Nokea
What is the diastole cycle in the heart?
- A. Relaxation of the heart
- B. Contraction of the heart
- C. Pulse rate of the heart
- D. Blood circulation
Correct Answer: A
Rationale: The diastole cycle in the heart refers to the relaxation phase, where the heart chambers relax and fill with blood. This phase is crucial for the heart to refill and prepare for the next contraction (systole), which pumps blood out of the heart. Therefore, the correct answer is choice A, 'Relaxation of the heart.' Choices B, C, and D are incorrect in the context of cardiac physiology. Choice B, 'Contraction of the heart,' refers to systole, the phase of heart contraction. Choice C, 'Pulse rate of the heart,' is related to the number of heartbeats per minute, not the diastole cycle specifically. Choice D, 'Blood circulation,' is a broader term that encompasses the entire circulatory system rather than focusing on the heart's specific relaxation phase.
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Which of the following describes a typical gas?
- A. Indefinite shape and indefinite volume
- B. Indefinite shape and definite volume
- C. Definite shape and definite volume
- D. Definite shape and indefinite volume
Correct Answer: B
Rationale: The correct answer is B: 'Indefinite shape and definite volume.' A gas does not have a definite shape as it takes the shape of its container, conforming to its surroundings. However, a gas does have a definite volume because it fills the entire volume of the container it occupies. This characteristic allows gases to expand to fill the available space provided by the container, while their volume remains constant within that container. Choice A is incorrect because gases do not have an indefinite volume but rather a definite volume. Choice C is incorrect as gases do not have a definite shape but take the shape of their container. Choice D is incorrect as gases do not have a definite shape and their volume is definite, not indefinite.
What is the structure and function of elastic arteries?
- A. They are the smallest arteries and constrict and dilate frequently.
- B. They are medium-sized arteries that distribute blood to various organs.
- C. They are the largest arteries and stretch and recoil to accommodate blood pressure changes.
- D. They are thin-walled arteries that supply blood to the capillaries.
Correct Answer: C
Rationale: The corrected answer is C. Elastic arteries, like the aorta, are the largest arteries in the body. They possess elastic fibers in their walls, allowing them to stretch and recoil in response to the pulsatile nature of blood flow from the heart. This elasticity helps to maintain blood pressure by absorbing the pressure waves generated by the heart's contractions and ensuring continuous blood flow to the organs. Choices A, B, and D are incorrect because elastic arteries are not the smallest arteries, do not constrict and dilate frequently, are not medium-sized arteries for distributing blood to various organs, and are not thin-walled arteries supplying blood to capillaries. Elastic arteries have a specific structure and function related to their ability to accommodate blood pressure changes due to their elastic properties, which is essential for the cardiovascular system's proper functioning.
Glial cells support and protect neurons within the central and peripheral nervous system. What are they called?
- A. Astrocytes
- B. Neuroglia
- C. Oligodendrocytes
- D. Schwann cells
Correct Answer: A
Rationale: Astrocytes are a type of glial cell that provide support and protection for neurons in both the central and peripheral nervous systems. While the term 'Neuroglia' is often used to refer to glial cells collectively, in this context, the question specifically asks for the name of the cells, making 'Astrocytes' the correct answer. Choice B, 'Neuroglia,' is a general term for all glial cells, not a specific type. Choices C and D, 'Oligodendrocytes' and 'Schwann cells,' are also types of glial cells but are not the primary cells responsible for supporting and protecting neurons as described in the question.
Which type of capillary is the most common and least permeable?
- A. Fenestrated capillaries
- B. Sinusoidal capillaries
- C. Continuous capillaries
- D. Discontinuous capillaries
Correct Answer: C
Rationale: The correct answer is C, continuous capillaries. Continuous capillaries are the most common and least permeable type of capillary. They are found in most tissues, including muscle and the nervous system. Continuous capillaries have a continuous endothelium without fenestrations or large gaps, which limits the movement of substances across their walls.
Choice A, fenestrated capillaries, have pores (fenestrations) in their endothelial cells, making them more permeable than continuous capillaries.
Choice B, sinusoidal capillaries, have a discontinuous endothelium with large gaps between cells, making them more permeable and allowing larger molecules and cells to pass through compared to continuous capillaries.
Choice D, discontinuous capillaries, are similar to sinusoidal capillaries with a discontinuous endothelium, allowing for enhanced permeability compared to continuous capillaries.
What is the function of the myelin sheath in a neuron?
- A. To transmit electrical impulses
- B. To insulate and speed up electrical signals
- C. To produce neurotransmitters
- D. To protect the neuron from damage
Correct Answer: B
Rationale: The myelin sheath serves to insulate neurons and accelerate the transmission of electrical signals along the axon. This insulation helps in the efficient conduction of nerve impulses by preventing signal loss or leakage. Choice A is incorrect because the myelin sheath does not transmit electrical impulses itself but rather helps in the conduction. Choice C is incorrect as the myelin sheath is not responsible for producing neurotransmitters. Choice D is also incorrect as the primary function of the myelin sheath is not to protect the neuron from damage. Therefore, the correct answer is B, as it accurately describes the function of the myelin sheath in a neuron.