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Questions and Answers
What is the process by which excess hormone leads to a reduction in receptor density?
What is the process by which excess hormone leads to a reduction in receptor density?
Which of the following mechanisms is NOT associated with receptor downregulation?
Which of the following mechanisms is NOT associated with receptor downregulation?
What is the result of hormone absence with respect to receptors?
What is the result of hormone absence with respect to receptors?
Which hormone is known to act as a positive regulator of its own receptors?
Which hormone is known to act as a positive regulator of its own receptors?
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Which receptors are primarily associated with fat-soluble hormones?
Which receptors are primarily associated with fat-soluble hormones?
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Which of the following hormones activates the cAMP signaling system?
Which of the following hormones activates the cAMP signaling system?
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What role do heat shock proteins (Hsp) play in the function of steroid hormone receptors?
What role do heat shock proteins (Hsp) play in the function of steroid hormone receptors?
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Which of the following hormones activates the calcium–phosphoinositol system?
Which of the following hormones activates the calcium–phosphoinositol system?
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What primary role do hormones play in the body?
What primary role do hormones play in the body?
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Which of the following is an example of how hormonal action is classified?
Which of the following is an example of how hormonal action is classified?
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Which substance is released from the heart and plays a role in endocrine secretion?
Which substance is released from the heart and plays a role in endocrine secretion?
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Which statement about hormones is true?
Which statement about hormones is true?
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What term describes the secretion of a substance that regulates neighboring cells?
What term describes the secretion of a substance that regulates neighboring cells?
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What is an example of a substance that can act both as a hormone in the digestive system and a neurotransmitter in the CNS?
What is an example of a substance that can act both as a hormone in the digestive system and a neurotransmitter in the CNS?
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What distinguishes autocrine signaling from other types of hormonal signaling?
What distinguishes autocrine signaling from other types of hormonal signaling?
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Which of the following hormones is synthesized in the liver?
Which of the following hormones is synthesized in the liver?
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What term is used to describe an episode of endocrine release that occurs every hour?
What term is used to describe an episode of endocrine release that occurs every hour?
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Which hormone is secreted by the pineal gland to help synchronize diurnal rhythms?
Which hormone is secreted by the pineal gland to help synchronize diurnal rhythms?
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What is the effect of ablating the suprachiasmatic nucleus (SCN)?
What is the effect of ablating the suprachiasmatic nucleus (SCN)?
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Which pattern of pulsatile secretion is critical for maintaining gonadal function when administered for fertility treatment?
Which pattern of pulsatile secretion is critical for maintaining gonadal function when administered for fertility treatment?
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What type of rhythm describes periodicity that is approximately 24 hours?
What type of rhythm describes periodicity that is approximately 24 hours?
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Which element assists in the control of the cortisol/ACTH axis concerning daily biorhythms?
Which element assists in the control of the cortisol/ACTH axis concerning daily biorhythms?
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Which stimuli primarily influence the hypothalamic hormones produced by magno- and parvocellular cell groups?
Which stimuli primarily influence the hypothalamic hormones produced by magno- and parvocellular cell groups?
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What is the primary consequence of slower-than-hourly frequency GnRH administration?
What is the primary consequence of slower-than-hourly frequency GnRH administration?
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What role do biogenic amines play in the neuroendocrine control mechanism?
What role do biogenic amines play in the neuroendocrine control mechanism?
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What is the primary function of negative feedback in an endocrine feedback system?
What is the primary function of negative feedback in an endocrine feedback system?
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How does an increase in hormone plasma concentration affect receptor exposure on target cells?
How does an increase in hormone plasma concentration affect receptor exposure on target cells?
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Which of the following hormones is involved in a positive feedback mechanism during ovulation?
Which of the following hormones is involved in a positive feedback mechanism during ovulation?
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What mechanism primarily regulates hormone release from magnocellular neurosecretory neurons?
What mechanism primarily regulates hormone release from magnocellular neurosecretory neurons?
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Which statement best describes positive feedback in the endocrine system?
Which statement best describes positive feedback in the endocrine system?
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What phenomenon occurs when hormone concentration reaches a peak in the case of positive feedback?
What phenomenon occurs when hormone concentration reaches a peak in the case of positive feedback?
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What type of feedback mechanism is typically involved in regulatory processes for maintaining stable hormone levels?
What type of feedback mechanism is typically involved in regulatory processes for maintaining stable hormone levels?
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What is the significance of down-regulating insulin receptors in target cells?
What is the significance of down-regulating insulin receptors in target cells?
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Which factor does NOT directly affect the magnitude of a hormone's effect on a cell?
Which factor does NOT directly affect the magnitude of a hormone's effect on a cell?
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Which method is NOT a functional test in endocrinology?
Which method is NOT a functional test in endocrinology?
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What is the role of recombinant DNA technology in hormone production?
What is the role of recombinant DNA technology in hormone production?
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What are the new techniques developed for the detection of low concentration molecules?
What are the new techniques developed for the detection of low concentration molecules?
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Which hormone is NOT mentioned as being produced through recombinant DNA technology?
Which hormone is NOT mentioned as being produced through recombinant DNA technology?
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In the context of hormonal response, what does up-regulation refer to?
In the context of hormonal response, what does up-regulation refer to?
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Which of the following conditions is associated with hyperfunction syndromes in endocrinology?
Which of the following conditions is associated with hyperfunction syndromes in endocrinology?
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What year did Brown-Séquard report enhancing his physical strength with animal testes extracts?
What year did Brown-Séquard report enhancing his physical strength with animal testes extracts?
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Who discovered the term 'hormone' to describe chemical messengers?
Who discovered the term 'hormone' to describe chemical messengers?
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Which hormone was discovered in 1922 that significantly impacted diabetes treatment?
Which hormone was discovered in 1922 that significantly impacted diabetes treatment?
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What medical condition was treated with posterior pituitary extracts by Farmi and von den Velden in 1918?
What medical condition was treated with posterior pituitary extracts by Farmi and von den Velden in 1918?
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Which discovery in 1915 linked parathyroid glands to calcium metabolism?
Which discovery in 1915 linked parathyroid glands to calcium metabolism?
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Which of the following is NOT mentioned as an important therapeutic advance in medical practice?
Which of the following is NOT mentioned as an important therapeutic advance in medical practice?
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In which year was the role of Leydig cells in male phenotype development deduced?
In which year was the role of Leydig cells in male phenotype development deduced?
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What field contributed significantly to the advances in hormonal therapies mentioned?
What field contributed significantly to the advances in hormonal therapies mentioned?
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Study Notes
Endocrine System Introduction
- Endocrine system works with nervous and immune systems to maintain homeostasis
- Endocrine glands are also called glands with internal secretion
- Claude Bernard introduced the concept of internal secretion
- Hormones are stimulatory substances released into the internal environment (blood, lymph)
- Hormones are chemical messengers, secreted by specialized cells, not necessarily in glands
- Hormones act on target cells, regulating physiological, metabolic, behavioral, and morphological effects
- Hormones don't create new processes, but regulate existing biochemical reactions
- Many organs have endocrine secretions (e.g., brain, heart, kidney, liver, skin, digestive tube)
- Endocrine secretion includes endocrine glands, APUD cells, paracrine secretions, autocrine secretions, and neurosecretion
- Hormones can have multiple roles (e.g., CCK is both a hormone and a neurotransmitter)
Hormone Classification
- Hormones are classified based on their structure:
- Proteic hormones: also called glycoproteic or peptidic hormones
- Amino acid-derived hormones: phenol or indol ring derived
- Lipid hormones: steroidal hormones
- Hormones can also be classified based on their target organs (e.g., thyroid stimulating hormone - TSH, growth hormone - GH, insulin)
Hormone Receptors
- Hormones interact with specific receptors
- Receptors are represented by a protein which has high affinity for the hormon
- The number of receptors can vary based on factors including hormone concentration
- Downregulation of receptors occurs with excess hormone, decreasing binding and response
- Downregulation mechanisms include internalization, compartmentalization, and degradation of receptors
- Upregulation of receptors occurs with lack of hormone
- Upregulation mechanisms include increasing receptor density and activation of protein kinases
- Hormones can act as positive regulators for other hormone receptors (e.g., thyroid hormones upregulate cathecolamines receptors)
- Receptors are categorized by location: membrane receptors, cytoplasmic receptors, and nuclear receptors
- Steroid hormones pass through cell membranes and bind cytoplasmic receptors
- Hormone-receptor complexes then move to the nucleus, acting on nuclear receptors to trigger gene transcription and protein synthesis
Second Messengers
- After binding with a receptor, a secondary messenger system becomes activated
- This system can activate other proteins or enzymes
- The cAMP system involves hormones that activate adenylate cyclase
- The Ca++, phospho-inositol system involves hormones that activate calcium channels and phospholipase C
- Hormones can be directly enzymes, or linked to an enzyme
- Hormone interaction with receptors can lead to activation or inhibition in a secondary messenger system
Transport of Hormones
- Hormones are transported mainly through blood, with some in lymph
- Most hormones are bound to transport proteins (e.g., Albumin, TBG, CBG)
- The free form of a hormone is less abundant but plays an active role
- Free hormones are more accessible to target tissues
Hormone Metabolism and Elimination
- Peptide hormones are inactivated via intracellular hydrolysis
- Catecholamines are inactivated via oxidation
- Steroid hormones undergo metabolic processes like dehydrogenation and conjugation
- Hormones are excreted in urine or bile after being conjugated with glucuronic acid or sulfate
- Enterohepatic circulation assists in reaccumulating these hormones
Hormone Secretion Regulation
- Secretion is regulated through chronic, nervous, feedback and regulatory mechanisms
- Biorhythms are endogenous or exogenous; examples include circadians rhythms (growth hormones and cortisol), diurnal rhythms, sleep-wake cycles, and seasonal cycles
- The suprachiasmatic nucleus (SCN) acts as a biological clock, influencing daily biorhythms
- Nervous control involves input from the hypothalamus, brainstem, and other areas of the brain to the hypothalamic nuclei
- Feedback control is a common regulatory mechanism, where the hormone itself can regulate its own secretion, maintaining the hormone concetration within physiological limits
Hormonal Receptor Regulation
- Downregulation: occurs when the plasma concentration of a hormone rises
- Reduced receptor number on target cells leads to a decreased effect from the hormone
- Upregulation occurs when the plasma concentration of the hormone falls
- Increased receptor number on target cells to maintain the level of the hormone interaction on the cell
Hormone Methods of Investigation
- Imaging techniques (X-rays, CT scans, MRI)
- Functional tests (measuring hormone levels at rest and during stimulation/inhibition)
- Radioimmunoassay (RIA), a technique used to measure hormones in blood samples
- Immunometric assays and chromatography/mass spectrometry, provide more sensitive methods in detecting molecules with very low concentrations
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Description
Test your knowledge on hormonal functions and receptor regulation mechanisms. This quiz covers various aspects of hormones, including their effects on receptor density, signaling systems, and classification of hormonal actions. Explore the intricate relationship between hormones and their receptors in the endocrine system.
