Hypothalamus and Pituitary Function Chemistry CLS415 Didactics Module 1 Introduction to Endocrinology: Basic Concepts

Objectives: Define the following terms: Exocrine system Receptors Hormone Target organ Endocrine system List the major endocrine glands and the hormones they secrete Describe the action of hormones in terms of their: Regulatory and physiologic functions Morphologic action Integrative action Exocrine system Receptors

What is Endocrinology? Study of intracellular and extracellular communication by hormones of the endocrine system

Transmission of Information Occurs through several systems or networks Nervous System Immune System Hormonal System Others Endocrine system is controlled by its linkage with CNS through hypothalamus and pituitary glands

The Endocrine System A ‘fine-tuned’ communication system Maintains cellular homeostasis Body metabolism Growth and development Reproduction

Major Endocrine Glands

Hypothalamus

What are Hormones? Chemical messengers Interact with target organs by specific receptors Illicit biologic response Different modes of transport and action Example: Endocrine Paracrine Exocrine Autocrine Juxtacrine Neuroendocrine Neurocrine Neurotransmission

Endocrine vs Exocrine Pancreas: insulin Pancreas: amylase & lipase

Hypothalamus Releasing Hormones (factors) Inhibiting Hormones (factors) Produce ADH and Oxytocin Act on anterior pituitary gland Release Tropic Hormones Stored in posterior pituitary gland

Stimulating (tropic) Hormones Stimulating = tropin = trophic = tropic Stimulating hormones are specific to a particular target organ or target cell

Stimulating (tropic) Hormones Gonadotropin: stimulates the gonads Target gland = testes and ovaries Thyrotropin: stimulates the thyroid Target gland = thyroid gland ACTH = adrenocorticotropic hormone: stimulates the adrenal gland Target gland = adrenal cortex

Stimulating (tropic) Hormones Stimulating hormones interact with their target glands through receptors Membrane receptors: Located on the cell membrane Interact with protein-type hormones Cytoplasmic receptors: Located in the cytoplasm of the cell Interact with steroid-type hormones

Site of hormone’s action (target) Table, page 2 of handout Endo Gland Hormone from endocrine gland Site of hormone’s action (target) Biological response of target Anterior Pituitary TSH ACTH FSH, LH GH MSH Prolactin Thyroid gland Adrenal cortex Ovary, testis Body as a whole Skin Mammary glands Form T3,T4 Form Steroid Sexual maturation Bone/muscle Darken skin Lactation tropic hormones

Pituitary Gland (hypophysis) Posterior pituitary Anterior pituitary

Table, page 2 of handout Endo Gland Hormone from endocrine gland Site of hormone’s action (target) Biological response of target Posterior Pituitary ADH Oxytocin Renal tubules, arterioles Uterus, Breast tissue Reabsorb H2O  BP Contraction Milk ejection

Table, page 2 of handout Endo Gland Hormone from endocrine gland Site of hormone’s action (target) Biological response of target Thyroid T3 and T4 Calcitonin General body tissue Bone  O2 consumption,  BMR Inhibits calcium resorption (keeps calcium in bone)

Table, page 2 of handout Endo Gland Hormone from endocrine gland Site of hormone’s action (target) Biological response of target Adrenal Cortex Steroid hormones: Cortisol Aldosterone General body tissue Kidney tubules (DCT, collecting) Carbohydrate, protein, fat metabolism Salt and water balance

Table, page 2 of handout Endo Gland Hormone from endocrine gland Site of hormone’s action (target) Biological response of target Adrenal Medulla Norepinephrine and Epinephrine Epinephrine = ‘Fight or Flight’ hormone Sympathetic receptors Liver, muscle, fat Stimulate sympathetic nervous system Glycogenolysis, lipolysis

Regulatory and Physiologic Functions Electrolyte and water balance Aldosterone: Na+ (and K+, H+) ADH: water reabsorption Storage and use of nutrients Insulin: carbohydrate (glucose) regulation Cortisol: carbohydrate, protein, lipid

Morphogenic Action Synthesis of cellular compounds Thyroid hormone Catecholamines Steroid hormones Growth and development GH (growth hormone) Thyroid hormones

Morphogenic Action Sexual maturation and reproduction Gonadotropins (LH and FSH) Estrogen (female sex hormone) Testosterone (male sex hormone) HCG (human chorionic gonadotropin)

Integrative Action No hormone works alone!

Integrative Action