Brain study Part 5 - An Introduction to the Brain(truth or dare?)

[Guest guest]

An Introduction to the Brain

The size of the modern human adult brain is about 1350 cc. It is a

spongy mass (and not very pleasing in appearance). The brain of

Ramidus, the walking ape/man of 4.5 million years ago, was about 400

cc. in size, that of Homo habilis, the first human at about 2 million

years ago , was about 575 cc. The largest human brain was in the

Neandertal at about 8% larger than the Homo sapien sapien.

 

SORRY...No PICTURES WILL PASTE.bn

 

The left side of a human brain is shown. The brain stem is a

communications trunk between the brain and the rest of the body. Two

of the five senses which provide current environment information from

the outside world (eyes and ears) are connected directly to the

periphery of the brain. Taste, smell and touch come from outside the

brain cage (the upper skull). Each element of each sense has a direct

connection to the brain. Each small area on the body has its own

touch sensor. Taste provides about 40,000 individual sensors, the

eyes well over two hundred million. The senses are connected into the

brain in parallel. All sensing elements enter the brain at the same

time. There is no time sharing or switching. The eyes are connected

in one area, the ears to another, etc.

 

The brain consists of many parts, the most conspicuous division being

the two hemispheres, which forms the cortex (outer surface). The

cortex is folded to get more surface area. It functions as if it was

a flattened surface. It is at the surface that the cortex brain cell

bodies are especially situated, while the internal parts of the

cortex carry the connections between the cells. The division of brain

cell bodies and their connections causes the cortex to be either

white matter (connections) or gray matter (active neural cells on the

outer surface). See the latter part of Man, the Digital Machine for

more detail on the neural cell mechanism and its functions.

 

The brain is divided into two hemispheres, the left one is shown. The

hemispheres can be divided into lobes, corresponding roughly with

deep fissures: temporal (side), occipital (back), parietal (top), and

frontal.