BIOL 320 1st EditionLecture 1 Outline of Current Lecture II. Review of Epithelial Tissue Cell TypesA. DescriptionB. FunctionC. LocationIII. Endocrine SystemA.Definition of EndocrinologyIV. HormonesA. DefinitionB. CategoriesC. Mechanism of ActionD. Target Cell SpecificityE. Interaction of Hormones at Target CellsF. Control of Hormone ReleaseV. Hypothalamus and PituitaryA. Structural and Functional RelationshipCurrent LectureReview of Epithelial Tissue Cell Types- Simple Squamousa. Description: single layer of flattened cells with disc-shaped central nuclei and sparse cytoplasm; the simplest of the epitheliab. Function: allows passage of materials by diffusion and filtration in sites where protection isnot important; secretes lubricating substances in serosaec. Location: kidney glomeruli; air sacs of lungs; lining of heart, blood vessels, and lymphatic vessels; lining of ventral body cavity (serosae)- Simple Cuboidala. Description: single layer of cube-like cells with large spherical central nucleib. Function: secretion and absorptionc. Location: kidney tubules; ducts and secretory portions of small glands; ovary surface- Simple Columnara. Description: single layer of tall cells with round to oval nuclei; some cells bear cilia; layer may contain mucus-secreting unicellular glands (goblet cells)b. Function: absorption; secretion of mucus, enzymes, and other substances; ciliated type propels mucus (or reproductive cells) by ciliary actionc. Location: non-ciliated type lines most of the digestive tract (stomach to anal canal), gallbladder, and excretory ducts of some glands; ciliated variety lines small bronchi, uterine tubes, and some regions of the uterus- Psuedostratified Columnara. Description: single layer of cells of differing heights, some not reaching the free surface; nuclei seen at different levels; may contain goblet cells and bear ciliab. Function: secretion, particularly of mucus; propulsion of mucus by ciliary actionc. Location: non-ciliated type in male’s sperm-carry ducts and ducts of large glands; ciliated variety lines the trachea, most of the upper respiratory tract- Stratified Squamousa. Description: thick membrane composed of several cell layer; basal cells are cuboidal or columnar and metabolically active; surface cells are flattened (squamous); in the keratinized type, the surfaces cells are full of keratin and dead; basal cells are active in mitosis and produces the cells of the more superficial layersb. Function: protects underlying tissues in areas subjected to abrasionc. Location: non-keratinized type forms the moist linings of the esophagus, mouth, and vagina; keratinized variety forms the epidermis of the skin, a dry membrane- Transitionala. Description: resemble both stratified squamous and stratified cuboidal; basal cells cuboidal or columnar; surface cell dome shaped of squamous-like, depending on degree of organ stretchb. Function: stretches readily and permits distension of urinary organ by contained urinec. Location: lines the ureters, bladder, and parts of the urethraEndocrine System- Definition of Endocrinologyo Chemical communication between cells over distances…OVER DISTANCES…travels via blood or other part of vascular systemo Endocrine System vs. Nervous System Endocrine System:- Slower to respond, requires transport system Nervous System:- Rapid response, transmits signal electrically the chemical at synapseo Important Terms Autocrine: releases a chemical that acts upon itself Paracrine: releases a chemical that acts upon a neighboring cell Exocrine: release material via ducts (pancreas in digestion) Endocrine: releases chemical into the blood stream to target cell somewhere else in the bodyHormones- Definitiono- Categorieso Steroid Lipid-soluble Formed from cholesterol Produced by gonads and adrenal cortexo Protein Water-soluble Consists of amino acid chains Three subgroups- Polypeptides- Oligopeptides- Glycoproteinso Biogenic amines Water-soluble (except TH) Derived from amino acid that is modified- Mechanism of Actiono Possible Actions: Alter plasma membrane permeability; open/close ion channels Stimulate protein synthesis Activate/deactivate enzymes Induce secretory activity Stimulate mitotic activityo Characteristic of Protein/Biogenic Amine Hormones: Plasma Membrane Receptors & 2nd Messenger Systems- cAMP 2nd Messenger System:o Hormone binds to specific receptor in plasma membrane on target cell…activates a G protein…activates adenylyl cyclase…converts ATP to cAMP…cAMP activates protein kinases…affect protein synthesis or other cellular processo Can be stimulatory (turn on response) or inhibitory (turn off response)o Used by: Epinephrine ACTH FSH LH Glucagon PTH TSH Calcitonin- PIP2-calcium Signaling Mechanismo Used by some amino acid-based hormones in some tissueso Involves a G proteino G protein activates phospholipase C enzymeo Hormones functioning through activation of phospholipase Co Phospholipase C splits membrane phospholipid PIP2 into two 2ND messengers: diacylglycerol (DAG) and IP3o DAG activates protein kinases; IP3 triggers release of Ca2+o Ca2+ alters enzymes or channels or binds to the regulatory protein calmodulino Characteristic of Steroid Hormones: Direct Gene Activation Mechanism- Directly affect genes…specific genes…indirectly affecting the protein generated- Lipid-soluble hormones passively diffuse…doesn’t require energy but needshelp- Target Cell Specificityo Each hormone has specific target cells (can have many or one target)o Specificity = target cells have receptors for specific hormoneo Three Factors that Regulate Activation of Target Cells: Hormone levels in blood Number of receptors on target cell Affinity of hormoneo Receptor Dynamics: Up-regulation: usually occurs (“positive-feedback” in a way)…targets cells form more receptors in response to rising blood levels of the specific hormones to whichrespond Down-regulation: lessen the activity of receptors (“negative-feedback” in a way)…prolonged exposure to high hormone concentration desensitizes the target cells, sothat they respond less vigorously to hormonal stimulation- Duration of Hormone Activity:o Concentration of circulating hormone in blood at any time reflects: Its rate