Nokea
What is the primary hormone secreted by the thyroid gland?
- A. Oxytocin
- B. TSH
- C. Adrenaline
- D. T4
Correct Answer: D
Rationale: The correct answer is D: T4. The primary hormone secreted by the thyroid gland is thyroxine, also known as T4. T4 plays a crucial role in regulating metabolism, growth, and energy levels in the body. It is converted into the more active form, triiodothyronine (T3), which exerts most of the biological effects of thyroid hormones. Choices A, B, and C are incorrect. Oxytocin is not produced by the thyroid gland but by the pituitary gland, TSH (thyroid-stimulating hormone) is secreted by the pituitary gland to stimulate the thyroid gland, and adrenaline is produced by the adrenal glands, not the thyroid gland.
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Which type of muscles are involved in peristalsis?
- A. Smooth muscles
- B. Cardiac muscles
- C. Skeletal muscles
- D. Epaxial muscles
Correct Answer: A
Rationale: Peristalsis is a coordinated, wave-like muscular contraction that propels food and other materials through the digestive tract. Smooth muscles are responsible for this movement in the gastrointestinal tract, providing the involuntary contractions needed for peristalsis to occur. Skeletal muscles, cardiac muscles, and epaxial muscles are not directly involved in peristalsis. Cardiac muscles are found in the heart and are responsible for its contraction. Skeletal muscles are attached to bones and control voluntary movements. Epaxial muscles are located along the vertebral column and are involved in the movement and stabilization of the spine.
What is the normal pH of human arterial blood?
- A. 6.8
- B. 7.4
- C. 7.9
- D. 8.2
Correct Answer: B
Rationale: The normal pH of human arterial blood is approximately 7.4. This slightly alkaline pH is crucial for the proper functioning of enzymes and biochemical processes in the body. Any significant deviation from this pH level can result in serious health issues such as acidosis or alkalosis. Choice A (6.8) is incorrect as it is lower than the normal pH of arterial blood, indicating acidity. Choice C (7.9) and Choice D (8.2) are incorrect as they are higher than the normal pH of arterial blood, indicating alkalinity.
Which structure of the respiratory system is involved in gas exchange?
- A. Trachea
- B. Bronchioles
- C. Alveoli
- D. Larynx
Correct Answer: C
Rationale: The alveoli are the primary site for gas exchange in the respiratory system. These tiny air sacs in the lungs are where oxygen is taken up into the bloodstream and carbon dioxide is released from the bloodstream into the lungs to be exhaled. The trachea (Choice A) is the windpipe that carries air to and from the lungs but is not directly involved in gas exchange. Bronchioles (Choice B) are smaller airway branches that lead to the alveoli but do not participate in gas exchange themselves. The larynx (Choice D) plays a role in producing sound and protecting the airway but is not primarily responsible for gas exchange.
The skull is positioned ________ to the spinal cord.
- A. anterior
- B. posterior
- C. lateral
- D. superior
Correct Answer: D
Rationale: The correct answer is D. The skull is superior to the spinal cord, meaning it is located above the spinal cord in anatomical position. Superior in anatomy refers to a structure being positioned higher or above another structure in the body. Choices A, B, and C are incorrect because they refer to different directional relationships. Anterior means in front of, posterior means behind, and lateral means to the side. In this case, the relationship between the skull and the spinal cord is based on a superior-inferior orientation.
Which of the following is not an example of a nonspecific immune response?
- A. Inflammation
- B. Vasodilation
- C. Release of histamine
- D. Production of antibodies
Correct Answer: D
Rationale: The correct answer is D, 'Production of antibodies.' Antibodies are generated as part of the specific immune response, which targets specific antigens. Nonspecific immune responses, such as inflammation, vasodilation, and histamine release, are general defense mechanisms aimed at combating various pathogens. Inflammation is a localized response to infection or injury, vasodilation increases blood flow to the affected area, and histamine release triggers inflammatory responses. It's vital to differentiate between nonspecific responses that provide immediate, general protection and specific responses designed to tackle particular threats.