18. The cerebrum originates from: a. Diencephalon. b. Metencephalon. c. Myelence
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Question
18. The cerebrum originates from: a. Diencephalon. b. Metencephalon. c. Myelencephalon. d. Telencephalon. 19. The descending tracts of the spinal cord: a. Are composed of dendrites. b. Carry impulses for transmission to museles and glands c. Are extensions of the sensory organs at the body surfa d. Both B and C are correct. 20· The myelin sheath functions to: a. Increase speed of nerve impulse (AP) transmission. b. Protect the axon. c. Electrically insulate fibers. d. All of the above. 21. Neurotransmitters are important in the functioning a. Chemical. b. Electrical. c. Gap d. Intercalated discs. 22.The primary motor area of the brain is in the: a. Temporal cortex. b. Frontal cortex. c. Medulla oblongata. d. Pons. 23. Which electroencephalogram brain wave (e.g, test taking)? a. Alpha waves.Explanation / Answer
18. Cerebrum develops from Telencephalon
Explanation:
all the options provided are embryonic parts from which different parts of brain develops before birth.
Diencephalon gives rise to Thalamus, hypothalamus, 3rd ventricle
Telencephalon gives rise to Cerebrum
Metencephalon gives rise to Pons, cerebellum
Myelencephalon gives rise to medulla oblongata
19. B
Descending tracts are mainly responsible to carry command from higher centers to peripheral muscles and organs.
They are composed of long axons.(Hence A incorrect)
Sensory inputs are carried by Ascending tracts.(Hence C incorrect)
Various descending pathways are
Corticospinal tract
Corticobulbar tract
Rubro spinal tract
Tecto spinal tract
Vestibulospinal tract
Reticulo spinal tract
20. D
Myelin sheath is the covering fatty layer on Myelinated Nerve Fibres.
There are 2 types of neurons: Myelinated and Unmyelinated
Myelin is formed from Schwann cells in Peripheral nervous system AND from Oligodendrocytes in Central nervous system.
The major function of Myelin sheath is to increase the speed of transmission of Action potential(AP) via nerve.
The gaps between myelin sheaths are k/a Node of Ranvier. AP, while moving on nuronal surface, jumps at every node of Ranvier to overcome the insulator Myelin. This particular type of movement is k/a Saltatory conduction.
It increaes speed of nerve impulse conduction manifold in myelinated neurones.
Apart from these Myelin also act as Insulator and protective coating around neuron
21.A
various chemical neurotransmitters are important for function of neourological systems.
Some are excitatory, They cause excitatory post synaptic potential, e.g. Glutamate
Some are inhibitory, They cause Inhibitory post synaptic potential , e.g. GABA
22. B
Primary motor area is frontal cortex
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