LUNGS : THE BREATH OF LIFE

LUNGS

"Is he breathing?" This is almost the very first question you ak when you fear the worst has happened and that a person may be dead. Spontaneous breathing is one of the most easily recognised signs of life. It is also the first act of the newborn; and it is a huge effort too, to take the first breath. But once taken, the process continues non-stop and rhythmically, till death. And our hardworking lungs are the organs we must thank for every breath we take whether awake or asleep.

  ANATOMY

• The respiratory system consists of the airways, the lungs, and the respiratory muscles that facilitate the movement of air into and out of the body.
• Humans have two lungs-- the right lung and the slightly smaller, left lung. These fill up most of the chest cavity. 
• The bony structure of the rib cage protects them from injury. 
• The lungs extend from just above the first rib down to the diaphragm, which is the muscular sheet separating the chest cavity from the abdomen.
• The lungs are spongy in texture.
• The trachea or windpipe carries the air towards the lungs.
• It divides into two just before reaching the lungs. This gives rise to the two primary bronchi, each of which enters one lung.
• within the lungs , bronchi divided into smaller tubes bronchioles. These are made up of alveolar sacs.
• Each sac contains about 20 tiny alveoli.
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BRAIN :- DON OF OUR BODY

BRAIN - THE SEAT OF INTELLIGENCE

• Humans are scientifically classified as the species "Homo sapiens" meaning "wise man". It is indeed the capacity for learning, language, emotion and abstract thought that distinguishes the human species from others. And the plinth for all that is the human brain.
• A human brain accounts for about 2% of the body weight. A full grown brain weighs about 1.4 kilograms.
• Though Almost all its constituent , nerve cells or neurons are already present, the brain weighs only about .5 kgs of birth.
• A human brain contains about 10-100 billion neurons and even more supporting cells named , glia. 
• At rest it consumes about 20% of the oxygen used by the entire body. More than 3-5 minutes of oxygen deprivation may result in serious damage to the brain.
• Human brains have twelve pairs of cranial nerves that originate directly from the brain.
• The brain looks like a large wrinkled walnut made of a greyish -pink, jelly like substance.
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• It sits inside the skull, at the upper end of the spinal cloumn. The bones of the skull shield it from the injuries.
• The brain has three main divisions 

1. CEREBRUM
2. CEREBELLUM
3. BRAIN STEM         

FOOD CHAINS

FOOD CHAINS

• The transfer of food energy from the source in plants through a series of organism with repeated eating and being eaten is called a food chain.
• The animal being eaten is called the prey and the animal eating a prey is called the predator.
• There is a tremendous loss of energy at every link of the food chain. In a food chain , an animal passes on only about 10 percent of the energy it receives. About 90 percent of the potential energy is lost as heat.
• The shorter the food chain the more energy is available to orgainsms. Most food chains have no more than four or five links.
•  Food chains are of two types :

1. GRAZING FOOD CHAIN :- This begins with algae and other green plants and ends with a carnivore.
2. DECOMPOSER OR DETRITUS FOOD CHAIN :- This includes orgainsms such as fungi and bacteria that are largely responsible for decomposition.

LINKS OF A FOOD CHAIN

                                                     

1. Primary producer
2. Primary consumer
3. Secondary consumer
4. Tertiary consumer
5. Decomposer

PRODUCER :- Producers are called so because they can produce their own food. In terrestrial ecosystems, producers are usually green plants . Freshwater and marine ecosystems frequently have algae as the the dominant producers.

CONSUMERS :- Consumers depend on others for the food they eat. They may subsist directly on the primary producer or on other consumers.
                       since herbivores take their food directly from the producer level, they are called primary consumers. 

• Animals that eat only plants are called herbivores.
• Animals that eat only other animals are called carnivores.
• Animals that eat both plants and animals are called omnivores.

DECOMPOSERS :- Decomposers are organisms that speed up the decaying process and thus recycle nutrients. These break down non-living organic matter into inorganic matter. 
                  Decomposers help release minerals back into the food chain for absorption by the producers--- the plants.


FOOD WEBS :- One or more interconnected food chains form a food web. A food web is a more realistic and accurate representation of energy flow.  Most animals are part of more than one food chain as they eat more than one kind of food in order to meet their energy requirements.