Friday, 16 SeptemberChapter 11 The Endocrine System

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

Wednesday 1QQ to be returned on Monday

Lab next week: Analyzing a research paperPick up your photocopy from the Piano, read it before lab!

Feedback (n=25) from Wednesday’sInteractive Class: “Be the Hormone”

Cons

• Few/no notes• Not all hormones were

introduced• Covered less material

Pros

• Mental image of chemical categories of hormones and relative numbers

• Visualization of shared properties

• Better able to answer chapter questions

• More engaging

1QQ # 5 for 8:30

1. Epinephrine is an amine hormone.

2. If you don’t know which category a hormone belongs to, the best guess is “peptide.”

3. The thyroid hormones and steroid hormones have intracellular receptors and affect gene expression and have long-lasting effects in their target cells.

4. All amine and peptide hormones are transported in the plasma in two forms: bound and free.

5. Thyroid hormones and steroid hormones are stored in vesicles and secreted later.

Each True/False Question counts 2 points. Answer all five.

1QQ # 5 for 9:30

1. Dopamine is an amine hormone.

2. If you don’t know which category a hormone belongs to, the best guess is “steroid.”

3. The thyroid hormones and steroid hormones have cell-surface receptors and usually have long-lasting effects in their target cells.

4. T3 and T4 and peptide hormones are transported in the plasma in two forms: bound and free.

5. Catecholamines and peptide hormones are stored in vesicles and secreted later.

Each True/False Question counts 2 points. Answer all five.

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

Fig. 11.08

Thyroid hormone stimulates production of beta-adrenergic receptors,

Makes target cells more sensitive to EPI

Permissive effect

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 Glands

Part of Sympathetic Nervous System

How do adrenal cortex cells “know” which hormone to synthesize from cholesterol?

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.

BV& BP

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!

Na+, K+, Ca++, Glucose, etc.

NE (sympathetic)ACh (parasympathetic)etc. Tropic

Thyroid Gland

• TH =T3 and T4

Fenestrated Capillary(typical of endocrine glands)

S1

Synthesis, Storage and Secretion of T3 and T4Roles of TSH (Thyroid Stimulating Hormone)

TH increases cell metabolism & heat production (BMR)

Tropic: directs controls, regulatesTrophic: growth

S2

Fig. 11.12a

Receives inputfrom manyregions ofbrain; many factorsAffect its functionHomeostatsis center.

S3

Fig. 11.12b

Vasopressin (= Antidiuretic hormone)Oxytocin

NeurohypophysisAdenohypophysis

6

S4

Tropic hormones control the function

Trophic hormones promote survival and growth of targets

Releasing Hormone

Release-inhibiting Hormone

Hypothalamo-hypophyseal portal system

A

A

S S

P

P

PPPPP

PPPP

S 6

Tropic hormones control the function

Trophic hormones promote survival and growth of targetsReleasing Hormone Release Inhibiting Hormone

Long

-loop

neg

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edba

ck

Sho

rt-lo

op N

eg. F

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