크ㅡ린한 영어 문제 - 원주민 회관

The Structure of the Human Brain

The brain is an organ and the main component of the central nervous system which allows one to perceive and respond to external stimuli. The human brain is usually around 15cm in length and is approximately 2% of a typical human’s bodyweight. Yet, it consumes about 20% of one’s energy. Scientists say that there are around 100 billion neurons in the brain, with multiple times more glial cells supporting them. Neurons signal chemically and fire electrically. They control every word said, decision made, memory stored and retrieved, and action in a person’s lifetime. Contrastingly, glial cells lack the components necessary to do this. Instead, some glial cells function to clean the brain while others insulate neurons and neural pathways, and provide nutrients, allowing the brain to function properly and remain healthy. The brain is also laced with blood vessels which help with the three main arteries’ cerebral circulation.

The brain can be divided into several major structures. The largest section is the cerebrum. It makes up 85% of the brain’s total mass. It is divided into two hemispheres, the right and left which predominantly control the left and right side of a person’s body respectively. (1) Additionally, language, logic, reasoning, and creativity functions are centered here. Covering the cerebrum is the cerebral cortex. (2) This is a thin layer of grooved tissue that is jam-packed with neurons and performs the majority of the brain’s higher functions. (3) It is here that memory is stored. (4) It allows one to perceive their environment, to pay attention to what is around them, and to have the awareness of thought to respond. This area of the brain is known as grey matter and is darker in color that the white matter underneath which is made up of nerve fibers that allow different parts of the cerebral cortex to share information.

Beneath the cerebrum lies the brainstem which connects the brain to the spinal column. It is the essential component of the autonomic nervous system that regulates heart rate, breathing, swallowing, and vasomotor control which alters blood pressure by constricting the diameter of arteries. Behind this, the cerebellum is mainly responsible for motor control, balance, and movement. Between the brainstem and the cerebrum, one will find the thalamus and hypothalamus. The first is responsible for regulating sleep and consciousness. The second connects to the endocrine system including the pituitary gland at the bottom of the hypothalamus. This secretes hormones such as human growth hormone, and endorphins which are released to dull pain. The hypothalamus concurrently is in charge of maintaining a natural body temperature and regulating hunger and thirst. About the size of a pea, it is responsible for a multitude of functions in the body.

13. The word retrieved in the passage is closest in meaning to

(A) recalled

(B) reclaimed

(D) restored

14. The word others in the passage refers to

(A) components

(B) neurons

(D) neural pathways

15. It is NOT mentioned in paragraph 1 that

(A) the brain has multiple blood vessels which help perform cerebral circulation

(B) glial cells transport nutrients to the structures of the brain

(D) neurons send chemical signals to the brain to respond in both thought and action

16. Why does the author mention two hemispheres in the passage?

(A) To explain that the right side of the brain is essential to higher thought

(B) To explain certain structures and functions of the brain

(D) To prove that the cerebrum is the biggest structure in the brain

17. The word grooved in the passage could best be replaced by

(A) engraved

(B) chiseled

(D) etched

18. Look at the four numbers that indicate where the following sentence could be added to the passage.

“The neural pathways in the cerebral cortex represent all the information a person has ever learned.”

Where would the sentence best fit?

19. Which of the sentences below best expresses the essential information in the highlighted sentence in the passage? Incorrect choices change the meaning in important ways or leave out essential information.

(A) The primary difference between the two layers of the cerebral cortex is in their respective colors.

(B) In contrast to grey matter, white matter helps the different areas of the brain communicate with each other.

(D) Grey matter is darker in color that white matter because it helps share information across the cerebrum.

20. According to the passage, which of the following is true about the cerebral cortex?

(A) It is the top layer of the brain, filled with neurons and glial cells.

(B) It is where memory is stored and is known as white matter.

(D) It is responsible for most of the brain’s higher functions.

21. Which of the following does the word It refer to?

(A) the cerebrum

(B) the brainstem

(D) the spinal column

22. It is indicated in paragraph 3 that

(A) sleeping and wakefulness are regulated by the thalamus

(B) vasomotor control provides blood flow to the most essential structures of the brain

(D) the cerebellum is located between the brainstem and the pituitary gland

23. According to the passage, what can be inferred about the endocrine system?

(A) With an impaired endocrine system a person would look old for his or her age.

(B) In a case of severe injury, the hypothalamus would increase the hunger drive.

(D) A person’s fever is an endocrine-based response to deal with an illness or infection.

24. Directions: Select the appropriate phrases from the answer choices and match them to the brain structure to which they relate. TWO of the answer choices will NOT be used.