Human Body

What is Human Body?

The human body is a machine which have 206 bones in elders body, and 650 muscles, and 75 trillion  smaller unit called cells.

Scientists have studied the human body in detail, the human body is diveded in some regions according to their functions, these are 1. Nervous system 2. Respiratory system 3. Circulatory system. 4.Digestive system 5. Reproductive system 6. Muscular system 7. Immune system 8. Skeleton system. Let's discuss these functions in detail.

1. Nervous system:

This system allows your body to react with speed. Thousand of nerves run through the body, carrying electric signals, to and from the brain. Some nerves brings signals from sense organs to the brain. Other sends signals to muscles to make the body react.

2. Respiratory system:

All your body's cell require a supply of life - giving oxygen, which comes from air. Your respiratory job is to take in oxygen and pass it a blood. The main organ in this system are the lungs  which suck in air when you breathe.

3. Circulatory system:

The heart, blood, and a network of blood vessels makeup the circulatory system. It's job is to transport vital supplies such as oxygen and food molecules around the body. blood also carries away waste chemicals for disposal. 

4. Digestive system:

Everything you eat passes through your digestive system- a long, complicated tube that runs from your mouth to your anus. The organs of the digestive system break down the large molecules in food into smaller molecules your blood can absorb.

5. Reproductive system:

This body system works only during adulthood and is different in men and women. It's job is to produce babies. Male sex cells from a man's reproductive system join with female sex cells inside a woman's reproductive system and grow into a baby.

6. Muscular system:

Muscles are what make you move. Your largest muscles work by pulling on bones to move your skeleton, allowing you to run, jump, tie your shoelaces, or kick a ball. Muscles also keep your heart beating and churn the food inside your stomach.

7. Immune system:

The immune systems job is to keep you healthy by fighting off germs - microscopic organisms that can cause disease. Any germs that get inside your body are attacked by white blood cells, which patrol the blood and other tissue for invaders.

8. Skeleton system:

The skeleton is a tough, living framework of bones that supports the weight of your body and protects delicate internal organs, such as the brain and heart. The skeletal and muscular system work together to move your body.

Smaller unit of Body:

Atoms and molecules:

The smallest individual parts in the body are atoms and molecule. The DNA molecule (left) stores the instructions needed to build and maintain the body.

Cell:

Every part of the body is made up of tiny living units called cells. There are 75 trillion cells in the human body. Most are specialized to do specific jobs, from storing fat to carrying nerve signals.

Tissue:

Cells join in groups to form tissues. The wall of the heart, for instance, is made of a special kind of muscle tissue. Include skin, fat, and bone.

Organ:

Tissues join together to form organs, such as the heart, stomach, or brain. Organs perform a specific job. The hearts job is to pump blood around the body.

System:

Organ work together in systems. The heart is part of the circulatory system, along with blood vessels and the blood.

*Study of human Body is called ANATOMY.

HUMAN BODY important points:

1.Largest artery - Abdominal aorta.

2.Largest bone - Femur 

3.Largest heterocrine organ - Alimentary canal

4.Largest endocrine gland - Thyroid

5.Largest gland- Liver

Largest salivary gland - Parotid gland

6.Largestvein - Inferior Vena cava

7.Least regenerative capacity - Brain

8.Longest cell in the body - Neuron

9.Longest cranial nerve - Vagus

10.Longest nerve of the body - Sciatic

11.Muscles Number - 639

12.Smallest muscle - Stapedius

13.Largest muscle - Gluteus maximus

14.Longest muscle - Sartorius

15.Number of cranial nerves - 12 pairs

16.Smallest cranial nerve - Abducens

17.Smallest bone - Stapes (2.6 – 3.4 mm)

18.Smallest endocrine gland - Pituitary

19.Speed of Sneezing - 60-100 miles/hour

20.Spinal cord : Weight - 35g. Length - 42-45 cm

Human body: ORGAN location,