INTRODUCTION TO ANP 102 [CELL, TISSUE, ORGAN, SYSTEM]

We discussed the cell in full context back in ANP 101. You can click here to see full explanation on cell.

In this chapter, we will be discussing very briefly on cell, tissue, organs and systems.

I'm sure that by now, cell should not be new to you.

A cell is the basic, functional unit of every living organism — you know that right?

Structure of the Animal Cell

We have unicellular organisms, they have just one cell. We also have multicellular organisms, these organisms have more than one cell.

Some multicellular organisms have their cells in non-specialised or less advanced form like sponges while many others have their cells in differentiated and specialized forms.

Majority of animals arose from one fertilised cell (or fusion of two half cells called haploid cells)

This fertilized cell actually multiplied. The many cells then become specialised, differentiated to give rise to a whole multicellular organism.

When cells are becoming many, they begin to specialise. 

Various similar cells group together to form a tissue.

A tissue is simply a collection of several cells that have come together to perform a specific function.

Structure of an Animal tissue

Any Animal, from its head to its tail, are composed of tissues.

Every Animal basically has 4 tissues:

• Epithelial tissue
• Connective tissue
• Muscle tissue
• Nervous tissue

When several tissues work together to perform one specific function they give rise to an organ.

An organ is composed of several tissues that have decided to work hand-in-hand to perform an action. For instance, the heart is an organ, it is a combination of several tissues that aim at performing one function — Pumping of blood.

An Animal organ

One organ in the body of a multicellular animal cannot carry out any life process efficiently. 

Therefore, several organs need to work together to successfully perform well defined functions. 

When several organs work together to perform a function, they give rise to a system.

A system is formed as a result of the cooperation of several organs that work together to perform a specific function.

Digestive system of an animal

Every multicellular animal are composed of upto 11 systems.

These systems are:

• Circulatory system
• Endocrine system
• Nervous system
• Respiratory system
• Reproductive system
• Muscular system
• Skeletal system
• Digestive system
• Immune or lymphatic system
• Excretory system
• Integumentary or outer body layer system

Some human systems 

While learning the several systems of organisms, you may view them like they are in different formats, but in reality these systems are tightly packed together.

Some of these systems and the physiology of these systems are what we will basically be studying in ANP 102.

So sit back, relax and learn the several systems that make up a functional multicellular organism in this course.