The myelin sheath around axons in the peripheral nervous system is formed by:
A. Schwann cells
B. Astrocytes
C. Microglia
D. Oligodendrocytes
Answer: Option A
Solution (By JKSSB Mock Tests)
In the peripheral nervous system (PNS), Schwann cells wrap around axons to form the myelin sheath, which insulates axons and increases the speed of nerve impulse conduction (saltatory conduction). In the central nervous system (CNS), oligodendrocytes perform this function. Astrocytes support neurons, microglia act as immune cells. Nodes of Ranvier are gaps in the myelin sheath.
Explanation:
The oblique entry of the ureters into the bladder creates a valve-like effect, preventing reflux. The urethral sphincter controls urination.
Explanation:
Metabolism is the sum of all chemical reactions occurring in a living body. It is the only feature present in all living organisms without exception. While growth and reproduction are common, they are not universal (e.g., sterile mules). Non-living things can also exhibit growth by accumulation or movement, making metabolism the true defining property.
No comments yet. Be the first to start the discussion!