Cells in the Human Body | 14 Types with Examples and Functions
There are different types of cells in the human body which make up the tissues and organs.
A Cell is the basic unit of our life. You can read more about the basic types of cells in living beings.
It decides the type, nature and also the functions of the tissues.
An organ is formed from a group of tissues and tissue is formed from a group of different types of cells
These organs working in a mutually beneficial manner form the organ systems.
If any tissue is damaged, it means the cells and cell structure in the organ are damaged.
These broken ones can decide the fate of the entire tissue, i.e., either to recover or die.
So, from the above, it seems cell decides the whole life 🙂
Different Types of cells in the human body (based on tissue formation)
1. Bone cells:
They are the most robust body cell systems and are bound together by calcium and phosphate. As you know, they give strength, support, and framework to the body by enclosing organs in the skeletal system, i.e., bones.
2. Cartilage cells (chondrocytes) These cells are similar to bone cells, but the surrounding material is just loose and flexible compared to those of bone cells. Hence they are freely bendable. They are present in ear bone (therefore ears are fold-able), in between large bones to help them bend and move freely like in between two ribs, spinal bones, joints, etc.
3. Nerve cells: These cells form the nervous system.
Its features are like they are very long, having many branches at either end. They never multiply or divide in one’s lifetime. Once formed during fetus, they live until the entire life of an individual. They are present all over the body and are sometimes as long as a few meters long.
These cells are found in plenty in the brain and the spinal cord. They combine to form the nervous tissue.
4. Epithelial cell:
These cells are very simple cells which form a covering of other cells.
They form covering layers of all the organs and hence are present in skin, scalp, respiratory tract, in the buccal cavity surface, over the surface of the heart, etc. Ex: Skin cells, mucous cells.
They also form the essential structures like the nephrons in the kidney which help infiltration of the blood.
5. Muscle cells: These cells are responsible for the movements of our body. They are also called as myocytes and are present in the muscle tissues.
They are rich in proteins like actin and myosin due to which they contract. They are mostly long, large and can provide movements to the body. They are three types as the skeletal, cardiac and smooth muscle cells.
- Skeletal muscles cells are attached to long bones and assist in their movements (by muscle contraction).
They are also called striated cells as they have bands or striations on them as seen above (white and red bands). These bands are indicative of actin and myosin filaments which help in contraction.
- Cardiac muscles cells are present only in heart muscle and responsible for heartbeats.
These are also striated but have branches with others.
- Smooth muscle cells are flexible yet, can contract and relax and are present in the stomach, intestine, blood vessel walls (vascular tissue), etc. helping in the movement of food through the gut.
Muscle cells also store glucose due to which they generate energy and heat required by the body.
6 Secretory cell: These cells as the name indicates are secretory in function. They form glands and secrete something important ex; pancreatic cells which secrete insulin, glucagon, salivary gland secrete salivary amylase, sebaceous gland secrete oil on the skin, etc. They are found in all secretory organs.
7. Adipose cells: These are fat cells and are sites where fat is stored. They are mainly seen in the soles, palms, bums, etc. They reduce friction to the body.
8. Blood cells: 
These cells include RBC’s, WBC, Thrombocytes, etc. They are always motile and never stay in one place. They have a limited lifespan, and they never multiply to form new cells. Instead, new cells are formed from other cells.
Cells in the human body-based on their function
Different cells carry out distinct functions in the body like
Conductive cells: Nerve cells, muscle cells come under this category. They have an inherent ability to conduct an electric impulse from one region to other distant regions in the body.
Connective cells: Bone cells, blood cells come under this category. They help connect other cells and tissues.
Glandular cells: These cells secretory cells. They form glands like the pancreas, salivary glands, etc. and help in the production of enzymes, hormones, etc.
Storage cells: Adipose cells, some liver cells, etc. act to store materials like fat for later use. This fat is consumed in times of starvation and also in excess cold temperatures.
Supportive cells: These are the cells which are present as support to adjacent cells. Ex: Glial cells in the brain and spinal cord help provide nourishment to the nerve cells and also protect them from shocks and trauma.
The special type of cells: These are specialized cells with some crucial functions. They are
a) Sperms:
Sperm cell with its parts in detail
These cells, unlike others, have haploid DNA (i.e., have only one set of a chromosome). They are present only in the males after puberty. These cells have a tail which enables them to swim and move in the female uterus. They have an enzyme hyaluronidase which helps them penetrate through uterine tissue and reach into oocytes.
b) Oocytes: Cells are haploid and present in the adult female genital system. They are also haploid like sperms. They start to form after puberty and continue so till the stage of menopause. They accept sperm cells to form a zygote (fertilized egg). This zygote further grows in the uterus to form a baby.
c) Stem cells: These are primary cells or parent cells which can differentiate into any required cell based. These stem cells in the human body are given so much importance due to their promising role in the treatment of disorders in the future. Have a glance at stem cell types.
d) Rods & cones: These cells are in the eye and can capture image color and light.
e) Ciliated cells: These cells are present as the lining of the respiratory tract, esophagus, etc. and have pointed threadlike cilia which move in one particular direction to pass material.
f) Blood cells: These are quite interesting cells and they are never attached. Blood cells freely flow in the liquid blood. Some of them are not alive (RBC‘s) while others are alive and have varied shapes like WBC, platelets (spindle shape). Further, these WBC’s are of different types. Of them, macrophages can eat (gulp) any foreign particle like bacteria in the body. Hence they are body defense cells.
g) Pancreatic cells: These cells have both exocrine and endocrine types. There are a total of 5 types. Check out pancreatic cells for details.
h) Hepatocytes: These cells are present in the liver and constitute 80% of its mass. They are involved in the synthesis of proteins, carbohydrates, fats (cholesterol) and also the breakdown of toxins like drugs and other waste materials. The cells are large and many mitochondria and abundant endoplasmic reticulum to help in their function in the liver. Unlike other cells, they can regenerate.
i) Kupffer cells: These cells are located in the liver and involved in macrophage action. The destroy the old and worn out red blood cells in the liver.
Besides, there are cells which form covering tissue. These can be of different shapes, will ability to constrict, dilate, secrete and even absorb. Such cells are seen in the lining of the intestine, stomach, lungs, nephrons, etc. The examples include goblet cells, paneth cells, etc.
And guess how many cells are in the human body? There are 37 trillion cells in our body by an estimate.
Reference: Book-Essentials of Cell Biology-Albert Bruce.
Also, there is no significant difference between cells of animals and humans. But there are quite a lot between that of animal and plant cells.
