Friday, 18 SeptemberChapter 11 The Endocrine System

• Classes of hormones• The adrenal gland• Fates of hormones• RAA system• -------------------------------• Hypothalamus-Pituitary System• Hormone interactions• Control of hormone secretion• Categories of endocrine disorders

Endocrine Organs (Table 11-1)

• Pituitary Gland• Thyroid Gland• Pancreas• Gonads• Gastrointestinal Tract• Heart• Kidney• Hypothalamus• Liver• Etc.

Hormone: chemical messengerscarried by blood to target cells

upon which they act.

Only those cells having receptorsCan respond to a given hormone

Hormone

Paracrine agent

Autocrine agent

Neurotransmitter

Neuromodulator

3 Chemical Classes of Hormones

• 1: Amine hormones (from amino acid tyrosine)– Thyroid hormones – Adrenal medullary hormones (catecholamines)

• 2: Peptide hormones (peptides & proteins)• 3: Steroid Hormones (derivatives of cholesterol)

Knowing chemical classes is important because chemical class is related to 1)How hormones are synthesized and2)How hormones are stored before secretion3)How hormones are transported in blood and 4)Where receptors are located on target cells and5)The duration of the effect on the target cells.

Fig. 11.01

Catecholaminessoluble in plasma

ThyroidHormones Not soluble in plasma, bound & free

AmineHormones

Adrenalmedulla

NT

NT

Fig. 11.02Peptide Hormones

Examples:Insulin, glucagonprolactin, erythropoietin,parathyroid hormone,gastrin, leptin, growth hormone,oxytocin, vasopressin,FSH, LH, GHRH, andmany more!

Cell surface receptors on target cells

Guess peptide!

Soluble in plasma

e.g.Beta cell

Fig. 11.03Steroid hormones

not soluble in plasma, not storable in vesicles

Target cells have intracellular receptors,Commonly changes is gene expression

Timecourse?

Mostly Bound & Some Free

Thyroid hormones: special synthesis and storage

Questions so far?

Know Table 11-2 p 323

• Hormone class

• Major form in plasma

• Location of receptors

• Signal transduction mechanisms

• Rate of excretion / metabolism

Fig. 11.05

Adrenal Gland

Part of Sympathetic Nervous System

Adrenal Medullary Hormones• Adrenal medulla is modified sympathetic ganglion• Catecholamines: EPI (80-85%), NE (15-20%)• Short half-life in plasma (soluble)• Receptors on surface of target cells (adrenergic) • Effects response to stress• Effects generally prepare for “Fight or Flight”

Hormones of the Adrenal Cortex

Glucocorticoids

Mineralicorticoid

Androgens

DHEA

Fig. 11.06Gonadal Steroids(not adrenal cortex)