Chapter 10 Endocrine System Lecture Outline PDF

1 Chapter 10 Endocrine System Lecture Outline © 2019 McGraw-Hill Education  2 Endocrine System Glands...

1 Chapter 10 Endocrine System Lecture Outline © 2019 McGraw-Hill Education  2 Endocrine System Glands Figure 10.1 © 2019 McGraw-Hill Education  3 Cell Secretion Types 1 Autocrine: released by cells and a have local effect on same cell type Example - eicosanoids Paracrine: released by cells that affect other cell types in close proximity Example - somatostatin © 2019 McGraw-Hill Education  4 Cell Secretion Types 2 Neurotransmitter and neuromodulators: secreted by nerve cells Example - nervous system function Hormones and neurohormones: secreted into blood and bind to receptor sites Example - epinephrine and insulin © 2019 McGraw-Hill Education  5 Endocrine System Functions 1 1. Metabolism 2. Control of food intake and digestion 3. Tissue development 4. Ion regulation 5. Water balance © 2019 McGraw-Hill Education  6 Endocrine System Functions 2 6. Heart rate and blood pressure regulation 7. Control of blood glucose and other nutrients 8. Control of Reproductive functions 9. Uterine contraction and milk release 10. Immune System regulation © 2019 McGraw-Hill Education  7 Characteristics 1 The endocrine system is composed of endocrine glands and specialized endocrine cells located throughout the body. Endocrine glands and cells secrete minute amounts of chemical messengers called hormones into the bloodstream, rather than into a duct. Hormones then travel through the general blood circulation to target tissues or effectors. © 2019 McGraw-Hill Education  8 Characteristics 2 The target tissues have receptors for a specific hormone. Hormones produce a particular response in the target tissues. © 2019 McGraw-Hill Education  9 Types of Hormones Water-soluble hormones: includes proteins, peptides, amino acids most common Examples - growth hormone, antidiuretic, prolactin Lipid-soluble hormones: includes steroids and eicosanoids Examples - LH, FSH, androgens © 2019 McGraw-Hill Education  10 Control of Hormone Release 1 Blood-borne chemicals can directly stimulate the release of some hormones. These chemicals are referred to as humoral stimuli because they circulate in the blood, Humoral refers to body fluids, including blood. Hormone release can also be under neural control. Following action potentials, neurons release a neurotransmitter into the synapse with the cells that produce the hormone. © 2019 McGraw-Hill Education  11 Control of Hormone Release 2 Hormone release can also be controlled by other hormones. It occurs when a hormone is secreted that, in turn, stimulates the secretion of other hormones. The same three types of stimuli (humoral, neural, and hormonal) can stimulate or inhibit hormone release. © 2019 McGraw-Hill Education  12 Humoral Regulation Figure 10.2 © 2019 McGraw-Hill Education  13 Neural Regulation Figure 10.3 © 2019 McGraw-Hill Education  14 Hormonal Regulation Figure 10.4 © 2019 McGraw-Hill Education  15 Inhibition of Hormone Release 1 Humoral inhibition of hormone release generally involves the actions of companion hormones. Usually each of the companion hormones performs an opposite function. For example, to raise blood pressure, the adrenal cortex secretes the hormone aldosterone in response to low blood pressure, but to lower it the heart atria secrete atrial natriuretic peptide. They work together to maintain homeostasis of blood pressure. © 2019 McGraw-Hill Education  16 Inhibition of Hormone Release 2 Neurons inhibit targets just as often as they stimulate targets. If the neurotransmitter is inhibitory, the target endocrine gland does not secrete its hormone. In control of hormone release by other hormones, some hormones are inhibitory hormones, that reduce the release of the hormone being controlled. For example, thyroid hormones can control their own blood levels by inhibiting their anterior pituitary tropic hormone. © 2019 McGraw-Hill Education  17 Regulation of Blood Hormone Levels Two major mechanisms maintain hormone levels in the blood within a homeostatic range: negative feedback and positive feedback Most hormones are regulated by a negative- feedback mechanism, whereby the hormone’s secretion is inhibited by the hormone itself once blood levels have reached a certain point. Some hormones are regulation by positive feedback, as exemplified by tropic hormone action. © 2019 McGraw-Hill Education  18 Negative and Positive Feedback Figure 10.5 © 2019 McGraw-Hill Education  19 Hormone Receptors 1 A hormone can stimulate only the cells that have the receptor for that hormone. The portion of each receptor molecule where a hormone binds is called a receptor site. The receptor site has specificity, allowing only one hormone to bind to it. Some hormones, such as epinephrine, can bind to a “family” of receptors that are structurally similar. This specificity is due to molecular shape and chemical characteristic. © 2019 McGraw-Hill Education  20 Hormone Receptors 2 Lipid-soluble and water-soluble hormones bind to their own classes of receptors. Lipid-soluble hormones bind to nuclear receptors due to their lipid solubility and small molecular size allowing to easily pass through the cell membrane. Water-soluble hormones bind to membrane- bound receptors. Water-soluble hormones are polar molecules and cannot pass through the cell membrane. © 2019 McGraw-Hill Education  21 Lipid-Soluble Hormone Receptors Lipid-soluble hormones bind to nuclear receptors due to their lipid solubility and small molecular size, allowing to easily pass through the cell membrane and nuclear membrane. Nuclear receptors can also be located in the cytoplasm, but then move to the nucleus when activated. When hormones bind to nuclear receptors, the hormone-receptor complex interacts with nuclear DNA to regulate specific gene transcription. © 2019 McGraw-Hill Education  22 Water-Soluble Receptors Water-soluble hormones, such as protein and peptide types, cannot pass through the cell membrane. Interactions are with membrane-bound receptors, that are proteins that extend across the cell membrane, with their hormone-binding sites exposed on the cell membrane’s outer surface. When the hormone binds to the receptor, it turns on intracellular enzymes that ultimately cause the response dictated by the hormone-receptor interaction. © 2019 McGraw-Hill Education  23 Target Tissue Specificity and Response Figure 10.6 © 2019 McGraw-Hill Education  Nuclear and Membrane-Bound 24 Receptors Figure 10.7 © 2019 McGraw-Hill Education  25 Action of Nuclear Receptors Lipid-soluble hormones stimulate protein synthesis. Lipid-soluble hormones diffuse across the cell membrane and bind to their receptors, with the complex now binding to hormone-response elements on DNA. This action regulates the transcription of specific messenger ribonucleic acid (mRNA) molecules and protein synthesis occurs. © 2019 McGraw-Hill Education  26 Nuclear Receptor Model Figure 10.8 © 2019 McGraw-Hill Education  27 Membrane Receptor Actions 1 Membrane receptors act in two ways, either altering the activity of G proteins on the inner surface of the cell membrane or directly altering the activity of intracellular enzymes. Activation of G proteins, or intracellular enzymes, elicits specific responses in cells, including the production of molecules called, second messengers. © 2019 McGraw-Hill Education  28 Membrane Receptor Actions 2 A second messenger molecule is produced inside a cell once a ligand binds to its membrane-bound receptor. A second messenger, such as cyclic adenosine monophosphate (cAMP), then activates specific cellular processes inside the cell in response to the hormone. © 2019 McGraw-Hill Education  29 G-Protein Activation 1 Many membrane-bound receptors produce responses through the action of G proteins, which consist of 3 subunits. The G proteins are so named because one of the subunits binds to guanine nucleotides. G-proteins, after several sequential actions, interact with adenylate cyclase, an enzyme that converts ATP to cAMP (cyclic adenosine monophosphate). Cyclic adenosine monophosphate binds to protein kinases and activates them. © 2019 McGraw-Hill Education  30 G-Protein Activation 2 Protein kinases are enzymes that, in turn, regulate the activity of other enzymes. Depending on the other enzyme, protein kinases can increase or decrease its activity. Phosphodiesterase, an intracellular enzyme, breaks down cAMP and thus results in no further cell stimulation. © 2019 McGraw-Hill Education  31 G-Protein Activation 3 Figure 10.9 © 2019 McGraw-Hill Education  32 Cyclic AMP Synthesis Figure 10.10 © 2019 McGraw-Hill Education  33 Signal Amplification 1 Hormones that stimulate the synthesis of second messengers act quickly and have an amplification effect. Each receptor produces thousands of second messengers, leading to a cascade effect and ultimately amplification of the hormonal signal. © 2019 McGraw-Hill Education  34 Signal Amplification 2 With amplification, a single hormone activates many second messengers, each of which activates enzymes that produce an enormous amount of final product. The efficiency of this second-messenger amplification is virtually unparalleled in the body. © 2019 McGraw-Hill Education  35 Cascade Effect Figure 10.11 © 2019 McGraw-Hill Education  36 Pituitary Gland 1 Small gland in brain Controlled by hypothalamus Divided into 2 regions: anterior and posterior Secretes at least 6 hormones © 2019 McGraw-Hill Education  37 Pituitary Gland 2 Figure 10.12 © 2019 McGraw-Hill Education  38 Anterior Pituitary Gland Actions The anterior pituitary gland synthesizes hormones, that is under the control of the hypothalamus. Neurons of the hypothalamus secrete releasing hormones that stimulate the production and secretion of a specific hormone. Inhibiting hormones decrease the secretion of a specific anterior pituitary hormone © 2019 McGraw-Hill Education  39 Hypothalamus and Anterior Pituitary Figure 10.13 © 2019 McGraw-Hill Education  40 Anterior Pituitary Hormones 1 Growth Hormone: Target tissues: most Functions: stimulates growth of bones, muscles, and organs Abnormalities: Too much GH causes giantism Too little GH causes pituitary dwarfism © 2019 McGraw-Hill Education  41 Anterior Pituitary Hormones 2 Thyroid-Stimulating Hormone (TSH): Target tissues: thyroid gland Functions: regulates thyroid gland secretions Abnormalities: Too much TSH, thyroid gland enlarges Too little TSH, thyroid gland shrinks © 2019 McGraw-Hill Education  Regulation of Thyroid Hormone 42 Secretion Figure 10.16 © 2019 McGraw-Hill Education  43 Anterior Pituitary Hormones 3 Gonadotrophin Hormone LH LH (Luteinizing) for females: Target tissue: ovaries Function: promotes ovulation and progesterone production LH for males: Target tissue: testes Function: sperm production and testosterone © 2019 McGraw-Hill Education  44 Anterior Pituitary Hormones 4 Gonadotrophin Hormone FSH Follicle-Stimulating for females: Target tissue: follicles in ovaries Function: follicle maturation and estrogen secretion FSH for males: Target tissue: seminiferous tubules (testes) Function: sperm production © 2019 McGraw-Hill Education  45 Anterior Pituitary Hormones 5 Prolactin: Target tissues: mammary glands and ovaries Functions: milk production © 2019 McGraw-Hill Education  46 Anterior Pituitary Hormones 6 Melanocyte Stimulating Hormone (MSH): Target tissues: melanocytes in the skin Functions: stimulate melanin production in melanocytes Adrenocorticotrophic Hormone (ACTH): Target tissues: cells of adrenal cortex Functions: stimulate production of certain corticosteroids © 2019 McGraw-Hill Education  47 Posterior Pituitary Actions The posterior pituitary gland synthesizes and releases hormones produced by neuroendocrine cells in the hypothalamus. The two hormones released from the posterior pituitary are antidiuretic hormone (ADH) and oxytocin. © 2019 McGraw-Hill Education  48 Posterior Gland Hormones 1 Antidiuretic Hormone (ADH): Target tissues: kidneys Functions: conserve water Abnormalities: Diabetes insipidus low ADH kidneys to produce large amounts of dilute (watery) urine can lead to dehydration and thirst © 2019 McGraw-Hill Education  49 Posterior Gland Hormones 2 Oxytocin: Target tissues: uterus Functions: increases uterine contractions during labor © 2019 McGraw-Hill Education  50 Hypothalamus and Posterior Pituitary Figure 10.14 © 2019 McGraw-Hill Education  51 Thyroid Gland One of largest glands Requires iodine to function Secretes thyroid hormone and calcitonin Thyroid hormones secreted by follicular cells: Target tissues: most Functions: regulates metabolic rates and is needed for growth Calcitonin secreted by parafollicular cells: Target tissues: bone and some other tissues Function: reduces blood calcium level when high © 2019 McGraw-Hill Education  52 Thyroid Hormone Disorders Hypothyroidism: Hyperthyroidism: Decreased metabolism Increased metabolism Weight gain, reduced Weight loss, increased appetite, fatigue appetite, nervousness Low temp. and pulse Higher temp. and pulse Dry, cold skin Warm, flushed skin Myxedema in adults Graves’ disease (leads to goiter) Cretinism in infants © 2019 McGraw-Hill Education  53 Parathyroid Gland Parathyroid hormone (PTH): Target tissues: bones and kidneys Functions: regulates blood Ca2+ levels (more than calcitonin) If Ca 2+ is low then osteoclasts break down bone matrix and less Ca 2+ is lost in urine. If Ca 2+ is high then osteoclasts don’t break down bone matrix and more Ca 2+ is lost in urine. © 2019 McGraw-Hill Education  54 Regulation of Blood Calcium Levels Figure 10.17 © 2019 McGraw-Hill Education  55 Thyroid Gland and Parathyroid Glands Figure 10.15 © 2019 McGraw-Hill Education (d) ©Victor Eroschenko  56 Adrenal Gland Actions The adrenal glands are two small glands located superior to each kidney Each adrenal gland has an inner part, called the adrenal medulla, and an outer part, called the adrenal cortex. The adrenal medulla and the adrenal cortex function as separate endocrine glands. © 2019 McGraw-Hill Education  57 Adrenal Glands Figure 10.18 © 2019 McGraw-Hill Education (c) ©Victor Eroschenko  58 Adrenal Gland Hormones 1 Adrenal medulla hormones: Epinephrine/Norepinephrine: Target tissues: heart, blood vessels, liver, fat cells Functions: released as part of fight or flight response © 2019 McGraw-Hill Education  Regulation of Adrenal Medullary 59 Secretions Figure 10.19 © 2019 McGraw-Hill Education  60 Adrenal Gland Hormones 2 Adrenal cortex hormone: Aldosterone: Type of mineralocorticoids Target tissues: kidneys Functions: causes Na+ and H2O to be retained and K+ to be secreted, indirectly involved with blood pressure and blood volume © 2019 McGraw-Hill Education  61 Regulation of Aldosterone Secretion Figure 10.20 © 2019 McGraw-Hill Education  62 Adrenal Gland Hormones 3 Cortisol: Type of glucocorticoids Target tissues: most Functions: increases breakdown of fat and protein for energy uses reduces inflammatory and immune responses © 2019 McGraw-Hill Education  63 Regulation of Cortisol Secretion Figure 10.21 © 2019 McGraw-Hill Education  64 Adrenal Gland Hormones 4 Androgens: Target tissues: most Functions: Males: secondary sexual characteristics Females: sex drive © 2019 McGraw-Hill Education  65 Pancreas Actions 1 The pancreas is a mixed gland, with an exocrine portion and an endocrine portion. The exocrine portion of the pancreas secretes digestive enzymes. The endocrine part of the pancreas consists of pancreatic islets (islets of Langerhans), which are dispersed throughout the exocrine portion of the pancreas. © 2019 McGraw-Hill Education  66 Pancreas Actions 2 The islets consist of three cell types, each of which secretes a separate hormone. Alpha cells secrete glucagon, beta cells secrete insulin, and delta cells secrete somatostatin. These three hormones regulate the blood levels of nutrients, especially glucose © 2019 McGraw-Hill Education  67 Pancreas Structure Figure 10.22 © 2019 McGraw-Hill Education ©Biophoto Associates/Science Source  68 Pancreas Hormones 1 Insulin: Target tissues: liver, skeletal muscle, adipose tissue Functions: regulates blood glucose levels after a meal glucose levels are high and insulin is secreted extra glucose is stored in form of glycogen © 2019 McGraw-Hill Education  69 Insulin Abnormalities Diabetes mellitus: Causes: too little insulin or faulty insulin receptors Symptoms: exaggerated appetite,excess urine, dehydration, thirst, fatigue Type I: insulin dependent (daily injections required) Type II: insulin independent, often found in obese people, can be treated with diet but can turn into type I © 2019 McGraw-Hill Education  70 Pancreas Hormones 2 Glucagon: Target tissues: liver Function: regulates blood glucose levels between meals glucose levels drop and glucagon is secreted glucagon allows glycogen to be broken down into glucose © 2019 McGraw-Hill Education  71 Regulation of Blood Glucose Levels Figure 10.23 © 2019 McGraw-Hill Education  72 Testes Hormone Testosterone: Target tissues: most Functions: aids in sperm and reproductive organ development and function © 2019 McGraw-Hill Education  73 Ovarian Hormones Estrogen/Progesterone: Target tissues: most Functions: involved in uterine and mammary gland development and menstrual cycle © 2019 McGraw-Hill Education  74 Thymus Gland Hormone Thymosin: Target tissues: immune system tissues Functions: promotes immune system development and function © 2019 McGraw-Hill Education  75 Pineal Gland Hormone Melatonin: Target tissues: hypothalamus Functions: plays a role in onset of puberty and controls circadian rhythms. Light affects its function. © 2019 McGraw-Hill Education