BIOKIMIA 1

Hormon

IntroductionIntroduction

• The endocrine system and nervousThe endocrine system and nervous systems act together to regulate systems act together to regulate many activities within the body.many activities within the body.

• Both systems utilize chemicalBoth systems utilize chemical messengers, to communicate signals.messengers, to communicate signals.

• Endocrine system produces homonesEndocrine system produces homones as chemical signals to bring about as chemical signals to bring about affects in other body parts. affects in other body parts.

• Endocrine glands such as testes Endocrine glands such as testes produce hormones like testosterone. produce hormones like testosterone.

Hormone

Hormone

Growth and development: Thyroid, GH, Sex Steroids, Cortisol

Reproduction: Estrogen, Testosterone, FSH, LH, Thyroid

Homeostasis: Thyroid, Cortisol

Changes in environment: Cortisol, Thyroid Aldosterone

Hormone Functions

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Hormones are released by the glands

• And travel through the blood until they reach their particular receptor cell

• Where they fit, like a key in a lock, to turn on or off functions

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Hormon

Hormon

Circulate in blood stream bound to transporter proteins or free

Free hormone is the active hormone

Enter cells to alter biological activity

Mechanism of Action of Hormones

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Classes of Receptors

Ligand: molecule which binds to a protein and affects its function. Hormone is one type of ligand.

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Hormone Regulation

• Feedback loops

• Receptor specificity

• Receptor concentration

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Feedback Regulation of the Anterior Pituitary:

Target Organ

Hypothalamus

+ -

+

-

-

-

?

Short LoopFeedback

Pituitary

Long LoopFeedback

negative feedback : secretion of hormone leads directly or indirectly to inhibiting its secretion

positive feedback: secretion of hormone leads directly or indirectly to its increase secretion

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- Subunits

- Subunit

TSH

LH hCG

FSH

Receptor specificity

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Congenital Hypothyroidism

CretinismStunted growth

Neurological/ cognitive defects/mental retardation

Finally

• Hormones

You can’t live with them but…

You can’t live without them!