Central Nervous System Lab Report

The central nervous system (CNS) and the peripheral nervous system (PNS) constitute the two main parts of the vertebrate nervous system. Whereas the brain and the spinal cord form part of the CNS, nerves, which are enclosed bundles of axons, form part of the PNS and functions to link the CNS to each body part. Motor neurons transmit signals from the brain while afferent are the sensory function to transmit information from the body to the CNS. However, majority of the nerves perform this dual functionality and these are referred to as mixed nerves.

Three divisions of the PNS are documented and this includes the somatic, the autonomic and the enteric nervous system. In this division, the autonomic system is further categorized into the sympathetic

Method

Cutaneous receptors

Four diverse types of sensations mediated by their own receptors can be felt in the epidermis. These sensations include warmth, touch, cold and pain. The receptors of these sensations are however unevenly distributed in the epidermis. This experiment demonstrates this varied epidermal distribution pattern. The experiment involved drawing of a

2cm square on the upper side forearm of selected group members. The subjects then closed their eyes while diverse bristle points within the square were touched. Areas where pain was felt were then marked with a small X. The bristle was moved methodically across the whole marked zone using different stimuli. Dry rods, ice cold rods and a probe were all used while all the sensitive areas were marked. This record of the X spots and the mapped triangles was kept.

Patellar reflex

The patellar reflex or knee jerk reaction was conducted to demonstrate simple reflexes. A group member was selected to sit on an elevated stool in the lab with their legs suspended in the air freely. A rubber mallet was then used to firmly and gently strike their patellar

tendon.

Eye

An experiment was conducted on the eye to demonstrate

The EEG readings produced mingled alpha, beta, delta and theta readings. Alpha waves for my group was 8.5 waves per second (Hz), the beta wave had a frequency of 15 Hz, Delta had 2.5Hz while Theta had a

6.5 frequency.

Discussion

The recorded results indicated varying distribution of sensory receptors. Regions with a high presence of receptors had more X and triangles. The knee jerk reaction produced a stretch of knee muscles as the patellar tendon stretched pulling the spindles in the quadriceps femoris. In the blind spot experiment, the disappearance of the cross occurred as the image passed the blind spot in the eye. The re- appearance of the cross occurred since the image had passed the blind

spot.

In the experiment to demonstrate the detection of sound waves, the bones of the skull were responsible for transmitting vibrations to the cochlea hence the sounds could be heard. The Rinne Test results were indicative of plausible middle ear defects in some participants in the experiment. The taste bud experiment was informative in revealing that the vertebrate tongue has varying receptor areas for diverse