Đề thi, bài tập trắc nghiệm online Sinh lý nội tiết – Đề 1

PTH primarily targets the kidneys and bones to increase blood calcium levels. In the kidneys, PTH stimulates calcium reabsorption and the production of calcitriol (active vitamin D), which further enhances calcium absorption in the intestines.

Melatonin, produced by the pineal gland, is primarily involved in regulating circadian rhythms, the body′s natural sleep-wake cycle. Its secretion is influenced by light exposure and is highest at night.

Hormones are primarily classified into three major classes based on their chemical structure: peptide hormones, steroid hormones, and amine hormones. Carbohydrate hormones are not a recognized major class of hormones.

Calcitonin is a hormone produced by the thyroid gland that acts to decrease blood calcium levels. It primarily does this by inhibiting osteoclast activity (reducing bone breakdown) and promoting calcium deposition in bones.

Steroid and thyroid hormones, being lipid-soluble, can cross the cell membrane and bind to intracellular receptors. This hormone-receptor complex then directly interacts with DNA to influence gene transcription, leading to direct gene activation.

The adrenal cortex is divided into three zones. The zona fasciculata is the middle layer and is primarily responsible for producing glucocorticoids, with cortisol being the main glucocorticoid in humans.

Aldosterone′s main function is to regulate sodium and potassium balance in the body. It acts on the kidneys to increase sodium reabsorption and potassium excretion, thereby influencing blood volume and blood pressure.

The adrenal medulla is the inner part of the adrenal gland and is responsible for producing catecholamines, primarily epinephrine (adrenaline) and norepinephrine (noradrenaline). These hormones are involved in the 'fight-or-flight′ response to stress.

Estrogens, primarily estradiol, are the main female sex hormones. They are responsible for the development of secondary sexual characteristics in females, such as breast development, widening of hips, and changes in fat distribution.

Peptide hormones are water-soluble and cannot easily cross the cell membrane. They exert their effects by binding to receptors on the cell surface. This binding activates intracellular second messenger systems, like cAMP or calcium, which then mediate the hormone′s effects within the cell.

Steroid hormones are lipid-soluble and can enter cells to act on intracellular receptors, leading to slower but more sustained effects. Peptide hormones are water-soluble and act on cell surface receptors, generally resulting in faster but shorter-lived effects.

Steroid hormones, including cortisol, aldosterone, estrogen, progesterone, and testosterone, are all derived from cholesterol. Insulin and growth hormone are peptide hormones, and epinephrine is an amine hormone derived from tyrosine.

Thyrotropin-releasing hormone (TRH) is released by the hypothalamus and travels to the anterior pituitary, where it stimulates the release of thyroid-stimulating hormone (TSH). TSH then acts on the thyroid gland to stimulate thyroid hormone production.

Hyperthyroidism, or overactive thyroid, is characterized by excessive thyroid hormone production. Common symptoms include heat intolerance, weight loss, increased heart rate (tachycardia), anxiety, and tremors.

Cortisol, a glucocorticoid hormone released by the adrenal cortex in response to stress, is often referred to as the 'stress hormone′. It plays a key role in the body′s response to stress by mobilizing energy stores and suppressing inflammation.

Glucagon is secreted by the pancreas in response to low blood glucose levels. Its primary effect is to raise blood glucose by stimulating gluconeogenesis (glucose production from non-carbohydrate sources) and glycogenolysis (breakdown of glycogen into glucose) in the liver.

Acromegaly is a disorder caused by chronic hypersecretion of growth hormone (GH) in adults, typically due to a pituitary tumor. It leads to excessive growth of bones and soft tissues, particularly in the hands, feet, and face.

Antidiuretic hormone (ADH), also known as vasopressin, is released in response to dehydration or increased blood osmolarity. Its primary function is to increase water reabsorption in the kidneys, reducing urine volume and conserving body water.

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 leads to an absolute deficiency of insulin.

The endocrine system uses hormones released into the bloodstream to communicate, leading to slower but more sustained responses compared to the nervous system, which uses rapid electrical and chemical signals for communication and faster, shorter-lasting effects.

Growth hormone promotes lipolysis, the breakdown of fats, to provide energy for growth. It also stimulates protein synthesis and bone growth, and it is a counter-regulatory hormone to insulin, increasing blood glucose levels.

The anterior pituitary gland secretes FSH, LH, prolactin, growth hormone (GH), adrenocorticotropic hormone (ACTH), and thyroid-stimulating hormone (TSH). Antidiuretic hormone (ADH) is secreted by the posterior pituitary gland.

Leptin is secreted by adipose tissue in proportion to body fat stores. It acts on the hypothalamus to suppress appetite and increase energy expenditure, thus playing a key role in long-term regulation of energy balance and body weight.

The RAAS is activated in response to low blood pressure or decreased blood volume. The kidneys release renin, initiating a cascade of hormonal events that ultimately lead to increased blood pressure and sodium∕water retention.

Oxytocin, released from the posterior pituitary, plays a critical role in both childbirth and breastfeeding. It stimulates uterine contractions during labor and triggers the 'milk let-down′ reflex during breastfeeding by causing contraction of myoepithelial cells in the mammary glands.

The posterior pituitary gland stores and releases two hormones that are produced in the hypothalamus: antidiuretic hormone (ADH) and oxytocin. The anterior pituitary produces and releases GH, ACTH, prolactin, and other hormones.

In females, luteinizing hormone (LH) primarily targets the ovaries. It stimulates ovulation and the development of the corpus luteum, which then produces progesterone. LH also plays a role in estrogen production in the ovaries.

In males, follicle-stimulating hormone (FSH) primarily targets the Sertoli cells in the testes and is essential for spermatogenesis, the process of sperm production. Luteinizing hormone (LH) in males stimulates testosterone production.

Cushing′s syndrome, also known as hypercortisolism, is caused by prolonged exposure to high levels of cortisol. This can result from various factors, including adrenal tumors, pituitary tumors (Cushing′s disease), or long-term use of glucocorticoid medications.

Negative feedback loops work to oppose the initial stimulus. In the thyroid hormone feedback loop, increased levels of thyroid hormones (T3 and T4) inhibit the release of TRH from the hypothalamus and TSH from the anterior pituitary, thus reducing further thyroid hormone production.