what is the myelin sheath and what does it do

ATI TEAS 7

ATI TEAS 7 science review

1. What is the myelin sheath and what does it do?

A. A group of nerve cells that perform a specific function.
B. A fatty substance that insulates some nerve fibers.
C. A fluid-filled cavity within the brain.
D. The junction between two neurons.

Correct answer: B

Rationale: The myelin sheath is a fatty substance that insulates some nerve fibers. It is made up of specialized cells that wrap around the axons of neurons, providing insulation and speeding up the transmission of nerve impulses. Choice A is incorrect as the myelin sheath is not a group of nerve cells but rather a substance that surrounds nerve fibers. Choice C is incorrect as the myelin sheath is not a fluid-filled cavity within the brain. Choice D is incorrect as the myelin sheath is not the junction between two neurons.

2. Which of the following is the neutral subatomic particle found in the nucleus of an atom?

A. Electron
B. Proton
C. Neutron
D. Positron

Correct answer: C

Rationale: The correct answer is C, Neutron. Neutrons are subatomic particles found in the nucleus of an atom that have no charge. They have a mass of approximately 1 atomic mass unit (amu). The number of neutrons in an atom's nucleus contributes to the mass number of the atom, which is the total number of protons and neutrons in the nucleus. Choice A, Electron, is incorrect as electrons are negatively charged particles found outside the nucleus. Choice B, Proton, is incorrect as protons are positively charged particles found in the nucleus. Choice D, Positron, is incorrect as positrons are positively charged antiparticles of electrons and are not typically found in the nucleus of an atom.

3. Which of the following is a risk factor for developing kidney stones?

A. Consuming a diet rich in fruits and vegetables
B. Maintaining adequate hydration with water
C. Having a family history of kidney stones
D. Regularly engaging in moderate exercise

Correct answer: C

Rationale: Having a family history of kidney stones is a risk factor for developing kidney stones. Genetic predisposition can increase the likelihood of developing kidney stones due to inherited traits that affect the body's ability to process and excrete certain substances. Consuming a diet rich in fruits and vegetables (option A) and maintaining adequate hydration with water (option B) are actually recommended strategies to help prevent kidney stones by promoting overall kidney health. Regularly engaging in moderate exercise (option D) can also be beneficial for kidney health by promoting circulation and overall well-being. Therefore, options A, B, and D are not risk factors but rather beneficial for kidney health.

4. Which of the following substances is an example of an acidic gas?

A. Nitrogen (N₂)
B. Carbon dioxide (CO₂)
C. Sulfur dioxide (SO₂)
D. Oxygen (O₂)

Correct answer: C

Rationale: The correct answer is C, Sulfur dioxide (SO₂). Sulfur dioxide is an acidic gas because when dissolved in water, it forms sulfurous acid, which imparts acidic properties. Nitrogen (N₂), carbon dioxide (CO₂), and oxygen (O₂) are not considered acidic gases. Nitrogen is a neutral gas, carbon dioxide forms a weakly acidic solution when dissolved in water, and oxygen is a neutral gas.

5. A collection of organs working together to perform a specific physiological function is known as a(n):

A. Tissue
B. Organ system
C. Organelle
D. Organ

Correct answer: B

Rationale: An organ system is a group of organs that work together to perform specific functions in the body. Each organ within the system has a unique role, but they collaborate to achieve a common physiological function. This collaboration allows the body to carry out complex processes efficiently, demonstrating the interconnectedness and interdependence of different organs within the system. Choice A, 'Tissue,' refers to a group of cells that work together to perform a specific function, not a collection of organs. Choice C, 'Organelle,' is a subunit within a cell that has a specific function and is not a collection of organs. Choice D, 'Organ,' is a single structure composed of different tissues that performs a specific function, not a collection of organs working together.