Endocrine System Quiz

Endocrine System

• The endocrine system is a collection of glands that produce hormones.
• Hormones are compounds produced in secretory tissues, transported in blood to target tissues. These changes in tissues are functional
• Hormones can be secreted by tissues like osteoblasts, adipocytes, and kidneys, not just glands. Hormone signals can occur outside the circulatory system (autocrine or paracrine effects)

Hormones

• Hormones are compounds; that are produced in secretory tissues and transported in the blood to target tissues, where they induce functional changes.
• Hormones can be produced by tissues other than glands (e.g., osteoblasts, adipocytes, kidneys), and the signal can occur outside the circulatory system (autocrine or paracrine effects).

Types of Signaling

• Autocrine signaling: hormones are secreted by a cell and act on the same cell.
• Paracrine signaling: hormones are secreted by a cell and act on a neighboring cell.
• Endocrine signaling: hormones are secreted by a cell, carried in the bloodstream to distant target cells

Hormone Classifications

• Steroids: Includes adrenal cortical hormones (e.g., corticosteroids), sex hormones (e.g., estrogen, progesterone, testosterone), and others
• Peptide hormones: Includes hormones from the pancreas (e.g., insulin, glucagon) and others
• Amino acid derivatives: Includes thyroid hormones (e.g., T3, T4), and other hormones
• Miscellaneous: Includes prostaglandins and cytokines (e.g., miscellaneous)

Hypothalamus

• The hypothalamus is a region of the brain regulating the endocrine system.

Vasopressin (ADH)

• Vasopressin (antidiuretic hormone), a nonapeptide, produced in the hypothalamus, plays a key role in osmotic balance, blood pressure, sodium homeostasis, and kidney function.
• ADH affects the kidneys' ability to reabsorb water, increase water reabsorption, and thus elevate blood pressure
• It acts on the kidney to increase water reabsorption, elevating blood pressure

Oxytocin

• Oxytocin, released from the posterior pituitary, plays a critical role in birth, breastfeeding, and social-emotional processes (empathy, trust, sexual activity, building relationships).
• Oxytocin also has anti-inflammatory and antioxidant properties influencing the autonomic nervous system and immune system

Pituitary Gland

• The pituitary gland, located near the hypothalamus, releases multiple hormones that regulate various bodily processes.
• This gland releases various hormones influencing the function of other glands.

Growth Hormone (GH)

• Human growth hormone (GH), also known as somatotropin, is a polypeptide produced in the anterior pituitary gland.
• GH production is a complex feedback mechanism; regulated by factors like stress, exercise, nutrition, and sleep. The primary factors include Growth hormone-releasing hormone (GHRH), somatostatin, and ghrelin
• GH has direct and indirect actions. Its direct effects involve binding to target cells and stimulating responses; indirect effects involve the stimulation of the activity of insulin-like growth factor-1 (IGF-1) which subsequently promotes a wide range cellular processes.

Thyroid Hormones

• Thyroid hormones influence every organ in the body, affecting heart function, the CNS, the autonomic nervous system, bone health, and digestive function.
• Thyroid hormones increase metabolic rate and body temperature.
• Thyroid hormones are lipophilic and circulate bound to transport proteins, with a tiny fraction being unbound and active.

Hyperthyroidism

• Hyperthyroidism, often caused by Graves' disease, involves overproduction of thyroid hormones (T3 and T4), leading to elevated T3/T4 levels and decreased TSH.

Graves' Disease

• Graves' disease is an autoimmune disease. It triggers thyroid gland growth and thyroid hormone release.
• In Graves' disease, antibodies activate orbital fibroblasts, increasing adipocyte proliferation and hyaluronic acid/glycosaminoglycan (GAG) production, leading to intraorbital fat and muscle tissue swelling.

Hypothyroidism

• Primary hypothyroidism is caused by reduced thyroid hormone production, resulting in elevated TSH.
• Secondary hypothyroidism is linked to pituitary gland issues, resulting in reduced TSH and T3/T4 levels.
• Tertiary hypothyroidism originates from hypothalamic dysfunction, leading to decreased TRH, TSH, and T3/T4 levels.

Hashimoto's Disease

• Autoimmune destruction of the thyroid gland, by CD8+ T-cells. Basal metabolic rate decreases, leading to symptoms like cold intolerance, weight gain, loss of appetite, hair loss, and dry skin. Other symptoms may include muscle stiffness, cramps, delayed deep tendon reflex relaxation and hoarseness.

Calcitonin

• A hormone decreasing blood calcium levels.
• Inhibits osteoclasts' action, increasing calcium excretion by the kidney.

Parathyroid Hormone (PTH)

• Parathyroid hormone (PTH) is secreted by chief cells in the parathyroid glands, crucial for maintaining normal calcium levels.
• In the kidneys, it plays a role in the synthesis of active vitamin D and calcitriol.
• PTH increases calcium reabsorption in the kidneys and decreases phosphate reabsorption, decreasing blood phosphate ions.

Prolactin

• A polypeptide hormone involved in lactation and breast development
• Release is regulated through negative feedback from dopamine and self-regulating mechanisms promoting dopamine release.

Pancreatic Hormones

• Pancreatic hormones, particularly insulin, play critical roles in glucose metabolism, influencing glucose uptake, appetite control, neuroprotection, and lipid metabolism.

Insulin Effects

• Insulin's effects vary across tissues.
• It facilitates glucose uptake, glycogen synthesis, amino acid uptake, protein synthesis, and K+/ketone uptake in adipose tissue and muscles.
• It increases protein synthesis and decreases ketone and glucose output in the liver.
• Lastly, insulin promotes cell growth throughout the entire body.

Diabetes

• Different forms of diabetes exist, each with varying causes and effects. Type 1 diabetes results from insulin deficiency, while Type 2 diabetes involves insulin resistance in the body.
• Gestational diabetes develops during pregnancy, and MODY (maturity-onset diabetes of the young) occurs in adults younger than 25, caused by genetic variations.

Diabetes Complications

• Diabetes complications affect various systems (e.g., nervous, cardiovascular, renal, eye) resulting in complications like stroke, heart attack, diabetic neuropathy, diabetic nephropathy, diabetic foot, and retinopathy.

Glucagon

• Glucagon effects on brain, heart, liver, GI tract, pancreas, brown adipose tissue, and heart, influencing appetite, energy expenditure, and body weight. It increases glucose production, breakdown of glycogen and lipids, and synthesis of ketones.

Adrenal Glands

• Adrenal glands are located near the kidneys, with a cortex and a medulla.
• Cortisol, aldosterone, epinephrine, and norepinephrine are produced in the adrenal glands.

Adrenal Hormones

• The adrenal hormones include glucocorticoids (cortisol), mineralocorticoids (aldosterone), and catecholamines (epinephrine and norepinephrine).
• These hormones regulate various bodily functions such as metabolism, salt and water balance, and stress response.

Catecholamines

• Catecholamines, including adrenaline and noradrenaline, primarily arise from dopamine, a crucial precursor.
• Released in response to stress, exercise, cold, and reduced blood sugar, catecholamines increase glycogen and triglycerides breakdown.
• They also impact heart contractility, blood pressure, and smooth muscle relaxation in the respiratory system.

Glucocorticoids

• Glucocorticoids, like cortisol, are steroid hormones synthesized by the adrenal glands, following a circadian pattern and in response to stress and other physiological stimuli.
• Primarily working in an inactive form bound to binding globulins or albumin, they play vital roles in mediating stress responses.

Aldosterone

• Aldosterone is a mineralocorticoid hormone that regulates salt and water balances in the body, particularly in the kidneys.
• Acts in the nephrons, impacting sodium and water reabsorption, and potassium/ and therefore influencing blood volume and blood pressure.

Test your knowledge on the endocrine system, focusing on key hormones such as insulin-like growth factor-1 (IGF-1), thyroid hormones, and human growth hormone (HGH). This quiz covers their effects on metabolic rate, glucose metabolism, and various related conditions like hyperthyroidism and Graves' disease.