orifice is located behind the left, and the aortic orifice is located in front of the right. The left atrial orifice has two valves, called the left atrioventricular valve. The aortic orifice has three semilunar valves called aortic valves.
(ii) Wall of the heart
The wall of the heart consists of three layers: the endocardium, the myocardium and the epicardium. The endocardium is a smooth membrane that covers the inner surface of the walls of the atria and ventricles. Deep within the endocardium is the myocardial layer. The atrial muscle is thin and the ventricular muscle is hypertrophied, especially the left ventricular muscle is the most developed. The epicardium is a smooth plasma membrane covering the outer surface of the heart wall.
(C) Cardiac conduction system
It is not easy to find the cardiac conduction system in the anatomical specimen of the human heart. It can be observed in sheep or bovine heart specimens to understand the components of the cardiac conduction system.
1. Sinus node Sinus node is located in the vena cava and the right atrium at the outer side of the combination, the epicardium deep and. Sinus node and atrial muscle contact, but also with the atrioventricular node contact.
The atrioventricular node is located in the lower part of the interatrial septum, the right atrium after the coronary sinus orifice force a deep endocardial surface. The atrioventricular node is a flat oval structure, the lower end of the node continues in the atrioventricular bundle.
From the lower end of the AV node, the AV bundle enters the ventricular septum. It then divides into left and right bundle branches, which line the left and right sides of the ventricular septum, and branch out subendocardially into the ventricular myocardium.
(iv) Blood vessels of the heart
Observe with a dissected specimen of the isolated heart.
Arteries The arteries that nourish the heart itself are the left and right coronary arteries, which emanate from the origin of the aorta and travel through the coronary groove and the anterior and posterior interventricular grooves. The right coronary artery branches into the right half of the heart and a small part of the left half of the heart. The left coronary artery branches into the left half of the heart and the right half of the heart. Note the anastomosis between the vessels of the heart.
The veins are small veins distributed within the wall of the heart that open directly into the chambers of the heart. Many small holes are seen in the walls of the atria and ventricles as openings for these small veins. The anterior wall of the right ventricle has two to three larger veins that cross the coronary groove and open into the right atrium. The other veins of the heart converge on the coronary sinus (which is located in the posterior part of the coronary groove) and open into the right atrium.
(E) Pericardium
For wrapping the heart and the root of the large blood vessels in and out of the heart of the conical capsule, can be divided into fibrous pericardium and plasma membrane pericardium. Only the plasma membrane pericardium is observed here. The plasma membrane pericardium is divided into wall and dirty layers, the dirty layer is close to the heart, i.e. epicardium; the wall layer is close to the inner surface of the fibrous pericardium. The narrow gap between the dirty and wall layers is the pericardial cavity.
Branches and distribution of major blood vessels in the body
(A) arterial system
Observe the following major arteries on cadaveric and systemic arterial models:
1. The pulmonary trunk is short and thick, emanating from the right ventricle, traveling obliquely along the anterior aorta to the posterior and superior aorta, and dividing into the left and right pulmonary arteries on the "side" of the aortic arch. The left pulmonary artery runs to the left into the left hilum, while the right pulmonary artery is longer and runs to the right into the right hilum. There is a fibrous arterial ligament to the left of the branch of the pulmonary trunk, attached to the lower edge of the aortic arch, which is a remnant of embryonic atresia of the ductus arteriosus.
The aorta emanates from the left ventricle, first obliquely upward to the right, and then curved to the left behind, along the left anterior spine downward, through the diaphragmatic aortic fissure into the abdominal cavity, to the 4th lumbar vertebrae at the lower edge of the division of left and right common iliac arteries. According to its course, it is divided into the ascending aorta, the aortic arch, and the descending aorta. The aorta is further divided into the thoracic aorta and abdominal aorta by the aortic dissection of the diaphragm.
Observe the major branches and distribution of the aorta according to the table below. 
(ii) Venous system
The veins are thin-walled, and after death the blood is mostly concentrated in the veins, so the color of the blood clots can be seen through the thin walls, and it is easy to distinguish the veins from the arteries accordingly. The following veins are observed on autopsy specimens:
1. Pulmonary veins There are a pair of pulmonary veins on each side, which are divided into upper left, lower left and upper right, and lower right pulmonary veins. These veins originate from the pulmonary hilum and pass through the pericardium into the left atrium.
2. Body veins Only the superior vena cava, inferior vena cava, hepatic portal vein, superficial veins of the upper and lower extremities and their main branches are required to be observed.
(1) The superior vena cava is a thick and short vein, formed by the confluence of the left and right cephalic and brachial veins. The superior vena cava injects into the right atrium.
It collects mainly venous blood from the head, neck, chest, and upper extremities, as well as lymph returning throughout the body (see later).
(2) Superficial veins of the upper limbs Observation is made with cadaveric specimens and in conjunction with live bodies. There are three main superficial veins of the upper limbs, namely, the cephalic vein, the noble vein and the median elbow vein. In the elbow fossa and arm, the cephalic vein is on the outer side and the vital vein is on the inner side. The median elbow vein has many variations and generally joins the cephalic vein and the vital vein at the elbow socket. The cephalic vein joins the axillary vein, the median elbow vein joins the vital vein, and the vital vein may join the brachial vein or the axillary vein.
(3) Inferior vena cava is the largest vein in the human body and is formed by the confluence of the left and right common iliac veins. It runs up the right side of the abdominal aorta to the diaphragm, enters the thorax through the vena cava of the liver, and injects into the right atrium. It mainly collects venous blood from the lower body.
(4) Hepatic portal vein The splenic vein and superior mesenteric vein converge to form a short and thick vein, which ascends to the hepatic hilum and divides into left and right branches into the liver. The hepatic portal vein collects venous blood from the unpaired organs of the abdominal cavity (e.g., gallbladder, stomach, small intestine, large intestine, pancreas, and spleen).
(5) Superficial veins of the lower limbs The superficial veins of the lower limbs are mainly the great saphenous vein and the small saphenous vein. The saphenous vein originates from the medial end of the dorsal arch of the foot, runs along the medial side of the calf, then up the medial side of the thigh to the front of the thigh, and is injected into the femoral vein below the groin. The small saphenous vein originates from the lateral portion of the dorsal venous arch of the foot and travels up the posterior aspect of the calf to inject into the popliteal vein at the popliteal fossa.
3. Observation of venous valve Take a section of lower limb vein, cut the wall of the vein longitudinally along its long axis, and then immerse it in water to observe the structure of the venous valve. The valve is half-moon shaped, with its convex edge attached to the wall of the vein and its concave edge free. Alternatively, the venous valves of the superficial veins of the anterior wall and the dorsum of the hand can be observed in vivo. By pressing the superficial vein on the dorsal aspect of the left anterior wall with the right hand to block venous blood flow, a bulbous elevation of the superficial vein on the dorsal aspect of the hand can be seen, and this elevation is the location of the venous valve.
Lymphatic vessels
Observe the direction of convergence of the lymphatic vessels on the model and the lymphatic ducts on the cadaveric specimen.
1. Thoracic duct is the largest lymphatic duct in the body. Thoracic duct is usually in front of the I lumbar vertebrae, which is formed by the confluence of the left and right lumbar trunks and the intestinal trunks, and the beginning of which is mostly cystic and enlarged, called celiac pool. The thoracic duct begins and passes upward into the thoracic cavity through the main meridian fissure of the diaphragm, along the anterior aspect of the spine, and through the upper thoracic opening to the root of the neck before injecting into the left venous angle. The left bronchial mediastinal trunk, the left jugular trunk, and the left subclavian trunk are collected at the confluence with the left venous angle. What parts of the body does the thoracic duct collect lymph?
2. Right lymphatic conduit A short trunk, approximately 1.5 cm in length, is formed by the confluence of the right subclavian trunk, right jugular trunk, and right bronchomediastinal trunk, and is then emptied into the right venous horn. The right lymphatic duct collects lymph from which parts of the body?
V. Microstructure of the Blood Vessel Wall
(a) The microstructure of the wall of the aorta
Take a transverse section of cat's aorta (H-E staining and Weigert elastic fiber staining), observe with low magnification: first distinguish the inner membrane, middle membrane and outer membrane of the wall. Pay attention to the characteristics of the middle membrane.
The endothelium is very thin and consists of a layer of endothelial cells, a subendothelial layer and an inner elastic membrane. The endothelial cells are often detached on section and do not become a continuous layer. The connective tissue of the subendothelial layer is dense. The internal elastic membrane is attached to the elastic membrane within the mesentery, with no clear demarcation.
The middle membrane is thicker, and most of the wall of the aorta is composed of the middle membrane. In the H-E stained sections, the main structure of the middle membrane is the elastic membrane composed of dozens of layers of elastic fibers dyed red and bright, with a small number of collagen fibers and smooth muscle fibers interspersed between the elastic membrane. In the elastic fiber stained section, can clearly see many dyed blue-brown, wave-like layers of elastic fibers arranged. Abundant elastic fibers are the main feature of the aortic wall.
3. The outer membrane is slightly thicker than the inner membrane, composed of loose connective tissue. In this layer can be seen in the nutrition of blood vessels and nerves of various sections.
(ii) Microstructure of the wall of the middle artery and middle vein
Take a transverse section of mesenteric blood vessels of a cat (H-E stained) and observe the wall layering and organizational features of the middle artery and middle vein with low magnification, and compare the structural differences between the middle artery and the middle vein in relation to their functions.
The middle artery has a thick wall and a small, rounded lumen. The inner membrane has a layer of inner elastic membrane which is obviously stained red and highly reflective. In the section, this membrane is curved and corrugated due to the constriction of the wall. The middle membrane was thicker, with more layers of smooth muscle. The thickness of the outer membrane is comparable to that of the middle membrane.
The middle vein has a thin wall, a large lumen, and a flat or irregular shape. The inner elastic membrane is not obvious. The middle membrane is thinner, with less smooth muscle. The outer membrane is thicker than the middle membrane.
Demonstration of the ultrastructure of capillaries
Observe with capillary transmission electron microscope pictures.
1. choroid plexus perforated capillaries The pores of the endothelium are seen to be covered by a thin septum. A surface view of the pores is shown on an oblique section of the endothelium.
2. Continuous capillaries Continuous endothelium and basement membrane are visible. The walls of the tubes are continuously surrounded by endothelial cells through cellular junctions. The endothelial cell nucleus protrudes into the lumen, and there are drinking vesicles in the cytoplasm.