A human body is like a machine which is comprised of following systems, viz.
(i) Skeleton and Bones/Spinal Cord
(ii) Respiratory System
(iii) Digestive System
(iv) Circulatory System
(v) Urogenital System
(vi) Excretory System
(vii) Skin/Cutaneous System
(viii) Nervous System
(ix) Endocrine Glands
(x) Sense Organs
Skeleton and spinal cord
All the bones of body are fused into and interconnected by means of tendons, sheaths, cartilages etc. Upper parts of the body are supported by spinal column which has direct relation with our brain. This is the longest and most complex organic structure of human body- it starts from Medula oblangata (in back side of neck) and ends up with the tailbone or coccyx. Spinal cord is made up of 32 vertebrae, comprising of cervical, thoracic, lumbar, sacral and coccygeal bones.
Each spinal bone has a control rung to give passage and support to spinal cord which is an important part of bony cage of human body- on its top, it supports skull, in the middle lungs and chest bones, and on the lower side pelvis, sacrum and coccyx.
Spinal cord is fully nurtured, and supported by muscles, blood vessels and nerves, Neck ,Heart lungs, chest, entire diges¬tive system, diaphragm, etc. Spinal cord serves to send messages to various parts of our body.
Skeleton consists of Skull, Vertebral Column, Clavicle, Rib, Sternum, Humeus, Radius, Carpal and Metacarpal bones, Tarsal Bones, Tibia, Fibula, Patella, Femur, Pubic Bone and Ilium as is succintly visible when looked upon the bony cage of the body (skeleton).
There are three types of bones, viz
1. Long Bones – As found in bones of arms and legs
2. Short Bones – As found in fingers and toe bones
3. Flat Bones- As found in skull, Ribs and breast bonesMuscles: A muscle is a collection of stringy substances and has the property to ‘contract’ and ‘expand’. A muscle is formed of several muscle-fibres, and each fibre is made up of many cells which originate from body-spot to be inserted into any bony-spot . Belly of muscle is the central thick part of muscle which has two ends (points of insertion and origin). It is made of ‘tendons’ which are very strong shiny fibres which are bereft of any flexibility. Terminal divisions of nerves and nerve-endings end up into muscles. Muscles are nourished and enriched by blood , supplied by blood vessels. Muscles have the following salient features-
2. Flexibility or Elasticity