Structural Organisation in Animals - Notes | Class 11 | Animal Tissues | Muscle and Neural Tissues
III. Muscle Tissue
The tissues made of many muscle fibres (muscle cells).
Muscle fibres are composed of numerous fine myofibrils.
Muscle fibres can contract (shorten) and relax (lengthen).
Muscles take part in locomotion and movements.
Muscles are 3 types: skeletal, smooth and cardiac.
1. Skeletal (striated or voluntary) muscle
They are attached to bones. E.g. Biceps.
Striations are present in muscle fibres.
Muscle fibres are bundled together in a parallel fashion.
A sheath of tough connective tissue encloses several bundles of muscle fibres.
2. Smooth (non-striated or visceral) muscle
Involuntary and fusiform (Fibres taper at both ends).
No striations.
Cell junctions hold them together and they are bundled together in a connective tissue sheath.
They are seen in the wall of internal organs such as the blood vessels, stomach and intestine.
3. Cardiac muscle
Involuntary muscle seen only in the heart.
Cell junctions fuse the plasma membranes of cardiac muscle cells and make them stick together.
Communication (gap) junctions (intercalated discs) at some fusion points allow cells to contract as a unit, i.e., when a cell receives signal to contract, other cells also contract.
IV. Neural Tissue
Made up of neurons (unit of neural system).
Responsible for control and coordination of the body.
Neurons are excitable cells. They carry impulses.
Neurons are protected and supported by neuroglial cells.
Neuroglia make up more than half the volume of neural tissue.
Organ and Organ System
Cells → tissues → organs → organ systems.
This organization is essential for better coordinated activities of cells.
An organ is made of one or more type of tissues. E.g. Heart has epithelial, connective, muscular & neural tissues.
