Monday, 19 September Chapter 11 The Endocrine System
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Transcript of Monday, 19 September Chapter 11 The Endocrine System
Monday, 19 SeptemberChapter 11 The Endocrine System
• Classes of hormones• The adrenal gland• Fates of hormones• Renin-Angiotensin-Aldosterone System• Control of hormone secretion• Hormone interactions (permissive effects)
1QQ # 61. Stress leads to the secretion of epinephrine which alters
the metabolism of many cell types. Describe the effects of EPI on two different cell types and explain how these effects are beneficial to the person.
2. Starting with the arrival of carbohydrates in the stomach list the sequence of events, cell types, and hormone(s) that comprise a feedforward mechanism. What is the purpose of this feedforward mechanism?
3. Beginning with the ingestion of a large amount of sugar, list the sequence of events in a reactive hypoglycemic person that ultimately leads to a headache, fast heart rate, and cold, clammy skin.
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
Analogy: SSNs and receptors
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)
Why does the chemical class matter?
Fig. 11.01
Catecholaminessoluble in plasma
ThyroidHormones Not soluble in plasma, bound & free
AmineHormones
Adrenalmedulla
NT
NT
Fig. 11.03Steroid hormones
not soluble in plasma, not storable in vesicles
Target cells have intracellular receptors.Changes is gene expression.
Timecourse?
Bound & Free
Fig. 11.02Peptide Hormones
Examples of Peptide Hormones: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
Know Table 11-2 p 323
• Hormone class
• Major form in plasma
• Location of receptors
• Signal transduction mechanisms
• Rate of excretion / metabolism
Questions so far?
Fig. 11.05
Adrenal Gland
Part of Sympathetic Nervous System
Hormones of the Adrenal Cortex
Hormones of the Adrenal Cortex
Glucocorticoids
Mineralicorticoid
Androgens
DHEA
“Andro”
What regulates the secretion of cortisol and aldosterone?
Fig. 11.06Gonadal Steroids(not adrenal cortex)
King DS, Sharp RL, Vukovich MD, Brown GA, Reifenrath TA, Uhl NL, Parsons KA . Effect of oral androstenedione on serum testosterone and adaptations to resistance training in young men: a randomized controlled trial. JAMA 1999; 281(21):2020-8
Estrogens
Fast if freeSlow if bound
Be able to giveExamples.
T4 to T3 and Testosterone to Estradiol
Ex: Renin
What happens to hormones once released?
Renin-angiotensin-aldosterone
Angiotensinogenfrom liver, anever-present plasma protein
ReninAngiotensin IAngiotensin converting
enzyme (ACE)
Angiotensin II
ThirstArterial smooth muscle … vasoconstriction…increase blood pressure
Zona Glomerulosa of Adrenal Cortex
Aldosterone Promotes Na+ retention in Kidney
Renin is an enzyme released from kidney cells into bloodstream, its “substrate” is a plasma protein called Angiotensinogen.
Aldosterone
Na+ reabsorption in kidney
Plasma volume
Blood pressure
Renin from Juxtaglomerular cells in Kidney
Multi-step process involving Angiotensin I and II
(-)
Angiotensin II
thirst
Drink
vasoconstriction
K+ in plasma
_______
Blood Pressure
Fast if freeSlow if bound
Be able to giveExamples.
T4 to T3 and Testosterone to Estradiol
Ex: Renin
What happens to hormones once released?
Factors that affect hormone secretion
Recall example: beta cells of Islets of Langerhans
Secretion is usually pulsative, may be diurnal.
Integrator!
Fig. 11.08
Thyroid hormone stimulates production of beta-adrenergic receptors
Permissive effect