Animal Tissue
The four types of animal tissue are namely epithelial tissue, connective tissue, muscular tissue, and neural tissue.
Epithelial Tissue
This type of tissue form covers the internal and external surfaces of the body. The cells are compactly packed with a little intercellular matrix.
Epithelial tissue is of two types simple and compound epithelial tissue. Simple epithelium comprises a single layer of cells and functions as a protective lining for body cavities. The compound epithelium comprises more than one layer of cells and functions are limited to secretion and absorption.
Connective Tissue
This tissue is named connective tissue because of its specific function of supporting and linking with other tissues/organs of the body. It is the most abundant and widely distributed type of tissue in the body. It can be soft tissue or hard types like cartilage and bone. Connective tissue is of three types loose connective, dense connective, and specialized connective tissues.
- Loose connective tissue has loosely arranged cells and fibers in a semi-fluid ground substance.
- Dense connective tissue is compact fibers and fibroblasts in which the orientation of fibers can be regular like in tendons and ligaments or irregular like in skin.
- Specialized connective tissue is cartilage, bones, and blood. Blood is the fluid connective tissue that functions as the main circulating fluid. Bones are hard and non-pliable rich in calcium salts that function as a structural framework. Cartilage is solid, pliable, and resists compression.
Muscle Tissue
Muscles are made of long, cylindrical parallel arranged numerous fine fibers called myofibrils. Muscles are of three types skeletal, smooth and cardiac.
- Skeletal muscles: they are attached to skeletal bones.
- Smooth muscles: these muscles are concerned with involuntary functioning organs.
- Cardiac muscles are related to the heart muscle.
Neural Tissue
Neural tissue controls the body’s response system to changing external environments. Neurons are the basic unit of the nervous system which are excitable in nature and send information from one place to other. When stimuli are exerted an electrical disturbance travels from neuron to neuron.
Structural Organization in Animals
Every living organism is made up of cells. The basic structural organization of any multicellular living organism is as follows:
Cells-Tissue-Organ-Organ System