17 Questions
What is the first step in the mechanism of action of steroid hormones?
The steroid hormone diffuses across the cell membrane and enters the target cell.
What is the role of the zinc fingers in the steroid hormone receptor?
The zinc fingers are responsible for the binding of the hormone-receptor complex to specific DNA sequences called steroid-responsive elements.
Which of the following is a characteristic of steroid hormone receptors?
Steroid hormone receptors are located in the cytosol or nucleus of the target cell.
What is the final step in the mechanism of action of steroid hormones?
The new proteins produced have specific physiologic actions.
Which of the following is a characteristic of the E domain of the steroid hormone receptor?
The E domain is located near the N-terminus of the receptor and is where the steroid hormone binds.
What is the role of the hormone-receptor complex in the mechanism of action of steroid hormones?
The hormone-receptor complex binds to specific DNA sequences called steroid-responsive elements.
Which of the following is NOT a characteristic of hormones?
Hormones are produced in large amounts by endocrine cells
Which of the following is NOT a location where endocrine cells can be found?
Skeletal muscle
Which of the following best describes the mechanism of hormone action?
Hormones bind to receptors on target cells and initiate a signaling cascade
Which of the following is NOT a class of hormones?
Amino acid hormones
What term is used to describe the organs that synthesize and secrete hormones?
Endocrine glands
Which of the following statements accurately describes the role of the anterior pituitary in the endocrine system?
The anterior pituitary releases hormones that stimulate the release of hormones from target endocrine glands, which then produce physiological responses.
What is the primary function of negative feedback in endocrine signaling?
To maintain hormonal balance and prevent excessive hormone production.
Which of the following types of feedback loops involves the target endocrine gland inhibiting the release of hormones from the anterior pituitary or the hypothalamus?
Long-loop negative feedback
Which of the following statements accurately describes positive feedback in the endocrine system?
Positive feedback reinforces and amplifies the physiological response to a hormone, leading to explosive events.
In the context of endocrine signaling, what is the role of the target cells?
To respond to the hormones released by the target endocrine glands and elicit physiological responses.
Which of the following feedback loops involves the anterior pituitary inhibiting the release of neurocrines from the hypothalamus?
Short-loop negative feedback
Study Notes
Steroid Hormone Mechanism
- Steroid hormones diffuse across the cell membrane and enter target cells, binding to specific receptor proteins in the cytosol or nucleus.
- Steroid hormone receptors are monomeric phosphoproteins with six domains, including the E domain that binds the hormone near the C terminus.
- The central C domain is highly conserved among different steroid hormone receptors, has two zinc fingers, and is responsible for DNA binding.
Hormone-Receptor Complex Formation
- The hormone-receptor complex undergoes a conformational change and enters the nucleus of the target cell.
- The complex dimerizes and binds to specific DNA sequences, called steroid-responsive elements (SREs), via the zinc fingers.
Gene Transcription and Translation
- The hormone-receptor complex becomes a transcription factor, regulating the rate of transcription of target genes.
- New messenger RNA (mRNA) is transcribed, leaves the nucleus, and is translated to new proteins.
- The new proteins have specific physiologic actions, accounting for the specificity of the hormone's actions.
Endocrine Physiology
- Endocrine physiology involves the secretion of hormones and their subsequent actions on target tissues.
- Hormones are synthesized and secreted by endocrine cells, usually found in endocrine glands, and delivered to target tissues.
- Endocrine cells also reside in other organs, including the GI tract, kidney, heart, adipose tissue, and liver.
Feedback Mechanisms
- The hormones of the anterior pituitary stimulate the release of hormones from the target endocrine gland.
- The hormones of the target endocrine glands then produce a physiological response at the target tissues.
- Feedback mechanisms can be negative (inhibiting) or positive (stimulating), depending on the specific response.
- Negative feedback reduces the physiological response, while positive feedback reinforces it.
- There are three types of inhibitory loops: long-loop, short-loop, and ultrashort-loop negative feedback.
Learn about the production, secretion, and actions of hormones in the endocrine system. Explore how hormones are synthesized, secreted, and function in target tissues. Understand the role of endocrine glands in hormone production.
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