PHYG103B Hormones Docx

adenylyl cyclase

membrane-bound enzyme that converts ATP to cyclic AMP, creating cAMP, as a result of G-protein activation

cyclic adenosine monophosphate (cAMP)

second messenger that, in response to adenylyl cyclase activation, triggers a phosphorylation cascade

cyclic adenosine monophosphate

cAMP stands for

diacylglycerol (DAG)

molecule that, like cAMP, activates protein kinases, thereby initiating a phosphorylation cascade

downregulation

decrease in the number of hormone receptors, typically in response to chronically excessive levels of a hormone

first messenger

hormone that binds to a cell membrane hormone receptor and triggers activation of a second messenger system

G protein

protein associated with a cell membrane hormone receptor that initiates the next step in a second messenger system upon activation by hormone–receptor binding

hormone receptor

protein within a cell or on the cell membrane that binds a hormone, initiating the target cell response

inositol triphosphate (IP3 )

molecule that initiates the release of calcium ions from intracellular stores

phosphodiesterase (PDE)

cytosolic enzyme that deactivates and degrades cAMP

phosphorylation cascade

signaling event in which multiple protein kinases phosphorylate the next protein substrate by transferring a phosphate group from ATP to the protein

protein kinase

enzyme that initiates a phosphorylation cascade upon activation

second messenger

molecule that initiates a signaling cascade in response to hormone binding on a cell membrane receptor and activation of a G protein

upregulation

increase in the number of hormone receptors, typically in response to chronically reduced levels of a hormone

Growth hormone (GH)

Promotes growth of body tissues

Prolactin (PRL)

Promotes milk production

Thyroid-stimulating hormone (TSH)

Stimulates thyroid hormone release

Adrenocorticotropic hormone (ACTH)

Stimulates hormone release by adrenal cortex

Follicle-stimulating hormone (FSH)

Stimulates gamete production

Luteinizing hormone (LH)

Stimulates androgen production by gonads

Antidiuretic hormone (ADH)

Stimulates water reabsorption by kidneys

Oxytocin

Stimulates uterine contractions during childbirth

Thyroxine (T4), triiodothyronine (T3)

Stimulate basal metabolic rate

Calcitonin

Reduces blood Ca2+ levels

Parathyroid hormone (PTH)

Increases blood Ca2+ levels

Aldosterone

Increases blood Na+ levels

Cortisol, corticosterone, cortisone

Increase blood glucose levels

Epinephrine, norepinephrine

Stimulate fight-or-flight response

Melatonin

Regulates sleep cycles

Insulin

Reduces blood glucose levels

Glucagon

Increases blood glucose levels

Testosterone

Stimulates development of male secondary sex characteristics and sperm production

Estrogens and progesterone

Stimulate development of female secondary sex characteristics and prepare the body for childbirth

GH, PRL, TSH, ACTH, FSH, LH

Hormones from Anterior Pituitary Gland

ADH, Oxytocin

Hormones from Posterior Pituitary Gland

T3, T4, Calcitonin

Hormones from Thyroid Gland

PTH

Hormones from Parathyroid Gland

Aldosterone, Cortisol, corticosterone, cortisone

Hormones from Adrenal cortex

Epinephrine, norepinephrine

Hormones from Adrenal medulla

Melatonin

Hormones from Pineal Gland

Insulin, Glucagon

Hormones from Pancreas

Testosterone

Hormones from Testes

Estrogen and Progesterone

Hormones from Ovaries

PRL, ACTH, ADH, Oxytocin, Calcitonin, PTH

Hormones with PEPTIDE Chemical Class

GH, Insulin, Glucagon

Hormones with PROTEIN Chemical Class

TSH, FSH, LH,

Hormones with GLYCOPROTEINChemical Class

T3, T4, Epinephrine, Norepinephrine, Melatonin

Hormones with AMINE Chemical Class

Aldosterone, Cortisol, corticosterone, cortisone, Testosterone, Estrogens and progesterone

Hormones with STEROID Chemical Class

Derived from Amino acids and Lipids

2 Major groups of Hormones on the basis of their chemical structure

amines, peptides, and proteins

Hormones derived from amino acids

steroids

Hormones derived from lipids

Amine Hormone

Amino acids with modified groups

Norepinephrine

example of Amine Hormone

Peptide Hormone

Short chains of linked amino acids

Oxytocin

example of Peptide Hormone

Protein Hormone

long chains of linked amino acids

Human Growth Hormone

example of Protein Hormone

Steroid Hormone

derived from the lipid cholesterol

Testosterone, Progesterone

examples of Steroid Hormones

Amine hormones

are synthesized from the amino acids tryptophan or tyrosine.

melatonin

An example of a hormone derived from tryptophan

melatonin

is secreted by the pineal gland and helps regulate circadian rhythm.

Tyrosine derivatives

include the metabolism-regulating thyroid hormones, as well as the catecholamines, such as epinephrine, norepinephrine, and dopamine.

Epinephrine and norepinephrine

are secreted by the adrenal medulla and play a role in the fight or-flight response

dopamine

is secreted by the hypothalamus and inhibits the release of certain anterior pituitary hormones.

protein hormones

longer polypeptides

antidiuretic hormone (ADH)

a pituitary hormone important in fluid balance

atrial-natriuretic peptide

is produced by the heart and helps to decrease blood pressure.

follicle-stimulating hormone (FSH)

has an attached carbohydrate group and is thus classified as a glycoprotein. It helps stimulate the maturation of eggs in the ovaries and sperm in the testes.

steroids

primary hormones derived from lipids

aldosterone

The adrenal glands produce this steroid hormone which is involved in osmoregulation

cortisol

The adrenal glands produce this steroid hormone which plays a role in metabolism.

Steroid Hormones

Like cholesterol, they are not soluble in water (they are hydrophobic).

half-life

is the time required for half the concentration of the hormone to be degraded.

60 to 90 minutes

cortisol has a half-life of approximately ___

1 minute

epinephrine has a half-life of approximately ___

Positive feedback loops

are characterized by the release of additional hormone in response to an original hormone release.

positive feedback loop

What feedback loop is the release of oxytocin during childbirth

Negative feedback loop

The more common method of hormone regulation

Negative feedback loop

is characterized by the inhibition of further secretion of a hormone in response to adequate levels of that hormone.

Negative feedback loop

What feedback loop is the release of glucocorticoid hormones from the adrenal glands, as directed by the hypothalamus and pituitary gland.

lipid soluble

Steroid hormones and thyroid hormone are

water soluble

All other amino acid–derived hormones are

Hydrophobic hormones

are able to diffuse through the membrane and interact with an intracellular receptor

hydrophilic hormones

must interact with cell membrane receptors. These are typically associated with a G protein, which becomes activated when the hormone binds the receptor.

Second messenger systems

greatly amplify the hormone signal, creating a broader, more efficient, and faster response.

Humoral, Hormonal, Neural

3 Major types of Stimuli

Humoral stimuli

are changes in ion or nutrient levels in the blood.

Hormonal stimuli

are changes in hormone levels that initiate or inhibit the secretion of another hormone.

neural stimulus

occurs when a nerve impulse prompts the secretion or inhibition of a hormone.