121 Questions
Which communication system reacts quickly but stops quickly?
Nervous system
Which system's response to long-term stimuli adapts quickly?
Nervous system
Which system has targeted and specific effects on one organ?
Nervous system
Which chemical functions as both a hormone and a neurotransmitter?
Catecholamines
Which gland is shaped like a flattened funnel and regulates homeostasis mechanisms?
Hypothalamus
Which pituitary gland arises from an outgrowth of the pharynx?
Anterior pituitary
'Adenohypophysis' is another name for which part of the pituitary gland?
Anterior pituitary
'Growth Hormone' is also known as:
'Somatotropin'
What is the main difference between endocrine and exocrine glands?
Exocrine glands secrete products directly into the bloodstream, while endocrine glands secrete products onto an open surface or organ cavity.
What is the function of hormones in cell communication?
Hormones are chemical messengers that travel in the bloodstream to stimulate responses in target tissues.
Which of the following is NOT a mechanism of cell communication mentioned in the text?
Endocytosis
Where do hormones primarily act in the body?
In the bloodstream
What are target cells?
Cells with receptors for a specific hormone
Which gland is responsible for producing hormones like thyroxine and triiodothyronine?
Thyroid
In paracrine signaling, where are hormones secreted?
Into the interstitial fluid to affect nearby cells
What is the purpose of eicosanoids in cell communication?
To regulate local cell activities through paracrine signaling
What clinical manifestations are associated with excess thyroid hormone secretion?
Heat intolerance and increased tissue sensitivity to sympathetic nervous system stimulation
What is the treatment for hyperparathyroidism due to excess parathyroid hormone secretion?
Surgery
Which disorder is characterized by excess cortical secretion, leading to hyperglycemia, hypertension, weakness, and muscle and bone loss?
Cushing syndrome
What are the signs and symptoms of hyposecretion of insulin in diabetes mellitus?
Hypoglycemia, polyuria, polydipsia
What are the major risk factors associated with Type II diabetes mellitus?
Obesity, age (40+), insulin resistance
What is the chronic pathology associated with chronic hyperglycemia in diabetes mellitus?
Peripheral neuropathy and cardiovascular damage from atherosclerosis
What condition can be caused by excess insulin injection or pancreatic islet tumor?
Hypoglycemia, weakness, and hunger
What side effects are associated with hyperinsulinism?
Anxiety, sweating, and increased heart rate
Which cell type in the pancreas secretes glucagon?
Alpha (a) cells
What is the primary function of insulin secreted by the pancreas?
Stimulates nutrient storage
When are hyperglycemic hormones like cortisol secreted?
To raise blood glucose levels
What is the main function of somatostatin secreted by the pancreas?
Inhibit insulin and glucagon secretion
Which organ releases atrial natriuretic peptide in response to an increase in blood pressure?
Heart
What is the primary function of erythropoietin produced by the kidneys?
Stimulate bone marrow to produce red blood cells
How are steroid hormones synthesized?
Functional groups attached to a 4-ringed steroid backbone
Where are hormone receptors typically located?
Plasma membrane, mitochondria, and other organelles
Which type of hormones need to bind to cell-surface receptors for their action?
Hydrophilic hormones
How do hydrophilic hormones typically exert their effects?
By using cAMP as a second messenger
What is the main function of Na+-K+ ATPase in response to thyroid hormone binding?
Increasing the rate of aerobic respiration
Which process is NOT typically influenced by hydrophilic hormones?
Mitochondrial respiration rate
What is the main function of cAMP in the mode of action of hydrophilic hormones?
Promoting enzyme activation through kinases
Where does insulin formation start with preproinsulin being converted to proinsulin?
RER
Which hormone is synthesized from tryptophan instead of tyrosine?
Melatonin
What mineral is required for the synthesis of thyroid hormone?
Iodine
Which protein hormones are transported in the bloodstream as free, unbound forms?
Peptides
What is the composition of T4 (thyroxine)?
Two DITs
Which hormone stimulates follicular cells to release T3 and T4 from thyroglobulin into the plasma?
Thyroid-stimulating hormone (TSH)
What is the effect of Ca++ influx and increased K+ efflux in beta 1 receptor activation?
Inhibitory
Which enzyme is inhibited by beta 2 receptor activation leading to smooth muscle relaxation?
MLCK
What is the effect of long-term high levels of insulin on target cells?
Down-regulation
Which type of hormone interaction involves one hormone enhancing the response to a second hormone?
Permissive effects
In the context of hormones, what does 'MCR' stand for?
Metabolic Clearance Rate
Which system describes the way the body reacts to stress and occurs in stages like alarm reaction and stage of resistance?
General Adaptation Syndrome
Which system is responsible for general, widespread effects on many organs?
Endocrine system
What is the speed of response of the endocrine system compared to the nervous system?
Nervous system is quicker
Which chemical can function as both a hormone and a neurotransmitter?
Dopamine
What is the primary function of ACTH (Adrenocorticotropic Hormone)?
Regulates response to stress
Which hormone stimulates the production of Testosterone in males?
FSH
What is oxytocin primarily responsible for in females?
Stimulating milk synthesis after delivery
Which gland is suspended from the hypothalamus by a stalk and housed in the sella turcica of the sphenoid bone?
Pituitary gland
Where do hydrophobic hormones like estrogen and aldosterone bind?
Cytoplasmic receptors
What is the role of cAMP in the mode of action of hydrophilic hormones like epinephrine?
Activates adenylate cyclase
Which organelle's function is directly affected by the binding of Thyroid Hormone (TH) to its receptors?
Ribosomes
Which protein is activated by G(s) protein in the signaling pathway of hydrophilic hormones through cAMP as a second messenger?
Protein Kinase A (PKA)
In Hydrophilic Hormones' mode of action, which process is NOT typically influenced by the activation of enzymes through second messengers?
Cell division
Which protein plays a critical role in smooth muscle contraction in the G-coupled protein signaling pathway?
Protein Kinase C (PKC)
What hormone is responsible for sodium and water retention in the initial response stage of stress?
Aldosterone
What long-term effect is associated with the stage of resistance during stress?
Depressed immune function
Which chemical messenger diffuses from the adrenal medulla to the cortex?
Catecholamines
What is the primary function of prostacyclin in the body?
Inhibits blood clotting
What condition results from excessive hormone release, such as toxic goiter in Graves disease?
Hypersecretion disorder
What disorder results from antibodies that mimic the effect of TSH on the thyroid gland?
Toxic goiter
What clinical manifestation is associated with congenital hypothyroidism in infants?
Low temperature
'Thyrotoxicosis' is a condition resulting from increased levels of which hormone?
Thyroxine
What is a long-term effect associated with stress that leads to protein breakdown and muscle wasting?
Hypokalemia
What is the primary function of somatotropin secreted by the anterior pituitary?
Promotes tissue growth through cellular differentiation
Which hormone is responsible for the glucose sparing effect in the body?
Somatotropin
What is the primary role of oxytocin in the body?
Causing uterine contractions and milk ejection
Which gland produces serotonin during the day and converts it to melatonin at night?
Pineal gland
Which hormone is produced by the thymus gland to regulate T-lymphocyte activation?
Thymosin
Where is calcitonin produced in the body to regulate blood calcium levels?
Thyroid gland
What is the primary function of cortisol produced by the adrenal cortex?
Stimulates fat and protein catabolism
Which hormone is responsible for increasing alertness, anxiety, and fear in response to stress?
Adrenaline
What is the primary role of mineralocorticoids produced by the adrenal cortex?
Promoting sodium retention and water reabsorption
What is the primary role of epinephrine and norepinephrine released by the adrenal medulla during stress?
Increasing blood sugar levels
What is the main difference between the nervous and endocrine systems in terms of communication?
The nervous system reacts quickly but stops quickly, while the endocrine system reacts slowly but the effects may continue for weeks.
Which of the following systems has a response area that is general and has widespread effects on many organs?
Endocrine system
Which hormone acts to regulate the body's response to stress and stimulates the adrenal cortex to produce corticosteroids?
Adrenocorticotropic Hormone (ACTH)
Which hormone stimulates the growth of the thyroid and secretion of thyroid hormones?
Thyroid Stimulating Hormone (TSH)
Which gland is suspended from the hypothalamus by a stalk and housed in sella turcica of sphenoid bone?
Pituitary Gland
Which hormone regulates milk synthesis after delivery in females and LH sensitivity in males?
Prolactin
What is a key function of oxytocin in the body?
Stimulates milk ejection in lactating females
Which mechanism describes the way endocrine glands interact?
Axis control
Which type of hormones target other endocrine glands?
Tropic hormones
What is the primary function of LH in males?
Stimulates testes to secrete testosterone
Which part of the pituitary gland arises from an outgrowth of the pharynx?
Anterior lobe
What is the general adaptation syndrome and how many stages does it occur in?
A syndrome describing the body's reaction to stress; 2 stages
Which hormone interaction involves one hormone enhancing the response to a second hormone?
Permissive effects
What effect does activation of beta 1 receptor have on Ca++ influx and K+ efflux?
Excitatory due to increased Ca++ influx and K+ efflux
What is the main effect of long-term high insulin levels on target cells?
Down-regulation of cell sensitivity
Which gland is involved in hormone clearance by degrading hormones and then excreting them?
Liver
What does the metabolic clearance rate (MCR) of hormones refer to?
Rate at which hormones are cleared from plasma
Where do hydrophobic hormones like estrogen and aldosterone bind?
Cytoplasmic receptors
What is the primary effect of TH binding to receptors on ribosomes and chromatin?
Augmented protein synthesis
Which organelle is affected when hydrophilic hormones activate kinases through second messenger systems?
Endoplasmic reticulum
In the context of hydrophilic hormones, what is the role of cAMP as a second messenger?
Activates kinases to initiate metabolic reactions
What is the direct result of G(s) protein activation by hydrophilic hormones?
Elevation in enzyme activity
What is the main outcome of smooth muscle contraction due to Gq protein activation by alpha 1 receptors?
Phosphorylation of myosin leading to muscle contraction
What is a long-term effect associated with stress that leads to protein breakdown and muscle wasting?
Depressed immune function and susceptibility to infection
Which endocrine disorder is characterized by inadequate hormone release due to head trauma or a lesion affecting the pituitary gland?
Diabetes insipidus
What is the primary function of prostacyclin in the body?
Inhibits blood clotting
Which condition results from antibodies that mimic the effect of TSH and leads to excessive thyroid hormone production?
Toxic goiter
What does hypersecretion refer to in the context of endocrine disorders?
Excessive hormone release
What effect do eicosanoids have on blood clotting and vasoconstriction?
Stimulate vasoconstriction
Which hormone is responsible for sodium and water retention in the initial response stage of stress?
Aldosterone
What clinical manifestation is associated with congenital hypothyroidism in infants?
Growth retardation
Which hormone is produced by the thymus gland to regulate T-lymphocyte activation?
Thymosin
What is the composition of T4 (thyroxine)?
Four iodine atoms and two tyrosine molecules
Which chemical messenger diffuses from the adrenal medulla to the cortex?
Epinephrine
Which gland produces serotonin during the day and converts it to melatonin at night?
Pineal gland
What is the primary function of prostacyclin in the body?
Regulate blood clotting, vasodilation, and inflammation
Which gland is shaped like a flattened funnel and regulates homeostasis mechanisms?
Adrenal gland
What is a long-term effect associated with stress that leads to protein breakdown and muscle wasting?
Muscle wasting and protein breakdown
Which endocrine disorder is characterized by inadequate hormone release due to head trauma or a lesion affecting the pituitary gland?
Pituitary insufficiency
Which type of hormone interaction involves one hormone enhancing the response to a second hormone?
Synergistic effect
Study Notes
Communication Systems
- Two communication systems: Nervous System and Endocrine System
- Nervous System: electrical and chemical signals, reacts quickly (1-10 msec), stops quickly
- Endocrine System: only chemical signals, reacts slowly (seconds to days), effects may continue for weeks
Endocrine System Overview
- Produces and secretes hormones into bloodstream
- Hormones: chemical messengers that stimulate response in another tissue or organ
- Target cells: have receptors for hormones
- Endocrine glands: produce hormones (e.g., thyroid, adrenal, pancreas, gonads)
Pituitary Gland
- Located at base of brain, suspended from hypothalamus
- Anterior pituitary (adenohypophysis): arises from hypophyseal pouch
- Posterior pituitary (neurohypophysis): arises from brain
- Regulates homeostasis and some endocrine functions
Hypothalamo-Hypophyseal Portal System
- Connection between hypothalamus and anterior pituitary
- Allows for communication and regulation of hormone secretion
Control of Pituitary
- Anterior pituitary controlled by releasing and inhibiting hormones from hypothalamus
- Posterior pituitary controlled by neuroendocrine reflexes (hormone release in response to nervous system signals)
Pituitary Hormones
- Tropic hormones: stimulate other endocrine glands (e.g., FSH, LH, TSH, ACTH)
- PRL: stimulates milk synthesis and secretion
- GH: regulates growth and development
Endocrine Disorders
- Hypoparathyroidism: surgical excision, fatal tetany
- Hyperparathyroidism: excess PTH secretion, tumor in gland, soft bones, kidney stones
- Cushing's syndrome: excess cortisol secretion, hyperglycemia, hypertension, muscle and bone loss
- Diabetes mellitus: insulin deficiency or resistance, polyuria, polydipsia, polyphagia
Pancreas
- Both exocrine and endocrine functions
- Islets of Langerhans: produce hormones (insulin, glucagon, somatostatin, pancreatic polypeptide)
- Insulin: lowers blood glucose, promotes glycogenesis and lipogenesis
- Glucagon: raises blood glucose, stimulates glycogenolysis and fat catabolism
Endocrine Functions of Other Organs
- Heart: atrial natriuretic peptide
- Skin: helps produce vitamin D3
- Liver: regulates glucose and lipid metabolism, produces IGF-I
- Kidneys: produces erythropoietin, regulates electrolyte balance
- Placenta: produces estrogen, progesterone, and other hormones during pregnancy### Hormone Formation and Synthesis
- Insulin formation: preproinsulin is converted to proinsulin in the rough endoplasmic reticulum, then split into insulin and C peptide in the Golgi complex
- Thyroid hormone synthesis: thyroid hormones (T3 and T4) are synthesized from tyrosine and iodine in the follicular cells of the thyroid gland
Thyroid Hormone Synthesis
- T3 and T4 synthesis: thyroglobulin is synthesized and stored in the lumen, where tyrosine and iodine combine to form T3 and T4
- TSH (thyroid-stimulating hormone) stimulates the release of T3 and T4 from thyroglobulin into the plasma
Hormone Transport
- Hydrophilic hormones (monoamines and peptides): transported in the bloodstream as free, unbound water-soluble molecules
- Hydrophobic hormones (steroids and thyroid hormones): must bind to transport proteins for transport, which prolongs their half-life and protects them from enzymes and kidney filtration
Communication by the Nervous and Endocrine Systems
- Nervous system: responds quickly (1-10 msec), stops quickly, and has a targeted and specific effect
- Endocrine system: responds slowly (seconds to days), effects persist for weeks, and has a general, widespread effect
Hypothalamus and Pituitary Gland
- Hypothalamus: regulates homeostasis mechanisms and some endocrine functions, shaped like a flattened funnel
- Pituitary gland: suspended from the hypothalamus, consists of anterior and posterior lobes, and regulates various endocrine functions
Control of Pituitary: Hypothalamic and Cerebral Control
- Anterior lobe control: releasing and inhibiting hormones from the hypothalamus
- Posterior lobe control: neuroendocrine reflexes, hormone release in response to nervous system signals
Pituitary Hormones
- Anterior pituitary hormones: tropic hormones that target other endocrine glands, including FSH, LH, TSH, ACTH, PRL, and GH
- Posterior pituitary hormones: ADH and oxytocin, produced by the hypothalamus and stored in the posterior pituitary
Adrenal Gland
- Adrenal cortex: produces corticosteroids, including mineralocorticoids, glucocorticoids, and sex hormones
- Adrenal medulla: produces catecholamines, including epinephrine and norepinephrine, in response to sympathetic stimulation
Stress and Adaptation
- General adaptation syndrome: the body's response to stress, occurring in three stages (alarm reaction, stage of resistance, and stage of exhaustion)
- Alarm reaction: initial response to stress, characterized by increased epinephrine and norepinephrine levels
- Stage of resistance: adaptation to stress, characterized by increased ACTH and cortisol levels
- Stage of exhaustion: prolonged stress, characterized by depleted energy reserves and protein breakdown
Hormone Interactions
- Synergistic effects: hormones interact to produce a greater effect
- Permissive effects: one hormone enhances the response to another hormone
- Antagonistic effects: hormones interact to produce opposing effects### Endocrine System Overview
- The endocrine system is a network of glands and organs that produce hormones that regulate various bodily functions.
- It includes the hypothalamus, pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, and gonads.
Cell Communication
- Cell communication involves the exchange of information between cells through various mechanisms, including:
- Gap junctions: pores in cell membranes that allow signaling chemicals to move between cells.
- Neurotransmitters: chemicals released by neurons that travel across gaps to affect target cells.
- Hormones: chemical messengers that travel through the bloodstream to reach target cells.
- Paracrine signaling: local signaling between cells that are in close proximity.
Endocrine System Components
- Endocrine glands:
- Produce hormones that are secreted into the bloodstream.
- Include the pituitary gland, thyroid gland, parathyroid glands, adrenal glands, pancreas, and gonads.
- Hormones:
- Chemical messengers that stimulate responses in target cells.
- Examples: insulin, growth hormone, thyroid hormone, epinephrine.
- Target cells:
- Have receptors for specific hormones.
- Respond to hormone signals by altering their metabolism or function.
Exocrine vs. Endocrine Glands
- Exocrine glands:
- Secrete products through ducts onto an open surface or organ cavity.
- Examples: salivary glands, sweat glands, pancreas (exocrine function).
- Endocrine glands:
- Secrete hormones directly into the bloodstream.
- Examples: pituitary gland, thyroid gland, adrenal glands.
Growth Hormone
- Produced by the anterior pituitary gland.
- Stimulates tissue growth and cell differentiation.
- Regulates metabolism, particularly in childhood and adolescence.
Posterior Pituitary Hormones
- Produced by the hypothalamus and stored in the posterior pituitary gland.
- Examples: antidiuretic hormone (ADH), oxytocin.
Pineal Gland
- Produces melatonin, which regulates sleep-wake cycles.
- Peak secretion occurs in childhood and decreases by puberty.
Thyroid Gland
- Produces thyroid hormones (T3 and T4) that regulate metabolic rate.
- Thyroid hormones:
- Increase oxygen consumption and heat production.
- Stimulate heart rate and contraction strength.
- Promote breakdown of CHO, lipids, and proteins.
Parathyroid Glands
- Produce parathyroid hormone (PTH), which regulates calcium levels.
- PTH:
- Increases calcium absorption from the gut.
- Stimulates bone resorption.
- Increases vitamin D production.
Adrenal Gland
- Produces corticosteroids, catecholamines, and androgens.
- Corticosteroids:
- Regulate electrolyte balance and blood pressure.
- Stimulate fat and protein catabolism.
- Catecholamines:
- Increase alertness, anxiety, and fear responses.
- Stimulate glycogenolysis and lipolysis.
Pancreas
- Produces insulin, glucagon, somatostatin, and pancreatic polypeptide.
- Insulin:
- Lowers blood glucose levels by stimulating glucose uptake and storage.
- Promotes glycogenesis and lipogenesis.
- Glucagon:
- Raises blood glucose levels by stimulating glycogenolysis and gluconeogenesis.
- Inhibits insulin secretion.
Hormone Synthesis
- Steroid hormones: derived from cholesterol.
- Peptide hormones: synthesized through cellular processes involving the rough endoplasmic reticulum and Golgi complex.
Stress Response
- Alarm reaction: initial response to stress, characterized by increased epinephrine and norepinephrine levels, heart rate, and blood pressure.
- Stage of resistance: prolonged stress response, characterized by increased cortisol levels, gluconeogenesis, and fat and protein breakdown.
- Stage of exhaustion: severe stress, characterized by depleted energy stores, muscle wasting, and impaired immune function.
Endocrine Disorders
- Hyposecretion: inadequate hormone release, leading to disorders such as diabetes insipidus and hypothyroidism.
- Hypersecretion: excessive hormone release, leading to disorders such as acromegaly and Cushing's syndrome.
- Autoimmune disorders: Graves' disease (thyroid), Hashimoto's thyroiditis.
Diabetes Mellitus
- Type I (insulin-dependent diabetes mellitus): autoimmune destruction of pancreatic beta cells, requiring insulin injections.
- Type II (non-insulin-dependent diabetes mellitus): insulin resistance, often associated with obesity and physical inactivity.
- Symptoms: polyuria, polydipsia, polyphagia, and hyperglycemia.
Test your knowledge on the endocrine system with a focus on hypothalamus, pituitary gland, hormones, eicosanoids, and endocrine disorders. Explore cell communication mechanisms in both the endocrine and nervous systems as covered in Dr. Joseph Curione's lectures based on McCance-Heuther's chapter 21.
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