18. Which of the following best describes the overall function of hormones?

A. To control physiological processes in the body
B. To provide a pathway for nerve messages
C. To stimulate the growth and maturation of body organs
D. To determine masculine or feminine reproductive traits19. Which one of the following processes is performed by the endocrine system?
A. Secretion of hormones from cells
B. Breakdown of hormones into simpler molecules
C. Transport of hormones to muscles
D. Excretion of hormones from the body
20. What is the best available treatment for hypothyroidism?
A. Increased dietary iodine
B. Supplementary thyroid hormone
C. Avoidance of certain drugs
D. Thyroid gland transplantation
21. Which part of the ear is normally filled with fluid to aid in the transmission of sound
waves?
A. Auditory canal C. Semicircular canals
B. Cochlea D. Malleus

18. The overall function of hormones is best described as A. To control physiological processes in the body. Hormones are chemical messengers that are produced by various glands in the body's endocrine system. They are released into the bloodstream and travel to specific target cells or organs where they regulate and control various physiological processes.

To determine this answer, you can eliminate the other options by understanding their functions:
- B. To provide a pathway for nerve messages: This describes the function of neurons and the nervous system, not hormones or the endocrine system.
- C. To stimulate the growth and maturation of body organs: While hormones do contribute to the growth and maturation of organs, this is not their overall function. It is a specific function of certain hormones.
- D. To determine masculine or feminine reproductive traits: While hormones do play a role in the development of reproductive traits, this is not their overall function and is limited to specific hormones and processes.

19. The process performed by the endocrine system is best described as A. Secretion of hormones from cells. The endocrine system consists of glands that secrete hormones into the bloodstream. These hormones then travel to target cells or organs where they elicit specific responses and regulate various bodily functions.

To determine this answer, you can eliminate the other options:
- B. Breakdown of hormones into simpler molecules: Hormones can be broken down or metabolized in the body, but this is not the primary process performed by the endocrine system.
- C. Transport of hormones to muscles: While hormones do travel through the bloodstream to reach target cells or organs, the endocrine system is responsible for their secretion, not their transport to muscles specifically.
- D. Excretion of hormones from the body: Hormones can be metabolized and excreted from the body, but this is not the primary function of the endocrine system.

20. The best available treatment for hypothyroidism is B. Supplementary thyroid hormone. Hypothyroidism is a condition where the thyroid gland does not produce enough thyroid hormone. The most effective treatment for this condition is to provide supplementary thyroid hormone, usually in the form of a medication like levothyroxine, which helps to restore normal thyroid function.

To determine this answer, you can evaluate the options:
- A. Increased dietary iodine: While iodine is necessary for the production of thyroid hormone, it does not address the underlying issue of hypothyroidism. This option would be more relevant for iodine deficiency, not hypothyroidism.
- C. Avoidance of certain drugs: Some drugs can interfere with thyroid function, but avoiding them alone would not treat the underlying cause of hypothyroidism.
- D. Thyroid gland transplantation: This is not a commonly performed or recommended treatment for hypothyroidism. In most cases, supplementary thyroid hormone medication is sufficient to manage the condition.

21. The part of the ear that is normally filled with fluid to aid in the transmission of sound waves is B. Cochlea. The cochlea is a spiral-shaped, fluid-filled structure in the inner ear. It is responsible for converting sound vibrations into electrical signals that can be interpreted by the brain. The fluid-filled cochlea helps to amplify and transmit sound waves to the sensory cells responsible for hearing.

To determine this answer, you can eliminate the other options:
- A. Auditory canal: The auditory canal is a tube that connects the outer ear to the middle ear. It does not play a role in the transmission of sound waves or contain fluid.
- C. Semicircular canals: The semicircular canals are part of the vestibular system, which is responsible for detecting changes in the position and movement of the head. They do not directly aid in the transmission of sound waves.
- D. Malleus: The malleus is one of the three small bones in the middle ear known as the ossicles. These bones help to transmit sound vibrations from the eardrum to the inner ear but do not themselves contain fluid.