The occipital lobe combines the input of both eyes creating a three dimensional image and compensates for the focussing action of the lens by flipping the image around to the correct perspectives.
As you can see, we do not technically see with our eyes. Our brain is creating an image from the electrical impulses created from photoreceptors. (02) ‘We see with our brains’ 7/4/11, (03) Sensory systems 7/4/11.
The organs involved in the senses sight, smell, taste and hearing are located within the central nervous system. This is because they all in some manner connect directly to the brain. Your sense of touch however is found all over. This is where the peripheral nervous system would come into play.
Touch
Sense of touch originates in the bottom layer of skin known as the dermis. This is filled with a number of tiny nerve endings which receive information about what your body comes into contact with. This information is sent to the spinal cord through the peripheral nervous system, which in turn sends messages to the brain where the feeling is registered.
The human body has twenty five variations of nerve endings that all send messages to the brain. (09) Senses; Touch 15/4/11.
The most common of these nerve endings detect pain, temperature and pressure. (09) Senses; Touch 15/4/11, (11) Your sense of touch 25/4/11.
These sensory receptors cover the entire body, including the skin, epithelia, skeletal bones, muscles, joints, internal organs and the cardiovascular system.
Some areas of the body are more sensitive than others. This is determined by the number of nerve endings located there. For example: if you were to bite your tongue, there would be a considerable amount of pain due to the large number of nerve endings that are sensitive to pain found on either side of your tongue.
These nerve endings indicate to our brain that what we are doing is causing damage to our body. Meaning we will have to stop what we are doing in order to avoid further damage. Basically, that is what pain is; a signal for us to avoid damage to our body. Unpleasant thought it may be… (12) Feeling Pain 27/4/11.
You would think that the deeper a cut, the more it hurts, but often this is not the case. Deeper cuts sever nerve endings. Meaning the signal of pain can’t reach the brain. Without these nerve endings we cannot feel the pain.
The Musculoskeletal system works with the somatic nervous system to allow us to move in such situations as well as in everyday life. The somatic nervous system controls voluntary movements such as those performed by the musculoskeletal system.
Our senses are vital to our survival. Therefore the nervous system must interact with all other systems of the body in some way or another. It can be said it is a messenger to our body which tells us when we need to avoid certain things in order to protect ourselves.
The Digestive System
The nervous system also plays a role in the digestive system.
We often mistake our hunger for an empty stomach. Rather it is our body detecting a decrease in nutritive materials in our blood. This sends signals to the hypothalamus which indicates our stomach and intestines to become more active, often resulting in our stomach rumbling. (13) What makes us Hungry pt. 1 6/5/11.
The digestive system actually has its own nervous system known as the Enteric Nervous System. The ENS is within the Autonomic Nervous System; a part of the Peripheral Nervous System that works almost independently of the brain. Meaning we have mostly no control over these actions. (16) Autonomic Nervous System 6/5/11.
This explains why we are unable to stop our digestive system being active when we are hungry. You could contrast this to how you are able to hold your breath.
We cannot stop our body taking actions to gain nutritive materials. The only way to stop our stomach rumbling is to give in and eat. (15) What makes us Hungry pt. 2 6/5/11, (14) Hunger and Eating 6/5/11.
When we see, smell or think about food, this stimulates the nerves involved in digestion we will begin producing saliva; one of the first steps to breaking down food into nutrients.
Conclusion
Sensitivity is a very difficult subject to cover in its entirety. It includes all of our senses and feelings; even some that we may not be directly aware of.
The nervous system is found throughout the body. When you begin to look into how we are able to achieve a particular sense, it will prove more complicated with each step you take.
You can conclude that the nervous system plays the biggest role in sensitivity. Without our nervous system and by extension our senses; basic human function and survival would not be possible.
Bibliography
(00) Anatomy and Structure of Human senses-
: Date Accessed; 7/4/2011, (01) Human Nervous System Diagram- : Date Accessed; 7/4/2011.
(02) ‘We see with our brains’- : Date Accessed; 7/4/2011, (03) Sensory systems- : Date Accessed; 7/4/2011, (04) Lateral geniculate nucleus- : Date Accessed; 7/4/2011,
(05) Primary Visual Cortex- : Date Accessed; 7/4/2011, (06) Photoreceptor Cells- : Date Accessed; 9/4/2011, (07) Central Nervous System- : Date Accessed; 9/4/2011, (08) Visual System/Retina- : Date Accessed; 15/4/2011.
(09) Senses; Touch- : Date Accessed; 15/4/2011, (10) Somatosenory System- : Date Accessed; 25/4/2011, (11) Your sense of touch- : Date Accessed; 25/4/2011, (12) Feeling Pain- : Date Accessed; 27/4/2011.
(13) What makes us Hungry pt.1- ; Date Accessed; 6/5/2011, (14) Hunger and Eating- ; Date Accessed; 6/5/2011,(15) What makes us Hungry pt. 2-; Date Accessed; 6/5/2011, (16) Autonomic Nervous System-; Date Accessed; 6/5/2011.
