Wednesday, 14 SeptemberChapter 11 The Endocrine System

• Classes of hormones• The adrenal gland• Fates of hormones• Control of hormone secretion• Hormone interactions (permissive effects)• Hypothalamus & Pituitary• The story of Aunt Dot• Endocrine disorders (lab next week)

1QQ # 4 8:30 am1. What changes in hepatocyte metabolism are

produced by glucagon?

2. A) What advise would you give to a person who is a reactive hypoglycemic and B) provide the reasons for your advise.

3. Your patients plasma glucose level is 45 mg/dl. A) What hormone is responsible for her rapid heart rate, pale clammy skin, and irritability? B) Why does she have a headache?

1QQ # 4 9:30 am1. Explain in some detail how beta cells of the Islets of

Langerhans are affected by anticipating an excellent meal.

2. A) Describe a situation that would lead to the activation of the sympathetic nervous system. B) How does sympathetic stimulation affect the secretion from beta cells in the Islets of Langerhans? C) Why is this beneficial for the person in terms of fuel supply?

3. After an overnight fast, a patient arrives for an Oral Glucose Tolerance Test. The first blood sample (even before ingestion of the Tru-Glu cola shows a plasma glucose concentration of 150 mg/dl. A) Do you have the patient drink the Tru-Glu? Why or why not? B) What might you do next to determine what is “wrong” with your patient?

Class activity

• 24 students were hormones and we classified these hormones as amines, peptides or steroids, considered how they are synthesized and stored (or not) in secretory cells, transported in the plasma, the locations of their receptors in/on target cells, the nature of the response in target cells (latency & duration),

24 Hormones, 24 Students

• Corticosterone• Testosterone• Estriol• Cortisol• Aldosterone• Estrone• TSH• ADH• CRH• TRH• PTH• LH

• Glucagon• DA• EPI• NE• T3• Insulin• T4• GH• ACTH• FSH• EPO• CCK

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)

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: longer latency, longer lasting

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 319

• 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

Steroids

Catecholamines

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?

Factors that affect hormone secretion

Recall example: beta cells of Islets of Langerhans

Secretion is usually pulsative, may be diurnal.

Integrator!

Na+, K+, Ca++, etc. NE, ACh, etc. TRH, TSH, DA, etc.

Fig. 11.08

Thyroid hormone stimulates production of beta-adrenergic receptors, which increases the target cell’s responsiveness to EPI.

Permissive effect