Lecture 26-Endocrine System II - organs & disorders II

(a) ADH=Anti-Diuretic Hormone; (b) vasopressin, because it produces vasoconstriction (decrease blood vessels diameter through vascular smooth cell contraction)

(a) ADH=Anti-Diuretic Hormone; (b) vasopressin, because it produces vasoconstriction (decrease blood vessels diameter through vascular smooth cell contraction)

(a) What does ADH stand for?, (b) is there an alternative name for it? (if so, why is called like that?)

What are the organs responsible for the production and release of ADH? ?

(a) "against excessive urine production", prevents making too much urine; (b) ADH

(a) What does anti-diuresis mean? (b) which hormone induces this effect? ?

(a) An increase in blood osmolality (hemoconcentration), caused for example by excessive sweating.(b) Restore the water lost during physical activity.

(a) What triggers the secretion of ADH, and (b) what is the significance of its release during or after a workout?

Blood sodium levels increases, plasma volume (water) decrease (which decreases blood pressure), dry skin.

In diabetes insipidus, does the concentration of sodium in the blood increase or decrease, and what about water volume, blood pressure, and skin condition?

Central: decreased production or secretion of ADH. Nephrogenic: failure of kidneys to respond to ADH.

What is the difference between central and nephrogenic diabetes insipidus?

(a) Syndrome of inappropriate ADH secretion. (b) Excessive ADH production. (c) High plasma volume (water, which increases blood pressure), sticky thick urine, low blood sodium (is diluted), seizures (due to ions concentration changes)

(a) What does SIADH stand for? (b) What causes it? (c) What are the main symptoms of this disorder?

(a) Adrenal cortex and adrenal medulla (inside). (b) Glomerulosa, fasciculata, and reticularis.

(a) What are the two components of the adrenal gland? (b) and the three layers (or zones) of the adrenal cortex?

Zona glomerulosa: mineralocorticoids such as aldosterone. Zona fasciculata: glucocorticoids (mostly cortisol). They are collectively known as corticosteroids.

What are the hormones produced by the zona glomerulosa and zona fasciculata, and what collective term is used for these hormones?

Androgens, mostly DHEA. Require peripheral conversion (in other organs such as gonads) to active sex steroids (Testosterone & Dihydrotestosterone) .

Which hormones are secreted by the zona reticularis, and are they active?

Dehydroepiandrosterone

What does DHEA stand for?

Catecholamines, mostly epinephrine but also norepinephrine and dopamine. By Chromaffin cells (sympathetic postganglionic neurons, without dendrites or axon= neuroendocrine cells)

What hormones are releases by the adrenal medulla? by which cells?

Benign tumor affecting the chromaffin cells of the adrenal medulla in which there is an increase in the production of catecholamines.

What does pheochromocytoma refer to?

Aldosterone stimulates the kidneys to retain sodium. Water is retained with it by osmosis. Increase blood pressure (BP)

What is the main function of aldosterone and what is the impact on blood pressure?

it increases protein degradation in muscle (catabolism) to use the aminoacids to form glucose (stimulates gluconeogenesis in liver). Decrease glucose uptake by muscle, increase abdominal fat (fat deposition in abdomen) although increase lipolysis in other peripheral fat. As overal effect, it will produce hyperglycemia.

What are the metabolic effects of cortisol on muscle, liver, and adipose tissue?

By the hypothalamic-pituitary-adrenal (HPA) axis. CRH from hypothalamus stimulates the release of ACTH by the anterior pituitary gland which in turn stimulates the adrenal gland to produce cortisol

How is cortisol secretion regulated? What does the HPA axis stand for?

(a) ACTH. (b) They have very low biological activity, in many tissues (such as gonads) they are transformed into testosterone and dihydrotestosterone (more potent forms)

(a) Which hormone regulates the secretion of adrenal androgens, (b) are they biologically active? If not, what are the active forms and where are they formed?

Adrenarche occurs first, marking the maturation of the adrenal glands and an increase in adrenal androgens. Gonadarche follows, signaling the activation of the gonads and the production of sex hormones

Define adrenarche and gonadarche and specify which occurs first

Fetus: Prenatal development of male reproductive tract. At puberty: stimulation of growth of pubic and axillary hair and their associated apocrine sweat glands

What are the main functions of adrenal androgens in the fetus and at puberty?

(a) The development of masculine physical traits in females. (b) Excessive adrenal androgens production in women.

(a) What is virilization? (b) what can cause it?

Estradiol. After menopause (since the ovaries no longer function properly).

What is the primary adrenal estrogen, and when in life is this estrogen source important?

Increase in the levels of cortisol.

Cushing's syndrome is attributed to alterations in the levels of which hormone?

Adrenogenital syndrome= congenital adrenal hyperplasia- hypersecretion of DHEA (caused by increased ACTH levels produced by compensatory mechanisms due to insufficient cortisol production). Primary adrenal insufficiency=Addison's disease- Hyposecretion of adrenocortical hormones.

Can you provide alternative names for adrenogenital syndrome and primary adrenal insufficiency, along with their causes?

(a) Sleeping, stress (physical and emotional), hypoglycemia, the hormone ghrelin [which increase levels of GHRH] (b) Aging and carbohydrates. Also by negative feedback, IGF-1 and GH

(a) Which stimuli triggers GH release from the anterior pituitary gland? (b) which stimuli inhibits GH release?

Glucose-sparing effects: increases lipolysis (fats are broken down to serve as source of energy); and decreases glucose uptake by adipocytes.

What are the effects on GH in adipose tissue?

Diabetogenic effects: increases glucosa production; also GH induces the liver to secrete growth stimulants called insulin-like growth factors (IGF-I).

What are the effects on GH in the liver?

By promoting cellular growth and proliferation, as well as enhancing bone length and muscle mass through the stimulation of protein synthesis and the transport of amino acids into cells for protein production

How does GH exert its growth effects?

Growth stimulants: insulin-like growth factor I (IGF-I).They are produced by tissues such as liver in response to GH. IGF-I has growth effects similar to GH and prolongs GH action.

What is IGF1 and what is its relationship with GH?

(a) Gigantism, pituitary dwarfism, and acromegaly. (b) Gigantism and acromegaly.

(a) What disorders are related to GH?, (b)which two are associated with hypersecretion of that hormone?

(a) Hypersecretion of GH in childhood or adolescence, before the epiphyseal plates (growth zones) of the long bones are depleted. (b) Chidhood GH hyposecretion

(a) What produces gigantism. (b) What hormone alteration leads to pituitary dwarfism and how does it manifest?

(a) Acromegaly. (b) Gigantism.

(a) What does GH hypersecretion in adulthood, after the epiphysial plates of bones have closed, produce? (b) and during childhood before closing?

It describes the body's response to stress and consists of three stages: alarm, resistance, and exhaustion.

What does the term "general adaptation syndrome" refer to? What are its three stages?

Fight-or-flight response, the goal is to mobilize resources (energy) to deal with the stressful stimulus. Acute short-term intense response. Neural and neuroendocrine pathways

What distinguishes the alarm stage? (nature of the response, duration, key players)

Higher metabolic level (more energy needed to cope with stressor); chronic long-term, less-intense response. HPA-Corticoid axis.

What distinguishes the resistance stage? (nature of the response, duration, key players)

Prolonged exposure to the stressor will result in the depletion of the body’s resources (energy) and, later on, death.

What characterizes the exhaustion state?

(a) Alarm, (b) resistance, (c) exhaustion

(a) In which stage does the fight or flight response take place? (b) In which stage does the HPA-corticoid axis play an important role in coping with the stressor? (c) In which stage are energy reserves depleted?

The stored glycogen as be depleted during the alarm state. It will increase gluconeogenesis (synthesis of glucose from amino acids and fats)

During the long-term body adjustment to stress (resistance stage), why does the system seek to provide alternative fuels to glycogen for metabolism, and how is this achieved?

Cortisol, long-term adjustment or resistance stage.

What is the main adrenal cortex hormone related to the stress response, and in which stage are its actions most prominent?

Epinephrine and norepinephrine.

Which hormones secreted by the adrenal medulla play an important role during the short-term response to stress?

Neural- through sympathetic innervation of organs (ANS) (releasing neurotransmitters, mostly norepinephrine); neuroendocrine- through the release of epinephrine and norepinephrine from the adrenal glands (acting as hormones)

Which neural and neuroendocrine pathways are activated during the alarm stage?

(a) Ergocalciferol (vitamin D2), cholecalciferol (vitamin D3). (b) 1,25-dihydroxyvitamin D

(a) What are the alternative names for vitamin D2 and vitamin D3? (b) What constitutes the active form of vitamin D?

Skin, liver, and kidneys.

Which organs are involved in the biosynthetic pathway of vitamin D?

Skin: formation of cholecalciferol (with help of UV rays); liver: transformation into 25-hydroxyvitamin D; kidneys: transformation into 1,25-dihydroxyvitamin D

Can you sequence the pathway of vitamin D formation, starting from the skin and culminating in its active form produced in the kidneys?

7-dehydrocholesterol

Which molecule in the skin serves as a precursor for vitamin D (cholecalciferol) synthesis and is derived from skin cholesterol?

Cholecalciferol is a form of vitamin D, specifically vitamin D3. It is one of several forms of vitamin D that the body can produce or obtain from dietary sources.The skin synthesizes cholecalciferol when exposed to ultraviolet B (UVB) radiation from the sun

What is cholecalciferol?

(a) 25-hydroxyvitamin D, in the liver. (b) In the kidneys.

(a) What is the predominant circulating form of vitamin D, and where is it produced? (b) Where does the production of 1,25 dihydroxyvitamin D occur?

Erythropoietin (EPO); in the liver and kidneys.

What is the full name of EPO, and which organs secrete it?

It stimulates the red bone marrow to produce erythrocytes (red blood cells)

What is the primary function of EPO?