Lecture Final: Chapter 26 Flashcards
INTERCELLULAR COMMUNICATION BY SECRETED MOLECULES
+ integration of what (5)
Chemical communication is slow / long lasting / and coordinates / integrates multiple organs and organ systems
– In reality, chemical and nervous communication are integrated
MAIN FOCUS = endocrine release of hormones into bloodstream → control and integrate the following
- Reproduction
- Growth and development
- Maintenance of electrolyte / H2O / nutrient balance → remember ADH?
- Regulation of cellular metabolism → thyroid hormone
- Mobilization of body defenses
Define the following:
- endocrine
- neurocrine
- paracrine
- autocrine
Endocrine: no duct; release into blood by true epithelial cell; only those with receptors will respond
Neurocine: same but released by neural cell
Paracrine: same but release into local interstitial fluid to stimulate neighbors
Autocrine: same but stimulate self
Water Soluble Hormones (3)
- hypothalamus (3)
- pituitary 2, A and P
- pancreas (2)
- pineal
- adrenal medulla (2)
- hydrophilic, therefore can be stored in secretory vesicles
- captured transmembrane receptors for secondary messenger systems, which will amplify the message
- transported through blood but short half-life bc removed by kidneys
Hypothalamus: luteinizing hormone, follicle stimulating hormone; also stimulates hormones from pituitary as well
Pituitary: growth hormone, thyroid stimulating hormone (thyroxine)
- anterior: ACTH
- posterior: oxytocin
Pancreas: insulin, glucagon
Pineal: melatonin
Adrenal medulla: norepinephrine, epinephrine (aka tyrosine based catecholamines)
Lipid soluble hormones (3)
- adrenal cortex (5)
- thyroid glands
- hydrophobic, therefore cannot be stored in secretory vesicles bc will diffuse right through – instead, will be created on demand
- captured by receptors inside the cell, activating genes and the synthesis of new proteins
- bound to plasma proteins, therefore long half life bc metabolized in liver
Adrenal cortex: glucocorticoids, mineralcorticoids; estrogen; progesterone; androgens (last three are steroid hormones)
Thyroid glands: thyroid hormones (tyrosine based)
Transmembrane receptors
G protein coupled receptors (GPCR) – incl ADH, glucagon, rhodopsin (captures photons)
– GPCR is the largest family of hormone receptors
Protein / peptides / catecholamines cannot pass through membrane bc WATER SOLUBLE – will need to bind to something on extracellular face
THREE DOMAINS
- Extracellular, high affinity hormone binding domain –induces a conformational shift in all three domains
- One to seven hydrophobic transmembrane domain
- Cytosolic domain linked to signaling proteins in a single transduction pathway
- - transduces into activation of one or more intracellular signalling molecules
- - Intracellular signalling molecules will act on effector proteins, which will modify cellular function
Intracellular Receptors
Concerns steroid hormones and thyroid hormones
– structurally similar and belong to same nuclear hormone receptor family THEREFORE nuclear hormone receptors act as transcriptional regulators
- Hormone-receptor complex binds to specific DNA sequence (aka hormone response element close to promoter of a gene)
- HRC acts like a transcription factor to stimulate gene expression
- pre-mRNA processed inside nucleus into mRNA, exported into cytoplasm, and translated into protein by ribosomes
Endocrine Glands throughout the body
H T(PT) A P P OT
Hypothalamus - pituitary: main center for homeostatic regulation of the body
Thyroid gland: thyroid hormone influences metabolism and growth; calcitonin with clinical affects of Ca2+ regulation
– Parathyroid gland: PTH involved in Ca2+ regulation
Adrenal glands: cortical hormones influence energy metabolism and osmotic balance; medullary hormones interact with sympathetic nervous system
Pancreas
- exocrine for digestive enzymes
- endocrine for insulin and glucagon to regulate blood sugar level
Pineal gland: melatonin with diverse effects
Ovaries and Testes: synthesize steroidal sex hormones
Endocrine Glands in the human brain
- hypo
- post lobe (3)
- ant lobe (2)
Hypothalamus: main homeostatic control center; monitors physiological status of body; affects changes by controlling release of hormones from pituitary glands
POSTERIOR lobe of pituitary: aka neurohypophysis; derived from neural tissue;
- oxytocin: milk creation in mammals and uterine contractions during childbirth
- vasopressin: influences polygamy / monogamy desire; affects water conservation
- ADH: reduces urine volume at collecting duct in kidney
ANTERIOR: aka adenohyophysis; derived from epithalial tissue; location of third portal system
– THREE LEVEL ENDOCRINE AXES: tropic, therefore target and regulate other endocrine glands»_space;> 1. GH – 2. LH, FSH – 3. ACH
– PATHWAY: hypothalamus secretes releasing hormones
into portal system > bind to receptors of hormone producing cells of anterior > anterior hormones released into capillary bed > enter general circulation and affect target organs
