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HSF II Endocrine
Endocrine PowerPoint
| Term | Definition |
|---|---|
| Aldosterone | regulates K+ concentration in plasma, brings it back down |
| Neuroendocrine Reflexes | hypothalamus is the integrator, output to endocrine system |
| Common Features of Nervous system and Endocrine system | 1) sometimes anatomically and/or functionally related 2) both use ligands to bind to cell receptors 3) share many chemical messengers (neurotransmitters and hormones) 4) negative feedback mechanisms 5) preserve homeostasis |
| Nervous system and Endocrine system differ: | 1) neurotransmitters disperse and disappear quickly 2) hormones disperse and disappear slowly, long-term |
| Endocrine Glands | develop from glandular epithelium, whose connection to the free surface is not maintained. Secretions (hormones) into the blood |
| Neurohormone | a hormone that is produced by a neuron |
| Paracrine | hormones that affect the body in its direct vicinity |
| Autocrine | hormone that affects the cell it came from, self regulating |
| Target Tissues | (or cells) the effectors in an endocrine reflex arc. Defining characteristic is that it has a receptor for that hormone |
| Hyposecretion/Hypersecretion | too little/too much hormone released |
| Hyper-responsiveness/hypo-responsiveness | too many/too few receptors on target |
| Hypo/hypersecretion of hGH | Pituitary dwarf/giant |
| Type 1 Diabetes | Insulin-dependent diabetes mellitus, IDDM, hyposecretion of insulin |
| Type 2 Diabetes | Non-insulin-dependent diabetes mellitus, NIDDM, hyporesponsiveness to insulin |
| Two Groups of Hormones | Based on chemical structure: Amino acid derivatives and Lipid derivatives |
| Amino Acid Derivatives Hormones | Tryptophan, tyrosine = catecholamines, peptides. Modification of amino acids, peptides are most common |
| Lipid Derivative Hormones | steroid hormones and eicosinoids Eicosinoids derived from membrane phospholipids |
| Cholesterol | parent compound for all classic steroid hormones, lipid derivative |
| Arachidonic Acid | parent molecule for eicosinoids, phospholipidase A acts on membrane phospholipids to produce arachidonic acid. |
| Four Classes of Eicosinoids: | important paracrines: 1) prostaglandins, 2) thromboxanes, 3) prostacyclins, 4) leukotrienes. |
| Cyclooxygenases | prostaglandins, thromboxanes, prostacyclins. Pathway proceeds through COX-1 and COX-2 |
| Lipoxygenase | produces leukotrienes, produced by collections of cells and not endocrine organs |
| COX-1 | Constitutive (produced under all physiological conditions), made in kidney, stomach, and platelets. Homeostatic functions: GI tract, renal tract, platelet function, macrophage differentiation |
| COX-2 | Induced, causes inflammation |
| Non-Steroidal Anti-Inflammatory Drugs (NSAIDS) | Drugs like aspirin and ibuprofen. Inhibit cyclooxygenase activity of PGH2 synthase (COX enzymes). Inhibit formation of prostaglandins involved in fever, pain, and inflammation. Inhibit blood clotting by blocking thromboxane formation in blood platelets |
| Leukotrienes | involved in asthmatic and allergic reactions and act to sustain inflammatory reactions. Work on smooth muscle in respiratory system. |
| Anti-asthma medications | inhibit lipoxygenase and leukutriene-receptor interactions. Smooth muscle in the respiratory system |
| Amino acid and peptide hormones | functional for <1 hour. usually not complexed with a transport protein. quickly degraded/no reserve. They and their derivatives are hydrophilic, lipophobic, and polar |
| Thyroid and steroid hormones | Remain in circulation much longer. 99% become attached to special transport proteins and thus bloodstream contains substantial reserve of bound hormones. Hydrophobic, lipophilic, and nonpolar, only soluble in blood because of carrier protein |
| Membrane Permeability | dependent on lipids, not freely permeable to hydrophilic/lipophobic molecules (like amino acid hormones), freely permeable to hydrophobic/lipophilic molecules (thyroid hormones) |
| Body Temperature reflex | Body temp down, detected by thyroid, increase thyroid hormones, hormones increase metabolism, and heat increases |
| Two Receptor Locations on Target Cells | Plasma Membrane and cytoplasm or nucleus |
| Plasma Membrane Receptor | catecholamines/peptide hormones: Hormone acts as a first messenger, relaying message to intercellular intermediary. Second messenger affects enzyme activity and changes cellular metabolic reactions |
| Cytoplasm or Nucleus Receptor | lipid-soluble hormones, diffuse through plasma membrane. Exert their effect by changing gene expression. |
| Steroids as Cytoplasm or Nucleus Receptor | Affect DNA transcription rate and protein synthesis. Change synthesis of enzyme and structural proteins affecting cell's metabolic activity and structure |
| Thyroid hormones as Cytoplasm or Nucleus Receptor | bind to receptors in nucleus, affecting cell's metabolic activity and structure. Bind to receptors on mitochondria, affecting energy production |
| Consequences of hormone stimulation are determined by: | amount of hormone present "amplitude coding", and number & kind of receptor present "sensitivity or responsiveness" |
| Endocrine Reflexes | functional counterparts of neural reflexes, most cases as negative feedback loops |
| Target Tissue Sensitivity | determined by the number of receptors present |
| Down-Regulation | decrease the number of receptors to a molecule on the membrane |
| Up-Regulation | increase the number of receptors to a molecule on the membrane |
| Interaction | the action of a hormone depending on another |
| Types of Interactions | 1) Synergistic - multiple stimuli, more than additive. 2) Permissive - need second hormone to get full expression. 3) Antagonistic - glucagon opposes insulin |
| Stimuli for Endocrine Reflexes | Humoral stimuli - changes in composition in the interstitial fluid. Hormonal stimuli - changes in levels of a particular hormone in the interstitial fluid (thyroid hormone). Neural stimuli - the arrival of neurotransmitters at a neuroglandular junction. |
| Pineal Gland Location | posterior margin of the diencephalon, pouch in the third ventricle. |
| Pineal Gland Development | develops from out-pocketing of the diencephalon during neural development, loses most neural connections to the brain, but innervated by sympathetic and, to a lesser degree, parasympathetic fibers. |
| Pinealocyte | functional/adult cell of the pineal. "neuron-like" cells that "synapse" on pineal blood vessels |
| Pinealocyte hormone example | pinealocyte produce melatonin from amino acid tryptophan. Melatonin synthesis shows a circadian rhythm. Melatonin is the only one that comes from tryptophan. |
| Melatonin Synthesis | Darkness stimulates sympathetic output and consequently melatonin synthesis is highest at this time. Light inhibits the sympathetic system, melatonin synthesis declines. |
| Melatonin Roles | Has significant antioxidant activity and enhances many aspects of immune function, biological clocks and may have roles in jet lag, SAD, and sexual behavior |
| Pituitary (hypophysis) Location | located on the inferior surface of the hypothalamus, to which it is anatomically and functionally connected. Lies in sella turcica in sphenoid bone |
| Anterior Lobe (Adenohypophysis) | Divided into the pars tuberalis, pars intermedia, pars distalis. Consists of Tropic Cells |
| Posterior Lobe (Neurohypophysis) | Divided into infundibulum and pars nervosa. Consists of axons of hypothalamic neurons and glial cells |
| Infundibulum Role | physically and functionally connects the pituitary to the hypothalamus |
| Pituitary Development | From roof of the mouth (anterior lobe) and the brain (posterior lobe and infundibulum) |
| Rathke's Pouch | appearance varies considerably. The pouch/space between the pituitary lobes leftover from anterior pituitary in development |
| Posterior Pituitary Hormone Synthesis | Made in hypothalamic nuclei and released from the posterior lobe. They are neurohormones. Posterior lobe does not make anything |
| Hypothalamic-Hypophyseal Tract | 1) hormone is made and packaged in cell body of neuron. 2) Vesicles are transported down the cell. 3) Vesicles containing hormones are stored in posterior pituitary. 4) Hormones are released into blood |
| ADH/Vasopressin | Peptide Hormone. Involved in blood volume and pressure regulation. Kidney is target. |
| Oxytocin | exerts primary effects during parturition and lactation. |
| Lactation | When a baby suckles at the breast, the sensory stimulus goes to hypothalamus and causes pituitary to produce more milk. The target tissues are not endocrine in nature |
| Tropic Hormones | Some of, but not all, hormones have other endocrine organs as their target tissues. |
| WBC Stains | Acidophils, basophils, chromophobes stain differently because based on the hormonal content of the cells |
| 6 Major Hormones of the Anterior Pituitary | 1) Adrenocorticotropic hormone (ACTH). 2) Thyroid stimulating hormone (TSH). 3) Follicle stimulating hormone (FSH) 4) Luteinizing hormone (LH) 5) Prolactin (PR) 6) Growth Hormone (GH) |
| Hypothalamic-Hypophyseal Portal System | functionally links the hypothalamus and the anterior love. Establishes a vascular linkage between the hypothalamus and anterior pituitary |
| Portal System | any exception to the "normal" sequence of artery-capillary-vein |
| Three Causes of Hyper- or Hyposecretion of a Hormone | Tertiary - the hypothalamus, Secondary - the anterior pituitary, Primary - the final endocrine organ |
| Cushing's Syndrome | Three possibilities of Cushing’s (too much cortisol) Tertiary – hypothalamus CRH keeps going up, so then ACTH and Cortisol are high Secondary – anterior pituitary is still producing ACTH Primary – due to adrenal gland not responding to decreased ACTH |
| Thyroid Gland | lies in cervical region anterior to the laryngeal cartilages and the trachea. Largest of endocrine glands |
| Thyroid Development | Develops as a pouch in the area of the tongue and descends into its final location |
| Thyroid Follicles | structural unit, each follicle is a sphere of follicular cells |
| Follicular Cells | synthesize the precursor to thyroid hormones, thyroglobulin, stored in the follicle as a gelatinous colloid by taking up amino acids and iodine |
| T4 and T3 | Thyroxine and Triiodothyronine, derived from thyroglobulin and made of tyrosine and iodine. Named for number of iodine atoms in them. Stimulate growth processes like osteogenesis |
| Thyroid Binding Globulin | transports T3 in blood after T3 is made from T4 |
| Juvenile Hypothyroidism | results from stunted growth of the skeletal system |
| Thyroid Receptors | located in nucleus and cytoplasm |
| Endemic Goiter (iodine deficient hypothyroidism) | Very large nodules developing in the neck in the thyroid. The lack of Iodine in the diet is driving the thyroid into overdrive. Without Iodine there’s no T3 or T4 so no negative feedback to stop making TSH. |
| Parafollicular Cells | in thyroid, located between follicles. Are neural crest cells that invade developing thyroid. Produce calcitonin |
| Calcitonin | lowers calcium levels via a humoral reflex arc. Target tissues are bones and kidneys, it is an antagonist to PTH |
| Parathyroids | located on posterior surface of thyroid, composed of principle (chief) cells, produce PTH, in response to low levels of Ca++. |
| Parathyroid Hormone | raises concentrations of calcium via a humoral endocrine reflex, target Bone, GI tract, and kidneys |
| Adrenal Gland | rostral pole of the kidney, consists of an outer cortex and inner medulla. Targeted by ACTH |
| Adrenal Cortex | three layers, each with different hormones- zona reticularis, zona fasciculata, zona glomerulosa |
| Zona Glomerulosa | appears independent of anterior pituitary/hypothalamus. ACTH has no effect on it, produces aldosterone (steroid) |
| Aldosterone | stimuli that indicate a decrease in blood pressure stimulate it. salt retaining hormone. regulates how much sodium you lose in urine/how much kept in blood. Targets kidney |
| How does Aldosterone increase Na+ reabsorption? | increases the number of transporters |
| Zona Fasciculata | target of ACTH. produces glucocorticoids, like cortisol |
| Gluconeogenesis | formation of glucose from other substances e.g. proteins and fats |
| Cortisol | glucocorticoid, promotes gluconeogenesis, profound/conflicting effect on immune system, long term effect of stress/short term fight or flight |
| Zona Reticularis | largely independent of the hypothalamus and anterior pituitary, produce adrenal androgens, gonadocorticoids: primary androgen product DHEA |
| Adrenal Androgens | male sex hormones, but males and females both have them |
| DHEA | dehydroepiandrosterone, intermediate in biosynthesis of testosterone and estrogen, calls for secondary sex characteristics in males |
| Androgens in Adult Males | insignifficant |
| Androgens in Adult Females | supports the maintenance of muscle mass and erythropoiesis, implication in the female libido |
| Adrenal Medulla | controlled by sympathetic div. of ANS. has Chromaffin cells, which produce neurohormone epinephrine, stimulated by preganglionic nerves |
| Human Growth Hormone (hGH) | direct effects are anabolic, releasing energy and stimulating growth. indirect effect of mediating somatomedin hormones from liver |
| IGF-1 | somatomedin, insulin-like growth factor. Has a strong effect on cartilage and bone and skeletal muscle. Effect normally associated with osteogenesis. stimulate cartilage, bone, and muscle growth |
| LH (Leutenizing Hormone) | produced by a trophic cell in anterior pituitary, target gonads, stimulates testosterone, estrogen, and progesterone |
| FSH (Follicle Stimulating Hormone) | produced by trophic cell in anterior pituitary, targets gonads, stimulates gamete production |
| Seminiferous Tubules (Males) | target tissue of LH and FSH, where male gametes and testosterone are produced |
| Nurse/Sertoli Cells (Males) | where LSH targets for meiotic division for haploid sperm, spermatogenesis |
| Interstitial/Leydig Cells (Males) | LH binds to them to produce testosterone |
| (Females) LH and FSH regulates: | ovarian and uterine cycles, which are cyclical productions |
| Corpus Luteum | source of estrogen and progesterone during second half of menstrual cycle |
| FSH on Ovary | binds to follicle and causes ovum to mature |
| LH on Ovary | binds to corpus luteum to secrete estrogen and progesterone |
| Pancreas | both exocrine and endocrine function, most is exocrine for digestive secretions into the duodenum, islets are endocrine |
| Pancreatic Islets (of Langerhans) | endocrine portion of pancreas. alpha cells produce glucagon, beta cells produce insulin |
| Glucagon | produced by pancreatic alpha cells, targets liver and adipose, mobilizes lipid reserves, promotes glucose synthesis and glycogen breakdown in liver, elevates blood glucose |
| Insulin | produced by pancreatic beta cells, facilitates uptake of glucose by target cells, stimulates formation and storage of lipids and glycogen, reduce blood glucose by increasing number of glucose transporters |
| Pancreatic Alpha Cells | produce glucagon |
| Pancreatic Beta Cells | produce insulin |
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connorquinby
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