1- Intro Endo/Repro & Feedback loops

Estradiol

Example of positive feedback loop

Acts on anterior pituitary

Steroid Hormones

Derivatives of cholesterol

Amine Hormones

Derivatives of tyrosine

Interpreting Hormone Measurements

• Hormones should be evaluated with their regulatory factor

• Simultaneous elevation of a pair = hormone resistance state

• Target hormone excess should be evaluated with the right tropic hormone (insulin/glucose, PTH/Ca)

  

Neural or Nutrient/Ion

Additional regulators of hormone release are due to THIS control.

• Neural=ADH

• Ion=Glucose

Physiologic Responses

Can provide some negative feedback on hypophysiotropic parvicellular neurons (hypothalamus)

Peripheral Hormone

Can give negative feedback to tropic hormones

Can give negative feedback to hypothalamus (hypophysiotropic parvicellular neurons)

Urine Analysis

THIS of hormones is restricted to the measurement of catecholamines and steroid hormones.

Being an integrated sample helps to counteract the variability of hormone levels

Plasma analysis

Reflects only the hormone(s) levels at the time of sampling

Hormone Release

Can be affected by:

• Sleep/wake cycle - Cortisol

• Age - GH (growth hormone)

• Reproductive cycles - Estrogen/Progesterone

  

Protein & Peptide Hormones

Have short half lives

Are stored in vesicles, dissolve in plasma

Faster acting than the others

Produce second messengers

• Exception= insulin (doesn’t use cAMP, activates tyrosine kinase)

Water soluble!

Steroid & Amine Hormones

Have long half-lives

Attach to transport carriers in the plasma

Are synthesized as needed

Stimulate synthesis of new proteins

Take longer to act than the others

Lipid soluble!

Amine Hormones

Examples are catecholamines and thyroid hormones

• Derivatives of tyrosine

Steroid Hormones

Examples are adrenal and sex hormones

• Derivatives of cholesterol!

Peptide/Protein Hormones

Bind cell surface receptors

Endocrinology

Study of communication and control within a living organism by means of chemical messengers

Metabolism

Study of the biochemical control mechanisms that occur within living organisms

Hormones

Endogenous informational molecules that are involved in both intracellular and extracellular communication

Endocrine Organs

• Hypothalamus

• Pituitary Gland

• Thyroid Gland

• Parathyroid Glands

• Adrenal Glands

• Pancreas

• Ovaries

• Testes

Peptide Hormone Synthesis

Preprohormone → Prohormone → Hormone