adrenocorticotropic hormone

Examples of adrenocorticotropic hormone in the following topics:

• Epinephrine and Norepinephrine

  • As a hormone and neurotransmitter, epinephrine acts on nearly all body tissues.
  • Binding to α-adrenergic receptors inhibits insulin secretion by the pancreas, stimulates glycogenolysis (the breakdown of glycogen) in the liver and muscle, and stimulates glycolysis (the metabolic pathway that converts glucose into pyruvate) in muscle. β-Adrenergic receptor binding triggers glucagon secretion in the pancreas, increased adrenocorticotropic hormone (ACTH) secretion by the pituitary gland, and increased lipolysis by adipose tissue.
  • It is the hormone and neurotransmitter most responsible for vigilant concentration in contrast to its most-chemically-similar hormone, dopamine, which is most responsible for cognitive alertness.
  • They are the flight/fight hormones that are released when the body is under extreme stress.
  • These hormones go one step further and trigger the renin-angiotensin-aldosterone system, the hormone system that regulates blood pressure and water (fluid) imbalance.

• Hypothalamic-Pituitary Axis

  • The anterior pituitary produces seven hormones: growth hormone (GH), prolactin (PRL), thyroid-stimulating hormone (TSH), melanin-stimulating hormone (MSH), adrenocorticotropic hormone (ACTH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH).
  • Anterior pituitary hormones are sometimes referred to as tropic hormones because they control the functioning of other organs.
  • While these hormones are produced by the anterior pituitary, their production is controlled by regulatory hormones produced by the hypothalamus.
  • These regulatory hormones can be releasing hormones or inhibiting hormones, causing more or less of the anterior pituitary hormones to be secreted.
  • Negative feedback then regulates how much of these regulatory hormones are released and how much anterior pituitary hormone is secreted.

• Hormonal Regulation of Stress

  • 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.
  • Interactions of the endocrine hormones have evolved to ensure the body's internal environment remains stable.
  • Instead, other hormones come into play.
  • The adrenal cortex is stimulated by ACTH to release steroid hormones called corticosteroids.
  • These hormones target the breakdown of fat into fatty acids in the adipose tissue.

• Lipid-Derived, Amino Acid-Derived, and Peptide Hormones

  • All hormones in the human body can be divided into lipid-derived, amino acid-derived, and peptide hormones.
  • One of the key, distinguishing features of lipid-derived hormones is that they can diffuse across plasma membranes whereas the amino acid-derived and peptide hormones cannot.
  • The primary class of lipid hormones in humans is the steroid hormones.
  • Examples of steroid hormones include estradiol, which is an estrogen, or female sex hormone, and testosterone, which is an androgen, or male sex hormone.
  • The structures of peptide hormones (a) oxytocin, (b) growth hormone, and (c) follicle-stimulating hormone are shown.

• Humoral, Hormonal, and Neural Stimuli

  • The release of hormones can be triggered by changes in the blood ("humor"), by the actions of other hormones, or by neurological stimuli.
  • Hormonal stimuli refers to the release of a hormone in response to another hormone.
  • A number of endocrine glands release hormones when stimulated by hormones released by other endocrine glands.
  • The anterior pituitary, in turn, releases hormones that regulate hormone production by other endocrine glands.
  • The hypothalamus stimulates the anterior pituitary gland, via hormones, to release thyroid-stimulating hormone (TSH).

• How Hormones Work

  • Hormones are chemical messengers that relay messages to cells that display specific receptors for each hormone and respond to the signal.
  • All multicellular organisms produce hormones; plant hormones are also called phytohormones.
  • Hormones mediate changes in target cells by binding to specific hormone receptors.
  • Cells can have many receptors for the same hormone, but often also possess receptors for different types of hormones.
  • Cells respond to a hormone when they express a specific receptor for that hormone.

• Plasma Membrane Hormone Receptors

  • Amino acid-derived hormones and polypeptide hormones are not lipid-derived (lipid-soluble or fat-soluble); therefore, they cannot diffuse through the plasma membrane of cells.
  • Lipid-insoluble hormones bind to receptors on the outer surface of the plasma membrane, via plasma membrane hormone receptors.
  • Unlike steroid hormones, lipid-insoluble hormones do not directly affect the target cell because they cannot enter the cell and act directly on DNA.
  • The effect of a hormone is amplified as the signaling pathway progresses.
  • Describe the events that occur when a hormone binds to a plasma hormone receptor

• Hormone Functions

  • The endocrine system plays a role in growth, metabolism, and other processes by releasing hormones into the blood.
  • An animal's endocrine system controls body processes through the production, secretion, and regulation of hormones.
  • Target cells, those having a receptor for a signal, respond to a hormone when they express a specific receptor for that hormone.
  • Different tissue types may also respond differently to the same hormonal signal.
  • By releasing hormones, the endocrine system plays a role in growth, metabolism, and sexual development.

• Hormonal Responses to Food

  • The system is made of a series of glands that produce chemicals called hormones.
  • One of the important factors under hormonal control is the stomach acid environment.
  • Secretin acts in tandem with another hormone called cholecystokinin (CCK).
  • Another level of hormonal control occurs in response to the composition of food.
  • Scientists are exploring the role of each hormone in the digestive process and developing ways to target these hormones.

• Hormonal Regulation of Growth

  • Hormonal regulation is required for the growth and replication of most cells in the body.
  • GH levels are regulated by two hormones produced by the hypothalamus.
  • GH release is stimulated by growth hormone-releasing hormone (GHRH) and is inhibited by growth hormone-inhibiting hormone (GHIH), also called somatostatin.
  • A balanced production of growth hormone is critical for proper development.
  • Oversecretion of growth hormone can lead to gigantism in children, causing excessive growth.