BIOM 4090

What are hormones?

Chemical messengers involed in the regulation and cordination of bodily functions through cell-cell communication

What type of horme act locally to affect the cell that produces them?

Autocrine

What are examples of autocrine hormones?

• growth factors

• Cytokines

• Beta cells in pancreas

• T cell maturation

Hormones that act locally to affect nearby cells

Paracrine

What are examples of paracrine hormones?

NO

Cytokines

Endothelins

Insulin

IGFs

What is Juxtacrine signalling?

Cell is binded to adjacent cell. It is a subtype of paracrine

Hormones that are secreted by cells to enter bloodstream to affect distant target cells

Endocrine

What are examples of endocine hormones?

• thyroxine

• Insulin

• Estrogen

• Renin

• IGFs

Hormones secreted by neurons can act as … or …

Neurotransmitters, neurohormones

How is the transportation of neurotransmitter different from neurohormone?

Short distances/synapses

Secreted into blood stream

Examples of NT and NH

ACh

Oxytocin, epinephrine

What are the three types of endocrine hormones?

• Amines

• Peptides-Proteins

• Steroids

What types of hormones are more hydrophilic?

Amines, peptides-proteins

What type of hormone is lipophilic?

Steroids

What are examples of amine hormones?

Catecholamines, thyroid hormones

What are examples of Peptide-Proteins hormones?

Insulin, GH, ACTH, gonadotrophins

What are examples of steroid hormones?

Sex steroids, corticosteroids, Vit D

What are the four types of release patterns of endocrine hormones?

Constitutive, stimulated, pulsatile, circadian rhythms

Ex of constitutive pattern

Insulin, cortisol, thyroxine

Ex of stimulated pattern

Insulin, cortisol

Ex of pulsatile pattern

Hypothalamic releasing hormones

Ex of circadian rhythms pattern

Cortisol, thyroxine

What are the two types of receptor types?

Cell surface and nuclear/cytosolic

What types of hormones bind to cell surface receptors?

Protein-peptiide and amines (more hydrophilic) ex: GFs, insuline, IGFs

What type of receptor are cell surface receptors?

G-protein receptors.

What occurs after ligand binding to cell surface receptor?

Signal transduction for intracellular response

The response is rapid and immediate

What types of hormones bind to nuclear and cytosolic receptors?

Steroids, thyroid, vitamin D, retinoic acid

Why does lipophilic hormones have a delayed effect?

They cross cell membrane and affect transcription to create response

What are the three main sections of the endocrine system?

1. Traditional endocrine system, regulated by CNS feed back loops - hypothalamus-anterior pituitary target gland axes, gonads, thyroid, adrenal cortex

2. Independent endocrine glands - pancreas, posterior pituitary, parathyroids

3. Dispersed endocrine cells - liver (IGFs), gut (GI hormones), kidneys (renin)

What could cause hormone hypersecretion?

Primary (adrenal adenoma) or secondary (pituitary adenoma) tumours

What causes hormone hyposecretion?

Primary gland malfunction (autoimmune destruction, congenital or surgery, age dependent atrophy, toxicities or nutritional basis)

Secondary or tertiary gland malfunction

What causes inappropriate target tissue response?

Receptor expression abnormalities (ovarian tumours expressing GnRH receptors)

Mutated receptors

Latrogenic, drug therapy