Chapter 6 Flashcards
What are the two roles of sensory systems and what is the difference between these two roles?
The two roles of the sensory systems is detection and understanding. Detection is perceiving the stimuli, whilst understanding is the processing of the input to make a decision, plan or reason. Our detection is always working, however it does not always the conscious perception.
What are the common five senses most mammals have? Name some special sensory systems too.
The five common senses are hearing, touch, sight, taste and smell. However animals like the platypus has developed a system called electroreception, and dolphins and bats have developed echolation.
Some animals also have an enhanced or deteriorated version of the common senses such as the mole which has lost almost all of its sight, while the dogs have an incredible sense of smell.
What are receptors?
Receptors converts some form of energy such as light or sound into a graded electrical potential. This process is called transduction. This graded potentials are sent to the CNS through the sensory axon.
How can receptors show different intensities of a similar stimuli?
Since the actions potentials are identical, the receptors alter the rate of neuronal firing. This is same for increase in duration and intensity.
What is different in the receptors found between vertebrates?
The specialisation in a sensory system varies the exact type of the receptor and the numbers. For example, primates are largely visual mammals. Some receptors are even specialised to detect colours.
How is the action potential transmitted from the sensory receptors?
The sensory receptors generates the action potential is passed onto the ganglion cell, whose job is to carry the signal to the spinal cord or the brain.
How is fine touch sensation, fine pressure, proprioception and vibration transmitted?
The receptors sends their action potentials to the dorsal root ganglion neuron which travels through the spinal cord into the cuneate(C1-T6) and gracile fasiculus. The neurons synapse at the cuneate or gracile nucleus in the hindbrain. The second neuron immediately decussates and carries the signal to the thalamus. The thalamus then sends a third neuron to the cortex.
What are the different levels of understanding the sensory information?
The lowest levels of the sensory understanding is the triggering of reflexes based on stimuli. The next level is the use of this information for feedback on our activity and modifying our actions. The third level is the highest level and is using the sensory information for taking decisions, make plans and in order to make the right response.
What are sensory maps?
The receptors mapped according to nearby receptors for the comparison of the intensities of stimuli. This is called somatotopy. The mapping of retinal cells is called retinotopy, and tonotopy is the mapping of different tonal regions of the auditory stimuli.
Where are the sensory systems in the brains?
The somatosensory cortex(S1) lies in the parietal lobe behind the central sulcus. The primary visual cortex(V1) lies in the posterior part of the cerebrum. Most of it is located medially, between the two hemispheres. The auditory cortex(A1) is located below the the lateral fissure below the somatosensory cortex. The taste information is received by the insula, which is buried deep in the lateral fissure.
What are some secondary sensory areas?
V1 has surrounding cortical areas that process certain information like face recognition. Similarly, auditory cortex has separate cortical areas to analyse and decode music.
Why is the pathway of the olfactory system totally different?
The fibres do not cross over and the thalamus is not involved. The signals are directly sent to an area near the amygdala called the piriform cortex.
What is the spinothalamic tract convey
Temperature and pain
What are the 2 major somatosensory pathways
The dorsal column medial lemniscus pathway and the spinothalamic pathway
What does the dorsal lemniscus pathway convey
Fine touch and proprioception.
It transmits signals from low threshold mechano receptors in the skin, muscles and joints. This enables tactile discrimination, vibration detection , form recognition and proprioception.
