Topic: Control of equilibrium, posture and muscle tone, descending pathways, functions of cerebellum, basal ganglia
Question: A 69-year-old man goes to consult his physician. As he sits in the waiting room, he is
observed to have tremors in his hands and fingers. His face is unexpressive and he
makes few movements. When he is invited to enter the physician’s office, he has
difficulty in standing up. He walks slowly into the office, and his arms do not swing
appreciably. When he talks to the physician, his speech is monotonous but he shows
no intellectual deficit. There was no sensory loss. The stretch reflexes were normal
and the muscles exhibited rigidity.
a) What is your diagnosis b) Which part of the nervous system is involved in this disease c) Explain the connections and functions of the part of the nervous system
involved. d) Why are the movements so few and slow.
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a) The diagnosis is likely Parkinson’s disease based on the typical clinical features of rest tremor, rigidity, bradykinesia, and mask-like facial expression.
b) The basal ganglia are the parts of the nervous system involved in Parkinson’s disease. Specifically, the substantia nigra pars compacta suffers degeneration of its dopaminergic neurons.
c) The basal ganglia are a group of subcortical nuclei that include the caudate, putamen, globus pallidus, subthalamic nucleus, and substantia nigra. The substantia nigra pars compacta contains dopaminergic neurons that project to the striatum (caudate and putamen) via the nigrostriatal pathway. Dopamine acts on D1 and D2 receptors in the striatum to facilitate desired movements and inhibit undesired movements.
In Parkinson’s disease, there is progressive death of dopaminergic neurons in the substantia nigra pars compacta leading to reduced dopamine transmission in the striatum. This causes an imbalance between the direct and indirect pathways within the basal ganglia circuitry, resulting in increased inhibition of thalamocortical circuits involved in movement.
In Parkinson Disease neurons in Substantia Nigra Compacta (SNc) are lost. They cannot excitate certain neurons of the Putamen and cannot inhibit others. This results in an excessive inhibition by Putamen of Globus Pallidus Externus (GPe) which cannot inhibit Sub-Talamic-Nucleus (STN) which therefore activates Globus Pallidus Internus (GPi) and Substantia Nigra Reticulata (SNr) too strongly. GPi and SNr inhibit Thalamus which activates the cortex to start a movement. Therefore the cortex does not receive a strong signal to start the movement and this is the main cause of slowness of movement, postural instability and rigidity. The causes of tremor are not well understood and are subject of intense research.
d) The loss of dopamine in the nigrostriatal pathway causes increased inhibition of the motor cortex by the basal ganglia, leading to hypokinesia (poverty and slowness of movement). Patients have difficulty initiating movements and movements become smaller and slower. This manifests as bradykinesia, reduced arm swing, and other Parkinsonian motor features. The rigidity and tremor also contribute to reduced mobility.
The reduction in dopamine and imbalance in the basal ganglia pathways causes the major motor features of Parkinson’s disease:
– Bradykinesia – slowness of movement due to reduced facilitation of voluntary movements.
– Rigidity – stiffness and increased muscle tone caused by increased tonic inhibitory output.
– Tremor – caused by oscillations in basal ganglia output.
– Hypokinesia – reduced amplitude of movements due to decreased facilitation of motor programs.
Title: UPSC Medico Test Series: The Ultimate Guide to Cracking the UPSC CSE
Introduction:
The UPSC Civil Service Examination (CSE) is one of the most competitive exams in India. Every year, lakhs of candidates appear for the exam, but only a few thousand are selected. If you are a medical graduate and planning to take the UPSC CSE, then you need to take a UPSC medico test series.
A UPSC medico test series is a comprehensive preparation program that helps you to assess your strengths and weaknesses, identify your areas of improvement, and get familiar with the UPSC CSE exam pattern. It also provides you with an opportunity to practice answering questions under timed conditions.
Benefits of taking a UPSC medico test series:
There are many benefits of taking a UPSC medico test series. Some of the key benefits include:
- Helps you to assess your strengths and weaknesses: A UPSC medico test series will help you to identify your strengths and weaknesses in the various subjects that are covered in the UPSC CSE exam. This will help you to focus your preparation on the areas where you need the most improvement.
- Helps you to identify your areas of improvement: A UPSC medico test series will also help you to identify the areas where you need to improve. This will help you to develop a more targeted preparation plan.
- Gets you familiar with the UPSC CSE exam pattern: The UPSC CSE exam is a very different exam from the exams that you have taken in your college or university. A UPSC medico test series will help you to get familiar with the exam pattern, the type of questions that are asked, and the time constraints.
- Provides you with an opportunity to practice answering questions under timed conditions: The UPSC CSE exam is a timed exam. A UPSC medico test series will provide you with an opportunity to practice answering questions under timed conditions. This will help you to improve your time management skills and to develop a sense of urgency.
- Gives you a competitive edge: A UPSC medico test series will give you a competitive edge over other candidates. This is because you will be better prepared for the exam and you will have a better understanding of the exam pattern.
How to choose a UPSC medico test series:
There are many UPSC medico test series available in the market. When choosing a UPSC medico test series, you should consider the following factors:
- The reputation of the institute: Choose a UPSC medico test series that is offered by a reputable institute. This will ensure that the quality of the content and the teaching methodology are good.
- The syllabus coverage: Make sure that the UPSC medico test series covers the entire syllabus of the UPSC CSE exam.
- The number of tests: Choose a UPSC medico test series that offers a good number of tests. This will give you enough practice to answer questions under timed conditions.
- The feedback mechanism: Choose a UPSC medico test series that has a good feedback mechanism. This will help you to identify your areas of improvement and to track your progress.
- The price: UPSC medico test series can be expensive. Choose a UPSC medico test series that is affordable for you.
Conclusion:
A UPSC medico test series is an essential part of your preparation for the UPSC CSE exam. If you are serious about cracking the exam, then you should definitely take a UPSC medico test series.
Here are some additional tips for choosing a UPSC medico test series:
- Read reviews of different test series before making a decision.
- Ask your friends or colleagues who have taken the UPSC CSE exam for their recommendations.
- Consider taking a free trial of the test series before you commit to buying it.
I hope this article has been helpful. Good luck with your preparation for the UPSC CSE exam!
