Download Hormones & Endocrine System

Hormones & Endocrine System

Introduction
 Endocrine System – Sum of all hormone secreting cells and
tissues
 Endocrine Gland – ductless glands that secrete hormones
directly into body fluids
 Hormones – chemical signals that cause a response in target
cells
 Affect body tissues or other endocrine glands (tropic hormone)
 Endocrine secretion is determined by Positive & Negative
Feedback
Target Cell Receptors
 Cell-Surface Receptors
 Most common receptor for initiating a signal transduction
pathway
 Receptor  Transduction  Response
 Intracellular Receptors
 ONLY lipid-soluble ligands are able to pass through the
membrane & bind intracellular receptors
 Testosterone & estrogen (transcription factors)
The Boss…
 Hypothalamus
 Receives signals from
nervous system
 Initiates endocrine
signal response
Pituitary Gland
Note Hypothalamus

Pituitary Gland
 Anterior Pituitary
 Regulated by hypothalamus
 Growth hormone (GH)
 Thyroid-stimulating hormone (TSH) – seriously?
 FSH – (Follicle stimulating Hormone)
 Stimulates development of ovarian follicles (female) or
spermatogenesis in seminiferous tubules (male)
 Luteinizing Hormone
 Triggers ovulation in females
 Stimulates testosterone production production in testes
Thyroid Gland
 Stimulates & maintain metabolic processes
 Controls calcium level in blood
 Calcitonin
Adrenal Gland
 Epinephrine – Increase metabolic level
 Constrict blood vessels
 Raise blood-glucose levels
 Glucocorticoids