14. Анатомия и физиология пищеварительной системы



 

-          Hello. How do you do!

-          How do you do!

-          Are you free now?

-          Yes, I’m. I’m trying to prepare my anatomy lesson on alimentary tract? But I don’t know it well. Can you help me?

-          Sure. To begin with, the alimentary tract is a musculomembraneous canal about 8.5 meters in length. It extends from the oral cavity to the anus.

-          I know this. If I’m not mistaken it consists of the mouth, pharynx, esophagus, stomach, small intestine and large intestine.

-          Yes, you are right. The first division of the alimentary tract is formed by the mouth, important structures of which are the teeth and the tongue.

-          Where does the food go from the mouth?

-          It passes through the pharynx to the esophagus and then to the stomach. Do you know what stomach is?

-          Certainly. It’s a dilated portion of the alimentary canal. It is in the upper part of the abdomen under the diaphragm. It has a capacity of from 2.14 to 4.28 liters.

-          Ok. I’ve already mentioned that there is the small intestine and the large intestine in the alimentary tract. So the small intestine is a thin-walled muscular tube about 6.5 meters long. It is located in the lower and central portions of the abdominal and pelvic cavities. The small intestine is composed of the duodenum, jejunum and ileum. Do you want me to tell you about the large intestine?

-          No, thanks. As far as I know it’s about 1.5 meters long and it is divided into caecum, colon and rectum.

-          Right. Do you know that the largest gland in the human body is the liver? Its weight is about 1500 g.

-          Yes, I do. I know that the gallbladder and the pancreas are also the large glands of the alimentary tract. The gallbladder is a hollow sac lying on the lower surface of the liver and the pancreas is a long thin gland lying under and behind the stomach.

-          You are absolutely right.

-          Thank you very much for helping me.

13. Анатомия и физиология сердечно-сосудистой системы.



 

-          Hello. Are you studying anything?

-          Yes, I’m trying to remember everything about the heart and the vascular system.

-          Oh, that’s good. Let’s do it together and check each other. So what do you know about the heart?

-          Well, it’s an inner hollow muscular organ, placed within the chest and included in the pericardium. The weight of the heart is about 300 gr in the male and about 220 gr in the female. How many parts does the heart consist of?

-          Let me think… it consists of 2 separate chambers divided by the septum. Each chamber has 2 connected parts: the atrium and the ventricle. By the way, the right atrium is larger than the left one, but the walls of the left atrium are thicker than the walls of the right atrium.

-          Right you are. Speaking about the ventricles, the left ventricle is longer and more conical than the right one and its walls are 3 times as thick as the walls of the right one. Do you know what the muscular structure of the heart consists of?

-          Well, it consists of fibrous bands of two groups. They are the fibrous bands of the atria and those of the ventricles. What can you say about the vascular system?

-          It consists of 3 groups of vessels – arteries, veins and capillaries. The general system is composed by systemic vessels, carrying blood to and from the tissues of the body. Pulmonary system is formed by the vessels, carrying blood to and from the lungs. The portal system is formed by the veins passing to the liver.

-          Right. Moreover arteries dilate and contract simultaneously with the action of the heart. The contractions of the heart pump the blood through the arteries to all the parts of the body. Physiologists have determined that in the adult the heart makes from 60 to 72 beats per minute. In children the rate of heartbeat is much higher.

-          By the way, each wave of contraction and a period of rest following it compose a cardiac cycle, which consists of 3 phases: the atrial systole (phase of short contraction of both atria), the ventricular systole (a more prolonged contraction of both ventricles) and the diastole (the period of rest of the cardiac muscle).

-           Have you ever heard that the role of ventricle was estimated to serve as the main pump?

-          Yes, I have. And I also know that the atria act as receiving chambers. The contraction of the atria which sends the final portion of the blood into the ventricle is considerably less.

-          You see, we’ve discussed almost everything.

-          Yes, thank you for helping me.