Chapter 17 The Endocrine System
Page 3: Overview of the Endocrine System
Definition: Comprised of ductless glands synthesizing and secreting hormones.
Hormones: Released into the bloodstream and transported to target cells with specific receptors.
Transport Mechanism:
Hormones are released into interstitial fluid > enter blood > diffuse into interstitial fluid > bind to target cell receptors.
Page 4: Comparison of Control Systems
Endocrine and Nervous Systems:
Both systems release ligands as chemical messengers that bind to receptors on target cells.
Differences:
Endocrine system transmits hormones through blood, targets all cells with appropriate receptors, has widespread effects, longer reaction times, and more prolonged effects (minutes to weeks).
Page 5: Nervous and Endocrine System Communication Methods
Figure illustrating the communication methods between these two systems.
Page 6: General Functions of the Endocrine System
Development, Growth, and Metabolism Regulation: Hormones regulate cell division, differentiation, anabolism, and catabolism.
Homeostasis: Maintain blood composition, volume, and regulate solute concentrations (e.g., glucose, ions).
Digestive Control: Hormones influence digestive tract movement and secretion.
Reproductive Control: Affect reproductive system development, function, and sexual behavior expression.
Page 7: Major Endocrine Glands Location
Endocrine Glands: Composed of epithelial tissue releasing hormones, some also serve non-endocrine functions.
Glands exclusively endocrine: Pituitary, pineal, thyroid, parathyroid, adrenal.
Endocrine cells also present in other tissues (e.g., hypothalamus, heart, pancreas).
Page 8: Major Endocrine Glands, Organs, and Tissues
Figure detailing locations of major endocrine glands and associated cells.
Page 9: Types of Endocrine Stimulation
Figure depicting various modes of endocrine stimulation.
Page 10: Circulating Hormones
Steroids: Lipid-soluble; synthesized from cholesterol.
Include gonadal steroids (e.g., estrogen) and adrenal cortex steroids (e.g., cortisol).
Calcitriol: Sometimes classified as a steroid, more accurately a sterol.
Page 11: Biogenic Amines (Monoamines)
Definition: Modified amino acids.
Include catecholamines, thyroid hormone, melatonin.
Water-soluble (except for thyroid hormone, which is lipid soluble).
Page 12: Local Hormones
Definition: Do not circulate in blood; bind to the releasing cells (autocrine) or neighboring cells (paracrine).
Eicosanoids: Derived from fatty acids; includes prostaglandins that induce pain and inflammation.
Drugs (e.g., Aspirin): Block prostaglandin formation.
Page 13: Hormone Interactions on Target Cells
Types of Hormonal Interactions:
Synergistic: One hormone enhances another's effects (e.g., estrogen and progesterone).
Permissive: One hormone depends on another's presence (e.g., oxytocin and prolactin).
Antagonistic: One hormone counteracts the effects of another (e.g., glucagon and insulin).
Page 14: Hormone Interactions
Figure illustrating interactions between different hormones.
Page 15: Hypothalamus and Pituitary Gland Connection
Control: Hypothalamus governs the pituitary, influencing other endocrine organs.
Pituitary Gland: Pea-sized structure located beneath the hypothalamus, comprised of anterior and posterior sections.
Page 16: Posterior Pituitary Gland
Structure: Smaller neural part of the pituitary.
Function: Stores hormones released by hypothalamic neurons (i.e., ADH and oxytocin).
Page 17: Hypothalamus and Posterior Pituitary Interaction
Posterior pituitary releases ADH and oxytocin produced by hypothalamic neurosecretory cells.
ADH: Decreases urine production, stimulates thirst, and constricts blood vessels.
Oxytocin: Causes uterine contractions and milk ejection.
Page 18: Hypothalamus and Anterior Pituitary Interaction
Regulation: Hypothalamus stimulates anterior pituitary via hormonal signals.
Page 19: Anterior Pituitary Hormones
Hypothalamic Hormones:
Releasing: TRH, PRH, GnRH, CRH, GHRH (increase pituitary hormones).
Inhibitory: PIH, GIH (decrease pituitary hormone secretion).
Page 20: Anterior Pituitary Hormones
Figure illustrating the hormones produced by the anterior pituitary.
Page 21: Anterior Pituitary Hormones Function
Hormones:
TSH: Stimulated by TRH, promotes thyroid hormone release.
PRL: Milk production; regulated by PRH and PIH.
ACTH: Release of corticosteroids from the adrenal cortex, stimulated by CRH.
Page 22: Anterior Pituitary Gonadotropins & GH
Gonadotropins (FSH and LH): Regulate reproductive functions and hormone secretion.
Growth Hormone (GH): Stimulates liver to secrete IGFs, promotes cell growth and division.
Page 23: Hypothalamo-Hypophyseal Tract
Figure showing the hypothalamo-hypophyseal tract.
Page 24: Clinical View: Hypophysectomy
Definition: Removal of the pituitary gland (due to tumors), affecting hormone levels which need to be monitored and replaced.
Page 25: Regulation and Effects of Growth Hormone
Control: Regulated by hypothalamic hormones (GHRH and GHIH).
Factors Influencing Release: Age, time of day, nutrient levels, stress, exercise.
Page 26: Effects of Growth Hormone
Functions similar to GH but with a longer half-life.
Stimulates protein synthesis, cell division, nutrient release, and affects glucose metabolism (glycogenolysis, gluconeogenesis, and lipolysis).
Page 27: Regulation and Action of Growth Hormone
Figure depicting the regulation of growth hormone action.
Page 28: Disorders of Growth Hormone Secretion
Growth Hormone Deficiency (Pituitary Dwarfism): Results from low production leading to short stature.
Pituitary Gigantism: Excess GH leading to excessive growth.
Page 29: Clinical View: Acromegaly
Acromegaly: Excessive GH in adults leading to enlarged bones and increased glucose production.
Page 30: Anatomy of the Thyroid Gland
Location: Inferior to the thyroid cartilage of the larynx, anterior to trachea.
Structure: Composed of follicles with surrounding epithelial cells, rich in blood vessels, producing thyroid hormones and calcitonin.
Page 31: Thyroid Gland Anterior View
Figure showcasing the anterior view of the thyroid gland.
Page 32: Thyroid Hormone Synthesis
Figure illustrating the synthesis, storage, and release of thyroid hormones.
Page 33: Regulation of Thyroid Hormone Release
Axis: Hypothalamic-pituitary-thyroid axis regulates TH levels.
TRH from hypothalamus stimulates TSH from anterior pituitary leading to T3 and T4 release.
Page 34: Effects of Thyroid Hormone
Role: Increases metabolic rate, protein synthesis; T3 is more active than T4.
Calorigenic Effect: Generates heat, stimulates glucose uptake, increases respiration rate, and heart function.
Page 35: Regulation and Action of Thyroid Hormone
Figure depicting the regulation and action of thyroid hormone.
Page 36: Continued Effects of Thyroid Hormone
Influences ATP production, regulates blood glucose, and has significant effects on bodily functions.
Page 37: Disorders of Thyroid Hormone Secretion 1
Hyperthyroidism: Caused by excessive TH with symptoms of weight loss and increased activity.
Hypothyroidism: Result from decreased TH, leading to lethargy and weight gain.
Page 38: Disorders of Thyroid Hormone Secretion 2
Goiter: Enlargement due to iodine deficiency, historically common in the U.S.
Page 39: Calcitonin: Regulation and Effects
Source: From parafollicular cells.
Function: Decreases blood calcium by inhibiting osteoclasts and promoting calcium excretion in urine.
Page 40: Adrenal Glands Anatomy 1
Location: On superior surface of each kidney.
Regions: Medulla (releases epinephrine/norepinephrine) and cortex (synthesizes over 25 corticosteroids).
Page 41: Adrenal Gland Location
Figure showing the location of adrenal glands.
Page 42: Adrenal Glands Anatomy 2
Cortex Hormones: Mineralocorticoids (e.g., aldosterone), glucocorticoids (e.g., cortisol), and gonadocorticoids (sex hormones).
Page 43: Cortisol Regulation and Effects 1
Regulation: Stress and sleep stages stimulate CRH > ACTH > cortisol release.
Feedback Loop: Cortisol inhibits CRH and ACTH release.
Page 44: Regulation and Action of Cortisol Hormone
Figure illustrating the regulation and effects of cortisol hormone.
Page 45: Cortisol: Effects and Side Effects
Therapeutic Use: Corticosterone for inflammation; high doses can lead to infections and tissue repair issues.
Page 46: Disorders in Adrenal Cortex Hormone Secretion 1
Cushing Syndrome: Results from excessive glucocorticoids leading to various health concerns.
Addison Disease: Adrenal insufficiency causing weight loss and fatigue.
Page 47: Disorders in Adrenal Cortex Hormone Secretion 2
Adrenogenital Syndrome: Hormone overproduction causes masculinization in newborns.
Page 48: Stress Response Stages
Stages:
Alarm Reaction: Sympathetic activation.
Resistance Stage: Cortisol secretion for energy demands.
Exhaustion Stage: Protein breakdown and weakening due to prolonged stress.
Page 49: Anatomy of the Pancreas
Location: Posterior to stomach, with both endocrine and exocrine functions.
Islets of Langerhans: Contain alpha (glucagon), beta (insulin), delta (somatostatin), and F cells (pancreatic polypeptide).
Page 50: Pancreas Image
Figure of the pancreas location.
Page 51: Pancreatic Hormones 1
Function: Maintain blood glucose.
Insulin: Secreted by beta cells post food intake to lower blood sugar levels.
Page 52: Regulation and Action of Insulin
Figure illustrating the mechanism of insulin action.
Page 53: Conditions Resulting in Abnormal Glucose Levels 1
Diabetes Mellitus: Leading to abnormal glucose levels, causing serious complications.
Type 1: Insulin deficiency; autoimmune component.
Page 54: Conditions Resulting in Abnormal Glucose Levels 2
Type 2 Diabetes: Related to insulin effectiveness; linked to obesity.
Gestational Diabetes: Occurs in some pregnant women; can cause fetal risk.
Page 55: Conditions Resulting in Abnormal Glucose Levels 3
Hypoglycemia: Low blood sugar; various causes and symptoms treatable with glucagon.
Page 56: Regulation and Action of Glucagon
Glucagon raises low blood sugar; stimulates glycogenolysis and lipolysis while inhibiting glycogenesis.
Page 57: Regulation and Action of Glucagon Figure
Figure illustrating glucagon regulation and action.
Page 58: Pineal Gland
Location: In the epithalamus; secretes melatonin for sleep regulation and mood.
Page 59: Parathyroid Glands
Structure: Small glands on the posterior thyroid.
Function: Chief cells secrete parathyroid hormone (PTH) for calcium regulation.
Page 60: Structures with Endocrine Function 1
Thymus: Matures T-lymphocytes during childhood.
Heart: Releases ANP to lower blood pressure.
Kidney: Secretes erythropoietin for red blood cell production.
Page 61: Structures with Endocrine Function 2
Liver: Secretes growth factors and angiotensinogen.
Stomach: Secretes gastrin for digestion.
Page 62: Structures with Endocrine Function 3
Small Intestine: Secretes secretin and CCK for digestion and bile release.
Skin: Converts cholesterol to vitamin D, crucial for calcium regulation.
Page 63: Structures with Endocrine Function 4
Adipose Tissue: Secretes leptin for appetite control; low levels may affect menstrual cycles and reproductive health.
Page 64: Aging and the Endocrine System
Effects of Aging: Decreased secretory activity leads to reduced efficiency and lower hormone levels, impacting bodily functions.