The vital functions of life

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LIVING AND NON-LIVING THINGS

There are many living and non-living things on the Earth. What's the difference?

As you see in the video, life is very complex and there are many facts in common with non-living things. So, who are living things?

Living things are those able to carry out the three vital functions of life: NUTRITION, REPRODUCTION AND INTERACTION.

FUNCTION OF NUTRITION

It is the process in whigh living things take nutrients, materials and energy from food to grow and survive.
E.g. Eating an apple, drinking water, breathing oxigen...

Four important systems are involved in this function:
- CIRCULATORY system
- RESPIRATORY system
- DIGESTIVE system
- EXCRETORY system

FUNCTION OF REPRODUCTION

It is the ability to create a similar individual.
E.g. Humans have babies, birds have chicks, plants have seeds...


FUNCTION OF INTERACTION

It is the process in which living things perceive stimulous from the environment and create a coherent response to the recieved information. 
E.g. Moving your hand when you notice you're burning; speaking with your friend; a plant moving looking for the sunshine...

Two important systems are involved in this function:
- NERVOUS system and senses
- LOCOMOTOR system (muscles, skeleton and joints)


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Following, let's see in deep how these functions are developed in humans.

THE NUTRITION FUNCTION

As we said before, there are four systems involved in the nutrition function.

The circulatory system

 

It consists of HEART and BLOOD VESSESLS (arteries and veins) and BLOOD.

1. Blood gives oxigen and nutrients to the whole body by arteries.

2. Blood collects waste products and Carbon dioxide from the whole body by veins.

3. The heart bumps to move the blood along the blood vessels.

Blood is involved in other systems: the digestive, the excretory and also the respiratory.

The digestive system

 

  
It consists of MOUTH, OESOPHAGUS, STOMACH, SMALL INTESTINE, LARGE INTESTINE, ANUS, LIVER AND PANCREAS. 
1. Food enteres through the mouth and oesophagus to the stomach.
2. Food mixes with stomach acids in the stomach.
3. Small intestine separates nutrients from waste. Nutrients pass to the circulatory system.
4. Waste travels through the large intestine and anus.

Liver and pacreas regulate the process.

The respiratory system

 It consists of NOSE, MOUTH, PHARYNX, TRACHEA, LUNGS, BRONCHI, ALVEOLI AND DIAPHRAGM.

1. Air enters in the body through the nose and moth, travels through the pharynx, trachea and bronchi to the lungs.
2. Blood takes oxigen from the air through the alveoli in the lungs, and leave carbon dioxide.
3. The diaphragm contracts to breath in (take oxygen) and relaxes to breathe out (leave carbon dioxide).

The excretory system

It consists of KIDNEYS, URETERS, BLADDER AND URETHRA.

1. Kidneys separate waste from our blood. Waste combines with water to make urine.
2. Urine travels through the ureters to the bladder.
3. When bladder is full, urine leaves our body through the urethra.

Waste is also eliminated when we sweat through our skin.

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THE REPRODUCTION FUNCTION

 In the human reproduction process we distinguish two important moments: fertilization and pregnacy.

 Pregnacy in humans lasts about 40 weeks. 

Let's see in a quick view, how babies are born.
 

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THE INTERACTION FUNCTION

The nervous system and senses

The nervous system controls everything you do: walking, speaking, breathing, sleeping, thinking... It consists of the CENTRAL NERVOUS SYSTEM (CNS) made of the BRAIN and the SPINAL CORD, and the PERIPHERAL NERVOU SYSTEM (PNS) made of many NERVES. 

Nerves connect the sense organs and muscles to the CNS. Sense organs recieve and send information (by neurons) to the brain who sends a response to the whole body.

The locomotor system

We find two important systems: the skeleton and the muscles.

The skeleton is made of bones and bones are connected by joints. The skeleton supports our body and protects the internal organs. 

 Muscles shape our body, help us to move and also protect internal organs. The movement they do can be voluntary (move your hand, open your mouth, run...) or involuntary (breathing, blinking, trembling). Muscles are conected to the bones through TENDONS.

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