BIOL 320 1st Edition Lecture 1 Outline of Current Lecture II Review of Epithelial Tissue Cell Types A Description B Function C Location III Endocrine System A Definition of Endocrinology IV Hormones A Definition B Categories C Mechanism of Action D Target Cell Specificity E Interaction of Hormones at Target Cells F Control of Hormone Release V Hypothalamus and Pituitary A Structural and Functional Relationship Current Lecture Review of Epithelial Tissue Cell Types Simple Squamous a Description single layer of flattened cells with disc shaped central nuclei and sparse cytoplasm the simplest of the epithelia b Function allows passage of materials by diffusion and filtration in sites where protection is not important secretes lubricating substances in serosae c Location kidney glomeruli air sacs of lungs lining of heart blood vessels and lymphatic vessels lining of ventral body cavity serosae Simple Cuboidal a Description single layer of cube like cells with large spherical central nuclei b Function secretion and absorption c Location kidney tubules ducts and secretory portions of small glands ovary surface Simple Columnar a 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 action c 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 Columnar a 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 cilia b Function secretion particularly of mucus propulsion of mucus by ciliary action c 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 Squamous a 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 layers b Function protects underlying tissues in areas subjected to abrasion c 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 Transitional a 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 stretch b Function stretches readily and permits distension of urinary organ by contained urine c Location lines the ureters bladder and parts of the urethra Endocrine System Definition of Endocrinology o Chemical communication between cells over distances OVER DISTANCES travels via blood or other part of vascular system o Endocrine System vs Nervous System Endocrine System Slower to respond requires transport system Nervous System Rapid response transmits signal electrically the chemical at synapse o 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 body Hormones Definition o Categories o Steroid Lipid soluble Formed from cholesterol Produced by gonads and adrenal cortex o Protein Water soluble Consists of amino acid chains Three subgroups Polypeptides Oligopeptides Glycoproteins o Biogenic amines Water soluble except TH Derived from amino acid that is modified Mechanism of Action o Possible Actions Alter plasma membrane permeability open close ion channels Stimulate protein synthesis Activate deactivate enzymes Induce secretory activity Stimulate mitotic activity o 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 process o 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 Mechanism o Used by some amino acid based hormones in some tissues o Involves a G protein o G protein activates phospholipase C enzyme o Hormones functioning through activation of phospholipase C o Phospholipase C splits membrane phospholipid PIP2 into two 2ND messengers diacylglycerol DAG and IP3 o DAG activates protein kinases IP3 triggers release of Ca2 o Ca2 alters enzymes or channels or binds to the regulatory protein calmodulin o 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 needs help Target Cell Specificity o Each hormone has specific target cells can have many or one target o Specificity target cells have receptors for specific hormone o Three Factors that Regulate Activation of Target Cells Hormone levels in blood Number of receptors on target cell Affinity of hormone o 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 which respond Down regulation lessen the activity of receptors negative feedback in a way prolonged exposure to high hormone concentration desensitizes the target cells so that they respond less vigorously to hormonal stimulation Duration of Hormone Activity o Concentration of circulating hormone in blood at any time reflects Its rate of release The speed at which it is inactivated and removed from the body o Hormone inactivation occurs by Enzyme degradation Kidneys filtering hormones from blood Liver recycling and detoxifying blood Interaction of Hormones at Target Cell o Target tissues can have receptors for many different hormones mix of hormones can have a range of effects o Three Types of Interaction Synergistic