Question

You are driving to the shops…

1. What information is being detected by you/your body? Provide one external and one internal example. For each, describe how the sensory information is being detected, integrated and processed in the CNS? (2 marks, 2 min)

2. Whilst you are driving a car, what is your body doing to meet its needs/your goals? What is your body doing? Provide one voluntary and one involuntary example. How is the response being generated; what effector pathways are involved? (2 marks, 2 min)

3. Now, tell me about the role of an example protein, expressed on an example cell in one of your examples. What is the protein/where is it expressed/what does it do (and why is this important/relevant)? (2 marks, 2 min)

4. Your protein is dysfunctional. Provide two reasons for why a protein may not be able to fulfil its functional role, and for each, indicate the permanence of this outcome. (2 marks, 2 min)

5. What are the consequences… build from micro to macro: cell/s - tissue/s - organ/s - system/s. Physiologically, what can you not do (and why is that a problem)? (2 marks, 2 min)

Answer 1

• Information about the changes in the external and internal environment is detected by the body.

Example of external sensation (exteroception) -  Sensation of changes in Temperature, Taste, smell or touch etc. come under this category.

Example of internal sensation (intraception) - sensation of change in oxygen and carbon dioxide levels or pH etc.

Detection of the sensory information occurs through particular receptors, while integration is done by the specific areas of the brain assigned for the purpose for eg- Occipital lobe for the integration and processing of visual stimuli.

• While driving a car, our body is undergoing motor control and coordination in order to execute the task.

In this case, body is performing a complex perceptual motor skill that requires the coordination of hands and feet along with attention segregation towards incoming stimuli.

Involuntary response- It includes working memory (procedural) responses for eg- Adjusting the speed and direction becomes a reflex i.e. a response generated without much conscious thought process.

Voluntary response - executive functions which involve decision making in response to the particular distractions on the way while driving.

In response to a particular stimuli, the signal generated by the 'autonomic nervous system' transverse to the effector organs through certain efferent pathways. In this example, effector pathways act on the muscles to generate the motor response.

• Adenylyl cyclase is a transmembrane example protein that is expressed in the excitable cells and acts responsive to G protein-coupled receptors (GPCRs) and other regulatory factors. It leads to the generation of cyclic adenosine 3′,5′-monophosphate (cAMP) from Adenosine triphosphate (ATP). This cAMP acts a 2nd messenger molecule that further activates a signaling cascade to regulate the transcription of certain genes.

• This protein can be dysfunctional due to two different reasons:

1. In the sorting of the protein - When it is not sorted to a particular membrane location inside the cell due to mutations in the sorting signal sequence.
2. Due to mutations in its substrate binding site - When it is not able to bind to ATP, it becomes dysfunctional as the reaction is not carried out.

This phenomenon is a permanent change in the structure of the protein 'adenylyl cyclase'.

Consequences of this protein dysfunction include reduction in excitability at the cellular level as the signal transduction process will get hampered. Physiologically,  responses to the carbohydrate and lipid metabolism gets disturbed alongwith impaired cell growth and differentiation.