Anatomy is a science that studies the normal shape, structure and various organs of the human body and the normal relations between these organs. Physiology is the science that studies body functions in living things. One of the prerequisites of physiological examination is to have morphological knowledge, namely Anatomy and Histology.
In order to determine whether the shape, structure and condition of any object is normal, we must have a measurement that we accept as normal in those objects. However, among people living together even in very small environments in human societies, it is striking that individual individuals differ greatly from each other in terms of the shapes and sizes of various organs whose bodies can be seen from the outside. These distinctions become even greater if we broaden the environment and compare people living far away from each other in various climates and continents. These distinctions between people are not limited to appearances alone. Examination of the cadaver or during surgery shows that the same organs are more or less different from each other in many respects in various individuals. When examining the detailed structure of organs, we see that the same organs differ from each other in this respect in various people. Even the molecules of various substances that make up the human body building material do not have the same properties in all humans. The existence of various blood groups clearly shows that albumin molecules do not have exactly the same properties in all humans.
This feature called variability, that is, that the bodies and organs of individual individuals differ from each other in terms of structure and shape is a feature unique to all living things.
The period in which the human body undergoes the most changes belongs to intrauterine life. This period, which lasts for nine months, is 50 cm from the grafted egg with a diameter of 200 microns. length and an average weight of 3.5 kg. Although the baby is underdeveloped and either not or very poorly developed in terms of function, all organs are formed in the baby when he is born.
Various blueprints seen in the first stages of embryonic life and originating from various organs are very different from the organs they form later in terms of shape and structure. During the whole development, the shape, structure and location of the organs change constantly. If we compare the organs of the human embryo at various stages of development with the permanent organs of the same genus of various animals belonging to the lower classes, we can see that in many cases there is a great resemblance.
For example, only the chorda dorsalis makes the skeleton of the human embryo in very early ages. The same situation remains in amphioxus throughout their lives. After a while, a spine made of cartilage tissue forms instead of the chorda dorsalis. This situation is seen in some fish belonging to a higher class than amphioxus and remains until the end of their life. However, in humans, this situation is temporary and ossification of the vertebrae begins in the third month of embryonic life. The same situation is observed in other organs. In the heart, the human embryo is made of only a straight tube, as in very simple animals at a very early age. After a short time, the outline of the heart begins to change and as a result of the different growth and change of state of its various parts, it slowly changes its shape and is divided into two, then three, and finally four parts through the partitions that occur in the pipe cavity. All these various shapes that the human heart shows in its development phase resemble the permanent shapes seen in animals belonging to various classes. In summary, we can say that in a very short time like nine months, the human embryo starts from the first step of the phylogenetic ladder (i.e., the single-celled state) and rises gradually and approaches the top steps. However, a newborn child is not a scaled-down model of the adult human being and is very different in all respects and shows very different stages of development after birth. In the extrauterine life, human development and maturation takes a very long time compared to animals. The period up to one year after the birth of the child is called the infancy period. At this age, great changes occur in the child’s body and various organs. Height increases by an average of 50%. As a result of first sitting and then standing up, the curvature of the spine begins to occur. 5.-7. In the first month, milk teeth begin to emerge. The development of the brain progresses and many centers begin to work, vision and hearing functions improve. Begins to be interested in the environment, recognizes some people and things, learns to do some simple movements in a purposeful way. The organs related to all these functions also vary a lot in terms of morphology.
The development of various organs takes a certain direction according to the genus, and the characteristics that are unique to the female or male gender, called secondary sexual symptoms, occur. As a result of these developmental distinctions, individuals belonging to two genders that are very different from each other in terms of both body and soul emerge. During puberty, the growth of the human body accelerates again. However, the duration of this rapid growth period is not the same in both sexes, and the growth of various body parts is not at the same rate. The rapid growth period begins later in boys than in girls, but lasts longer. The extermites are larger than the trunk in males. In girls, the pelvis expands too much. In contrast, the rib cage and shoulders remain narrower. In boys, the larynx enlarges more and faster at puberty, and therefore, their voices become thicker. The distribution of subcutaneous adipose tissue is different in both sexes. Clear distinctions between the two sexes are also seen in the enlargement of muscles and bones. In accordance with the way the whole body is built, there are more or less distinctions between all internal organs in terms of size and weight. Puberty lasts until the age of 16-18 in boys and 15 years in girls. However, this period varies according to the races people belong to and the climate. People living in warmer climates usually catch up more quickly.
After the puberty period comes the maturation period. This period lasts until the age of 25-28 in men and 20-22 in women. At this age, the growth of the body continues, but very slowly. In this period, the body and various organs do not show much difference in size, but they become more robust and develop more in terms of function in order to meet the increasing needs.
After this period, the age of maturity begins and lasts until the age of 50 in men and 35-40 in women. The cessation of functioning of the genital glands (climacterium) in women between the ages of 40-50, although it progresses in a very different way according to the person, it has a great effect on the soul and body of the woman. After the cessation of menstruation, women slowly enter the old age period. In men, the genital glands take longer to work and gradually decrease. Therefore, there is not much change in men in a short time as in women during the climactrium.
After the gender and age details, the important details seen in the human body in terms of shape and structure are racial distinctions. There are important differences between people living under various living conditions in various climates, especially in terms of appearance. These distinctions are particularly evident in the size of the body, the color of the skin, the shape of the various organs, and the proportions between the various parts of the body.
In our lessons, we will talk about the clinical importance of the normal shape, structure, functions, organs and systems of the mature human body. However, grouping people according to gender, age and racial distinctions is not sufficient to draw the normal limits of the human body and various organs in terms of size, shape and structure, and to determine the ratios between the organs and various parts of the body. There are sometimes significant differences between people belonging to various communities and even individual members of a small community within this size group. In order to overcome these difficulties, people of the same sex, same age and same race were divided into smaller groups according to the most important details seen among themselves. In this way, it has been easier to draw the normal boundaries of the body and various organs in terms of size, shape and structure among individuals belonging to a certain type. However, the difficulty was not completely resolved by this division. There are also some typical similarities between people of the same type, but there are sometimes quite significant differences as well.
It is not easy to categorize people of the same sex, same age and race into various types according to the important distinctions between them. There are divisions made according to various principles in this regard. Here, we will talk about the partition that was determined by Kretschmer and is widely used in medicine. Kretschmer divides humans into three types: leptosome, athletic, and picnic.
People belonging to the Leptosome type are tall and narrow-bodied (leptos-narrow). The length of various body parts and all organs of these people is greater than their thickness. Adipose tissue is less in all parts of the body, and people do not get too fat even though they take plenty of food. Their skulls are narrow, their faces are flattened from the sides, their faces are oval, their noses are thin, the gap between the eyes is narrow, they have bushy hair and beard, but the hair is less on other parts of the body. The thorax is long and narrow, and the legs and arms are long. In this type of people, peculiar features are seen in the shape and condition of the internal organs. For example, the heart is in the middle and in a vertical position. The stomach is long and narrow, with most of it vertical. The kidneys are mostly low and usually all the internal organs tend to hang down. Among people of this type, the less developed and weaker ones are called the asthenic type. Asthenic type people have narrow shoulders and chest, and the spine has a large convex curvature (kyphosis) in the chest part. Asthenic women are often also short in stature.
The most characteristic features of athletic type people are that their bones and muscles are overdeveloped and strong. Their stature is mostly medium to tall, with broad shoulders, narrow hips, thick wrists and large hands. Exterme muscles are overdeveloped and strong. The subcutaneous fat tissue is low, the skin is thick, taut and elastic.
Picnic type people are short and broad-bodied. Thorax (thorax) is short, but broad and rounded. Regio lumbalis (lumbar region) is barely visible. Thorax continues with a broad and rounded abdomen, the shoulders and thorax being relatively narrow to the abdomen, so the whole body takes the shape of a barrel. The neck is short and thick, the head is rounded, and the face is broad and rounded. The arms and legs are short, the hands are wide, the fingers are short, and the surrounding muscles are underdeveloped. After the age of 30 in picnic-type people, the fat layer develops especially on the abdominal walls and the width of the body increases more. Some people also have sides of the trunk whose various parts resemble various types in shape, structure, condition, and function.
There is a division of duties down to the smallest details among the various organs that make up the human body. Organs are adjusted according to the function they perform in shape, state and structures. In the future, while describing the various organs separately, we will explain the relationship between the morphological and topographic features and functions of each organ. However, it is difficult to determine a direct relationship between the shapes of some organs and the function they perform. For example, the liver can perform other tasks without disrupting bile secretion, carbohydrate metabolism and other functions. There is no relation between the external appearance and macroscopic shape of this organ and its function. But other features of the organ, for example; Its color, hardness and softness, especially its microscopic structure, are adjusted according to the tasks performed by the liver. As for the shape of the liver; Although it is related to the function of the organ, it did not occur without a reason and randomly. The shape that the liver takes, the area it takes in the body, was formed by the influence of the neighboring organs and in accordance with the general plan of the body. Topographical interests also have more or less effects on the shapes of other organs. The topographical conditions of various organs and their neighborhood affinities are mostly adjusted according to the functional interests of the organs. This interest is particularly evident among organs belonging to the same system and working for the same purpose. The topographical relationship between some organs belonging to separate systems and performing other functions is the same as, for example, the relationship between the intestines and the liver. However, if we consider the human body as a whole, we see that the state of each organ is very convenient in terms of its nutrition, protection and function, as well as very suitable for the general style and general order of the body in a way and structure that will not harm its neighboring organs.
Although different from each other in terms of shape, structure and function, the individual organs mean nothing and they are a useful element for the human body only as long as they maintain their condition in the general plan and in accordance with the general order of the body.
Organs have two main functions. The first of these is the material existence of the human body, the second is the continuation of the generation. All other events that depend on the activity of man depend on these two basic purposes that ensure the existence of man on earth. All of our organs that make up our body work together to fulfill these two basic purposes.
The human body, which is relatively small, contains various organs that accomplish great things in terms of variety and quality. The general principle of the general plan, which determines the shape, structure and condition of the whole body and individual organs, is to create a machine that occupies the smallest space but gives the most efficiency by using the least amount of material. This maximum-minimum principle exists in all areas of nature, but in the human body, this principle is best realized.
In this lesson; While separating the organs into various groups, we basically considered the dependence between the organs in terms of function and divided them into systems accordingly. As for the urogenital system, the reason why organs that differ from each other in terms of function are examined within a system is that some organs are very close in terms of neighborhood and some of them (such as the male urethra) serve as both urinary organs and genital organs at the same time.
Living things were formed by the smallest structural units called cells coming together to perform very complex functions. The cell is too small to be seen with the naked eye and is surrounded by a semi-permeable membrane. The cytoplasm, which gives the cell its shape, is a semi-liquid substance containing essential vital elements. Tissues with clustering of cells with the same task; Organs are formed when different tissues combine to perform a specific function. As a result of the coming together of organs with different structural features, systems that show a certain functional integrity are formed.
The term anatomy is formed by the combination of the ancient Greek words Ana (:through) and Tome (Temnein) (:to cut). The word anatomy means cutting apart. The Latin equivalent of the term anatomy is Dissection. Today, the term Dissection is used as a general expression for the method of dividing the cadaver into regions and examining these regions by cutting. Anatomy broadly means the normal shape of the body, its structure; It is a branch of science that examines the organs that make up the body and the structural and functional relations between these organs. The concept of Morphology, which means the science of shape, also indicates the study of living things in terms of shape. According to one view, the term Anatomy is also considered to be identical with Morphology. However, nowadays, not only the formal but also the functional (physiological) features of the formations have gained importance. Choosing a method that does not consider stereotyped rules and functional connections in anatomy education results in a learning that is based on rote learning and causes the acquired knowledge to be forgotten in a short time. Learning the functions of any structure and its connections with other structures together provides an easier understanding of Anatomy as a whole. For this reason, learning the functional (physiological) connections with diseases (clinical) or injuries rather than the details of the structures is more suitable for the contemporary Anatomy teaching approach.
Wishing you a healthy day…
Specialist Dr. Ali AYYILDIZ – Veterinarian – Human Anatomy Specialist Dr.(Ph.D.)
