Fundamental Body Tissues – Structural Organization of Human Body

What is a Human Body Tissue?

A tissue is a bunch of cells which have the same form and performanceSeveral types of tissues might be discovered in numerous organs.  In humans, there is 4 primary sorts of tissue:  epithelial, connective, muscular, and nervous tissue.  There could also be numerous sub-tissues inside every of the first tissues.

Types of Human Body Tissues:

1. Epithelial Tissue (Epithelium)

The Epithelial tissue is made up of sheets of cells which lie on a flat membrane called basement membrane. Epithelial tissue can be a simple layer of cells or may be multiple layers of different cells.

Squamous Epithelium (Figure is shown below)

A single layer of flat cells arranged like a pavement.

Fundamental Body Tissues                                                                                                Squamous epithelium

Squamous epithelium is very strong and can withstand trauma or abrasion to a great extent. That is why there is a squamous epithelium lining wherever the body is exposed to external environment e.g.
— Skin (modified squamous epithelium lining of the mouth, tongue, salivary glands)
— Pharynx (throat)
— Nasal sinuses
— Oesophagus (swallowing tube)
— Lining of the upper respiratory tract
— Uterine cervix
Because of constant exposure to irritation and injury, squamous epithelium turns cancerous more often than other types of epithelium. Squamous epithelial cells may be modified:
(a) A Tall column like cells—columnar epithelium. These cells have secretory function producing mucus. Columns are epithelium lines the gastrointestinal tract.
(b) Shorter cells which are like cubes are called cuboid. They have a secretory function in glands and can also absorb the liquid.
(c)
Some types of cuboid cells may have short hair which can sweep liquids and cells and propel them forward. This type is called ciliated epithelium and is present in the throat and uterus.

Modified Squamous Epithelium

Any one or more of the simple epithelium may be arranged in layers, e.g. in’ the
— Mouth
— Skin
— Nails
Sometimes (e.g. skin), the epithelium is covered by a hard layer, keratin which is mainly protective. The home of the rhinoceros is keratin.

2. Connective Tissue

Connective üssue contains cells separated by fibre. In between fibres there is intercellular Connecüve tissue makes up many of the common tissues of the body, e.g.
— Fat
— tissue
— Elastic
— Cartilage
— Bone
— Blod
Of these it is important to study in detail bone; joints, and blood. Blood and its functions are describd in the article “The Blood.

Fibrous Tissue

Fibrous tissue gives rigidity or stiffness and Elastic tissue gives elasticity. Fats area storage fom of excess energy.

Bones (Figure is shown below)

Bones make up the skeleton giving rigidity to the frame. However, their more important feature is that they contain bone marrow where blood is produced.
There are 2 types of bone:
(a) The solid or compact bone which gives strength to the frame and limbs. Compact bone forms the bones of the legs and arms.
(b) Cancdlous or spongy bone which forms the flat bones of the skull, ribs and the expanded ends of long bones.

Bones in Human Body

The bones

Bone is made up of bone cells arranged in concentric layers (like an onion) around a central canal which contain vessels. This is called Haversian system.

Calcium is deposited in the bone to give it rigidity. The salt is hydroxyapatite. Calcium in bone (hydroxyapatite) is being continuously and absorbed so that there is a constant interchange of calcium in bone with the calcium in the blood. The calcium concentration in blood must be maintained at a constant level. The calcium in bone acts as a storehouse for maintenance of a constant blood calcium level.

Calcium is deposited in the bone to give it rigidity. The salt is hydroxyapatite. Calcium in bone (hydroxyapatite) is being continuously and absorbed so that there is a constant interchange of calcium in bone with the calcium in the blood. The calcium concentration in blood must be maintained at a constant level. The calcium in bone acts as a storehouse for maintenance of a constant blood calcium level.

Bone is manufactured by a special cell called the osteoblast. Bone is also being constantly absorbed by another special cell called the osteoblast. The osteoblast and osteoclast keep on modeling the bone to give it the appropriate alignment and strength. Bones are covered externally by a thick membrane called periosteum which gives protection to the bone.

You may also read: Special fluid systems

Joints

A joint is where 2 bones meet (fig. below). At the joint, one bone moves on the other. The surfaces of the bones at the joint are protected by a smooth (frictionless) rubber like tissue called the cartilage. The cartilage on the ends of the 2 bones is also separated by a bag of fluid called the synovial fluid. The bag itself is made of a membrane called the synovial membrane. When the bones move, the movement is made frictionless because of the cartilage and the synovial fluid.

Joints in Human Body

The joint is encased in ligament, a tough rope like a sheet of tissue. It prevents the 2 bones from separating at the joint. The ligamentous sheet is called the capsule. The capsule is surrounded by muscles which travel across the joint and which are responsible for movement at the joint. When a joint is inflamed, the capsule, ligament, and synovial membrane swell up. Movement becomes painful. The condition is known as arthritis.

Nervous Tissue

Nervous tissue is made up of nerve cells (neurons) and the lipid sheath is called the myelin sheath.
(a) The nerve cell is star shaped.

The neurons system in human body

The neurons

(b) The nerve is interconnected so that the action in one nerve cell is always coordinated with all the other nerve cells with which it is interconnected. This may a few million nerve cells.
(c) In between the nerve cells, there is connective tissue. The connective tissue cells have a dual function. They support the nerve cells. They also form a part of the immune system of the body, a defense mechanism against infection.
(d) The nerve cells being connected with millions of the other nerve cells is like a giant computer. No computer can match the human brain in its complexity of action.

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