Endocrine System. Endocrine System. 1. Endocrine System. Functions of Hormones. What is A Hormone

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1 Endocrine System Endocrine System By Scott Ford, M.Ed. YouTube:mrfordsc lass Facebook:mrfordsclasslearning Twitter:mrfordsclass Endocrine Endo = inside Crine = secrete Composed of: Hormone producing glands Pituitary Gland Thyroid Gland Parathyroid Gland Adrenal Gland And more Regulates body activities What is A Hormone The endocrine system does its work through hormones All hormones are organic compounds It has physiological effect on other cells in the body A hormone is a chemical substance secreted into the internal body fluids by a cell or group of cells. A hormone can either be a steroid or non-steroid Steroid Non-Steroid Proteins and peptides Amines (derived from amino acid tyrosine) Functions of Hormones Homeostatic Maintenance Used to keep the body in a state of balance Growth & Development Hormones cause the body to grow, become bigger Also responsible for maturation process, turning us into adults Reproduction Besides causing people to go through puberty hormones are also responsible for creating and development of gametes ( sperm cells and egg cells) Functions of Hormones Emergencies Synergistically Helps other hormones Antagonistic Opposes other hormone Chemical Classification of Hormones Steroids Hormones with a steroid nucleus, similar to base structure of cholesterol All steroid hormones are derived from Cholesterol Proteins and peptides Can be amino acids or proteins Created on the rough endoplasmic reticulum Amines (derived from amino acid tyrosine) Produced in the thyroid and adrenal medulla 1

2 Hormone Control Most hormonal secretions are controlled by negative feedback Some positive feedback loops can be found in the reproductive system Endocrine glands tend to oversecrete hormones, which cause the target cells to functions The target cell will provide feedback to the endocrine glands causing it to stop Control Methods Tropic Hormones The hypothalamus controls the anterior pituitary that stimulates other glands Nervous System The nervous system stimulates some glands directly Glands affecting glands Some glands respond to the changes caused by hormone secretions of other glands Hormonal Action Hormones work by interacting with their receptor on their target cells The more receptors the hormone interacts with, the stronger the response Receptors are usually specific for a single hormone These receptors can: Be on or within the cell membrane Within the cell-the cytoplasm or nucleus Protein/Peptide & Catecholamine Do not pass easily through a cell membrane Will attach to a receptor on or inside cell membrane A secondary messenger is generated to deliver message to something within the cell Protein/Peptide & Catecholamine Types of secondary messengers Cyclic Adenosine Monophosphate (camp) Plasma membrane phospholipids Calcium-calmodulin Types of Secondary Messengers Cyclic Adenosine Monophosphate (camp) Most hormone will use this Activates protein kinase A, which causes phosphorylation that can turn on or turn off target enzymes Phosphorylation attaches a phosphate group to a protein or other organic molecule Plasma membrane phospholipids The interaction of the hormone and receptor activate a membrane-bound enzyme-phospholipase C Phospholipase C causes phospholipids in the cell membrane to split into the secondary messengers Calcium-calmodulin The interaction of hormone and receptor activates calcium channels in the cell membrane to open, letting calcium into the cell 2

3 Steroid and Thyroid Hormones Soluble in lipids (not water), easy diffuse across the cell membrane Can enter the cell and bind with intracellular (within the cell) receptors either in the cytoplasm or nucleus Interactions cause a change in the receptor Steroid and Thyroid Hormones Bind to particular DNA sequences, can active or deactivate Affects production of proteins May take hours for effects to become evident Glands A gland in an organized collection of secretory epithelium cells Derived from the invagination and in growth of lining epithelia into underlying connective tissue Can be a single cell or a group of cells Two general categories Exocrine Endocrine Endocrine Glands Pituitary Gland Thyroid Gland Parathyroid Gland Adrenal Gland Sex (gonad) Gland Pancreas Endocrine Glands Other Endocrine Organs Pineal Gland Hypothalamus Kidney Placenta Intestinal Mucosa Pituitary Gland Also knows as the Hypophysis May also hear the master gland About 1cm in diameter and 0.5 to 1 gram in weight Sits in the base of skull in Sella Turcica of Sphenoid Bone 3

4 Pituitary Gland Connected to the Hypothalamus by the Pituitary Stalk May also be called: Hypophyseal Stalk and Infundibul um Physiological there are two lobes Anterior Lobe Posterior Lobe Anterior Lobe aka Adenohypophysis Developed from epithelial tissue Made of five cell types Produces, store and secretes six polypeptide or peptide hormones that students need to know Anterior Lobe Hormones (covered in more detail later): Growth Hormone (GH) Prolactin (PRL) Follicle-Stimulating Hormones (FSH) Luteinizing Hormone (LH) Thyroid-Stimulating Hormone (TSH) Adrenocorticotropic Hormone (ACTH) Posterior Lobe aka Neurohypophysis Pars Nervosa Developed from Nervous Tissue The cell bodies of these are found in the hypothalamus Hormones are transported to the posterior lobe from the Hypothalamus via neurons Two Important Hormones from the Posterior (covered later) Oxytocin (OT) Antidiuretic Hormone (ADH) Thyroid Gland Located anterior to trachea at C3-C5 Palpable at root of neck, moves when swallowing Size and weight variable Large size does not always mean there is something wrong Has a rich blood supply and nerve supply Thyroid Gland Composed of 2 lobes a right and a left connected via the Isthmus The thyroid gland is a collections of spherical follicles and extrafollicular cells wrapped up in a connective tissue capsule 4

5 Thyroid Gland Makes three important hormones Powerful in effecting the metabolic rates of the body Thyroxine (T4) Triiodothyronine (T3) Important in impacting blood calcium and phosphate ion levels Calcitonin Cool Fact: Gets it name from the Greek adjective meaning shield shaped Parathyroid Glands Two pairs of glands on the posterior surface of thyroid glands Small yellowish brown dot encased in a thin capsule of connective tissue Secretes parathyroid hormone (PTH) Deals with calcium ion and phosphate ion level in the blood Adrenal Glands Located on top of the kidneys Around the level of the twelfth thoracic vertebra Embedded in adipose tissue Shaped like little pyramids Has two distinct structures: Adrenal medulla Adrenal cortex Adrenal Glands Adrenal medulla The center of the gland (surrounded by adrenal cortex) Functionally related to sympathetic nervous system Makes: epinephrine, and norepinephrine Adrenal Cortex Outside portion, surrounds medulla Make up most of the adrenal glands Has three distinct layers: zona glomerulosa, zona fasciculata, zona reticularis Makes: lots of steroid, hormones, of interest are mineralocorticoids, glucocorticoids, and sex hormones Pancreas Behind stomach Two major types of secretory tissues Acini (exocrine) Islet of Langerhans (endocrine) 5

6 Islet of Langerhans Endocrine part of the gland At least four different types of cells Alpha: makes glucagon Beta: makes insulin Delta: somatostatin PP cells: pancreatic polypeptide Thymus Located behind sternum Large in young children, after puberty fills with fat and atrophy Main purpose of thymus is to stimulate lymphoid tissue to produce lymphocytes Pineal Gland A small oval gland located deep between the cerebral hemispheres Attaches to the upper portion of the thalamus Makes melatonin Fun Fact: Was believed to the seat of the human soul Reproductive Organs The ovaries, placenta and the testes produce hormones Structure will be examined in more detail in the reproductive system Hormones covered later in this lesson A quick warning Most of the hormones have more then one name Depending on your instructor you may have to know one of them or all of them, be sure to ask what names you are accountable for your exams Pituitary Hormones Anterior Pituitary Growth Hormone (GH) Prolactin (PRL) Follicle-Stimulating Luteinizing Hormone (LH) Hormones (FSH) Thyroid-Stimulating Hormone (TSH) Adrenocorticotropic Hormone (ACTH) Oxytocin (OT) Posterior Pituitary Antidiuretic Hormone (ADH) 6

7 Growth Hormone GH, hgh Somatotrophin (STH) Causes the growth of all the body tissue Stimulates lipolysis-fat utilization for energy Inhibits actions of insulin on carbohydrate High concentrations can cause breast development (Gynecomastia) GH is highest during puberty and decreases in adults Prolactin Also known as: PRL Luteotrophic Hormone/LTH Primary functions is only in pregnant females, and female who breast feed it will stimulate the development of the mammary glands as well as stimulates milk production Does not deal with milk release Follicle Stimulating Hormone Foliotrophin, FSH Most potent hormone to stimulate gametogenesis In females it causes ova development and aids in ovulation. In males it cause sperm production Luteinizing Hormone Also know as: LH Interstitial Cell Stimulating Hormone, ICSH Stimulates gonads to produce sex hormones Males: it stimulates interstitial cell to produce testosterone Females stimulates maturation of follicle, stimulates rupture of follicle stimulates development of corpus luteum Thyroid Stimulating Hormone TSH Thyrotrophin Stimulates development and maintenance of Thyroid Gland Causes the thyroid to secret Thyroxines Stimulates the thyroid gland to secrete the hormones thyroxine (T 4 ) and triiodothyronine (T 3 ) Adrenocorticotrophin ACTH Development and maintenance of Adrenal Gland Stimulates secretion of Adrenal Cortex hormones. Stimulates secretion of Cortisol 7

8 Oxytocin OT Stimulates milk release Parturition, expulsion of fetus by contraction of myometrium Shrinks the uterus post-parturition (after the baby is born) Causes uterine contraction to help move sperm during intercourse Antidiuretic Hormone Also known as: ADH Arginine Vasopressin, AVP Causes renal reabsorption of H 2 O Kidneys pull water out of precursor to urine, to maintain homeostasis A smooth muscle contractor and can increase blood pressure Can cause vasoconstriction (makes the blood vessels shrink in diameter) Thyroid Hormones Powerful in effecting the metabolic rates of the body Thyroxine (T 4 ) Triiodothyronine (T 3 ) Iodine is essential to the synthesis of thyroid hormones Important in impacting blood calcium and phosphate ion levels Calcitonin Thyroid Hormones Triiodothyronine (T 3 ) and Thyroxines (T 4 ) They both have the same functions, T 3 is 5x more powerful then T 4 Stimulates metabolism (the most potent hormone) Stimulates growth Stimulates neuromuscular system Increases blood glucose Increases calcium Increase cardiovascular system Stimulates integument Increase immune response Calcitonin Also known as: CT Thyrocalcitonin, TCT Decrease plasma calcium The calcium levels in the blood Keeps the calcium and phosphate in the bones Will also increase the rate at which calcium and phosphate are deposited in bones Parathyroid Hormone From the Parathyroid Glands Parathormone, PTH Increase plasma calcium through bone resorption (destruction of bone) Increase Vit D. synthesis essential Hormone for Growth 8

9 Adrenal Glands Adrenal medulla Epinephrine Norepinephrine Adrenal cortex Mineralocorticoids Glucocorticoids Sex hormone Epinephrine/Norepinephrine Epinephrine also known as adrenalin Primary secretion of the adrenal medulla Norepinephrine also known as noradrenalin Increases heart rate Increases blood pressure Dilates airways Increases metabolic rate Mineralocorticoids Aldosterone The principal mineralocorticoid Around 90% of the mineralocorticoid activity Made by the zona glomerulosa Regulation of minerals It will conserve sodium, secrete potassium As a side effect it will increase blood pressure/volume Glucocorticoids Cortisol is the principal glucocorticoid Around 95% of the glucocorticoid activity Made in the zone fasciculata and some in the zona reticularis Regulation of blood glucose Inhibition of glucose uptake in muscle and adipose tissue Increases blood glucose concentrations A very powerful anti-inflammatory and immunosuppressive Sex Hormones Mostly weak androgens Made in zona reticularis and a little in the zone fasciculata Small amounts of sex hormones are typically secreted by the adrenal cortex Have little effect on reproductive functions Contribute to secondary sex characteristics Islet of Langerhans within the Pancreas Alpha Makes up about 25% of the cells Secretes glucagon Beta Makes up about 60% of the cells Secretes insulin Delta Secretes somatostatin PP cells Secretes pancreatic polypeptide 9

10 Glucagon Increases blood glucose Stimulates glycogenolysis Stimulates the liver to break down glycogen Increases the release of glucose into the blood Inhibits glycolysis Keeps glucose from being broken down-stops glycolysis Leads to increased glucose release from liver Stimulates the break down of fats Insulin Promotes uptake and metabolism of glucose within muscles Promotes glucose uptake and storage in liver Inhibits glucose production Decrease blood glucose Causes cellular uptake of glucose It is the only hormone that can cause cellular uptake of glucose Cool Fact: insulin has little effect on the brain s uptake and use of glucose Brain cells are very permeable to glucose without the aid of insulin Hormones of Reproduction Male Gonadotropins Follicle-Stimulating Hormones (FSH) Luteinizing Hormone (LH) Androgens Made mostly in the testes Tes tos terone Female Gonadotropins Follicle-Stimulating Hormones (FSH) Luteinizing Hormone (LH) Estrogens Progesterone Androgens Testosterone The most important of the androgens Made in testes and a small amount in adrenal cortex Starts during fetal development then for several weeks after birth à nearly stops during childhood à around age 13 will kick in (puberty) and continues throughout life Androgens Differentiation of male characteristics during fetal development Testes descent Stimulation of primary & secondary sexual characteristics Stimulate growth maturation of sperm Secondary Sexual Characteristics-Male Body Hair Increase growth on face, chest axillary and pubic regions Voice Causes enlargement of larynx (Adam's apple) and thickening of vocal folds, deepens the voice Muscles Increases muscle growth, broadening of shoulders, narrowing of waist Bone Thickening and strengthening 10

11 Estrogen Estradiol is the most abundant of the estrogens Made in the: Ovary Primary site of production in nonpregnant females Adrenal cortex Adipose tissue Differentiation of female characteristics Stimulation of primary & secondary sexual characteristics Stimulate growth Control of menstrual cycle Progesterone Made in the: Ovary Primary site of production in nonpregnant females Adrenal cortex Stimulation of primary & secondary sexual characteristics Stimulate growth Control of menstrual cycle Secondary Sexual Characteristics- Female Breasts Development of the breasts and the ductile system Adipose Tissue Increased deposition of adipose tissue in subcutaneous later around breasts, thighs and buttocks Hair Growth of body hair, most prominent in underarms and pubic regions Hips Widening of hips 11