Basic Physiology

Physiology

Physiology is the study of the normal functioning of the body, it mainly deals with "How the body works".
The goal of physiology is to explain the factors responsible for origin, progression and development of life.
In physiology, we consider the body as a machine and then study its mechanism of action. As a machine respond to certain stimuli, certain change ; the same way our body respond to the stimuli and respond in the form of a change in function. As an example, we can consider the shivering mechanism, In which the body tries to keep it's temperature maintained(In a Cold surrounding/environment) by generating heat mechanically by shivering.
As physiology deals with the mechanistic approach to explaining events, let's look at the basic levels of organization to explain it. starting from basic chemical level (atoms and molecules) to the organism itself.

Chemical level

It consists of atoms and molecules and their assembly to create cells. However,We will not go into detail for this level.

Cellular level:

the cell is the basic unit of structure and function in all organisms. Many organisms such as Bacteria are single-celled and are termed as unicellular organisms. The same way many organisms are made up of aggregate of cells and are called multicellular organisms as the Human body consists of trillion of cells.
All cells, however, perform certain basic functions for survival (in addition to specialized functions associated with certain multicellular organism's cells).eg. Obtaining food
Generation of energy
exchange of materials between cell and surroundings etc
In multicellular organisms, in addition to basic functions of survival,cells also perform specialized tasks
For Example:
Gland cells are concerned with secretions, Muscle cells help in contraction, nervous cells perform transmission of nerve impulse etc

Tissue level:

Cells sharing similar structure and function are organized to form tissues, of which there are four primary types:

• Muscle Tissues
• Nervous Tissues
• Epithelial Tissues
• Connective tissues

Muscle tissue:

Cells of muscle tissue are specialized for contraction and force generation. There are 3 types of muscle tissues

The table below shows some of their functions.

Skeletal Muscles	Smooth Muscles	Cardiac Muscles
These are specialized for skeleton's movement.	Form the hollow body tubes	Responsible for blood pumping

Nervous tissues:

They are responsible for the initiation and transmission of nerve impulse(electrical impulses). These impulses act as signals for carrying information from one part of the body to the other.

Epithelial Tissue

These are made of cells specialized in exchange of materials between the cell and its environment. This tissue is of two forms.

• Epithelial sheets
• secretory Glands

Connective Tissue

Connective tissue connects, supports and anchor various body parts.

Organs

Two or more types of primary tissues join to form an organ that performs a specific function/functions.
Eg. Stomach which is an organ is made up of 4 types of primary tissues.

Body System:

Organs are further organized into body systems. A body system is a collection of organs that perform related functions and is essential for the survival of the body.
Example:
The digestive system is a body system and it consists of mouth, pharynx, esophagus, stomach, intestines, some glands, liver, pancreas and gall bladder.
so a body system is an assembly of several organs.

All Body systems are joined to each other structurally and functionally to form Body (i.e an individual-a whole organism)