BIOL 314 Final Exam Ch. 17 Study Guide PDF

BIOL 314 FINAL EXAM New Material – Guide to Covered Topics (Study Outline) Chapter 17 will be approximately 25-40 points of this test This guide is written as a good faith outline of topic areas for the test as presented in your notes in class. Although unintentional, any items...

BIOL 314 FINAL EXAM New Material – Guide to Covered Topics (Study Outline) Chapter 17 will be approximately 25-40 points of this test This guide is written as a good faith outline of topic areas for the test as presented in your notes in class. Although unintentional, any items not explicitly mentioned (such as subheadings and statements/figures/tables that fall under larger topics) from the book or notes are still testable. Only items which are explicitly stated as "eliminated topics" can be assumed as such. Chapter 17 → Endocrine Physiology 1.​ Main Functions of the Endocrine System a.​ The main function of the endocrine system is to maintains homeostasis across many body systems b.​ Also responsible for regulates and affect many body processes i.​ Cellular metabolism and division ii.​ Bone growth and remodeling iii.​ Muscle tone, muscle anabolism/catabolism iv.​ Joint lubrication, ossification, etc v.​ Cognitive thought, mood, and behavior 2.​ Difference between secretion/signaling mechanisms a.​ Paracrine → secretes to nearby cell b.​ Exocrine → secretes through ducts to outside of body c.​ Endocrine → secreted into vasculature (hormones) and can have multiple target tissues 3.​ How do endocrine glands and hormones work? (blood supply to blood supply) a.​ Endocrine cells located inside an endocrine organ secretes hormones that are absorbed into capillary beds and into the bloodstream. b.​ Once in the bloodstream it travels to target cells/organs to stimulate a physiological response. 4.​ General understanding of the difference between a “pure” endocrine organ and a “multi-tasker” -​ Know some organs that are multi-taskers a.​ Pure i.​ Endocrine organs denoted as glands ii.​ Some organs include: 1.​ Pituitary gland 2.​ Pineal gland 3.​ Thyroid gland and parathyroid glands 4.​ Adrenal glands b.​ Multi-takers  i.​ Organs that produce hormones in addition to or in support of their primary functions ii.​ Some organs include: 1.​ Kidneys 2.​ Gonads 3.​ GI tract organs, liver, and pancreas 4.​ Lungs 5.​ Heart 5.​ Compare Nervous and Endocrine signaling both in terms of anatomy and in terms of physiology a.​ Chemical Overlap i.​ Several chemicals function as hormones and NTs 1.​ Norepinephrine, Cholecystokinin (CCK), Thyrotropin-releasing hormone (TRH), Oxytocin (OT), Angiotensin II (ANGII), Dopamine (DA), Serotonin (5-HT), & Antidiuretic hormone (ADH) b.​ Anatomical Overlap i.​ Some hormones are secreted by neurons of the hypothalamus that release their secretions into the bloodstream instead of a synapse c.​ Physiological/Functional Overlap i.​ Often have overlapping effects on target cells 1.​ Example: SNA increases blood pressure and heart rate just like the hormones epinephrine, thyroid hormone, and ANGII 2.​ Two systems converge on the same target cells ii.​ Autonomic and endocrine systems often regulate each other’s activity 1.​ Neurons stimulate or inhibit endocrine organs 2.​ Hormones stimulate or inhibit neurons 6.​ Be able to explain the hypothalamic control of autonomic functions and endocrine signaling to similar targets a.​ 7.​ Compare the signaling properties of the two systems a.​ Means of communication i.​ Nervous → electrochemical (chemical is very short distance almost paracrine-like) ii.​ Endocrine → chemical only (via bloodstream to distant target) b.​ Speed and persistence of response i.​ Nervous → reacts quickly and stops quickly ii.​ Endocrine → reacts slowly and effects persist c.​ Area of effect i.​ Nervous → targeted and specific (convergence of synapses on target) ii.​ Endocrine → general, widespread effects (often many organs) 1.​ Receptor expression on targets determines hormones specificity  8.​ Compare and contrast the three chemical classes of hormones. Recognize examples from each class Three Chemical Classes of Hormones a.​ Steroids i.​ Derived from cholesterol ii.​ Secreted by gonads & adrenal cortex iii.​ Sex steroids, glucocorticoids, and mineralocorticoids b.​ Monoamines i.​ Derived from single amino acids ii.​ Secreted by adrenal medulla, pineal, and thyroid glands iii.​ Epinephrine, NE, melatonin, and thyroid hormones c.​ Peptides and glycoproteins i.​ Created from amino acid chains ii.​ Most endocrine hormones Hormone Transport ​ Most monoamines and peptide hormones are hydrophilic ​ Steroids and the monoamine thyroid hormone are hydrophobic ​ Hydrophilic Hormones: ○​ Mix easily with blood plasma and travel within plasma filtrate in ground substance to target cell ​ Hydrophobic Hormones ○​ Bind to “carrier” proteins to travel through bloodstream ○​ Protected from clearance mechanisms that filter plasma ○​ Bound hormones have longer half-life 9.​ Understand the different receptor signaling mechanisms for different classes of hormones (note the special nature of thyroid hormone) 1st Mechanisms → Receptor-2nd messenger systems (hydrophilic amino-acid derived hormones) 1.​ Can’t enter the target cell because lipid tails of the cell are hydrophobic and the hormone itself is hydrophilic. 2.​ Hydrophilic hormones therefore must act on membrane-bound receptors a.​ They are the first messengers 3.​ The receptors are coupled to G proteins that activate an intracellular second messenger system to mediate the target cell’s response ​ Mechanism in Simple Steps 1.​ Hormone binds to cell-surface receptor 2.​ Activates G protein 3.​ Activates adenylate cyclase  4.​ Produces cAMP 5.​ Activates or inhibits enzymes ​ Hormones that use this 2nd messenger system **** (know these) ○​ Adrenocorticotropic Hormone (ACTH) ○​ Follicle-stimulating hormone (FSH) ○​ Luteinizing Hormone (LH) ○​ Parathyroid Hormone (PTH) ○​ Thyroid-stimulating hormone (TSH) ○​ Glucagon ○​ Calcitonin ○​ Catecholamines ​ Effects of downstream enzymes ○​ Protein synthesis ○​ Secretion ○​ Cellular metabolism ○​ Change membrane potentials 2nd Mechanism → Lipid-soluble (hydrophobic) hormones (steroid and thyroid hormones) 1.​ These hormones diffuse freely across the phospholipid bilayer. 2.​ Hydrophobic hormones then bind to cytoplasmic intracellular receptors. 3.​ This complex (the hormone bound to the receptor) then moves to the nucleus and translocates there. 4.​ This can directly activate or inactivate expression of target genes. ​ Slower mechanism but more long lived due to its effect on gene expression. ​ Differences between mechanisms: ○​ Hydrophilic hormones can’t penetrate into target cells and must indirectly stimulate physiology while hydrophobic hormones can penetrate plasma membranes and enter the nucleus. 10.​Explain why a small amount of a hydrophilic hormone can have potent effects on a target cell and how this permits low concentrations of circulating hormone a.​ One hormone molecule can activate many enzyme molecules which allows for low circulating concentrations to provide potent effects. 11.​Explain why hydrophobic hormones have longer-lasting effects (don’t forget about how long they last in the bloodstream) a.​ Hydrophobic hormones have a longer-lasting effect due to its ability to affect expression of target genes 12.​Compare the different stimulus mechanisms for the release of a hormone -​ Know basic examples of each Hormones are synthesized and released in response to: 1.​ Humoral stimuli → responsive to blood chemicals that are not hormones 2.​ Neural stimuli → responsive to synaptic neurotransmitter 3.​ Hormonal stimuli → responsive to other hormones in the blood called “releasing hormones” or “inhibiting hormones” Different Stimulus Mechanisms for the Release of Hormones Humoral Stimuli ​ Changing blood levels of ions or nutrients directly stimulates secretion of some hormones. ​ Example Mechanisms → Ca2+ homeostasis in the blood 1.​ Simulus → Blood Ca2+ a.​ Declining Calcium levels → directly stimulates parathyroid hormone release b.​ Rising Calcium levels → directly inhibited parathyroid hormone (PTH) release 2.​ Response: a.​ PTH increases blood Ca2+ by bone, resorption, dietary absorption, etc. until stimulus is removed by rising Ca2+ levels Neural Stimuli ​ Nerve fiber stimulate hormone release ​ Mechanism Example → Endocrine sympathetic response to acute stress 1.​ Stimuli → brain perceives “acute stress” a.​ activation of limbic system and ANS 2.​ Increased SNA in the Adrenal nerve a.​ Preganglionic to the adrenal medulla 3.​ Stimulates chromaffin cells (modified postganglionic cells) of the adrenal medulla to secrete catecholamines (Epi and NE). Hormonal Stimuli ​ Hormone stimulates other endocrine organs to release their hormones. ○​ Hormones from one endocrine organ trigger release of hormones from another endocrine organ. ​ Example → neuroendocrine axes (hypothalamus → anterior pituitary → target X) 1.​ Release of hypothalamic hormone from either a neural or humoral stimulus. 2.​ This stimulates the anterior pituitary gland to secrete another hormone. 3.​ This hormone then stimulates other endocrine glands to secrete hormones ​ Seemingly-redundant axes? ○​ Typically for increased control (multiple levels for homeostatic feedback) ○​ Hormones from downstream targets inhibit further release from the upstream source hormone.  13.​Summarize neuroendocrine axes and understand each particular axis, its regulation, and its results Neuroendocrine axis: ​ HPT axis → (hypothalamic-pituitary-thyroid) 1.​ Stimulus → Reduced Thyroid Hormone a.​ Leads to an increase in thyrotropin releasing hormone (TRH). 2.​ Hypothalamic neurons → release TRH into the blood. 3.​ This stimulates the release of thyrotrophs, which are cells in the anterior pituitary gland. 4.​ Thyrotrophs release thyroid stimulating hormone (TSH) into the blood. 5.​ TSH travels to and stimulates the thyroid gland itself. 6.​ This leads to the thyroid gland releasing thyroid hormone and thyroxine into blood and to its body targets ​ HPA Axis → Hypothalamo-Pituitary-Adrenal ○​ Corticotropin-releasing hormone (CRH) stimulates the pituitary glands to trigger the secretion of adrenocorticotropic hormone (ACTH) in the adrenal cortex ​ HPG Axis → Hypothalamo-Pituitary-Gonadal ○​ Gonadotropin hormone-releasing hormone (GnRH) stimulating the pituitary glands to trigger the secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH) at the testis and ovary ​ HPL Axis → Hypothalamo-Pituitary- Liver ○​ Growth Hormone releasing hormone (GHRH) stimulates the pituitary glands to trigger the secretion of growth hormone (GH) in the liver fate, muscle, and bone. 14.​Explain the mechanisms of hormone potency and regulation of receptor expression (“target cell sensitivity”) Potency depends on two major factors 1.​ Concentration of the hormone in the bloodstream (this is saturable) a.​ Concentration of a circulating hormone depends on: i.​ Rate of release 1.​ Varies by organ and by strength of stimulus/inhibition 2.​ Blood supply and regulation of flow (autonomic) is also a factor in regulation of how much hormone is picked up by a particular organ ii.​ Speed of inactivation or removal from the body (aka metabolic clearance rate or MCR) 1.​ Typically clearance pathway: a.​ Detoxified from blood by liver b.​ Get tagged for clearance c.​ Filtered through urine by kidneys  *Steroid persist longer due to bound carrier proteins 2.​ Relative number of receptors on/in target cell a.​ More important factor b.​ May vary among different targets of hormones that have widespread effects throughout the body Modulation of Target-Cell Sensitivity ​ Is adjusted by changing receptor densities ○​ One mechanism of endocrine negative feedback and homeostasis ​ Up-regulation of receptor expression: ○​ Sensitivity is increased ○​ Happens with low levels or absence of hormone ​ Down-regulation receptor expression: ○​ Cell less sensitive to hormone ○​ Happens with elevated hormone concentrations over an extended time period 15.​Describe the pituitary gland (contrast lobes) and the arrangement between the hypothalamus and pituitary to each lobe Hypothalamopituitary Arrangement ​ Hypothalamus → is a roughly funnel-shaped ​ Pituitary gland → hangs from the hypothalamus suspended by the infundibulum. ○​ Axonal tracts of the hypothalamic neuroendocrine cells run through the infundibulum to the posterior pituitary. ​ The Pituitary Gland (hypophysis) ○​ Composed of two structures with independent origins and distinct physiological differences. (2 lobes) ​ Anterior Pituitary → Adenohypophysis (⅔ of body) ​ Made of glandular epithelium ​ Arised from hypophyseal pouch (not the CNS) ​ Posterior Pituitary → Neurohypophysis (⅓ of body) ​ Neuroglia and connective tissue (hollow) ​ Arises from the diencephalon ○​ Outgrowth of hypothalamus as part of the neuroectoderm ​ Is a storage sac for neuroendocrine hormones from the hypothalamus 16.​Know the 8 hormones produced in the hypothalamus -​ 2 of the neurohypophysis and 6 that are regulatory hormones traveling through the hypophyseal portal vein to control secretions from the adenohypophysis 8 Hormones Produced in the Hypothalamus ​ Two Hormones are released to the Neurohypophysis:  ○​ Oxytocin and anti-diuretic hormone ​ Released directly into the posterior pituitary (neurohypophysis) when hypothalamic neuroendocrine neurons are stimulated ​ Six Hormones regulate the hormonal secretions of the Adenohypophysis: ○​ Releasing hormones that affect anterior pituitary secretion at various -troph cells (glandular epithelium): ​ Thyrotropin Releasing Hormone (TRH) ​ Corticotropin Releasing Hormone (CRH) ​ Gonadotropin Releasing Hormone (GnRH) ​ Growth Hormone Releasing Hormone (GHRH) ​ Inhibiting hormones ○​ Prolactin Inhibiting Hormone (PIH) ​ Inhibits secretion of PRL ○​ Growth Hormone Inhibiting Hormone (GHIH) ​ Aka somatostatin ​ Inhibits secretion of GH by the anterior pituitary 17.​Know the 3 reproductive and 3 metabolic hormones of the adenohypophysis Reproductive Hormones of the Adenohypophysis ​ Two reproductive hormones released by gonadotrophs (cells) that target the gonads (part of HPG axis) ○​ Follicle-stimulating hormone (FSH) ​ Stimulates secretion of ovarian estrogens, development of ovarian follicles, sperm production and secretion of inhibin in both sexes (neg. Feedback signal for FSH). ○​ Luteinizing Hormone (LH) ​ Stimulates ovulation, stimulates corpus luteum to secrete progesterone, and stimulates testes to secrete testosterone. ​ Third hormone of the adenohypophysis is released by lactotrophs to target the mammary glands or testes. ○​ Prolactin (PRL) ​ After birth, stimulates mammary glands to synthesize milk and also enhances secretion of testosterone by testes. ​ Intact but limited in functionality in males Metabolic Hormones of the Anterior Pituitary ​ Thyroid-stimulating hormone (TSH) ○​ released by thyrotrophs to target the thyroid gland ○​ Stimulates secretion of thyroid hormone ​ Adrenocorticotropic Hormone (ACTH) ○​ Released by corticotrophs to target the adrenal cortex ○​ Stimulates secretion of glucocorticoids  ​ Growth Hormone (GH) ○​ Released by somatotrophs to target muscle, liver, adipose, etc. ○​ Stimulates secretion of insulin-like growth factor 1 (IGF-1) ○​ Stimulates lipolysis, mitosis, and cellular differentiation 18.​Explain the effects of the HPL axis, particularly IGF-1 and growth hormone -​ Understand the homeostatic imbalances related to growth hormone (with effects) Growth hormone (GH) in Focus ​ Many indirect effects mediated by stimulating production of insulin-like growth factor 1 by the liver (last limb of HPL axis) ​ IGF-1 and GH stimulate most cells in the body ○​ Effects are most evident in bone and skeletal muscle ○​ Promotes hyperplasia and hypertrophy of muscle and bone ​ Promotes protein synthesis and encourages lipolysis (fat burning as fuel for growth) Homeostatic Imbalances of Growth Hormones ​ Hyposecretion (under secretion) ○​ In children, results in pituitary dwarfism ​ Tumor causing hypopituitarism (decreased hormonal output) ​ Hypersecretion ○​ In children, results in gigantism ○​ In adults results in acromegaly (similar to effects of abuse) 19.​Explain the effects of the HPT axis, particularly thyroxine -​ Understand the homeostatic imbalances related to thyroid hormone (with effects) Thyroxine (T4) in Focus ​ Primary function → increases energy metabolism and heat production (thermogenic/catabolic effect) ​ Auxiliary roles: ○​ Mood/emotional state ○​ Appetite ○​ Blood pressure ○​ Tissue growth ○​ CNS development ○​ Reproduction Homeostatic Imbalances of T4 ​ Hyposecretion → In infants, leads to cretinism ○​ Often caused by maternal iodine deficiency during fetal development ○​ Retardation of physical/mental development in children ○​ Treatable with supplement TH but must be caught early ​ Hyposecretion → In adults, leads to Hypothyroidism  ○​ Caused by insufficient TH production ​ Can lead to fetal coma if severe and untreated (myxedema) ​ Causes vary from thyroid atrophy, pituitary tumor, iodine deficiency (goiter), or autoimmune disease (Hashimoto's) ​ Hypersecretion → Graves’ disease ○​ Caused by thyroid or other endocrine gland tumors (adenocarcinomas) ○​ Possible symptoms: ​ Causes exophthalmos (protruding eyes) ​ Vitiligo (depigmentation of skin) ​ Weight loss and/or increased appetite ​ anxiety/paranoia/insomnia ​ Tachycardia and hypertension ​ Osteoporosis 20.​Review and address the effects of Parathyroid hormone -​ Understand the homeostatic imbalances related to parathyroid hormone (with effects) The Parathyroid Glands ​ Usually four glands partially embedded in posterior surface of thyroid gland ​ Secrete parathyroid hormone (PTH) ○​ Increases blood Ca2+ levels Homeostatic Imbalances of PTH ​ Hyperparathyroidism → due to parathyroid tumor (adenoma) ○​ Hypercalcemia ​ Causes general malaise, mood swings, and confusion, can eventually lead to coma) ○​ Bones soften and deform ○​ Can contribute to kidney stone formation ​ Hypoparathyroidism ○​ Acquired hypoparathyroidism → following gland trauma or removal ○​ Innate parathyroidism → Digeorge syndrome (genetic absence) ​ Autoimmune destruction of parathyroid glands ○​ Causes hypocalcemia ​ Petechiae → red blemishes on skin due to pinpoint hemorrhages ​ Potentially fatal neural and muscular complications 21.​Describe the adrenal gland (cortex vs medulla; zones of cortex and products of each zone) -​ Understand the function of each product The Adrenal Glands ​ Adrenal cortex and medulla are formed by merger of two different fetal tissues ○​ Recall the medulla is modified sympathetic postganglionic ​ Which comes from neuroectoderm (neural crest specifically) ○​ Adrenal cortex develops from mesenchyme (of the mesoderm) The Adrenal Medulla ​ Adrenal medulla → inner core, 10 to 20% of gland ​ Simultaneously acts as an endocrine gland and sympathetic ganglion of the autonomic nervous system ○​ Innervated by sympathetic preganglionic ○​ Responds to acute stressors ​ Consists of modified sympathetic postganglionic neurons call chromaffin cells ○​ Release catecholamines [epinephrine (80%) and norepinephrine (20%)] directly into bloodstream ​ Increases alertness and prepares body for physical activity ​ Mobilizes high-energy fuels (fatty acids and glucose) ​ Glycogenolysis and gluconeogenesis boost glucose levels ​ Increases blood pressure, heart rate, blood flow to skeletal muscle, pulmonary airflow, and metabolic rate ​ Decreases digestive and renal functions The Adrenal Cortex ​ Surrounds adrenal medulla → secretes steroids from 3 ayers of glandular tissue ○​ Zona glomerulosa (thin, outer layer) ​ Secrets mineralocorticoid (aldosterone) to regulate the body’s fluid/electrolyte balance ○​ Zona fasciculata (thick, middle layer) ​ Secretes glucocorticoids (cortisol) for response to chronic stress ○​ Zona reticularis (narrow, inner layer) ​ Secretes sex steroids (androgens and estrogens) ​ Androgenic effects in females ​ Estrogenic effects in males and post menopausal 22.​Explain the effects of the HPA axis, particularly cortisol -​ Understand the homeostatic imbalances related to cortisol (with effects) -​ Note that Cushing’s is due solely to cortisol hypersecretion but Addison’s is often due to both cortisol and aldosterone hyposecretion Cortisol ​ Steroid hormone → long-lasting ​ Regulates metabolism of glucose and other fuels ○​ Stimulates fat and protein catabolism ○​ Gluconeogenesis by breaking down len tissues ○​ Release of fatty acids and glucose into blood ○​ Anti-inflammatory effect that becomes immunosuppressive in the long-term ​ Helps body adapt to long-term stress and repair tissues ○​ Long-term stress → cortisol ○​ Short-term stress → catecholamines (of adrenal medulla) Homeostatic Imbalances of PTH ​ Hypercortisolemia → Cushing syndrome ○​ Causes → pituitary or adrenal tumors, corticosteroids therapy ○​ Effects: ​ Hyperglycemia, hypertension, weakness edema ​ Inhibits inflammation (immunosuppressive) ​ Rapid muscle and bone loss due to protein catabolism ​ Abnormal fat deposition ​ Moon face and buffalo hump ​ Adrenocortical Insufficiency → Addison’s disease → Addison’s disease is both cortisol and aldosterone hyposecretion​ ○​ Causes → Autoimmune disease, pituitary disorders, adrenal tumors ○​ Effects: ​ Bronzing of skin (hyperpigmentation) ​ Hypoglycemia and weight loss ​ Chronic fatigue and hypotension ​ Acne and keloidosis ​ Chronic pain, GI distress, and inflammation 23.​Testable non-lecture topics: -​ Details of hypothalamic releasing and inhibiting hormones -​ Details of pituitary cells releasing specific hormone products -​ Basic details of the gonads: testes and ovaries 24.​Non-Testable topics: -​ 17.6 Eicos & Signals -​ 17.7e Diabetes -​ All DI panels