adrenal gland

Examples of adrenal gland in the following topics:

• Overview of the Adrenal Glands

  • In mammals, the adrenal glands (also known as the suprarenal glands) are endocrine glands that sit atop the kidneys.
  • In mammals, the adrenal glands (also known as the suprarenal glands) are endocrine glands that sit atop the kidneys.
  • In humans, the right adrenal gland is triangular shaped, while the left adrenal gland is semilunar shaped.
  • Each adrenal gland has two distinct structures, the outer adrenal cortex and the inner medulla—both produce hormones.
  • The adrenal glands are triangular-shaped organs on top of the kidneys.

• Adrenal Gland Disorders

  • Primary adrenal insufficiency is due to impairment of the adrenal glands.
  • Other cases are due to congenital adrenal hyperplasia or an adenoma (tumor) of the adrenal gland.
  • An example of second adrenal insufficiency syndrome can be caused by craniopharyngioma which is a benign tumor that can damage the pituitary gland causing the adrenal glands not to function.
  • The adrenal glands are triangular-shaped organs on top of the kidneys.
  • Evaluate the types of adrenal insufficiency that lead to adrenal gland disorders

• Adrenal Medulla

  • The adrenal cortex is devoted to the synthesis of corticosteroid and androgen hormones.
  • The adrenal medulla is the core of the adrenal glands, and is surrounded by the adrenal cortex.
  • The adrenal medulla is responsible for the production of catecholamines, derived from the amino acid tyrosine.
  • The adrenal medulla secretes approximately 20% noradrenaline (norepinephrine) and 80% adrenaline (epinephrine).
  • The adrenal medulla sits below the three layers of the adrenal cortex and is innervated by nerve fibers.

• Overview of the Endocrine System

  • The endocrine system is a system of ductless glands that secrete hormones—chemical messengers that are carried for long distances.
  • For example, the pineal gland, located at the base of the brain, secretes the hormone melatonin, responsible for regulating sleep patterns.
  • The endocrine system is in contrast to the exocrine system, which features ducted glands that secrete substances onto an epithelial surface; for example, a sweat gland.
  • The major endocrine glands include the pituitary, pineal, ovaries, testes, thyroid, hypothalamus and adrenal glands, additionally other tissues such as the kidney and liver also display secondary adrenal functions.
  • The endocrine systems found in the head and neck include the hypothalamus, pineal, pituitary and thyroid glands.

• Glandular Epithelia

  • There are two major classifications of glands: endocrine glands and exocrine glands.
  • Examples of exocrine glands include the sweat glands, salivary glands, mammary glands, the pancreas, and the liver.
  • An endocrine gland is its counterpart.
  • Examples of endocrine glands include the adrenal glands, located atop the kidneys and responsible for the secretion of certain hormones such as adrenaline, cortisol, and others.
  • The sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals.

• Pituitary Gland Disorders

  • Disorders of pituitary gland can affect hormones which regulate growth and activity of other glands in the body.
  • The pituitary is a "small, pea-sized gland" located at the base of the brain .
  • In response to the releasing hormone rate, the anterior pituitary produces its hormones (TSH, ACTH, LH, FSH, GH) that stimulate effector hormone glands in the body, although prolactin acts directly on the breast gland.
  • Adrenocorticotropic hormone (ACTH) deficiency leads to adrenal insufficiency, a lack of production of glucocorticoids such as cortisol by the adrenal gland.
  • ACTH deficiency is highly similar to primary Addison's disease, which is cortisol deficiency as the result of direct damage to the adrenal glands; the latter form, however, often leads to hyperpigmentation of the skin, which does not occur in ACTH deficiency.

• The Stress Response

  • The body's stress response is mediated by the sympathetic nervous system and the hypothalmic-pituitary-adrenal (HPA) axis.
  • The body's stress response is mediated by the interplay between the sympathetic nervous system (SNS) and the hypothalmic-pituitary-adrenal (HPA) axis.
  • A complex interaction of direct influences and indirect feedback mechanisms among the SNS, the hypothalmus, the pituitary gland and the adrenal glands contributes to the neuroendocrine regulation involved in reactions to stress.
  • This response is also referred to as the sympatho-adrenal response of the body owing to the fact that the preganglionic sympathetic fibers that end in the adrenal medulla secrete acetylcholine, which activates the release of adrenaline and noradrenaline from the medulla.
  • These two hormones regulate the anterior lobe of the pituitary gland and stimulate the release of adrenocorticotropic hormone (ACTH), also known as corticotropin.

• Adrenal Cortex

  • The adrenal cortex is devoted to the synthesis of corticosteroid and androgen hormones.
  • The primary glucocorticoid released by the adrenal gland in the human is cortisol and corticosterone in many other animals.
  • Its secretion is regulated by the hormone ACTH from the anterior pituitary gland.
  • The layers of the adrenal cortex are shown in this figure.
  • Differentiate among the zones (and hormones produced) of the adrenal cortex

• Overview of Endocrine Glands

  • A collection of endocrine glands makes up the endocrine system: the pituitary (anterior and posterior lobes), thyroid, parathyroid, adrenal (cortex and medulla), pancreas and gonads.
  • The pituitary gland consists of two major regions, the anterior pituitary gland (adenohypophysis) and the posterior pituitary gland (neurohypophysis).
  • There are four parathyroid glands, all located on the thyroid gland.
  • The adrenal glands are a pair of ductless glands located above the kidneys.
  • Differentiate among the types of endocrine glands (pituitary [posterior pituitary, anterior pituitary], thyroid, parathyroid, adrenal, and pancreas) in the endocrine system

• Control of the Pituitary Gland by the Hypothalamus

  • The pituitary gland consists of the anterior pituitary and the posterior pituitary.
  • Whilst the pituitary gland is known as the master endocrine gland, both of the lobes are under the control of the hypothalamus: the anterior pituitary receives its signals from the parvocellular neurons, and the posterior pituitary receives its signals from magnocellular neurons.
  • The anterior lobe of the pituitary receives hypothalamic-releasing hormones from the hypothalamus that bind with receptors on endocrine cells in the anterior pituitary that regulate the release of adrenal hormones into the circulatory system.
  • The posterior lobe of the pituitary gland develops as an extension of the hypothalamus.
  • The anterior and posterior lobes of the pituitary (hypophysis) gland are shown.