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Questions and Answers
Which of the following is a correct statement about the endocrine system?
Which of the following is a correct statement about the endocrine system?
What is the primary difference between endocrine and exocrine glands?
What is the primary difference between endocrine and exocrine glands?
Which of the following is NOT a characteristic of hormones?
Which of the following is NOT a characteristic of hormones?
What is the main function of the endocrine system?
What is the main function of the endocrine system?
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What is the role of the hypothalamus in the endocrine system?
What is the role of the hypothalamus in the endocrine system?
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What is the main difference between the nervous and endocrine systems in terms of their response speed?
What is the main difference between the nervous and endocrine systems in terms of their response speed?
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How do the nervous and endocrine systems differ in their ability to adapt to long-term stimuli?
How do the nervous and endocrine systems differ in their ability to adapt to long-term stimuli?
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Which of the following statements accurately describes the area of effect for the nervous and endocrine systems?
Which of the following statements accurately describes the area of effect for the nervous and endocrine systems?
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How do the nervous and endocrine systems interact and influence each other?
How do the nervous and endocrine systems interact and influence each other?
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What is a characteristic shared by both the nervous system and the endocrine system?
What is a characteristic shared by both the nervous system and the endocrine system?
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Which of these hormones is primarily responsible for regulating blood calcium levels?
Which of these hormones is primarily responsible for regulating blood calcium levels?
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Which hormone, produced by the pineal gland, is known to influence the timing of puberty and is involved in circadian rhythms?
Which hormone, produced by the pineal gland, is known to influence the timing of puberty and is involved in circadian rhythms?
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Which of the following hormones is secreted by the adrenal medulla, and its primary function is to prepare the body for 'fight or flight' responses?
Which of the following hormones is secreted by the adrenal medulla, and its primary function is to prepare the body for 'fight or flight' responses?
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Which hormone, produced by the pancreas, is responsible for lowering blood glucose levels by stimulating cells to absorb glucose and store or metabolize it?
Which hormone, produced by the pancreas, is responsible for lowering blood glucose levels by stimulating cells to absorb glucose and store or metabolize it?
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Which of the following statements about the relationship between the adrenal medulla and cortex is CORRECT?
Which of the following statements about the relationship between the adrenal medulla and cortex is CORRECT?
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Which of these hormones is NOT part of the hyperglycemic group, meaning that it does NOT increase blood glucose levels?
Which of these hormones is NOT part of the hyperglycemic group, meaning that it does NOT increase blood glucose levels?
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Which of the following organs/tissues plays a role in the production of erythropoietin, a hormone that stimulates bone marrow to produce red blood cells?
Which of the following organs/tissues plays a role in the production of erythropoietin, a hormone that stimulates bone marrow to produce red blood cells?
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Which of the following hormones is primarily responsible for stimulating osteoblast activity and bone formation, particularly in children?
Which of the following hormones is primarily responsible for stimulating osteoblast activity and bone formation, particularly in children?
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What structure connects the hypothalamus to the anterior pituitary?
What structure connects the hypothalamus to the anterior pituitary?
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What is the main function of the hormone aldosterone, secreted by the adrenal cortex?
What is the main function of the hormone aldosterone, secreted by the adrenal cortex?
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Which of the following hormones is NOT secreted by the anterior pituitary?
Which of the following hormones is NOT secreted by the anterior pituitary?
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The hormone leptin is secreted by which organ/tissue and what is its primary function?
The hormone leptin is secreted by which organ/tissue and what is its primary function?
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What is the function of prolactin?
What is the function of prolactin?
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What is the primary function of the neurohypophysis?
What is the primary function of the neurohypophysis?
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Which pair of hormones is correctly matched with its primary function?
Which pair of hormones is correctly matched with its primary function?
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Which hormone, secreted by the liver, promotes intestinal absorption of iron?
Which hormone, secreted by the liver, promotes intestinal absorption of iron?
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Which of the following hormones is primarily responsible for stimulating the adrenal cortex to secrete cortisol?
Which of the following hormones is primarily responsible for stimulating the adrenal cortex to secrete cortisol?
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Which of these hormones is produced in the hypothalamus and released from the posterior pituitary?
Which of these hormones is produced in the hypothalamus and released from the posterior pituitary?
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Which of the following statements about the 'glucose-sparing effect' is CORRECT?
Which of the following statements about the 'glucose-sparing effect' is CORRECT?
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Which of these hormones promotes milk ejection during lactation?
Which of these hormones promotes milk ejection during lactation?
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Which of the following hormones is NOT produced by the gonads (ovaries or testes)?
Which of the following hormones is NOT produced by the gonads (ovaries or testes)?
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Which of the following statements about the anterior pituitary is TRUE?
Which of the following statements about the anterior pituitary is TRUE?
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Which of the following hormones has a negative feedback mechanism for its own secretion?
Which of the following hormones has a negative feedback mechanism for its own secretion?
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Which of the following hormones is NOT regulated by a hypothalamic releasing or inhibiting hormone?
Which of the following hormones is NOT regulated by a hypothalamic releasing or inhibiting hormone?
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What is the primary function of the enteroendocrine cells found in the stomach and small intestines?
What is the primary function of the enteroendocrine cells found in the stomach and small intestines?
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How does the hypothalamus influence the release of hormones from the anterior pituitary?
How does the hypothalamus influence the release of hormones from the anterior pituitary?
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What is the primary function of gonadotropin-releasing hormone (GnRH)?
What is the primary function of gonadotropin-releasing hormone (GnRH)?
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Which of the following hormones is primarily responsible for stimulating the release of thyroid hormone from the thyroid gland?
Which of the following hormones is primarily responsible for stimulating the release of thyroid hormone from the thyroid gland?
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Which of the following statements about the posterior pituitary is CORRECT?
Which of the following statements about the posterior pituitary is CORRECT?
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What is the function of somatostatin?
What is the function of somatostatin?
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What is the primary function of oxytocin?
What is the primary function of oxytocin?
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What is the role of the infundibulum in the pituitary gland?
What is the role of the infundibulum in the pituitary gland?
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Which of the following hormones is NOT produced by the anterior pituitary?
Which of the following hormones is NOT produced by the anterior pituitary?
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Which of the following is a correct statement about the secretion of steroid hormones?
Which of the following is a correct statement about the secretion of steroid hormones?
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Which of the following hormones is NOT synthesized from the amino acid tyrosine?
Which of the following hormones is NOT synthesized from the amino acid tyrosine?
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Which of the following is a correct statement about hormone transport?
Which of the following is a correct statement about hormone transport?
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Which of the following is an example of a synergistic effect of hormone interactions?
Which of the following is an example of a synergistic effect of hormone interactions?
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Which of the following is NOT a characteristic of the alarm reaction stage of the General Adaptation Syndrome (GAS)?
Which of the following is NOT a characteristic of the alarm reaction stage of the General Adaptation Syndrome (GAS)?
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Which of the following statements accurately describes the role of cortisol in the stage of resistance?
Which of the following statements accurately describes the role of cortisol in the stage of resistance?
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Which of the following is a correct statement about eicosanoids?
Which of the following is a correct statement about eicosanoids?
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Which of the following is an example of a humoral stimulus for hormone secretion?
Which of the following is an example of a humoral stimulus for hormone secretion?
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Which of the following is a correct statement about the mechanism of action of peptide hormones?
Which of the following is a correct statement about the mechanism of action of peptide hormones?
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Which of the following is an example of a hormone that undergoes up-regulation?
Which of the following is an example of a hormone that undergoes up-regulation?
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Which of the following is NOT a characteristic of hypersecretion of growth hormone?
Which of the following is NOT a characteristic of hypersecretion of growth hormone?
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Which of the following is a correct statement about the pathogenesis of diabetes mellitus?
Which of the following is a correct statement about the pathogenesis of diabetes mellitus?
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Which of the following is a correct statement about the treatment of diabetes mellitus?
Which of the following is a correct statement about the treatment of diabetes mellitus?
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Which of the following is NOT a common symptom of Cushing syndrome?
Which of the following is NOT a common symptom of Cushing syndrome?
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Which of the following is a correct statement about the effects of cortisol on the immune system?
Which of the following is a correct statement about the effects of cortisol on the immune system?
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Flashcards
Endocrine System
Endocrine System
Glands, tissues, and cells that secrete hormones.
Hormones
Hormones
Chemical messengers transported in the bloodstream to stimulate responses in distant cells.
Neurotransmitters
Neurotransmitters
Chemicals released from neurons to transmit signals across synapses.
Differences in Glands
Differences in Glands
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Four Mechanisms of Communication
Four Mechanisms of Communication
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Speed of response
Speed of response
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Adaptation to stimuli
Adaptation to stimuli
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Area of effect
Area of effect
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Similar substances in both systems
Similar substances in both systems
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Target organs or cells
Target organs or cells
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Hypothalamus
Hypothalamus
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Pituitary Gland
Pituitary Gland
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Infundibulum
Infundibulum
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Anterior Pituitary
Anterior Pituitary
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Posterior Pituitary
Posterior Pituitary
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Thyroid-Releasing Hormone (TRH)
Thyroid-Releasing Hormone (TRH)
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Oxytocin
Oxytocin
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Antidiuretic Hormone (ADH)
Antidiuretic Hormone (ADH)
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Corticotropin-Releasing Hormone (CRH)
Corticotropin-Releasing Hormone (CRH)
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Follicle-Stimulating Hormone (FSH)
Follicle-Stimulating Hormone (FSH)
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Luteinizing Hormone (LH)
Luteinizing Hormone (LH)
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Prolactin (PRL)
Prolactin (PRL)
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Adrenocorticotropic Hormone (ACTH)
Adrenocorticotropic Hormone (ACTH)
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Negative Feedback
Negative Feedback
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Positive Feedback
Positive Feedback
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Growth Hormone (GH)
Growth Hormone (GH)
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Insulin-like Growth Factors (IGF)
Insulin-like Growth Factors (IGF)
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Pineal Gland
Pineal Gland
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Thymus
Thymus
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Thyroid Gland
Thyroid Gland
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Parathyroid Hormone (PTH)
Parathyroid Hormone (PTH)
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Adrenal Medulla
Adrenal Medulla
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Cortisol
Cortisol
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Glucagon
Glucagon
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Ovaries
Ovaries
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Testes
Testes
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Erythropoietin
Erythropoietin
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Hormone Classes
Hormone Classes
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Sex Steroids
Sex Steroids
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Corticosteroids
Corticosteroids
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Monoamines
Monoamines
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Peptide Hormones
Peptide Hormones
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Thyroid Hormone Synthesis
Thyroid Hormone Synthesis
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Hormone Secretion Patterns
Hormone Secretion Patterns
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Neural Stimuli
Neural Stimuli
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Humoral Stimuli
Humoral Stimuli
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Transport of Hormones
Transport of Hormones
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Hormone Receptors
Hormone Receptors
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Peptide and Catecholamine Action
Peptide and Catecholamine Action
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Steroid Hormone Action
Steroid Hormone Action
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Signal Amplification
Signal Amplification
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Hormone Interactions
Hormone Interactions
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Diabetes Symptoms
Diabetes Symptoms
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Study Notes
Endocrine System Overview
- The endocrine system and nervous system are specialized for communication and coordination in humans.
- The endocrine system uses hormones, whereas the nervous system uses neurotransmitters.
- Four principal mechanisms of cellular communication exist: gap junctions, neurotransmitters, paracrines, and hormones.
- Endocrine system comprises glands, tissues, and cells that secrete hormones.
- Endocrinology studies this system and its disorders.
- Endocrine glands are traditional hormone sources.
- Hormones are chemical messengers transported by blood, stimulating physiological responses in distant target cells.
Endocrine vs. Exocrine Glands
- Exocrine glands have ducts, carrying secretions externally (e.g., digestive tract). Secretions have extracellular effects.
- Endocrine glands lack ducts; contain dense, fenestrated capillary networks facilitating hormone uptake. Secretions have intracellular effects.
Nervous vs. Endocrine Systems
- Speed and persistence of response differ significantly. Nervous system responds rapidly and effects are short-lived; endocrine system response is slow but effects can persist for extended periods.
- Adaptation to long-term stimuli differs. Nervous system quickly adapts, while endocrine system adapts more slowly.
- Effects are targeted and specific in the nervous system; general and widespread in the endocrine system.
- Several chemicals (e.g., norepinephrine, dopamine, ADH) function as both hormones and neurotransmitters, or have similar effects on target cells.
- The two systems interact; neurotransmitters can affect glands, and hormones affect neurons.
- Neuroendocrine cells share characteristics of both systems.
- Target cells are those possessing receptors for a hormone to respond to it.
The Hypothalamus
- Functions as a control center for primitive functions (childbirth, sex drive) and works with the pituitary gland.
- Connects to the pituitary via the infundibulum (a stalk).
- Located in the floor and walls of the third ventricle.
- Anterior pituitary: anterior ¾ of the pituitary; connected to hypothalamus by hypophysial portal system (primary-secondary capillaries).
- Posterior pituitary: posterior ¼ of pituitary; nerve tissue, not a true gland and stores/releases hormones from hypothalamus.
- Hypothalamic hormones affect the anterior pituitary (e.g., TRH, CRH, GnRH, GRH, PIH, somatostatin) and the posterior pituitary (OT, ADH).
Pituitary Gland
- Located in the sella turcica of the sphenoid bone.
- Shaped like a kidney bean.
- Composed of two structures (anterior and posterior pituitary) with independent origins and function.
Anterior Pituitary Hormones
- Six primary hormones are synthesized and secreted: FSH, LH, TSH, ACTH, PRL, and GH.
- Gonadotropins (FSH and LH) regulate gonads.
- TSH stimulates thyroid hormone secretion.
- ACTH stimulates adrenal cortex glucocorticoid secretion.
- PRL stimulates mammary gland milk synthesis.
- GH stimulates cell mitosis and differentiation.
Posterior Pituitary Hormones
- Two hormones produced in the hypothalamus and stored/released in posterior pituitary: ADH (vasopressin) and oxytocin.
- ADH increases water retention, reducing urine and preventing dehydration.
- Oxytocin is released during sexual arousal and orgasm, childbirth, and lactation, fostering bonding.
Control of Pituitary Secretion
- Rates vary; regulated by the hypothalamus, brain, and target organs.
Negative Feedback
- Increased target organ hormone levels inhibit hypothalamic and/or pituitary hormone release to maintain homeostasis.
Growth Hormone (GH)
- Widespread effects; boosts protein synthesis, lipid metabolism, and carbohydrate metabolism.
- Induces liver to release IGFs (insulin-like growth factors) to stimulate target cells.
- GH has a short half-life; IGFs have a longer half-life, prolonging action.
- Impacts bone growth, thickening, and remodeling, particularly during development.
- Secretion is high during initial sleep hours and can be triggered by exercise or hunger.
- GH levels decline with age.
Pineal Gland
- Located beneath the posterior end of the corpus callosum.
- Undergoes involution (shrinkage) after age 7.
- Synthesizes melatonin at night.
- Influences puberty timing and circadian rhythms.
- Seasonal affective disorder (SAD) symptoms are reduced by light exposure.
Thymus Gland
- Bilobed gland superior to the heart in the mediastinum; involved in the endocrine, lymphatic, and immune systems.
- Undergoes involution after puberty.
- Site of maturation for T cells.
- Secretes hormones (thymopoietin, thymosin, thymulin).
Thyroid Gland
- Largest purely endocrine gland.
- Two lobes and an isthmus below the larynx, dark reddish brown.
- Thyroid follicles contain colloid, surrounded by follicular cells (simple cuboidal epithelium).
- Secretes thyroxine (T4) and Triiodothyronine (T3) in response to TSH.
- Increases metabolic rate, oxygen consumption, heat production, appetite, growth hormone secretion, alertness, and reflex speed.
- Parafollicular cells secrete calcitonin to regulate blood calcium.
Parathyroid Glands
- Embedded in the posterior thyroid.
- Secrete parathyroid hormone (PTH) to increase blood calcium.
- Promotes calcitriol synthesis for calcium absorption.
Adrenal Glands
- Composed of cortex and medulla.
- Medulla: inner core, modified sympathetic neurons (chromaffin cells). Secretes epinephrine, norepinephrine, and dopamine, in response to stress.
- Increases alertness, mobilizes energy, has a glucose-sparing effect, and has widespread impact on body function (blood pressure, heart rate, blood flow, metabolic rate).
- Cortex: secretes corticosteroids from three zones:
- Zona glomerulosa: mineralocorticoids (aldosterone) regulates electrolyte balance, especially sodium content.
- Zona fasciculata: glucocorticoids (cortisol) regulate metabolism of glucose and other fuels; promotes fat and protein catabolism and gluconeogenesis.
- Zona reticularis: androgens for libido and prenatal male development.
Pancreatic Islets
- Endocrine tissue interspersed in exocrine pancreas.
- Alpha cells secrete glucagon (raises blood glucose).
- Beta cells secrete insulin (lowers blood glucose).
- Delta cells secrete somatostatin (partially suppresses glucagon and insulin).
- Pancreatic polypeptide (PP) acts as an inhibitor of digestion and absorption.
- Hyperglycemic hormones raise blood glucose (glucagon, GH, epinephrine, norepinephrine, cortisol, corticosterone)
- Hypoglycemic hormones lower blood glucose (insulin)
Gonads
- Ovaries and testes are both endocrine and exocrine organs.
- Ovarian hormones: Estrogen, progesterone, and inhibin.
- Testicular hormones: testosterone, androgens, estrogen, and inhibin.
- Gonads promote development of reproductive systems and regulate cycles (e.g., menstrual, pregnancy).
Other Tissues and Organs
- Various tissues besides traditional endocrine glands produce hormones (e.g., skin, liver, kidneys, heart, stomach, small intestine, adipose tissue, osseous tissue, placenta).
Hormone Chemistry
- Hormones are broadly classified into three groups: steroids, monoamines, and peptides.
Hormone Transport
- Hydrophilic hormones (peptides, monoamines) mix easily with blood plasma.
- Hydrophobic hormones (steroids, thyroid) bind to transport proteins, prolonging half-life in blood, protecting from breakdown, and ensuring only unbound hormones affect target cells.
Hormone Receptors and Mode of Action
- Target cells have specific receptors for hormones. Surface receptors for peptide and catecholamine hormones trigger intracellular second messenger systems; nuclear receptors for steroid and thyroid hormones affect gene expression.
Signal Amplification
- Hormone signals are potent; they can activate many enzyme molecules.
Modulation of Target Cell Sensitivity
- Receptor up-regulation increases sensitivity, receptor down-regulation reduces sensitivity.
Hormone Interactions
- Synergistic, permissive, and antagonistic interactions may occur between hormones affecting target cells.
Hormone Clearance
- Hormones are removed from the blood by the liver and kidneys to regulate blood levels.
Stress and Adaptation (General Adaptation Syndrome)
- Stress upsets homeostasis, triggering a response.
- Alarm reaction: characterized by elevated epinephrine and norepinephrine.
- Stage of resistance: dominated by cortisol to provide alternate fuels.
- Stage of exhaustion: occurs with prolonged stress.
Eicosanoids and Paracrine Signaling
- Paracrine and autocrine signaling involves local messengers (eicosanoids, histamine, nitric oxide). -Eicosanoids, like prostaglandins, regulate various physiological processes.
- NSAIDS inhibit eicosanoid synthesis.
Endocrine Disorders
- Hyposecretion and hypersecretion can result in various diseases (e.g., diabetes mellitus, pituitary, thyroid, parathyroid, adrenal disorders).
Pituitary Disorders
- Acromegaly (excess GH in adults), gigantism (excess GH in children), pituitary dwarfism (GH deficiency).
Thyroid and Parathyroid Disorders
- Hypothyroidism (low TH) and hyperthyroidism (high TH) manifest with different symptoms.
- Goiter: enlargement of thyroid gland, often due to iodine deficiency.
- Hypoparathyroidism and hyperparathyroidism cause imbalances in blood calcium.
Adrenal Disorders
- Cushing syndrome (excess cortisol), adrenogenital syndrome (excess adrenal androgens).
Diabetes Mellitus
- Caused by insufficient insulin or resistance to insulin. -Type 1 and type 2 are forms of the disease.
- Pathogenesis, chronicity, and treatment vary for the two forms.
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Test your knowledge on the endocrine system with this quiz. Explore key concepts such as the differences between endocrine and exocrine glands, the role of hormones, and the interaction between the endocrine and nervous systems. Ideal for students studying health sciences or biology.