HUMAN BODY
(1) Introduction and Definitions:
The Systematic study of the human body is performed under two disciplines, i.e.,Anatomy (Structure) and Physiology (Function).
(a)
Anatomy: It
is the study of structure and relationship between body parts.
(b)
Physiology:
It deals with the normal functioning of all living organism and their parts.
(c)
The Cells
are the basic structural, functional, and biological unit of all living
organisms.
Definition of some important terms related to the study of the human body:
(a) Gross Anatomy: It is also known as topographical anatomy, regional anatomy, or anthropotomy. It involves the study of those anatomical structures which can be seen with the naked eye.
(b)
Microscopic Anatomy: This
branch involves the study of microscopy anatomical structures like cells,
tissue, and organs of the body, using a microscope.
(c)
Comparative Anatomy: The
comparison of anatomical structures both gross and microscopic present in
different animals is studied in his branch of anatomy.
(d) Systematic Anatomy: The study of the structure of different parts of an organ system is termed as systematic anatomy. On the basis of the organ system involved, it is named differently for each system of the human body. For Example:
(i) Dermatology: It is the study
of the integumentary system (skin, hair, and nails).
(ii) Endocrinology: It is the study of the endocrine or
hormonal system.
(iii) Neurology: It is the study
of the Nervous system.
(e) Developmental Anatomy: The growth and development of an organism throughout its life is studied under developmental anatomy. Embryology is a specific field that involves the study of the embryo and its development(till birth).
(2). Scope of Anatomy and Physiology
1) Parameters of Normal Health: (i) By studying anatomy and physiology one can know about the normal temperature of the body. (ii)One can know the specific pH at which the food breaks down. If any changes occur then that means the individual is unhealthy.
2) Techniques of surgery: Not every
part is seen through the naked eye so for knowing the exact size and location of
any part for surgery anatomy and physiology are studied.
3) Pathology of Diseases: By studying the physiology of the human body all metabolic changes are known earlier and if in case any part of the body gets diseased then its cause can be easily detected.
4)
Mass Therapy and Athletics: Mass therapy is helpful in providing relief from
pain and makes the body relax and free from any muscle injury caused by athletics
so for knowing the position and muscle nerves and bones study of physiology and
anatomy is done.
5)
Human Evolution and Development: As we know by growing age the body parts also
grow. For example, a newborn body has small bones than the 2-year child, we can examine the changes by studying anatomy and
physiology.
6)
Advanced Scientific Studies: By studying the physiology and anatomy of the human body
new drugs and new techniques for the diagnosis of diseases can be done. Many
advancements can be done in the field of medical science.
7)
Effects of Various Factors on the Human Body: By the study of anatomy and physiology, one can understand the effects of changing environment on the human body and
make a note of various factors that affect the Human body.
8) Basis for Medical Study: In traditional medical courses, anatomy is studied in parallel with physiology forming a basis for the subsequent study of pathology and clinical disciplines.
(3) Levels of Structural
Organisation
The human body is a six – leveled organised stricture, comprising of the levels given
here from lower to higher hierarchy:
1)
Molecular Level or Chemical Level
2)
Cellular Level
3)
Tissue Level
4)
Organ Level
5)
System Level or Organ – System Level
6)
Organism Level
(3.1) Molecular
Level/Chemical Level
Chemically,
Human Body is formed by various elements, like carbon, oxygen, hydrogen,
nitrogen, etc. The whole mass of the human body is made up of 26
elements which can be divided as:
1)
Major Elements: Major
elements include Oxygen (O), Carbon (C), Hydrogen (H), and Nitrogen (N)
which forms 96% of the total body weight.
2)
Major Elements: Body
contain eight minor elements, i.e., Calcium (Ca), Phosphorus (P), Potassium
(K), Sulphur (S), Sodium (Na), Chloride (Cl), Magnesium (Mg), and Iron (Fe).
These Elements form 3.8% of the
total body mass.
3) Trace Elements: (i)These are additional elements required in trace amounts or in very minute quantity.
(ii)They form 0.2% of total mass of the body.
(iii) Trace elements include iron, iodine, fluoride, copper, zinc,chromium,selenium,manganese and molybdenum, nickel, tin, vanadium, silicon,and boron.
(3.2) Cellular Level
(i) Macromolecules (like
Lipids, proteins, fats, etc. ) combine
to form more organised structures known as Organelles. (or Cell
Organelles). Various organelles (e.g., Nucleus, Mitochondria, Golgi Body,
etc. ) collectively form a cell.
(ii)
Cell is the fundamental unit of all living beings which can sustain life and
reproduce themselves.
The Human Body is a highly organised structure consisting of a large number of
cells that begins its life as a newly fertilised single cell (known as Zygote).
(iii)
More than 75 trillions of cells are present in a human body, each of which is
equally competent to grow, metabolise, and respond towards stimuli; though with
few exceptions (such as reproduction).
(iv)
Even though all the cells have some common characteristics, they still undergo
a division process to become specialised and perform their specific functions.
(3.3) Tissue Level
Tissues
are formed by the organisational arrangements of similar type of cells, to
perform some particular functions, e.g,. Epithelial, connective, nervous
tissues. However,
tissues are much more complex structures than the single unit i.e., Cell.
According
to the definition “Tissue is an aggregation of similar type of cells that
perform similar functions”. All the organs and body part are made up of
different tissues, for example different organs of the body are covered by epithelial
tissue, made up of layer of cells, such as, skin surface, digestive tract inner
lining and all the tissues which perform protection, secretion and absorption.
In
human body, the following four types of tissues are present:
(1)
Epithelial Tissue
(2)
Muscle Tissue
(3)
Nervous Tissue
(4)
Connective Tissue
(3.4) Organ Level
Various
tissues collectively form the next level of organisation, i.e., an Organ (Stomach,
Liver, Kidney, Heart, etc. ) . Two or more different tissues combine
together to perform a general function, for example, stomach is an organ which
consists of all four types of tissues and perform digestion of food.
The
wall of the stomach is formed of muscle and connective tissues, epithelial and
connective tissues make up its inner lining, while the nervous tissue makes up
the portion of the wall to the inner lining.
(3.5) System Level or
Organ – System Level
A
System consists of two or more organs along with associated structures and
performs a general function. For example, Digestive system is made up of mouth,
salivary gland, oesophagus, stomach, small intestine and large intestine gall
bladder, pancreas and Liver.
Human body is majorly composed of eleven
systems, which are as follows:
(1)
Digestive System
(2)
Muscular System
(3)
Integumentary System
(4)
Excretory System
(5)
Reproductive System
(6)
Circulatory System
(7)
Respiratory System
(8)
Skeletal System
(9)
Immune System
(10)
Nervous System
(11)
Endocrine System
(3.6) Organism Level
Many
system combine to form an organism and each organ depends on others to perform
its functions efficiently. An Individual or Organism can survive, only if all
the systems of the body operate in harmony. The basic life processes carried
out by an individual are digestion of food, elimination of waste, energy production,
growth, response to any stimuli and reproduction.
Basic Life Process
Human
Body performs different physiological functions for its survival and
reproduction, which are the ultimate goals of living organism. To achieve these
goals, the body maintains and restores the homeostasis (a state of relative
constancy). All the living organisms have some specific life processes, which
are different from those of non-living. The basic life processes are as
follows:
(1)
Organisation: At
all the organisational levels of the Human Body, each component works to
perform its own function in coordination with other component. However, If a
single cell does not cooperate with the other cells, then it loses its integrity,
and become dead.
(2)
Metabolism: Metabolism
is divided into two phases, i.e., catabolism and anabolism, In catabolism, the
macro or complex molecules are broken down into micro or simpler substances
with the simultaneous release of energy, whereas, Anabolism is the
process of construction, involving formation of complex molecules by the
simpler molecules.
(3)
Responsiveness: Irritability
or responsiveness identifies the internal or external environment changes, and
thereby, react to it. It occurs in response to any stimulus experienced by the
sensory nerves and thereafter responds to it.
(4)
Movement: Different
types of movements are performed inside the body at each organisational level,
for example, movement of blood from one part of the body to the other part; and
movement of diaphragm with every breadth during the process of respiration. The
muscle fibres possess the ability to contract, thus producing a movement known
as contractility.
(5)
Reproduction: Reproduction is the process of formation of new cells for the
replacement and repair of old cells. It also promotes growth of the newly
formed cells.
(6)
Growth: Growth
is recognised as increase in the size; either by increasing the number of
cells, or their size. For promoting growth, anabolic process must proceed at a
faster rate than the catabolic process.
(7)
Differentiation: Differentiation
is the process of development in which the cells get specialised either
functionally, structurally or by both. Later, following differentiation, the
cells develop into tissues and organs.
(8)
Respiration: All
the external and internal (cellular) processes engaged in the gaseous exchange
are together termed as respiration. The external respiration includes ventilation,
diffusion of oxygen and carbon dioxide, and transport of gases within the blood
circulation.
Respiration
at the cellular level is a catabolic process, involving combustion of glucose
in the presence of oxygen within the cell, and release of ATP, water and carbon
dioxide.
(9)
Digestion: Digestion
involves degradation of macromolecules into micro molecules and their
absorption in the blood. These molecules are absorbed into the circulation for
further utilisation.
(10)
Excretion: The
process of removal of waste products from the body is known as excretion. The
by- products produced which cannot be used up.(Many of which are toxic
materials) are excreted out of the body.
(11)
Autophagy: Autophagy
is the natural, regulated mechanism of the cell that disassembles unnecessary
or dysfunctional components.
(12)
Autolysis: It
is the destruction of cells or tissues by their own enzymes, especially those
released by lysosomes.