Answer: The diffusion of ions along the axoplasm is faster,in myelinated compare to unmyelinated,
Neurons are the structural and functioning units of nervous system.They are the vehicles for transmission of impulses as electrical signals from one part of the cells,and from one part of the body to another.
The basic structural components of a typical neuron are the cellbody, the axon, and the dendrites.
Based on structure neurons are classified as myelinated and unmyelinated.This is based on the the surrounding layer of myelin sheath around the axon. The myelin provides the insulating layer for the axon.And ensures fast movement of impluses.
In myelinated neurons the myelin sheath are interrupted at intervals by gaps along the length of the axon called Nodes of Ranvier. These gaps contains more Na-K channels for influx and out-flux of K and Na+ ions for transmission of impulses.
The cytoplasm of axon is called axoplasm,Since this is surrounded by myelin sheath which contains Na-K+ channels,The rate of diffusion of ions along these channels is faster for depolarization to take place than in unmyelinated neurons. Inaddtion as these ions diffusion increases,its jump faster at the nodes of Ranvier (saltatory conduction) to the next axoplasm which further speed up the rate of transmission.
Unmyeinated lacks myelin sheath,therefore the exchange and the rate of diffusion of ions along the axons is low.
Explnation:
The possible result of the founder effect would be loss of genetic variation. The reason why this is so is because by definition, the founder effect is often considered to be the cause for a essened genetic variation in a specie or a certain area where organisms thrive.
Answer:
Apoptosis does not involve:
c. lysis of the cell
Explanation:
Apoptosis is a programmed cell death that occurs under normal physiological conditions and in a controlled manner. Normally seen in cell turnover, embryogenesis, also involved in processes of immune, nervous and endocrine systems.
The main morphological and biochemical changes seen during the apoptosis are the fragmentation of DNA by endonucleases, nuclear, chromatin and cytoplasmatic condensation, apoptotic bodies formation (membrane bound-vesicles form of cell parts) and the phagocytosis (digestion) of those bodies by the scavenger cells.
Apoptosis is regulated by cell- signaling pathways, the caspases, a family of cysteine proteases, are the ones involved in the process.
In the process there is no lysis of the cell as this could lead to a inflammatory response (just happens in necrosis) which would affect contiguous cells, and will involve immune cells. In apoptosis there is just a membrane blebbing, but it does not loss its integrity.
<em>In Roosevelt's speech, some of her main ideas are:</em>
'It would be better if people were not so busy competing with each other
'The role of women is changing'
'a good home life is based on strong relationships'.
