Hormones, tissues, skin & bone
Hormones, tissues, skin & bone BMS 300
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This 5 page Class Notes was uploaded by Caroline Hurlbut on Sunday September 25, 2016. The Class Notes belongs to BMS 300 at Colorado State University taught by John P Walrond in Fall 2016. Since its upload, it has received 7 views. For similar materials see Principles of Human Physiology in Biomedical Sciences at Colorado State University.
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Date Created: 09/25/16
• endocrine system - secretion without ducts endocrine response - chemical signaling between/among cells • —sending/secreting cell: releases chemical/hormone —receiving/target cell: responds to signal sent by secreting cell • intercellular chemical communication —autocrine: sending and receiving cell are the same —paracrine: receiving cell is nearby sending cell —endocrine: signal enters blood and is carried all over the body hormones • —protein hormones: large hydrophilic molecules that bind to transmembrane proteins —modiﬁed amino acids A. tyrosine: catecholamines (hydrophilic neurotransmitters like dopamine, epinephrine, norepinephrine) modiﬁed to hydrophobic thyroid hormone B. tryptophan: modiﬁed to serotonin (5 HT) • protein hormones and their transmembrane protein receptors—>G protein coupled receptors —7-path G protein receptors —cAMP signaling mechanism A. alpha subunit of hormone binds to GTP and activates G protein B. G protein binds to adenylyl cyclase and activates it C. adenylyl cyclase converts ATP to cAMP D. cAMP activates phosphorylation of proteins steroid hormones - cholesterol derivative that is planar and hydrophobic • —cortisol —corticosteroid —aldosterone —calcitrol/vitamin D • modiﬁed fatty acids are generated from phospholipids and modiﬁed to prostaglandins • receptor/hormone binding —hormone/reception complex [H] + [R] ⁶ [HR] A. association—>form complex B. dissociation—>form hormone + receptor C. complex requires afﬁnity and speciﬁcity —dissociation constant Kd: concentration of ligand at which 1/2 of the receptors are occupied —steroid hormones function as transcription factors A. steroid binding domain (speciﬁcity) B. nuclear access domain (access) C. DNA binding domain D. transactivation domain: recruits DNA polymerase • hypothalamic pituitary axis —posterior pituitary A. extension of hypothalamus B. neurons release oxytocin (muscle contraction) and vasopressin (kidney function) into blood —anterior pituitary A. originates as pharynx epithelial cells (Rathke’s pouch) B. troph cells contain receptors for releasing hormones—>travel through hypothalamic pituitary portal system to target gland C. negative feedback: hormones feed back to inhibit releasing hormone • skin structure (of a stratiﬁed squamous epithelium) —dermis: CTP with embedded proteins (ﬁbrocytes, elastin, collagen) —stratum basale: living keratinocytes continuously dividing —stratum spinosum: spiny living cells —stratum granulosum: dying glycolipids that waterproof skin —stratum lucidum: dead clear cells —stratum corneum: horny keratin layer of dead cells • keratinocytes of SB and SS absorb UV light—>production of vitamin D • melanocytes secrete melanin—>taken up by keratinocytes to protect cells from UV light • bone structure —epiphysis: end part of a long bone —diaphysis: shaft connecting 2 epiphyses —trabecular/spongy bone and compact bone —medullary cavity: contains yellow marrow (fat) • compact bone arranged in osteons, which are concentric rings of osteocytes —collagen ﬁbers for shear strength —hydroxyapatite (calcium phosphate) for hardness and rigidity • bone processes —osteoclasts: break down old bone tissue —osteoblasts: deposit new bone tissue —bone growth A. chondrocytes form a growth plate called the epiphyseal plate B. chondrocytes continuously divide as a person grows C. as older chondrocytes degenerate, osteoblasts ossify remains to form new bone • tissue - set of similar cells that perform similar functions tissue types • —epithelial: continuous cell layers —connective: widely separated cells linked by proteins A. connective tissue proper (CTP): dermis, ligaments, tendons B. cartilage C. bone D. blood —muscle —nerve • epithelial cells —form surfaces and boundaries —1 layer: simple epithelium —multiple layers: stratiﬁed squamous epithelium • structure of epithelium —cells attached to a basal lamina composed of extracellular proteins —cells oriented with respect to basal lamina A. basilar surface: attached to basal lamina B. apical surface: attached to basilar surface —cells self-replicate A. mutations—>carcinomas (tumors derived from epithelial cells) integrins - actin binding transmembrane proteins that anchor epithelial cells to basal lamina • and provide a bridge to extracellular proteins • cadherins - transmembrane proteins that form adherent junctions and bind cells together • cell junctions —anchoring junctions A. desmosomes: link adjacent epithelial cells together B. hemidesmosomes: attach epithelial cells to extracellular proteins —tight junctions: form seal between adjacent cells and prevent movement of molecules through those gaps —communication/gap junctions: form passages to allow exchange of small molecules between cells A. protein channels composed of connexons (made of 6 connexins) B. 2 connexons form intercellular channel • exocrine glands as modiﬁed epithelia —process for salivary, sweat, mammary glands and exocrine cells of pancreas A. secretory epithelia pump ions into spaces of duct epithelia B. duct epithelia remove ions and leave water C. water is moved through aquaporins of surface epithelia —adenocarcinomas are tumors that come from secretory epithelia (ex. breast cancer) • connective tissue —CTP: generated by ﬁbrocytes —cartilage: generated by chondrocytes —bone: generated by osteocytes —blood: generated by hematopoietic stem cells —all are embryologic mesenchymal cells characterized by widely separated cells embedded in the protein matrix secreted by the cells • connective tissue cell proteins —elastin —collagen —ﬁbronectin —laminin • cartilage types —elastic: enriched with elastin —ﬁbrocartilage: enriched with collagen —hyaline: enriched with glycosaminoglycan (glass-like)
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