A Nerve electrical impulse only travels in one direction. There are several reasons nerve impulses only travel in one direction. The most important is synaptic transport.
In order for a "nerve impulse" to pass from cell to cell, it must cross synaptic junctions. The nerve cells are lined up head to tail all the way down a nerve track, and are not connected, but have tiny gaps between them and the next cell. These tiny gaps are called synapses.
When you get a nerve firing, you have probably heard that it is an electrical impulse that carries the signal. This is true, but it is not electrical in the same way your wall outlet works. This is electrochemical energy. Neurotransmitters are molecules that fit like a lock and key into a specific receptor. The receptor is located on the next cell in the line. When the neurotransmitter hits the receptor on the next cell in line, it signals that cell to begin a firing as well.
This will continue all the way down the length of the nerve track. In a nutshell, a nerve firing results in a chain reaction down the nerve cell's axon, or stemlike section. Sodium (Na+) ions flow in, potassium (K+) ions flow out, and we get an electrochemical gradient flowing down the length of the cell. You can think of it as a line of gunpowder that someone lit, with the flame traveling down the length of it. Common electrical power is more like a hose full of water, and when you put pressure on one end, the water shoots out the other.
Therefore, nerve impulses cannot travel in the opposite direction, because nerve cells only have neurotransmitter storage vesicles going one way, and receptors in one place.
Answer:
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Explanation:
Pancreas is an exocrine gland as it has a duct to store pancreatic juice secreted by the pancreas and use it whenever required. It is considered as a endocrine gland as it does not have a duct to store the hormones insulin and glucagon which are directly supplied to the blood stream.
The statement is true that T-cells are a type of immune cell system that recognizes pathogens in the body.
T-cells are the lymphocytes that are involved in providing acquired immunity to the body. They can recognize the pathogens presented by the antigen presenting cells. There are two types of t cells: helper T cells and Cytotoxic T cells.
Immune cells are the cells of the immune system that are involved in protecting the body from infection, allergies and foreign pathogens. There are several immune cells that perform several functions. The example of such cells are: phagocytes, lymphocytes, dendritic cells, etc.
To know more about T cells, here
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Answer: The correct answer for the blank is-
evens out genetic differences between populations
Gene flow or migration of gene can be described as a process of transfer of genetic variation from one population into another population. This process leads to change in the frequency of a gene variant ( that is called allele) in a particular population and it reduces the genetic differences between population.
If the process of gene glow is high, then the two population will be considered equivalent in genetic diversity.
Thus, Gene flow evens out genetic differences between populations
Respiration is the type of biological exercise that raises Co₂ concentration in the atmosphere.
Explanation:
- RESPIRATION is said to be the basic biological and metabolic process that is essential for all living beings for their survival and growth with nourishment.
- Cells are the basic unit of living organisms that undergo cellular respiration. In this process, oxygen is in taken and carbon dioxide is respired out which adds the concentration of the carbon dioxide from the atmosphere.
- In the process of respiration, the living cells of the organism produce energy by the intake of oxygen for the oxidation of complex organic substances and expires out the carbon dioxide.
