Cells make up for an important structure of the body system, the tissues. Clusters of cells performing the same functions and similar in structure are known as tissues. When one studies tissues, it is called histology. It contributes to the study of complete anatomy. The cumulative result of this is the provision of structural basis to understand the physiology of organs.
Primarily, there are four types of tissues, weaved forming the fabric of the body. These are – epithelial tissue (provides covering), connective tissues (renders support), nervous tissues (Responsible for control) and muscle tissues (enabling movement). Let us take a look at each one briefly:
Types of Tissues
Epithelial tissue
Epithelium or the epithelial tissue are tissues lining the cavities of the body or forms the covering of the body surface. In the body, they appear as
- glandular epithelium – patterns the glands
- Lining and covering epithelium – forms the skin’s outer layer, open cavities of respiratory, digestive and cardiovascular systems, shielding the organs and walls of the closed ventral body cavity
In general, epithelium forms a barrier between various structures. Almost all particles must pass through this tissue. The epidermis for instance, lines the urinary bladder separating the cells underneath the wall of the bladder from the urine.
The epithelial tissue accomplishes these functions –
- Protection
- Absorption
- Excretion
- Sensory reception
- Secretion
These tissues provide protection to underlying tissues from any invasion by foreign particles, chemical and mechanical injury. They entail nerve endings which are responsive to stimuli which act on the surface of the skin.
The distinguishing characteristics of epithelial tissue are –
- Possess specialized contacts
- Property of polarity
- Supported by connective tissue
- Avascular, innervated
- Property of regeneration
Connective tissue
These widely distributed tissues are found almost everywhere in the body. However, the amount of this primary tissue in different structures varies. The role of these tissues is involvement in –
- Protection
- Support and binding
- Provide insulation
- Transporting substances in the body
To give an example, the cartilage and bones render protection and support to the organs of the body and render the hard underpinnings of the skeleton. Fat-cushions protect and insulate the organs of the body and provide reserve energy fuel.
The types of Connective tissue, their classification is as depicted below:
Connective tissue
Connective tissue proper
Loose connective tissue
Areolar
Adipose
Reticular
Dense connective tissue
Regular
Irregular
Elastic
Cartilage
Hyaline
Elastic
Fibrocartilage
Bone
Blood
Some specialized connective tissues involve a range of tissues performing dedicated functions due to the presence of specialized cells and unique substances. While some of these specialized tissues are strong and solid in nature, some others are flexible and fluid. Some connective tissue examples of this nature are cartilage, lymph adipose, blood and bone.
Nervous Tissue
The brain, nerves and spinal cord primarily consist of the nervous tissue. These tissues are pivotal in controlling and regulating the functions of the body. The nervous tissues consist of highly specialized cells – the nerve cells or neurons which cause the generation and conduction of nerve impulses.
Types of nervous tissues –
- Neurons
- Neuroglia
- White matter
- Gray matter
Muscle Tissue
These tissues are highly cellular, well-vascularized tissues participating in movements of the body. The cells are equipped with myofilaments which are the elaborate versions of the myosin and actin filaments causing contraction and relaxation.
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