The Endocrine System PowerPoint - PDF

The Endocrine System 1  Introduction Communication and coordination Nervous system= neurotransmitters Endocrine = hormones – Hormones Chemical messengers that travel in the bloodstream to other tissues and organs – Tissues, glands, and cel...

The Endocrine System 1  Introduction Communication and coordination Nervous system= neurotransmitters Endocrine = hormones – Hormones Chemical messengers that travel in the bloodstream to other tissues and organs – Tissues, glands, and cells secrete hormones  Before we start… Exocrine gland vs. endocrine gland  Feedback Loops Negative feedback – response is reverse of change detected  Feedback Loops Positive Feedback – response reinforces change detected The Endocrine System Major Organs Pituitary gland Adrenal gland Thyroid gland Parathyroid gland Pancreas Pineal gland Thymus Gonads 6  The Endocrine System Secondary Organs Skin Heart Gastrointestinal tract Kidneys Liver Placenta Adipose tissue 7  Endocrine System Pituitary Gland Sits in the sella turcica – Connects to the hypothalamus by the infundibulum Posterior Pituitary Anterior Pituitary – Stores and secretes – Regulated by hormones from hypothalamus hypothalamus – Antidiuretic and Oxytocin – 6 other hormones…. 8  Posterior Pituitary Antidiuretic Hormone (ADH) Origin – Supraoptic nuclei of the hypothalamus – Carried by the hypothalamo- hypophyseal tract Target tissue – Kidney Action(water retention) – Decreases urine volume – Raises blood pressure Stimulating factors – Low blood pressure – Certain drugs/substances 9  Antidiuretic Hormone Regulation - Drugs Stimulated - Nicotine - Morphine - Barbiturates Inhibited - Alcohol 10  Posterior Pituitary Oxytocin Origin – Paraventricular nucleus of the hypothalamus – Carried by the hypothalamo- hypophyseal tract Target tissue – 2 major (uterus, breast) – Important chemical messenger in the 11 brain  Oxytocin Regulation Stretch receptors in the uterus and cervix stimulate release Infant nursing triggers release 12  Oxytocin Effect Contraction of uterine muscles “Letdown” reflex in lactation Role in sexual arousal and orgasm Role in affectionate behavior (cuddle hormone) 13  Pituitary Gland Anterior Pituitary Composed of glandular tissue Produces and secretes its own hormones Tropins or Tropic Hormones Stimulated by the hypothalamus – Receives regulatory hormones through the hypothalamo- hypophyseal portal system 14  Anterior Pituitary Hormones Growth hormone (GH) Adrenocorticotropic hormone (ACTH) Thyroid stimulating hormone (TSH) Gonadotropins - Follicle stimulating hormone (FSH) - Luteinizing hormone (LH) Prolactin (PRL) Regulated by……. Hypothalamic Releasing and Inhibiting Hormones Growth hormone-releasing hormone (GHRH) Corticotropin-releasing hormone (CRH) Thyrotropin-releasing hormone (TRH) Gonadotropin-releasing hormone (GnRH) Prolactin-inhibiting hormone (PIH) Somatostatin Aka Growth hormone-inhibiting hormone (GHIH)  Anterior Pituitary Hormone Growth Hormone (GH) Target tissue – all cells but most drastic effect is on bone and skeletal muscle Origin – somatrope cells Increase Cell size Cell division Muscle mass Long bone growth 17  Growth Hormone Regulating Hormones Growth hormone- releasing hormone (GHRH) – Stimulates growth hormone release Induces liver to produce insulin growth stimulants Insulin-like growth factor (IGF-1) Somatostatin (or GHIH) – Inhibits – Produced in response to increasing GH levels 18  Growth Hormone Abnormalities Decreased – pituitary dwarfism Increased – acromegaly 19  Anterior Pituitary Adrenocorticotropic Hormone ACTH Origin – corticotrope cells Target tissue – adrenal cortex Causes production of glucocorticoids 20  Adrenocorticotropic Hormone Regulating Hormones Corticotropin-releasing hormone (CRH) Rising levels of glucocorticoids cause inhibition of the pituitary by decreasing CRH 21  Anterior Pituitary Thyroid Stimulating Hormone (TSH) Origin – thyrotrope cells Target tissue – thyroid Effects – Increases production and release of thyroid hormone 22  Thyroid Stimulating Hormone (TSH) Regulating Hormone Thyrotropin-releasing hormone (TRH) Elevated levels of thyroid hormone inhibit the production of: – TRH by hypothalamus – TSH by anterior pituitary gland 23  Anterior Pituitary Gonadotropins Follicle-stimulating hormone (FSH) – stimulates gamete production Luteinizing hormone (LH) – stimulates hormone production Origin – gonadotrope cells Target tissue – ovaries/testis 24  Gonadotropins Regulating Hormones Gonadotropin-releasing hormone (GnRH) Produced by the hypothalamus in response to gonadal hormones 25  Anterior Pituitary Prolactin Origin – lactotropes Target tissue – Breasts – Stimulates milk production 26  Prolactin Regulating Hormones Thyrotropin-releasing hormone (TRH) Prolactin-inhibiting hormone (PIH) Prolactin-releasing hormone (PRH) – MAYBE? 27  Prolactin Regulation - Female PRL levels rise – PIH levels decrease with a fall in estrogen – Prior to menstruation – Toward the end of pregnancy – Stimulated with infant nursing 28 Homework! Origin/ origin cells Target tissue Effect Regulation  Endocrine System Adrenal (Suprarenal) Gland Sits on the kidney Enclosed by a fibrous capsule and a fat pad Is structurally and functionally two glands Components – Adrenal Cortex – Adrenal Medulla 30  Adrenal Gland Adrenal Cortex Produces corticosteroids Composed of three layers Zona glomerulosa – Mineralocorticoids Aldosterone Zona fasciculata – Glucocorticoids and androgens Cortisol Sex hormones Zona reticularis – Glucocorticoids and Gonadocorticoids Cortisol 31 Sex hormones  Mineralocorticoid Aldosterone Effect Target tissue - kidneys Reduces sodium secretion in the kidney – Causes water retention Enhances sodium reabsorption - Urine - Sweat - Gut Raises blood pressure Regulation To be covered in chapter 23 32  Glucocorticoids Cortisol Target tissue – most body cells Effects Regulate metabolism Adapt to stress and repair tissues – Anti-inflammatory effect Gluconeogenesis – promotes glucose formation from fat and protein Enhances epinephrine’s vasoconstrictive effects 33  Cortisol Regulation CRH is produced by the hypothalamus ACTH is released from the pituitary in response to CRH ACTH stimulates the adrenal gland to produce cortisol Elevated cortisol levels inhibit the release of both CRH and ACTH 34  Cortisol Abnormalities Elevated – Cushing’s Syndrome Depressed – Addison’s Disease 35  Gonadocorticoids Effect and Regulation Effect Contribute to the onset of puberty Responsible for sex drive Changes in metabolism Regulation By FSH and LH 36  Adrenal Gland Adrenal Medulla Part of the autonomic nervous system Hormones Catecholamines - Epinephrine - Norepinephrine - Dopamine (trace amounts) * act as both neurotransmitters and hormones 37 Sympathetic Division of ANS  Adrenal Medulla Catecholamines Origin – chromaffin cells (modified postganglionic neurons) Target tissue – affects nearly all tissue 39  Catecholamines Effects and Regulation Effects Fight – or – flight - Elevates heart rate - Pupils dilate - Elevates blood pressure - Blood shunted to brain Regulation Sympathetic control 40  Endocrine System Thyroid Gland Largest of the pure endocrine glands Located in the anterior neck Structure – Butterfly shaped – Two lobes – Isthmus 41  Thyroid Gland Micro Structure Composed of hollow spherical follicles Follicular cells – Cuboidal or squamous epithelial cells that form the walls – Produce thyroid hormone Thyroxine (T4) Triiodothyronine (T3) Parafollicular cells 42 (C cells)  Thyroid Gland Thyroid Hormone Origin – follicular cells Target cells – all cells except: - Spleen - Testis - Uterus - Thyroid gland - Adult brain 43  Thyroid Hormone Effect Calorigenic effect – increases metabolism Increases – alertness/reflexes – respiratory rate – heart rate (strength of heartbeat) = BP – appetite – breakdown of carbs, fats, proteins – GH (growth hormone) – Fetal development 44  Thyroid Hormone Regulation TRH – thyrotropin-releasing hormone TSH – thyroid stimulating hormone 45  Regulation Thyrotropin-Releasing Hormone Overcomes the negative feedback loop in conditions requiring increased body energy need - Pregnancy - Prolonged cold 46  Regulation Thyroid Stimulating Hormone TSH rises in response to declining T4 levels TSH is suppressed by - Rising T4 levels - Somatostatin - Rising levels of glucocorticoids - Sex hormones 47 Thyroid Hormone Abnormalities Enlarged thyroid gland - goiter 48  Thyroid Hormone Abnormalities Decreased – hypothyroidism – Congenital iodine deficiency syndrome Increased – hyperthyroidism – Grave’s disease 49  Thyroid Gland Calcitonin Origin – parafollicular cells or C cells Target tissue – bone (mostly important in childhood) 50  Calcitonin Effect Responds to high blood calcium levels Inhibits osteoclast activity - Decreases bone resorption - Decreased calcium release Stimulates uptake of calcium into the bone matrix (by activity of which cell?) 51  Calcitonin Regulation Release stimulated by excessive blood levels of calcium Release inhibited by dropping levels of calcium Calcitriol 52  Endocrine System Parathyroid Gland Tiny glands imbedded in the thyroid Usually there is four, may be up to eight Produces parathyroid hormone (PTH) 53  Parathyroid Gland Parathyroid Hormone Origin – chief cells Target tissue - Skeletal - Kidney - Intestine 54  Parathyroid Hormone Effect Stimulates osteoclasts to release ionic calcium and phosphates into the blood Inhibits osteoblasts Enhances reabsorption of calcium in the kidney Increase absorption of calcium in the intestine (by activating calcitriol - Vitamin D) 55 Parathyroid Hormone Abnormalities Increased – hyperparathyroidis m 56  Endocrine System Pancreas Located behind the stomach Mixed gland – endocrine and exocrine Made up of acinar cells and pancreatic islets – (Islet cells of Langerhans) 57  Pancreas Hormones Insulin – Anabolic (converts smaller molecules into larger ones) – Glucose → Glycogen – Amino acids→ Proteins Glucagon – Catabolic (breaking down larger molecules into their subunits) – Reverse Everything Above! 58  Pancreas Insulin Origin - beta cells of the pancreatic islets Main effect – Removes glucose from the blood – Uses it for energy and then converts it to fat Target tissue – Muscle and fat cells – Insulin used to absorb glucose Excludes: – Liver* (glycogenesis) – Kidney – Brain All three absorb and use glucose without insulin 59  Insulin Effects Lower blood glucose levels Enhance membrane transport of glucose into body cells Inhibits breakdown of glycogen to glucose – This is the action of glucagon! Inhibits conversion of amino acids and fats to glucose 60  Insulin Regulation Stimulated by - Elevated blood sugar levels - Rising levels of amino acids and fatty acids - Acetylcholine released by parasympathetic nerves Inhibited by dropping serum glucose Inhibited by somatostatin (GHIH) 61  Insulin Abnormalities – Diabetes Mellitus (DM) Type I (IDDM) – Autoimmune disease Type II (NIDDM) – Reduced sensitivity to insulin Too much insulin – Hypoglycemia 62  Pancreas Glucagon Origin – alpha cells of pancreatic islets Target tissue - liver 63  Glucagon Effects Raises blood glucose levels Breakdown of glycogen to glucose (glycogenolysis) Synthesis of glucose (gluconeogenesis) Release of glucose from the liver 64  Glucagon Regulation Released in response to falling glucose levels Stimulated by sympathetic activity Stimulated by rising amino acids Insulin antagonizes effects Inhibited by rising blood sugar Inhibited by somatostatin (GHIH) 65 Homework! cataboli c anaboli c  Endocrine System Pineal Gland Tiny pine-cone shaped gland In the epithalamus Melatonin 68  Pineal Gland Melatonin Origin – pinealocytes Target tissue – suprachiasmatic nuclei 69  Melatonin Effect and Regulation Effect Regulates sleep cycles – Causes drowsiness – Circadian rhythm Regulation Light responsive Peak level is at night Lowest level at noon 70