Synthesis and Release mRNA Signal sequence Ribosome Golgi apparatus Messenger RNA on the ribosomes of the ER binds amino acids into a Preprohormone peptide chain called a preprohormone. The chain is directed into the ER lumen by a signal sequence of amino acids. Prohormone Endoplasmic 2 Enzymes in the ER chop off the signal reticulum(ER) sequence,creating an inactive prohormone. 3 The prohormone passes from the ER through the Golgi apparatus. Active hormone Peptide Prohormone Secretory vesicles containing enzymes fragment and prohormone bud off the Golgi.The Secretory enzymes chop the prohormone into one Release vesicle or more active peptides plus additional signal peptide fragments. 5 The secretory vesicle releases its contents by exocytosis into the 5 extracellular space. Extracellular space Blood The hormone moves into the circulation 6 vessel for transport to its target
Synthesis and Release
Mechanisms of Hormonal Action (1)Proteins or Polypeptides hormone second messenger mechanisms 敛素 细胞典 受体 《)数素受体 牌苷酸环化砖@ 复合物 G露白 (d) 酶 CAMP (无话性) e 有生 胞液 底物 (无活住) 夜物 有活健】 细胞拔 细胞功能改变
Mechanisms of Hormonal Action (1)Proteins or Polypeptides hormone second messenger mechanisms
cAMP-PKA pathway Hormone (first messenger) Bind to G protein-linked receptor Gprotein activated Adenylyl cyclase(AC)activated ATP cAMP(second messenger) Activate cAMP-dependent protein kinase A Cellular response
Hormone (first messenger) Adenylyl cyclase(AC) activated ATP cAMP(second messenger) Cellular response Activate cAMP-dependent protein kinase A Bind to G protein-linked receptor Gprotein activated cAMP-PKA pathway
Mechanisms of Hormonal Action (2)Steroid hormones modulation of gene expression Blood Steroid Cell surface receptor Most hydrophobic steroids are bound vessel hormone to plasma protein carriers.Only unbound hormones can diffuse into the target cell. 6 Rapid responses 2 Steroid hormone receptors are in the Protein cytoplasm or nucleus. carrier Nucleus Cytoplasmic 3 The receptor-hormone complex binds receptor Nuclear to DNA and activates or represses one receptor or more genes. DNA 4】 Activated genes create new mRNA Interstitial that moves back to the cytoplasm. fluid Endoplasmic reticulum Cell membrane 5Translation produces new proteins Transcription for cell processes. produces mRNA GSome steroid hormones also bind to Translation membrane receptors that use second New proteins messenger systems to create rapid cellular responses
(2)Steroid hormones modulation of gene expression Mechanisms of Hormonal Action
Control of hormone secretion nerve regulation Stimulus Hormonal regulation Hypothalamus (IC) feedback control Trophic hormone(H,) Anterior pituitary C Trophic hormone (H2) Long-loop negative feedback Endocrine gland (IC) KEY Hormone(Hj) Stimulus Target tissue ○Integrating center Efferent path ○Effector Response ●Systemic response
nerve regulation Hormonal regulation feedback control Control of hormone secretion