Anatomy & Physiology
Physiology means the science of the functions of living organisms and their parts. It is the branch of medical science in which the functions of the body are studied. In this branch, the functions of different organs and systems of the body and their causes as well as the rules of medical science related to them are also described. As ear acts as to hear and eyes as to see, but the physiology gives information about the secrets (reasons) of hearing and seeing. How does sound reach on the eardrums? How does light fall on the eyes’ lens? How do objects’ images being made on the retina of the eyes? How do the human beings eat? How does digestion take place? How does absorption take place by intestinal walls? How does assimilation take place after absorption of food? How do the human beings excrete out stools and urine? How does blood circulation take place? How does reproduction take place? About all these functions, we get information through physiology.
Anatomy means the science of animal or plant structure. It is the branch of medical science in which information about the structure of human body and the mutual (reciprocal) relations of its different organs is provided. It can be divided in to many special branches, few of them are describing below-
Gross or macroscopic anatomy- In this branch, visible structures (parts) of the body is studied. These structures can be studied according to regional or systematic anatomy. In regional anatomy, the muscles, bones and nerves of different body parts like- head, chest, arms or legs, etc. are studied. In systematic anatomy, all types of structures doing similar work i.e. a unit of muscles is studied.
Surface anatomy o r topog raphic anatomy- In this branch, the structures present on body surface (layer) or those related to it are studied, because they are related to the tissues and organs situated beneath them. For illustration- the jaw’s muscles are related to the face or skull, which can be felt or seen by closing the mouth. In surface anatomy of newly born baby, the edges of the skull bones can be seen on the anterior fontanel.
Applied anatomy - It is associated with treatment of disease especially with surgery. In this branch, surgeon operates the body for investigating or repairing the body. It is also known as surgical anatomy.
- Radiological anatomy - In this section, the anatomical defects are tested after observing the x-ray film of different body organs.
- Kinesiology - In this section, the muscular movements and the stretch and pressure of the muscles on particular bones are studied.
- Osteology - In this section, the bones are studied well. For setting the fractured bones again or making body organs, the orthopedic surgeon should be expert in both kinesiology and osteology.
Microscopic anato my- In this branch, the very tiny structures of human body are studied easily with the help of microscope. Earlier these structures could not be seen through naked eyes.
- Cytology- In the section of cytology, the growth, structure, functions and disorders of the cells are studied.
- Histology- In this section, the body tissues are studied through microscope.
- Organology- In it, the body organs made from the groups of primary tissues- epithelial, connective, muscular and nervous are studied with the help of microscope.
- Morphology- In this section, the outer structure and shape-size of any body parts or organs are studied.
Developmental anatomy- In this branch, the structural changes taken place from embryo to young stage is studied.
- Embryology- In it, the growth of embryo is studied. In human, this study is done from conceiving and up to about 8 weeks till the initial growth of organ systems.
- Fetal anatomy- In this section, the growth of organ systems from 8 weeks till birth is studied.
- Teratology- It is a branch of developmental anatomy. In it, the abnormal growth of embryo is studied.
- Genetics- In this branch, the genes and chromosomes and transferring of them from one generation to other ones are studied.
Neuroanatomy- In this branch, nervous system is studied.
Morbid or pathological anatomy- In this branch, abnormal, obsessed or injured structures are studied.
Anatomical terminology- Anatomy scientists have made special type of explained terminology for understanding anatomy, studying of which is very necessary.
Anatomical position- About the location of particular body organs, the experts of anatomy have defined anatomical position.
According to anatomical position, the body remains stand straightly- the face is frontward, eyes are seeing just opposite, the legs are closed together; the arms are as hanged both the sides and the palms remains frontward.
To know particular location of normal and alone structure or organ, following defined words are used-
Superior or cranial- Towards the head; example- the leg is present above the foot towards the head.
Inferior or caudal- Towards the feet; example- the feet are present below the legs.
Anterior or ventral- Towards the front of body; example- the nose is present before (front of) the ears.
Posterior or dorsal- Backward of the body; example- the ears are located behind the nose.
Medial- Towards the body midline; example- the nose lies in between both the eyes.
Lateral- Away from the midline; example- the eyes are present away (lateral) to the nose.
Proximal- Towards the trunk of the body or the connected end of any arm with the body; example- the shoulder is present nearer to the wrist.
Distal- Far away from the body trunk or the connected end of any arm; example- the wrist is present far away from the forearm.
External or superficial- Near the body surface; example- the ribs are more superficial than heart.
Internal or deep- Far away or deep from body surface; example- the heart is far away from the body surface than ribs.
Central- Towards the center of the body.
Peripheral- Far away from the central axis of the body; example- peripheral nerves grow from the brain and spinal cord and spread far away.
Plantar- Undersurface of the foot.
Parietal- Describing about the lining membrane of the wall of any body cavity.
Visceral- Describing about the membrane covered any internal organs and cavities like- abdominal cavity or internal organ.
For example- According to anatomical terminology, the head is superior to neck, but it is wrong to say that the head is located on (above) the neck. In anatomy, this type of word is used in pairs. If one word represents superior, another will represent inferior. If the thighs are superior to knees, the knees are inferior to thigh.
The word ‘Anterior’ is used for the front layer of the body and word ‘Posterior’ is used for back layer of it. ‘Anterior’ and ‘posterior’ are also known as ‘Ventral’ and ‘Dorsal’ respectively. These words are used for the internal organs of the body like- the heart is located in the dorsal of sternum and the dorsal surface of the sternum is the ventral of heart.
The word ‘Medial’ is used for the nearness of imaginary midline of the body or any body part while the word ‘Lateral’ is used for the farness of this midline, for example- the nose is medial to the eyes and the eyes are lateral to the nose.
Words ‘Proximal’ and ‘Distal’ are often used for arms, legs and fingers. The proximal is used for the parts nearer to the trunk connected with arm towards the head while the distal is used to indicate the parts connected with arms but far away from the head, example- the shoulder is the proximal of wrist while the wrist is the distal of forearm.
The word ‘Superficial’ means nearness to the body surface i.e. on the skin while the word ‘Deep’ means far away from the body surface i.e. deep in the skin. the word ‘External’ stands for outer and ‘Internal’ stands for inner, ‘External’ and ‘Internal’ are not same as ‘Superficial’ and ‘Deep’. These words indicate structures inside the hollow structures. Normally, these words are used for the head, chest and stomach as well as the walls of other internal organs. For illustration- the side of ribs towards chest cavity is called internal surface while the side towards outside far from chest cavity is called external surface.
The lower surfaces of the feet (soles) are called plantar while the upper surfaces of them are called dorsal. The palms are called palmar and the back part of claws is called dorsal.
Body regions (areas) - The body is divided into axial and appendicular parts at anatomical position for defining (describing) common regions of the body. the axial part includes head, neck, thorax, stomach and pelvis while the appendicular part includes shoulders, arm, forearm, wrist and hand as well as lower organs like- hips, thigh, legs, ankles and feet are also present in this part.
Customary, the abdominal region is divided into 9 parts through two horizontal and two vertical lines-
- Right hypochondriac region.
- Epigastric region.
- Left hypochondriac region.
- Right lumbar region.
- Umbilical region.
- Left lumbar region.
- Right iliac region.
- Hypo gastric region.
- Left iliac region.
The upper horizontal line passes between the gephoid pravardh of sternum and the navel and the lower horizontal line is located on the surface of tubercuils about 2 inches behind the anterior superior iliac spine on the crests of both the iliac bones. Vertical lines are the lines drawn in between anterior superior iliac spine and symphisis pubis on both the sides. With the help of it, one gets proper knowledge about the structures and the locations of the organs present inside the stomach and these organs are described according the position in their division.
Body planes or sections- For more clarification of the special regions of the body, it is divided through imaginary even planes.
Midsagittal plane- The midsagittal plane divides the body vertically (longitudinally) on the imaginary midline of the body i.e. from top to bottom into two equal sections- left and right. If midsagittal plane is at the little distance (parallel) of midline and divides the body into two unequal left and right sections, it is called sagittal plane. At the right angle of midsagittal plane, all the vertical planes are called frontal or coronal planes through which the body is divided into two unequal anterior and posterior parts. At the right angles of both midsagittal and frontal planes, the plane divides the body horizontally is called transverse or horizontal plane. As a result of it, the body is divided into superior and inferior sections. The body does not being divided in equal parts by transverse section (cut).
In histology too, planes or sections (cuts) are used, in which tissues are cut by longitudinal, transverse of cross and oblique planes.
Body cavities- The body cavities are situated inside the axial part of the body filled with viscera or fluid in them. There are two chief cavities found in the body- ventral and dorsal. Both of them remain divided into small cavities.
The ventral cavity is present in the trunk and remains divided in following cavities through diaphragm-
- Thoracic cavity.
- Abdominopelvic cavity.
Following cavities are present in dorsal cavity-
- Cranial cavity.
- Spinal or vertebral cavity.
Thoracic cavity- The thoracic cavity is situated in the superior part of the trunk. It is surrounded by rib cage and the muscles related to it. Sternum is present on the front in it and 12 thoracic vertebrae on the rear. Intervertebral discs are located in the middle of these thoracic vertebrae and intercostals muscles are present in its side.
In the right and left sides of it, pleural cavities are present. The lung is located in each of them and in the middle section of lungs, there is mediastinum found that separates both the lungs. In the mediastinum, the heart and the blood vessels related to it- aorta, superior and inferior vena cava, oesophagus, trachea, thymus gland, lymph nodes, thoracic duct, phranic and Vegas nerves, etc. are found. Pericardial cavity is present around the heart.
The heart and pericardial cavity are present closed in double layered (membrane) sac. It is called pericardium. Both the lungs and lungs cavities are remain closed inside a double layered sac.
Abdominopelviic cavity- It the biggest cavity of the body that is found from the inferior of diaphragm to pelvic bottom in the body. It remains divided at the superior margin of the pelvic through an imaginary line in the upper and lower sections. The upper section is called abdominal cavity and the lower section is called pelvic cavity.
In abdominal cavity, frontier abdominal muscles are presented frontward. At the back, the muscles of lumbar vertebrae and posterior abdominal wall are found. In lateral side, the lower muscle and the muscles of abdominal wall are present. The diaphragm is present above it that separates it from thoracic cavity.
In abdominal cavity, mostly the digestive organs like- stomach, small and large intestines, liver, gall bladder and pancreas are located. In addition to them, the upper part of spleen is also found inside this cavity.
Pubic bones and coccyx are present in the front part of the pelvic cavity and in the back side, innominate bones are located. It is fused in the abdominal cavity and present in the muscles of pelvic floor.
Inside it, the lower part of ureters, urinary bladder, sigmoid column, rectum and internal reproductive organs of male and female- uterus, fallopian tubes, ovaries and vagina in female while cawper glands, prostate glands, two ejaculatory tubules, two seminal vesicles, two vas deferens and two spermatic cords are found.
Cranial cavity- The brain in present in it and its boundaries are made up of cranial bones. The spinal cord is present in the spinal or vertebral cavity.
Body membranes- The thin soft layers of epithelial and connective tissues are called membranes. They help in expanding the body cavities or separate few particular regions, structures and organs from each other. There are mainly three types of membranes- mucous membrane, serous membrane and synovial membrane.