Anatomy and Physiology: Endocrine System
Anatomy and Physiology: Endocrine System BIOH 113 - 01
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BIOH 112 - 01
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This 9 page Bundle was uploaded by Meaghan Raw on Tuesday January 12, 2016. The Bundle belongs to BIOH 113 - 01 at University of Montana taught by Heather Dawn Labbe (P) in Spring 2016. Since its upload, it has received 28 views. For similar materials see Human Form and Function II in Biological Sciences at University of Montana.
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Date Created: 01/12/16
BIOH 113 Chapter 17: The Endocrine System February 9 to February 18 What You Need to Know to Start Off With: 3 major regions of a cell- chapter 3 in book nucleus: o Nucleus where the DNA is housed o Plasma membrane inside, inside; outside, outside has a selective membrane cytoplasm o Organelles ribosomes mitochondria etc. Receptor: part of plasma membrane; found inside of the cell; o molecule that has a specific location where another molecule bonds that has a change o very specific o only have the right shape for particular region of particular molecule; specificity Tissue: chapter 1 o accumulation of cells cells can be joined together cells are connected or not connected o cells do not have to be the same type but can be the same type depending on the type of tissue usually there is variation in the cell type Four types of tissues: o Epithelial: cells are connected and has a bunch of cells provides protection; epidermis, glandular tissue is epithelial tissue o Connective tissue; can cover anything from tendons, bone, etc. o Muscle: cardiac, smooth, skeletal o Nervous Glands: o Exocrine: secretory cells that produce something and secrete it into duct that opens into some other lumen Duct glands secrete into tube that has a lumen o Endocrine: no ducts but does have a vascular vent, situated around capillary beds doesn’t always have to circulate but normally does Overview of the Endocrine System Control system o use chemical messengers as the major means of control/communication Hormones o are used for communication o almost every tissue in the body produces a hormone Pay attention to glands o pancreas and gonads that also have exocrine product Hypothalamus o is an important endocrine organ that produces hormones Endocrine System Functions Endocrine System uses chemicals to effect change o has inhibitory or excitatory effect on a cell Target cells o any cell that has a specific target is a hormone o binding of receptors is also a hormone The hormones don’t just circulate in the blood stream o hormones tend to have characteristics: regulate metabolic function lag times ranging from seconds to hours have prolonged effects are classified as lipid soluble or water soluble Hormones Hormones – chemical substances secreted by cells into the extracellular fluids o Regulate the metabolic function of other cells o Have lag times ranging from seconds to hours o Tend to have prolonged effects o Are classified as lipid soluble or water soluble Lipid soluble o can pass right through plasma membrane o steroid based hormones Water soluble o has to have help accessing, bind to receptor on plasma membrane and use a second messenger system o most that are discussed are going to be water soluble Amino acid based Hormones o most hormones belong to this class, including: amines, peptide and protein hormones and eicosanoids (leukotrienes and prostaglandins) Hormones are specific o will bind like a lock and key to receptor on target cells o growth hormone will have ability to affect a large range of cells o change the way enzymes are working lower activation energy Hormones produce one or more of the following cellular changes in target cells o Alter plasma membrane permeability o Stimulate protein synthesis o Activate or deactivate enzyme systems o Induce secretory activity o Stimulate mitosis Hormones circulate in the blood in two forms o free or bound o Steroids and thyroid hormone are attached to plasma proteins o All others are unencumbered Target Cell Specificity Receptors are going to be inside the cell or imbedded in the plasma membrane Water soluble hormones/cells easily travel in the blood stream Lipid soluble hormones/cells have to piggy back on something o hard time traveling by themselves Target Cell Activation o depends on three factors; 1. blood levels of hormone 2. relative number of receptors on the target cell 3. the affinity of those receptors for the hormone o up regulation: receptors increase o down regulation: receptors decrease o affinity is how well/likely it is to bind there o if you have a drug you are trying to mimic the affinity of the receptor. hormone interactions: o permissiveness: one hormone can’t exert its effects without another hormone being present thyroid hormone has an effect on cardiac muscle with epinephrine o synergism: more than one hormone produces the same effects on a target cell; glucagon, cortisol o antagonism: one or more hormones opposes the action of another hormone glucagon, insulin, pituitary (hypophysis) o pituitary gland: develops in a cool way has an area that pushes down and an area that pushes upwards glandular tissue upwards; nervous tissue downwards regions remain distinct posterior is neural tissue and anterior is glandular tissue Hormone Types Oxytocin o is a strong stimulant of uterine contraction o regulated by a positive feedback mechanism to oxytocin in the blood o this leads to increased intensity of uterine contractions, ending in birth o Oxytocin triggers milk ejection (“letdown” reflex) in women producing milk o in males and females has a role in sexual arousal and orgasm o also is known as the “cuddle hormone”. Antidiuretic Hormone (ADH) o ADH helps to avoid dehydration or water overload o prevents urine formation o osmoreceptors monitor the solute concentration of the blood o with high solutes, ADH is synthesized and released, thus preserving water o with low solutes, ADH is not released, thus causing water loss from the body o alcohol inhibits ADH release and causes copious urine output o anti means not; diuresis means getting rid of water; antidiuretic means not getting rid of water o kidneys and sweat glands are used with ADH o negative feedback mechanism o no direct neuro contact with hypothalamus Adenophypophyseal Hormones o Seven hormones: 1. GH: Growth hormone 2. TSH: Thyroid stimulating hormone 3. ACTH: Adrenocorticotropic hormone 4. FSH: Follicle-stimulating hormone 5. LH: Luteinizing hormone 6. MSH: Melanocyte-stimulating hormone 7. PRL: Prolactin Tropic hormones o regulate the activity of other endocrine glands 1. TSH 2. ACTH 3. FSH 4. LH Growth hormone (GH) o somatotropin cells that have a broad range of target cell o target mainly bone and skeletal muscle o growth factors Prolactin (PRL) o stimulate lactation in females o may result in development of breast tissue in males and lactation o can be a sign of cancer in males Thyroid Stimulating Hormone (Thyrotropin) o Tropic hormone that stimulates the normal development and secretory activity of the thyroid gland o Triggered by hypothalamic peptide thyrotropin releasing hormone (TRH) o Rising blood levels of thyroid hormones act on the pituitary and hypothalamus to block the release of TSH o anterior pituitary o thyroid gland o regulated by the hypothalamus Adrenocorticotropic Hormone (Corticotropin) o Stimulates the adrenal cortex to release corticosteroids o Triggered by hypothalamic corticotropin-releasing hormone (CRH) in a daily rhythm o Internal and external factors such as fever, hypoglycemia, and stressors can trigger the release of o CRH o release is stimulated from the hypothalamus o any sort of stress can trigger the release of the hormone Gonadotropins o Gonadotropins – follicle-stimulating hormone (FSH) and luteinizing hormone (LH) o Regulate the function of the ovaries and testes o FSH stimulates gamete (egg or sperm) production o Triggered by the hypothalamic gonadotropin releasing o hormone (GnRH) during and after puberty o act on the gonads o important in males and females Thyroid Gland o The largest endocrine gland, located in the anterior neck, consists of two lateral lobes connected by a median tissue mass called the isthmus o Composed of follicles that produce the glycoprotein thyroglobulin o Colloid (thyroglobulin + iodine) fills the lumen of the o follicles and is the precursor of thyroid hormone o Other endocrine cells, the perifollicular cells, produce o Thyroid hormone – the body’s major metabolic hormone o Consists of two closely related iodine-containing compounds T4 – thyroxine; has two tyrosine molecules plus four bound iodine atoms T3 – triiodothyronine; has two tyrosine with three bound iodine atoms o Effects of Thyroid Hormone TH is concerned with: Glucose oxidation Increasing metabolic rate Heat production TH plays a role in: Maintaining blood pressure Regulating tissue growth Developing skeletal and nervous systems Maturation and reproductive capabilities Calcitonin o Regulated by a humoral (calcium ion concentration in the blood) negative feedback mechanism o Calcitonin targets the skeleton, where it: Inhibits osteoclast activity (and thus bone resorption) and release of calcium from the bone matrix Stimulates calcium uptake and incorporation into the bone matrix Regulated by a humoral (calcium ion concentration in the blood) negative feedback mechanism Parathyroid Glands o around the thyroid gland o they are aggregations of cells that are lentil bean size o there is a variability to number in a person o there are two populations of cells 1. chief/principal cells: produce PCH 2. oxyphil cells: tend to increase in number with individuals with neoplasms (cancer) and with kidney disease o Tiny glands embedded in the posterior aspect of the thyroid o Cells are arranged in cords containing oxyphil and chief cells o Chief (principal) cells secrete PTH o PTH (parathyroid hormone) regulates calcium balance in the blood Effects of Parathyroid Hormone PTH release increases Ca2+ in the blood as it: Stimulates osteoclasts to digest bone matrix Enhances the reabsorption of Ca2+ and the secretion of phosphate by the kidneys Increases absorption of Ca2+ by intestinal mucosal cells Rising Ca2+ in the blood inhibits PTH release Elevates blood calcium levels in a person Adrenal (Suprarenal) Glands o Adrenal glands – paired, pyramid-shaped organs atop the kidneys o Structurally and functionally, they are two glands in one o Adrenal medulla – nervous tissue that acts as part of the SNS (Fight or Flight) Inner region Epinephrine Norepinephrine o Adrenal cortex – glandular tissue derived from embryonic mesoderm Outer region is the cortex Adrenal Cortex o Synthesizes and releases steroid hormones called corticosteroids o Different corticosteroids are produced in each of the three layers Zona glomerulosa – mineralocorticoids SALT chiefly aldosterone Zona fasciculata – glucocorticoids SUGAR chiefly cortisol and cortisone Zona reticularis – gonad corticoids SEX chiefly androgens Adrenal Medulla o Secretion of these hormones causes: o The heart to beat faster o Blood glucose levels to rise o Blood vessels to constrict o Blood to be diverted to the brain, heart, and skeletal muscle o Made up of chromaffin cells that secrete epinephrine and norepinephrine Epinephrine is the more potent stimulator of the heart and metabolic activities Norepinephrine is more influential on peripheral vasoconstriction and blood pressure Mineralocorticoids o Regulate the electrolyte concentrations of extracellular fluids o Aldosterone – most important mineralocorticoid o Maintains Na+ balance by reducing excretion of sodium from the body o Stimulates reabsorption of Na+ by the kidneys o Aldosterone secretion is stimulated by: Rising blood levels of K+ Low blood Na+ o Decreasing blood volume or pressure Mechanisms of Aldosterone Secretion/Inhibition o Renin-angiotensin mechanism – kidneys release renin, which is converted into angiotensin II that in turn stimulates aldosterone release o Plasma concentration of sodium and potassium – directly influences the zona glomerulosa cells o ACTH – causes small increases of aldosterone during stress o Atrial natriuretic peptide (ANP) – inhibits activity of the zona glomerulosa Glucocorticoids (Cortisol) o Help the body resist stress by: Keeping blood sugar levels relatively constant Maintaining blood volume and preventing water shift into tissue o Cortisol provokes: o Gluconeogenesis (formation of glucose from non-carbohydrates o Rises in blood glucose, fatty acids, and amino acids Gonadocorticoids (Sex Hormones) o Most gonad corticoids secreted are androgens (male sex hormones), and the most important one is testosterone o Androgens contribute to: The onset of puberty The appearance of secondary sex characteristics Sex drive in females Androgens can be converted into estrogens after menopause Pancreas o A triangular gland, which has both exocrine and endocrine cells, located behind the stomach o Acinar cells produce an enzyme-rich juice used for digestion (exocrine product) o Pancreatic islets (islets of Langerhans) produce hormones (endocrine products) o The islets contain two major cell types: Alpha cells that produce glucagon Beta cells that produce insulin Glucagon o A 29-amino-acid polypeptide hormone that is a potent hyperglycemic agent o Its major target is the liver, where it promotes: o Glycogenolysis – the breakdown of glycogen to glucose o Gluconeogenesis – synthesis of glucose from lactic acid and non-carbohydrates o Release of glucose to the blood from liver cells Insulin o A 51-amino-acid protein consisting of two amino acid chains linked by disulfide bonds o Synthesized as part of proinsulin and then excised by enzymes, releasing functional insulin o Insulin: Lowers blood glucose levels Enhances transport of glucose into body cells Counters metabolic activity that would enhance blood glucose levels Hypoglycemic and Hyperglycemic Hormones o HYPOGLYCEMIC Insulin Adiponectin o HYPERGLYCEMIC Glucagon Epinephrine and Norepinephrine Glucocorticoids (cortisol/cortisone) Growth Hormone Resistin Diabetes Mellitus (DM) o Results from hyposecretion or hypoactivity of insulin o The three cardinal signs of DM are: Polyuria – huge urine output Polydipsia – excessive thirst Polyphagia – excessive hunger and food consumption Pineal Gland o Small gland hanging from the roof of the third ventricle of the brain o Secretory product is melatonin o Melatonin is involved with: Day/night cycles Physiological processes that show rhythmic variations (body temperature, sleep, appetite) Thymus o Lobulated gland located deep to the sternum in the thorax o Major hormonal products are thymopoietins and thymosins o These hormones are essential for the development of the T lymphocytes (T cells) of the immune system Other Hormone Producing Structures o Heart – produces atrial natriuretic peptide (ANP), which reduces blood pressure, blood volume, and blood sodium concentration o Gastrointestinal tract – enteroendocrine cells release local-acting digestive hormones o Placenta – releases hormones that influence the course of pregnancy o Kidneys – secrete erythropoietin, which signals the production of red blood cells, calcitrol and renin o Skin – produces cholecalciferol, the precursor of vitamin D o Adipose tissue – releases leptin, which is involved in the sensation of satiety, and stimulates increased energy expenditure, as well as adiponectin and resistin
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