Nokea
Identify the growth factor that is released by cancer cells to create a capillary network that aids the cancer growth.
- A. macrophage colony-stimulating factor
- B. platelet derived growth factor
- C. tumor angiogenesis factor
- D. epidermal growth factor
Correct Answer: C
Rationale: The correct answer is C, tumor angiogenesis factor. Cancer cells release this growth factor to promote the formation of new blood vessels (angiogenesis) around the tumor, providing a supply of nutrients and oxygen to support their growth. This process is essential for cancer progression.
A: Macrophage colony-stimulating factor is involved in the production and differentiation of macrophages, not in angiogenesis.
B: Platelet-derived growth factor promotes cell growth and division, but it is not specifically responsible for angiogenesis in the context of cancer.
D: Epidermal growth factor is a signaling molecule that promotes cell proliferation and differentiation but is not the primary factor released by cancer cells to induce angiogenesis.
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Which organ is responsible for synthesizing ANP?
- A. the heart
- B. the kidney
- C. the skin
- D. the spleen
Correct Answer: A
Rationale: The correct answer is A: the heart. Atrial Natriuretic Peptide (ANP) is synthesized and released by the atrial cells of the heart in response to stretching of the atrial wall due to increased blood volume or pressure. ANP functions to regulate blood pressure and fluid balance by promoting natriuresis and vasodilation. The kidney (choice B) is responsible for filtering blood and regulating electrolyte balance, but it does not synthesize ANP. The skin (choice C) is involved in thermoregulation and vitamin D synthesis, not ANP production. The spleen (choice D) plays a role in immune function and blood storage, but it does not synthesize ANP.
Which is not Na+ dependent for absorption?
- A. thiamin
- B. riboflavin
- C. niacin
- D. folate
Correct Answer: D
Rationale: The correct answer is D. Folate absorption is not Na+ dependent because it is absorbed in the small intestine through a carrier-mediated process independent of sodium. Thiamin, riboflavin, and niacin require sodium-dependent transport mechanisms for absorption in the small intestine. Thiamin is absorbed through thiamin transporters that are Na+ dependent. Riboflavin is absorbed by sodium-dependent multivitamin transporters. Niacin absorption also involves sodium-dependent transporters. Therefore, folate is the only option that is not Na+ dependent for absorption.
Which of the following hormones are responsible for the 'fight-or-flight' response?
- A. Epinephrine and norepinephrine.
- B. Insulin and glucagon.
- C. Esrtogen and progesterone.
- D. Thyroxin and melatonin.
Correct Answer: A
Rationale: The correct answer is A: Epinephrine and norepinephrine. These hormones are released by the adrenal glands during stressful situations to trigger the 'fight-or-flight' response. They increase heart rate, blood pressure, and energy production to prepare the body for action. Insulin and glucagon (B) regulate blood sugar levels. Estrogen and progesterone (C) are female sex hormones. Thyroxin and melatonin (D) are involved in metabolism and sleep regulation, respectively. Therefore, only A directly relates to the physiological response of 'fight-or-flight'.
Which of the following is most descriptive of cAMP?
- A. Second chemical messenger
- B. Catecholamine that contributes to the fight-or-flight response
- C. Steroid
- D. Releasing hormone
Correct Answer: A
Rationale: The correct answer is A: Second chemical messenger. cAMP is a second messenger in cellular signaling pathways, relaying signals from extracellular molecules to intracellular targets. It is not a catecholamine (B), steroid (C), or releasing hormone (D). Catecholamines are a class of neurotransmitters, steroids are lipids with different functions, and releasing hormones are secreted by the hypothalamus to stimulate the release of other hormones. Thus, the most descriptive term for cAMP is a second chemical messenger.
Hypersecretion of cortisol leads to:
- A. Addison’s disease
- B. Cushing’s syndrome
- C. Acromegaly
- D. Dwarfism
Correct Answer: B
Rationale: Step-by-step rationale for why choice B is correct:
1. Hypersecretion of cortisol is a hallmark of Cushing's syndrome.
2. Excessive cortisol levels can lead to symptoms like weight gain, high blood pressure, and muscle weakness.
3. Cushing's syndrome is characterized by an overactive adrenal gland producing too much cortisol.
4. Addison's disease (choice A) is caused by adrenal insufficiency, leading to low cortisol levels.
5. Acromegaly (choice C) is a growth hormone disorder, not related to cortisol.
6. Dwarfism (choice D) is typically due to growth hormone deficiency, not cortisol excess.
Summary:
Choice B is correct because hypersecretion of cortisol is specifically associated with Cushing's syndrome, causing a range of symptoms related to excess cortisol production. Choices A, C, and D are incorrect as they are not directly related to cortisol hypersecretion.