Endocrine System Overview

<p>Follicle-stimulating hormone (FSH) (A)</p> Signup and view all the answers

<p>Dopamine (DA) (D)</p> Signup and view all the answers

<p>Thyroid-stimulating hormone (TSH) (C)</p> Signup and view all the answers

<p>Stimulates secretion of testosterone (C)</p> Signup and view all the answers

<p>Adrenocorticotropic hormone (ACTH) (A)</p> Signup and view all the answers

<p>Increases overall basal metabolic rate (A)</p> Signup and view all the answers

<p>To integrate signals and convert them into chemical messages (D)</p> Signup and view all the answers

<p>Mineralocorticoids (C)</p> Signup and view all the answers

<p>Thyrotropin-releasing hormone (TRH) (D)</p> Signup and view all the answers

<p>Zona glomerulosa (D)</p> Signup and view all the answers

<p>Regulates urinary water loss and balance (C)</p> Signup and view all the answers

<p>By releasing hormones that directly stimulate it (B)</p> Signup and view all the answers

<p>Oxytocin (D)</p> Signup and view all the answers

<p>Catecholamines (A)</p> Signup and view all the answers

<p>Increases heart rate and myocardial contractility (D)</p> Signup and view all the answers

<p>Darkness and the suprachiasmatic nucleus (B)</p> Signup and view all the answers

<p>Tropic hormones (B)</p> Signup and view all the answers

<p>They prevent the release of certain hormones from the anterior pituitary (A)</p> Signup and view all the answers

<p>Control metabolism and stress adaptation (C)</p> Signup and view all the answers

<p>Thyroid gland (A)</p> Signup and view all the answers

<p>Regulates plasma volume (C)</p> Signup and view all the answers

<p>The hypothalamus (B)</p> Signup and view all the answers

<p>Biphasic effects on carbohydrate, fat, and protein metabolism (D)</p> Signup and view all the answers

<p>To stimulate the release of tropic hormones from the anterior pituitary (B)</p> Signup and view all the answers

<p>Secret calcitonin (A)</p> Signup and view all the answers

<p>Production of sex hormones (A)</p> Signup and view all the answers

<p>Uterine contractions during labor (C)</p> Signup and view all the answers

<p>Dopamine (B)</p> Signup and view all the answers

<p>Tiny and pinecone-shaped (C)</p> Signup and view all the answers

<p>Dihydrotestosterone (DHT) (D)</p> Signup and view all the answers

<p>Mediates cardio-protective effects (B)</p> Signup and view all the answers

<p>Promote maturation of reproductive organs (D)</p> Signup and view all the answers

<p>Luteal phase (C)</p> Signup and view all the answers

<p>Helps mediate sexual response in the brain (A)</p> Signup and view all the answers

<p>Increases rapidly (D)</p> Signup and view all the answers

<p>Increase bone density (B)</p> Signup and view all the answers

<p>Progesterone (A)</p> Signup and view all the answers

<p>To secrete hormones that regulate various bodily functions (C)</p> Signup and view all the answers

<p>Hormones are carried in the bloodstream to interact with distant target cells. (D)</p> Signup and view all the answers

<p>Peripheral endocrine glands (D)</p> Signup and view all the answers

<p>Enhanced physiological responses (C)</p> Signup and view all the answers

<p>Secreting hormones that affect distant targets (B)</p> Signup and view all the answers

<p>Hormones are released into the bloodstream to regulate distant target cells. (D)</p> Signup and view all the answers

<p>Neurons that release hormones into the bloodstream. (A)</p> Signup and view all the answers

<p>Reduced metabolic activity in target cells (C)</p> Signup and view all the answers

The endocrine system consists of specialized glands without ducts (ductless glands) and neurosecretory cells dispersed throughout the body.

Hormones are the biologically active chemical messengers produced and secreted by endocrine glands and neurosecretory cells.

Hormones travel through the bloodstream to reach distant target cells, initiating specific responses in these cells.

Hormones regulate various bodily functions like metabolism, growth, and reproduction.

Central endocrine glands are located within the central region of the body (e.g., pituitary, hypothalamus).

Peripheral endocrine glands are found in the extremities of the body (e.g., thyroid, pancreas).

Over-secretion of hormones can lead to excessive activity of target cells, leading to potential health issues.

Under-secretion of hormones can lead to insufficient activity of target cells, contributing to various disorders.

The hypothalamus is a region in the brain that acts as a control center for a variety of bodily functions including the endocrine system, behavior, and autonomic nervous system.

The hypothalamus receives signals from various parts of the brain and converts them into chemical messages (hormones) to regulate the release of hormones from the pituitary gland.

The pituitary gland, sometimes called the 'master gland', is located at the base of the brain and is responsible for releasing hormones that control other endocrine glands.

The anterior pituitary is the front lobe of the pituitary gland.

The hypothalamus secretes releasing hormones, which stimulate the anterior pituitary to release its own hormones.

The releasing hormones from the hypothalamus travel to the anterior pituitary, telling it to release specific tropic hormones into the bloodstream.

Tropic hormones are hormones that stimulate other endocrine glands to produce and release their hormones. They are released from the anterior pituitary.

The pituitary gland is located at the base of the brain and secretes hormones that control a wide range of bodily functions.

Vasopressin, also known as antidiuretic hormone (ADH), regulates the body's water balance by controlling how much water the kidneys reabsorb.

Oxytocin is a hormone that triggers contractions in the uterus during childbirth and stimulates milk release from the breasts during breastfeeding.

The pineal gland, located in the brain, secretes melatonin, a hormone that helps regulate the body's sleep-wake cycle.

The suprachiasmatic nucleus (SCN) in the hypothalamus acts as the body's master clock, influencing the production of melatonin by the pineal gland.

Melatonin production increases in darkness and decreases in light, helping to synchronize the body's internal rhythms with the 24-hour day-night cycle.

The thyroid gland, located in the neck, produces two iodine-containing hormones, T3 and T4, which regulate metabolism and energy production.

Follicular cells in the thyroid gland produce the thyroid hormones T3 and T4, while parafollicular cells, also known as C cells, release calcitonin, a hormone that regulates calcium levels in the blood.

Calcitonin is a hormone produced by the parafollicular cells of the thyroid gland, and it helps to lower blood calcium levels by promoting calcium deposition in bones.

Growth hormone (GH) is a peptide hormone produced by the anterior pituitary gland that plays a crucial role in promoting growth and development, particularly during childhood and adolescence.

GH secretion is regulated by various factors, including:

• Growth hormone-releasing hormone (GHRH) from the hypothalamus stimulates GH release.
• Somatostatin from the hypothalamus inhibits GH release.
• Ghrelin from the gastric fundus enhances GH secretion.

The function of growth hormone (GH) is multifaceted and crucial for growth and development. GH stimulates:

• Protein synthesis, promoting tissue growth.
• Lipolysis, breaking down fat for energy.
• Glucose sparing, reducing glucose utilization in tissues.

Thyroid-stimulating hormone (TSH) is secreted by the anterior pituitary gland. It controls the growth and function of the thyroid gland. TSH stimulates the release of thyroid hormones, crucial for metabolism and bodily functions.

Adrenocorticotropic hormone (ACTH) is another hormone released by the anterior pituitary gland. ACTH mainly controls the growth and function of the adrenal cortex. It stimulates cortisol production, which is critical for stress response and other vital functions.

Follicle-stimulating hormone (FSH) is a gonadotropin produced by the anterior pituitary gland. FSH plays a vital role in the reproductive system. In females, FSH stimulates follicle growth and estrogen production. In males, FSH stimulates spermatogenesis (sperm production).

Luteinizing hormone (LH) is another gonadotropin produced by the anterior pituitary gland. It plays a crucial role in both male and female reproductive processes. In females, LH triggers ovulation and the development of the corpus luteum, which produces progesterone. In males, LH stimulates testosterone production in the testes.

Prolactin (PRL) is a hormone produced by the anterior pituitary gland. PRL primarily plays a role in breast development during pregnancy and lactation. PRL stimulates milk production in the mammary glands.

Thyroid hormone (TH) increases the overall basal metabolic rate and heat production in the body, a process known as the 'calorigenic effect'.

TH has a biphasic influence on carbohydrate, fat, and protein metabolism, meaning it can both stimulate and inhibit different metabolic processes.

TH enhances cellular responsiveness to catecholamines, like adrenaline, by increasing the number of beta receptors on cells. This leads to increased heart rate and myocardial contractility.

The thyroid gland's secretion is controlled by a feedback loop involving the hypothalamus, pituitary gland, and thyroid itself.

The adrenal glands, situated on top of the kidneys, consist of two distinct parts: the outer adrenal cortex and the inner adrenal medulla.

The adrenal cortex secretes three categories of steroid hormones: mineralocorticoids (aldosterone), glucocorticoids (cortisol), and sex hormones (DHEA).

The adrenal medulla releases catecholamines, particularly adrenaline (epinephrine) and noradrenaline (norepinephrine), which are involved in the 'fight-or-flight' response.

The adrenal cortex is composed of three zones: zona glomerulosa, zona fasciculata, and zona reticularis, each responsible for producing specific steroid hormones.

Testosterone is a steroid hormone produced mainly by the Leydig cells of the testes. It plays a crucial role in the development and maintenance of male sexual characteristics, including the reproductive organs, secondary sex traits, and sexual drive.

Dihydrotestosterone (DHT) is a potent androgen hormone derived from testosterone. It is formed in target tissues like the prostate, skin, and hair follicles.

Testosterone production increases significantly during puberty, leading to the development of secondary male sexual characteristics like facial hair, deeper voice, and muscle growth.

Oestradiol, a type of estrogen, is the primary female sex hormone secreted by the granulosa cells of the ovarian follicle. It plays a key role in the development and maintenance of female reproductive organs and secondary sex characteristics.

Progesterone is a steroid hormone produced by the granulosa and theca cells of the ovarian follicle. It plays a crucial role in the female reproductive cycle, particularly during the luteal phase and pregnancy.

Oestradiol and progesterone work together to regulate the female reproductive cycle, supporting menstruation, pregnancy, and childbirth.

The male reproductive organs develop and mature under the influence of testosterone. These organs include the testes, epididymis, vas deferens, prostate, and seminal vesicles.

Oestradiol plays a critical role in the development and maintenance of female secondary sexual characteristics, including breasts, pubic hair, and a specific fat distribution pattern.