an organism must regulate the concentration of calcium ions ($\text{ca}^{2+}$) in its body fluids, because this concentration affects signaling pathways within cells.

in a healthy human, a homeostatic system ensures that the concentration of $\text{ca}^{2+}$ in blood stays within a narrow range. bone cells, called osteoblasts, create new bone through a process that removes $\text{ca}^{2+}$ from the blood. other bone cells, called osteoclasts, destroy existing bone through a process that releases $\text{ca}^{2+}$ into the blood.

when the concentration of $\text{ca}^{2+}$ in blood increases, parafollicular cells of the thyroid gland secrete a peptide called calcitonin. a molecule of calcitonin can bind to receptors in the membranes of osteoclasts. upon binding, calcitonin inhibits the activity of osteoclasts, preventing them from breaking down bone. at the same time, calcitonin stimulates osteoblasts to create new bone, removing $\text{ca}^{2+}$ from the blood. therefore, calcitonin increases the net rate at which bones remove $\text{ca}^{2+}$ from the blood.

the top figure shows a simplified diagram of how $\text{ca}^{2+}$ is removed from the blood by osteoblasts.

the bottom figure shows a path model of the homeostatic system that regulates the concentration of $\text{ca}^{2+}$ in blood. this regulated variable is represented by a dashed box. other variables are represented by a solid black box. an arrow connecting one box to another indicates a relationship between two variables. the sign above an arrow (+ or -) indicates whether the variables are positively or negatively related.

note: this information is repeated for questions 2 through 6.

which component in this model is most likely a sensor?

a. parafollicular cells
b. osteoblasts

Question

an organism must regulate the concentration of calcium ions ($\text{ca}^{2+}$) in its body fluids, because this concentration affects signaling pathways within cells.

in a healthy human, a homeostatic system ensures that the concentration of $\text{ca}^{2+}$ in blood stays within a narrow range. bone cells, called osteoblasts, create new bone through a process that removes $\text{ca}^{2+}$ from the blood. other bone cells, called osteoclasts, destroy existing bone through a process that releases $\text{ca}^{2+}$ into the blood.

when the concentration of $\text{ca}^{2+}$ in blood increases, parafollicular cells of the thyroid gland secrete a peptide called calcitonin. a molecule of calcitonin can bind to receptors in the membranes of osteoclasts. upon binding, calcitonin inhibits the activity of osteoclasts, preventing them from breaking down bone. at the same time, calcitonin stimulates osteoblasts to create new bone, removing $\text{ca}^{2+}$ from the blood. therefore, calcitonin increases the net rate at which bones remove $\text{ca}^{2+}$ from the blood.

the top figure shows a simplified diagram of how $\text{ca}^{2+}$ is removed from the blood by osteoblasts.

the bottom figure shows a path model of the homeostatic system that regulates the concentration of $\text{ca}^{2+}$ in blood. this regulated variable is represented by a dashed box. other variables are represented by a solid black box. an arrow connecting one box to another indicates a relationship between two variables. the sign above an arrow (+ or -) indicates whether the variables are positively or negatively related.

note: this information is repeated for questions 2 through 6.

which component in this model is most likely a sensor?

a. parafollicular cells
b. osteoblasts

Accepted Answer

{ "quality": "clear", "question_count": 1, "skills_matched": [ "direct_cot", "multiple_choice_formatter", "explain_then_answer", "tutor" ], "needs_drawing": false, "concepts_used": [ "Homeostasis", "Homeostatic Regulation", "Calcium Regulation", "Endocrine Feedback", "Homeostatic Control Loop" ], "new_concepts": [], "current_concepts": [ "Homeostasis", "Homeostatic Regulation", "Calcium Regulation", "Endocrine Feedback", "Homeostatic Control Loop" ] } ## Analyze homeostatic loop components The text describes how the body regulates blood calcium levels. A **Homeostatic Control Loop** requires a sensor to detect changes in the regulated variable. ## Identify the sensor The regulated variable is the concentration of $ \text{Ca}^{2+} $ in the blood. According to the text, when this concentration increases, the parafollicular cells of the thyroid gland detect this change and secrete calcitonin. Therefore, the parafollicular cells act as the sensor. ## Evaluate the options The parafollicular cells detect the stimulus directly, making them the sensor. Osteoblasts act as effectors that carry out the response to lower blood calcium.

a. parafollicular cells

b. osteoblasts

{ "subject": "Natural Science", "question_type": "Multiple Choice", "knowledge_point": [ "Natural Science", "Biology", "Homeostatic Control Loop" ] }

Sovi.AI - AI Math Tutor

QUESTION IMAGE

Question

Explanation:

Analyze homeostatic loop components

Identify the sensor

Evaluate the options

Answer: