Skeletal and Nervous System
Introduction to the Organ System
We know that our body work like a machine. Rather we can say that this is the most amazing machine. It does different types of works like digestion, reproduction, respiration, circulation etc. Our body is made of cells. Cells are made tissue. Different types of tissues make organ. Many organs make ORGAN SYSTEM. A group of organ workinf together, to perform a particular work for our body forms an Organ System. There are mainly seven types of Organ System in our body . These are Skeletal System, Nervous System, Respiratory System, Circulatory System, Reproductive System, Digestive System and Excretory or Urinary Sytem.
Movement is one of a characteristic features of living beings. Animals show different kinds of movements like walking, flying, creeping, jumping, running etc. There are many kinds of movements take place in body like blinking of eyes, heart beats, respiration, etc. Our body has a bone and mussels which help in all of such movements in our body.
SKELETAL SYSTEM
Skeletal system is the framework of bones. Skeletal system gives support and shape to our body. The human skeletal consists of 206 different bones. The bones in our body are of different shapes and sizes.
BONES
Hard, whitish tissues which make skeleton are called bones. Bones are hard structures present under our skin. The soft, spongy, fluid like material present in the cavity of long bones is called bone marrow. In bone marrow our blood cells are made. Bones together make frame to support our body.
SKULL
Skull is the part of skeleton that protects brain. Skull is made up of eight flat bones which are closely fused together. All bones in the skull are fixed except lower jaw. The lower jaw is only movable part of our skull which eanbles in talking and eating. The upper and lower jaws have teeth which help in cutting and chewing of food.
RIB CAGE
Rib cage forms the upper front part of our body which is called chest. Rib cage has 12 pairs of ribs attached to the vertebral column (back bone). Vertebral column is called back bones also. A long bone at the centre of the chest is called STERNUM. Sternum holds the ribs at their correct places. The last two pairs of ribs are not attached to the sternum, so they are called floating ribs. Floating ribs do not float around inside our body. They are attached to our back bone. Rib case protects our heart and lungs.
BACKBONE
Vertebral column is called back bones also. All vertebrate animals have vertebral column for example cat, dog, cow, tiger, lion, fish rabbit, etc. Some animals do not have vertebral column such as cockroach, ant, butterfly, earthworm snail. Such animals which do not have vertebral column are called invertebrate.
Vertebral column made up of a series of small bones called vertebrae. There are 33 vertebrae which together make backbones. Backbone protects the spinal cord. Spinal cord is bunch of nerve passed through back bone (vertebral column). Vertebral column protects spinal cord. These vertebrae form a hollow ring like structure. They are jointed with each other to give flexibility to our body because of which we can bend or move.
LIMBS
There are two pairs of limbs in our body. These are forelimbs (arms) and hind limbs (leg). The general name of forelimbs is arms and the general name of hind limbs is legs. In human being, the forelimbs are modified to do the work, while animals use forelimbs for walking. Forelimbs and hind limbs are collectively made up of 30 bones. The upper leg consists of one long bone called thigh bone. Thigh bones are also called femur. The femur is the longest bone in the human body.
Functions of Skeletal System
Skeletal system gives support, shape and strength to the body. Without skeleton system we cannot move and walk. Skeletal system controls the movement of all parts of body.
Muscles are fleshy parts attached to our bones. Cartilages are soft and elastic bones which are found at the end of bones. Muscles and Cartilages also help in movements of our body.
Skeletal system protects our soft internal organs. Skull protects our brain. Rib cage protects our lungs and hearts. And the backbone protects the delicate spinal cord.