Nervous system Qs

Nervous system (Qs 1-25 True/false)

1. The soma of neuron is resistant to hypoxia.

Ans: False. It is extremely vulnerable to hypoxia.

2. All nerve terminals can synthesize their own neurotransmitters.

Ans: False .Peptides NTs are made in the cell body and transported to the nerve terminals.

3. Plasticity in the adult CNS refers to the physical realignment of fibers after injury or stress.

Ans: False.Plasticity is a functional adaptation of physical linkages. Physical remodelling only occurs in the peripheral nervous system and in the immature CNS.

4. Neurons are incapable of division.

Ans: True.

5. Neuro-neuronal synapses are either axo-dendritic or axo-somatic.

Ans: False.Dendro-dendritic synapses are also found.

6. Neuroglia is derived from ectoderm.

Ans: True

7. Oligodendrocytes are the functional CNS counterparts of Schwann cells.

Ans: True.needed for the formation and repair of myelin sheaths.

8. Astrocytes are important in supplying omega-3 fatty acids to nearby neurons in starvation.

Ans: False. Neurons do not use fatty acids for energy even in starvation.

9. Astrocytes are believed to secrete K+ into the ECF of the brain.

Ans; True

10. The nodes of Ranvier are present in all motor nerves.

Ans: False. Present only in myelinated nerves.

11. Extracts of the Japanese puffer fish abolish the membrane potential.

Ans: False.Tetrodoxin blocks NA+ channels by blocking initiation or propagation of the action potential.

12. There is an overlap between the specific receptors for different modalities (pain, temperature, touch, vibration and pressure)

Ans: True.The specificity of receptors for individual modalities is not now regarded as absolute.

13. Free nerve endings are only found in the skin and surface epithelium.

Ans: False. In deeper tissue layers free nerve endings innervate muscle spindles, vascular smooth muscle, and chemo sensitive cells that subserve stretch and the local chemical environment.

14. All synaptic clefts have the same width.

Ans: False. Vary from about 20nm to as little as 2nm.

15. In the skeletal muscle endplate, IPSPs exceed EPSPs when the muscle is at rest.

Ans: False.There is no IPSPs at the motorend plate.

16. Presynaptic inhibition is very important in damping down visceral and somatic afferent activity in the spinal cord.

Ans: True

17. Postsynaptic inhibition occurs at Renshaw cell/Renshawcell synapses.

Ans: True. [Alcohol stimulates Renshaw cells.

18. IPSPcauses hyperpolarisation in postsynaptic neuron.

Ans: True

19. In convergence large numbers of presynaptic neurons have synaptic connections on a single postsynaptic neuron.

Ans: True

20. Fatigue that occurs at synapse is irreversible.

Ans: False

21. Receptors detecting changes in muscles length are proprioceptors.

Ans: True

22. Paccnian corpuscles adapt very quickly.

Ans: True

23. Meissner’s corpuscles are abundant at finger tips.

Ans: True.

24. Merkel’s discs are slowly adapting receptors.

Ans: True

25. A Dermatome is a segmental field of skin innervated by each spinal nerve

Ans: True.