Endocrinology

**Presentation on Chapter 45:**

All of the information needed for the quiz is in the presentation. All of the information is taken from Chapter 45 of the textbook. The links to the videos shown in class are also included in the presentation.

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__The Endocrine System __ ** Chapter 45.1 ** Introduction (45.1)    Nervous & Endocrine Systems   Control Pathways  Simple Pathways (p. 945) Feedback  <span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 14pt;">** Chapter 45.2 ** <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Introduction - 45.2 <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> Signalling Continued: <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Water-Soluble Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Signal Transduction Pathway <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Figure: 45.3a <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Example <span style="font-family: Arial,Helvetica,sans-serif;"> <span style="font-family: Arial,Helvetica,sans-serif;"> Diverse Response:   <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Lipid Soluble Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Local Regulators <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Chemical Compounds in Regulators <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> **<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 14pt; text-align: left;">Chapter 45.3 ** <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Hypothalamus and Pituitary Glands <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Tropic Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Nontropic Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Growth Hormone <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">
 * __ Hormone- __ a chemical signal secreted into the extracellular fluid and carried by the blood or hemolymph to communicate regulatory messages within the body
 * The cells that carry out the process of secreting these hormones into the blood make up the __ endocrine system __.
 * Organs that secrete hormones are called __ endocrine glands __.
 * Nervous- uses quick, electrical signals to send messages
 * Endocrine- secretes hormones to produce slower but longer-acting responses. Regulates long term development (like growth)
 * Both- communicate within the body
 * Neurosecretory cells- nerve cells that release hormones. Produce "neurohormones"
 * Receptor or sensor detects a stimulus
 * Information goes to the control center, where it is compared to a set point (or "desired level") An effector responds. This is called an efferent signal. It is a hormone or neurohormone.
 * Negative feedback- the effector reduces the stimulus, prevents overreaction
 * Positive feedback- reinforces the stimulus and leads to a greater response
 * Hormones travel through the bloodstream to convey information to cells throughout the body.
 * Other chemical signals:
 * // Local regulators // convey info to cells near the secreting cells
 * // Pheromones // carry messages between different members of the same species (ex. mating)
 * Three major types of molecules function as hormones
 * Proteins and peptides
 * Amines
 * Steroids
 * Signalling by all of these molecules has three major events:
 * Reception
 * Signal transduction
 * Response
 * // <span style="font-family: Arial,Helvetica,sans-serif;">Reception - //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 12pt;">when a signal molecule binds to a specific receptor protein in or on the target cell.\
 * //<span style="font-family: Arial,Helvetica,sans-serif;"> Signal transduction - //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 12pt;">Events that occur in the cell when a signal molecule binds to a receptor protein
 * //<span style="font-family: Arial,Helvetica,sans-serif;"> Response //<span style="font-family: Arial,Helvetica,sans-serif; font-size: 12pt;">- A change in the cells behavior triggered by a signal transduction
 * Receptors for water soluble hormones are embedded in the plasma membrane.
 * Cell surface receptors
 * The binding of a hormone to its receptor triggers a // signal transduction pathway //.
 * Signal transduction pathway: a series of changes in cellular proteins that convert an extracellular chemical signal to a specific intracellular response.
 * The responses may be:
 * Activation of an enzyme
 * Change in uptake/secretion of certain molecules
 * Rearrangement of the cytoskeleton
 * Some receptors can activate proteins in the cytoplasm that then move into the nucleus and can affect genes.
 * <span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;"> Changes in a frog’s skin color, an adaptation that helps camouflage the frog in changing light.
 * <span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;"> Skin cells called melanocytes contain the dark pigment melanin in cytoplasmic organelles called melanosomes.
 * <span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;"> Clustered melanosomes - lighter skin. Spread out melanosomes - darker skin
 * <span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;"> A peptide hormone called melanocyte-stimulating hormone controls the arrangement of melanosomes (skin color)
 * A particular hormone can cause diverse responses in target cells that have different // receptors //, different signal transduction // pathways // , and/or different // proteins // for carrying out the response. (45.4)
 * The receptors for lipid-soluble hormones are located inside the target cell.
 * Steroid hormones
 * Thyroid hormones
 * Hormonal form of Vitamin D
 * Small, nonpolar molecules that can diffuse through the hydrophobic interior of a cellular membrane
 * These enter target cells and bind to receptors in the cytoplasm or nucleus.
 * The intracellular receptor activated by a lipid-soluble hormone is usually a transcription factor, and the response is usually a change in gene expression. (45.3b)
 * Local regulators convey messages between neighboring cells (paracrine signalling)
 * They can have surface or intracellular receptors
 * The response from a local regulator is quicker than from a hormone, however similar events are triggered
 * Cytokines: A peptide/protein regulator. Plays a role in immune responses and most growth factors.
 * Growth factors must be present in order for cells to grow, divide, and develop.
 * Nitric Oxide: When blood oxygen levels drop, NO activates an enzyme that engorges blood vessels and improves blood flow.
 * When secreted by neurons, NO is a neurotransmitter, when secreted by white blood cells it kills bacteria and cancer cells.
 * Prostaglandins (PGs): modified fatty acids derived from lipids in the plasma membrane. They have multiple functions:
 * Secreted by cells in the placenta cause the nearby muscles of the uterus to become more excitable.
 * In the immune system, they help induce fever and inflammation and increase the sensation of pain
 * Aspirin and Ibuprofen work by inhibiting PGs
 * Regulate the clumping of platelets, a step in the formation of blood clots.
 * In the respiratory system, PGs signal the muscles cells to contract and relax.
 * Together, they control much of the endocrine system.
 * Hypothalamus- connects the nervous and endocrine system. It receives information from nerves and initiates endocrine responses
 * Pituitary gland- located at the base of the hypothalamus.
 * Posterior pituitary (neurohypophysis)- secretes hormones made by neurosecretory cells.
 * Anterior pituitary (adenohypophysis)- synthesizes and secretes other hormones (many of which target other endocrine glands)
 * Tropic hormones- regulate the function of endocrine organs
 * Follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH)
 * Adrenocorticotropic hormone (ACTH)- different from FSH, LH, and TSH in structure. Stimulates production and secretion of hormones by the adrenal cortex
 * All of them stimulate the release of a pituitary hormone
 * Nontropic hormone- made by the anterior pituitary, secretion is controlled by hypothalamic hormones
 * Prolactin (PRL)- a nontropic hormone, has a variety roles in different mammals
 * Melanocyte-stimluating hormone (MSH)- controls pigment-containing cells in reptiles, and prevents feelings of hunger in mammals
 * Endorphins- dulls feelings of pain
 * Growth hormone (GH)- similar in structure to prolactin
 * Releases insulin-like growth factors (IGFs) to circulate blood and help bone and cartilage grow
 * Hypersecretion of GH (too much) leads to gigantism and acromegaly (certain features grow)
 * Hyposecretion of GH (not enough) leads to prevention of bone growth and pituitary dwarfism.

<span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 14pt;">** Chapter 45.4 ** <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Nonpituitary hormones and their functions <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Functions Include: <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">
 * Regulation of metabolism
 * Maintaining homeostasis (maintaining internal environment including blood pH, CO2 concentration, blood glucose concentration, body temperature, and water balance)
 * Regulation of behavior

<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Types of Hormones: <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">Thyroid Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;"> <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; font-size: 12pt; text-align: left;">
 * Thyroid
 * Parathyroid
 * Calcitonin
 * Insulin
 * Glucagon
 * Adrenal
 * Gonadal
 * Melatonin
 * Thyroid gland: two lobes on ventral surface (lower front) of trachea oproduces triiodothyronine (T3) and thyroxine (T4) which are similar hormones derived from the amino acid tyrosine
 * In mammals: thyroid secretes mostly T4, but target cells generally remove one iodine atom so that it changes to T3 •secretion is controlled by the hypothalamus and anterior pituitary process of maintaining homeostasis involving monitoring of levels of variables and correcting changes in levels through the two negative-feedback loops
 * Thyroid gland is crucial in vertebrate development/maturation
 * ex. process of tadpole to frog
 * Secreted hormones allow both the function of bone-forming cells and the branching of nerve cells
 * In humans, thyroid hormones maintain blood pressure, heart rate, muscle tone, digestion, and reproductive functions

<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Associated Problems (hypo- & hyper-)

<span style="color: #000080; font-family: Arial,Helvetica,sans-serif; font-size: 12pt;">•Hypothyroidism: lack of thyroid hormone secretion

<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> ocan cause weight gain, lethargy, and an intolerance to cold <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oex. Cretinism: disease of slowed skeletal growth and brain development <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Hyperthyroidism: excessive secretion <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> of thyroid hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> ocan cause high temperatures, <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> sweating, weight loss, irritability <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> and high blood pressure

<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Lack of iodine --> goiter: enlargement of thyroid gland <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> othyroid gland cannot synthesize enough T3 and T4 so the regular negative feedback is not supported so TSH levels continually rise and thyroid size grows

<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Parathyroid Hormone and Calcitonin <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Work together to control calcium levels in bloodstream <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Necessary because all cells rely on calcium to be at appropriate levels to function correctly <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oideal level is 10mg/100mL <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> osee pg. 954 for negative-feedback diagram on hormonal control of calcium in mammals <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •low calcium levels require release of parathyroid hormone (PTH) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oconstructed with four structures called parathyroid glands which are physically in the surface of the thyroid <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oex. vitamin D (steroid-derived molecule) obtained from food/skin --> activation begins in liver and finishes in kidneys } process stimulated by PTH <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Resulting rise in calcium level --> release of calcitonin (hormone from thyroid gland) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Example of PTH and calcitonin shows necessary balance for homeostasis <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Insulin and Glucagon <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Work together to regulate glucose level of bloodstream <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Pancreas: endocrine gland <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> osections described as exocrine have tissues and glands that discharge secretions into ducts <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oislets of Langerhans: clusters of endocrine cells <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §scattered throughout exocrine tissue of pancreas <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §each islet has a population of alpha cells (produce glucagon hormone) and beta cells (produce insulin hormone) --> glucagon and insulin enter circulatory system --> antagonistically work together to maintain average blood glucose concentration level of 90mg/100mL in humans <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §see pg. 955

<span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Problems with Insulin/Glucagon Processes <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •//Diabetes mellitus//: endocrine disorder caused by deficiency of insulin or a decreased response to insulin in target tissues <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Blood glucose exceeds reabsorption capacity of kidneys --> kidneys excrete glucose <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Type I: insulin-dependent diabetes in which the immune system destroys beta (insulin) cells of pancreas; destroys ability to make insulin; treatment is daily insulin injections <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Type II: non-insulin-dependent diabetes in which there is either a deficiency of insulin or a reduced responsiveness of target cells due to a change in the insulin receptors; caused usually by excess body weight and lack of exercise; maintainable with eating healthy and exercise <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Adrenal Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •adrenal glands: fused endocrine and neuroendocrine glands made up of //adrenal cortex// (outer portion consisting of true endocrine cells) and //adrenal medulla// (central portion stemming from neural crest during embryonic development) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •"fight or flight": response stimulated by epinephrine(adrenaline) and norepinephrine(noradrenaline) hormones from class of catecholamine compounds (this means they are synthesized from the amino acid tyrosine) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> ohormones act directly on target tissues to give body a bioenergetic boost by: increasing rate of glycogen breakdown, promoting glucose release and stimulating release of fatty acids <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Steroid Hormones from Adrenal Cortex <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Adrenal cortex responds to endocrine signals <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> ostressful stimuli lead to release of corticosteroids from endocrine cells of adrenal cortex <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §types: <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •glucocorticoids (ex. cortisol) : promote glucose synthesis from noncarbohydrate sources which makes more glucose available; also can suppress the immune system because of their anti-inflammatory effect <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •mineralocorticoids (ex. aldosterone) : act on salt/water balance; <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Gonadal Sex Hormones <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •Gonads: main source of sex hormones (adrenal glands produce scant amounts) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oCategories: <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §androgens-synthesized by testes(mainly testosterone); stimulate development/maintenance of male reproductive system <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §estrogens-responsible for maintenance of female reproductive system (mainly estradiol) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> §progestins-include progesterone; prepare/maintain uterus <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oSynthesis of androgens and estrogens controlled by gonadotropins <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> Melatonin <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •pineal gland: mass of tissue near center of brain (in mammals) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> osynthesizes/secretes melatonin which is a modified amino acid <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> ogenerally contains light sensitive cells or has nervous connections to eyes <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> •melatonin: regulates functions related to light and season length <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> oprimary function related to biological rhythms associated with reproduction <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> osecreted at night (amount depends on length of night) <span style="color: #000080; display: block; font-family: Arial,Helvetica,sans-serif; text-align: left;"> odecreases activity of neurons in brain structures called suprachiasmatic nuclei (function as biological clock)

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