Đề thi, bài tập trắc nghiệm online Sinh lý nội tiết – Đề 13

Insulin, a peptide hormone, binds to cell surface receptors and utilizes second messenger systems (like the cAMP or IP3∕DAG pathways) to transduce its signal within the cell. Steroid hormones like cortisol and estrogen, and thyroid hormones like thyroxine, typically bind to intracellular receptors and directly influence gene expression.

Progesterone, primarily produced by the corpus luteum in the ovary after ovulation, is crucial for the secretory phase of the menstrual cycle. It causes the uterine lining (endometrium) to thicken and become receptive to implantation of a fertilized egg.

A surge in Luteinizing Hormone (LH) from the anterior pituitary triggers ovulation, the release of an egg from the ovary.

Thyroid hormones are crucial regulators of metabolism. They increase the basal metabolic rate (BMR), which is the rate at which the body uses energy at rest. This leads to increased oxygen consumption and heat production (thermogenesis).

The pineal gland, located in the brain, is responsible for producing melatonin. Melatonin secretion is influenced by light exposure and plays a key role in regulating circadian rhythms, including sleep-wake cycles.

Cushing′s syndrome, characterized by excess cortisol, often leads to increased appetite and weight gain, particularly in the central body (trunk) and face (moon face). Other symptoms include muscle weakness, skin changes, and elevated blood glucose levels.

Acromegaly, caused by GH excess in adults (after epiphyseal plates have closed), leads to disproportionate growth, particularly in cartilaginous tissues and bones of the hands, feet, and face, resulting in enlarged features.

The adrenal cortex primarily produces steroid hormones like cortisol and aldosterone. The adrenal medulla produces catecholamines like epinephrine and norepinephrine in response to sympathetic nervous system stimulation.

Epinephrine (adrenaline), secreted by the adrenal medulla, is the primary hormone responsible for mediating the 'fight or flight′ response to stress. It causes a rapid increase in heart rate, blood pressure, and blood glucose levels.

Melatonin, produced by the pineal gland, is a key hormone in regulating circadian rhythms, the body′s natural sleep-wake cycle. Its secretion is influenced by light and darkness, with levels typically rising in the evening to promote sleepiness.

Aldosterone, produced by the adrenal cortex, is a key component of the RAAS. Its primary effect is to increase sodium reabsorption in the kidneys, which also leads to water retention, and to promote potassium secretion into the urine. These actions contribute to increasing blood volume and blood pressure.

Epinephrine (adrenaline) and norepinephrine (noradrenaline), catecholamine hormones produced by the adrenal medulla, are derivatives of the amino acid tyrosine. Thyroid hormones (T3 and T4) are also tyrosine derivatives. Cortisol and aldosterone are steroid hormones derived from cholesterol; insulin is a peptide hormone.

Antidiuretic hormone (ADH) acts on the kidneys to increase water reabsorption from the kidney tubules back into the bloodstream. This reduces urine volume and helps to conserve body water, especially in cases of dehydration.

Parathyroid hormone (PTH) is the primary hormone responsible for increasing blood calcium levels. It acts on bones to release calcium, kidneys to reabsorb calcium, and indirectly on the intestines to increase calcium absorption.

Hormones exert their effects by binding to specific receptors located on the cell surface or within the cytoplasm or nucleus of target cells. This binding initiates a cascade of intracellular events leading to the cellular response.

Cortisol, a glucocorticoid hormone from the adrenal cortex, has multiple functions, including increasing blood glucose levels through gluconeogenesis, suppressing the immune system, and playing a role in stress response.

Steroid hormones are lipid-soluble and can diffuse across the plasma membrane to bind with intracellular receptors. Peptide hormones are water-soluble and generally bind to receptors on the cell surface, initiating signaling cascades inside the cell.

The hypothalamus controls the anterior pituitary by secreting releasing and inhibiting hormones into the hypophyseal portal system. These hormones travel directly to the anterior pituitary and regulate the secretion of anterior pituitary hormones.

Leptin is a hormone produced by fat cells that signals the brain about the body′s energy stores. Higher levels of leptin typically indicate sufficient energy reserves, leading to reduced appetite and increased energy expenditure, thus playing a role in long-term energy balance and preventing obesity.

Addison′s disease, due to adrenal insufficiency, results in deficiencies of cortisol and aldosterone. Symptoms include hypotension (low blood pressure), fatigue, muscle weakness, weight loss, and characteristic hyperpigmentation of the skin due to increased ACTH and melanocyte-stimulating hormone (MSH).

Increased thyroid hormone levels exert negative feedback on the hypothalamus and anterior pituitary, reducing the release of TRH and TSH respectively. This mechanism helps to prevent excessive thyroid hormone production.

Endocrine glands are ductless glands that secrete hormones directly into the bloodstream, allowing hormones to travel throughout the body to target cells. Exocrine glands secrete their products into ducts that lead to specific locations, such as the surface of the skin or the lumen of the digestive tract.

Glucagon is released when blood glucose levels are low. It acts primarily on the liver to stimulate the breakdown of glycogen (glycogenolysis) and the synthesis of glucose from non-carbohydrate sources (gluconeogenesis), thereby increasing blood glucose levels.

Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland. The anterior pituitary gland secretes hormones such as Growth Hormone (GH), Prolactin (PRL), Thyroid-Stimulating Hormone (TSH), Adrenocorticotropic Hormone (ACTH), Luteinizing Hormone (LH), and Follicle-Stimulating Hormone (FSH).

Testosterone, an androgen produced primarily by the testes, is the main hormone responsible for the development of secondary sexual characteristics in males during puberty.

Thyroid-stimulating hormone (TSH), secreted by the anterior pituitary, specifically targets the thyroid gland. TSH stimulates the thyroid gland to produce and release thyroid hormones (T3 and T4).

Prolactin (PRL), secreted by the anterior pituitary gland, primarily functions to stimulate milk production (lactation) in the mammary glands after childbirth. It also plays roles in reproductive function and immune regulation.

Type 1 diabetes is an autoimmune disease where the body′s immune system mistakenly attacks and destroys the insulin-producing beta cells in the pancreas. This results in a severe deficiency or absence of insulin production.

The liver is a major target tissue for GH. GH stimulates the liver to produce Insulin-like Growth Factor-1 (IGF-1), which mediates many of the growth-promoting effects of GH on various tissues including bone, muscle, and cartilage.

The endocrine system primarily uses chemical signals (hormones) for slower, sustained responses. Rapid responses to environmental stimuli via electrical signals are primarily the function of the nervous system.