adrenal cortex

Examples of adrenal cortex in the following topics:

• 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.

• Adrenal Glands

  • The adrenal glands consist of an outer adrenal cortex and an inner adrenal medulla, which secrete different hormones.
  • Androgens are produced in small amounts by the adrenal cortex in both males and females.
  • The hormones made by the adrenal cortex supply long-term responses to stress.
  • These glands are composed of the adrenal cortex and the adrenal medulla.
  • Distinguish between the hormones produced by the adrenal cortex and adrenal medulla and the functions they regulate

• Adrenal Cortex

  • The adrenal cortex is devoted to the synthesis of corticosteroid and androgen hormones.
  • The adrenal cortex comprises three zones, or layers: Zona glomerulosa (outer), Zona fasciculata and Zona reticularis.
  • Androstenedione (Andro): an androgenic steroid produced by the testes, adrenal cortex, and ovaries.
  • The layers of the adrenal cortex are shown in this figure.
  • Differentiate among the zones (and hormones produced) of the adrenal cortex

• Other Hormonal Controls for Osmoregulation

  • The renin-angiotensin-aldosterone system (RAAS) stabilizes blood pressure and volume via the kidneys, liver, and adrenal cortex.
  • Angiotensin II raises blood pressure by constricting blood vessels and also triggers the release of the mineralocorticoid aldosterone from the adrenal cortex.
  • Mineralocorticoids are hormones synthesized by the adrenal cortex that affect osmotic balance.
  • Patients who have Addison's disease have a failing adrenal cortex and cannot produce aldosterone.

• 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 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 cortex mainly produces mineralcorticoids, glucocorticoids, and androgens, while the medulla chiefly produces adrenaline and nor-adrenaline.
  • The adrenal glands are triangular-shaped organs on top of the kidneys.

• Hormonal Regulation of Stress

  • The adrenal glands respond to either short-term or long-term stressors by releasing different hormones that act differently on the body.
  • Stressful stimuli cause the hypothalamus to signal the adrenal medulla (which mediates short-term stress responses) via nerve impulses, and the adrenal cortex, which mediates long-term stress responses via the hormone adrenocorticotropic hormone (ACTH), which is produced by the anterior pituitary.
  • The hormones epinephrine (also known as adrenaline) and norepinephrine (also known as noradrenaline) are released by the adrenal medulla.
  • The adrenal cortex is stimulated by ACTH to release steroid hormones called corticosteroids.
  • Describe the role of the adrenal glands in the "fight-or-flight" response and the body's reaction to stress

• 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.
  • 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.
  • ACTH acts on the adrenal cortices that produce glucocorticoid hormones, like cortisol, which is a stress hormone that exerts many effects throughout the body.
  • ACTH is then transported through the circulatory system to the adrenal cortex where it promotes the biosynthesis of corticosteroids like cortisol and cholesterol.

• The Endocrine System and Stress

  • The hypothalamic-pituitary-adrenal (HPA or HTPA) axis is a complex set of direct influences and steroid-producing feedback interactions among the hypothalamus, the pituitary gland, and the adrenal glands.
  • The ACTH acts on the adrenal cortex, which produces steroids—in humans, primarily the steroid cortisol.
  • This causes a negative feedback cycle in which the steroids inhibit the hypothalamus and the pituitary gland, and it also causes the adrenal gland to produce the hormones epinephrine (also known as adrenaline) and norepinephrine.

• Congenital Adrenal Hyperplasia

  • Congenital adrenal hyperplasia refers to an autosomal recessive disease caused by mutated genes for enzymes that produce cortisol from cholesterol.
  • Congenital adrenal hyperplasia (CAH) refers to any of several autosomal recessive diseases resulting from mutations of genes for enzymes mediating the biochemical steps of production of cortisol from cholesterol by the adrenal glands (steroidogenesis).
  • Cortisol is an adrenal steroid hormone that is required for normal endocrine function.
  • Inefficient cortisol production results in rising levels of ACTH, which in turn induces overgrowth (hyperplasia) and overactivity of the steroid-producing cells of the adrenal cortex.
  • The defects causing adrenal hyperplasia are congenital (i.e., present at birth).

• Adrenal Gland Disorders

  • Addison's disease and congenital adrenal hyperplasia can manifest as adrenal insufficiency.
  • 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.
  • For chronic adrenal insufficiency, the major contributors are autoimmune adrenalitis, tuberculosis, AIDS, and metastatic disease.
  • Evaluate the types of adrenal insufficiency that lead to adrenal gland disorders