Endocrine System Fernandez, Alecz Gabrielle Kim, Ah Young Palad, Maria Karina Larni Plata, Kirk Reyes, Kristofer
The Endocrine System • Regulates long term metabolic processes in the human body, in comparison to the nervous system which performs short term responses • Maintains homeostasis or the balance within the internal environment of our body
Intercellular Communication Mechanism
Transmission
Chemical Mediators
Direct Communication
Gap junctions
Ions, small solutes, lipid soluble materials
Paracrine Communication
Extracellular fluid
Paracrine factors
Endocrine Communication
Blood stream
Hormones
Synaptic Communication
Synaptic clefts
Distribution of Effects Limited to adjacent cells of the same type Limited to local area where there is high paracrine factor concentration. Receptors required
Neurotransmitters
Target cells are located in various areas. Receptors required Limited to specific area
Hormones • molecules which bind to specific receptors in cells which causes various changes • Three groups based on chemical structure: 1) amino acid derivatives 2) peptide hormones 3) lipid derivatives (including steroids and eicosanoids)
Amino Acid Derivatives • Synthesized from tyrosine and tryptophan o Derivatives of Tyrosine Thyroid Catecholamines o Derivative of Tryptophan Melatonin
Peptide Hormones • Glycoproteins o More than 200 amino acids long o Contains carbohydrate chains o Examples are TSH, LH, and FSH • Small Proteins o The hormones produced are secreted by the hypothalamus, heart, thymus, digestive tract, pancreas, and posterior lobe
Lipid Derivatives • Eicosanoids o Coordination of cellular activities and enzymatic processes such as blood clotting o Leukotrienes, prostaglandins • Steroids o Secreted by reproductive organs (androgen and estrogen), cortex of adrenal glands (corticosteroids), and kidneys (calcitriol) o Bound to transport proteins
Hormones and Membrane Receptors • Lipid soluble hormones can readily cross the plasma membrane of a cell (steroids & thyroids) • Catecholamines, peptide hormones, eicosanoids require receptor interaction to enter the cell.
Endocrine Reflexes • Functional counterpart of neural reflexes o Triggered via the following: Humoral stimuli -Extracellular fluid Hormonal stimuli -Arrival or removal of specific hormones Neural stimuli -Neurotransmitter mediated
Pituitary Gland
Pituitary Gland Hormones: • Thryoid-Stimulating Hormone (TSH) • Adrenocorticotropic Hormone (ACTH) • Gonadtrophins (GnRH) o Follicle-stimulating hormone (FSH) o Luteinizing Hormone (LH) • Prolactin (PRL) • Growth Hormone (GH) • Melanocyte-Stimulating Hormone (MSH) • Antidiuretic Hormone (ADH) • Oxytocin (OXT)
Anterior Lobe of the Pituitary Gland • Adenohypophysis • Three Regions 1. Pars distalis 2 Pars tuberalis 3. Pars intermedia • Hypophyseal Portal system
Hypophyseal Portal System • Hypothalamus o Controls the production of hormones in the anterior lobe • Median eminence o Capillary network supplied by superior hypophyseal artery • Hypophyseal portal system o Efficient chemical communication o Ensures hypothalamic hormones reach target cells in the anterior lobe
Hypothalamic Control of the Anterior Lobe • Releasing Hormone (RH) o Stimulates the synthesis and secretion of one or more hormones from the anterior lobe • Inhibiting Hormone (IH)
Anterior lobe Hormones • Thyroid-Stimulating Hormone (TSH) o Thyrotropin o Targets thyroid glands o Triggers the release of thyroid hormones o Released in response to thyroptropinreleasing hormone from the hypothalamus
Anterior lobe Hormones • Adrenocorticotropic Hormone (ACTH) o Corticotropin o Stimulates the release of steroid hormones by the adrenal cortex o Targets cells producing glucocorticoids o Stimulation from corticotropin-releasing hormone (CRH)
Anterior lobe Hormones • Gonadotropins 1. Follicle-stimulating hormone (FSH) Promotes follicle development in women and stimulates nurse cells in males Inhibits by inhibin 2. Luteinizing Hormone (LH) induces ovulation and secretion of estrogens and the progestins in female Interstitial cell-stimulating hormone in males • Gonadotropin-releasing hormone (GnRH)
Anterior lobe Hormones • Prolactin (PRL) o Mammatropin o Stimulates mammary gland development o Inhibited by dopamine (prolactininhibiting hormone) o Prolactin-releasing hormone (PRF) o Milk ejections, however, is released through oxytocin
Anterior lobe Hormones • Growth Hormone (GH) o Somatotropin o Stimulates cell growth and replication o Stimulation of growth involves two mechanisms 1. Indirect 2. Direct o Regulated by growth hormone-releasing hormone and growth hormone-inhibiting hormone
Anterior lobe Hormones • Melanocyte-Stimulating Hormone (MSH o Melanotropin o Stimulates melanocytes of the skin o Dopamine inhibits the release of MSH o Human pars intermedia secretes MSH During fetal development 1. In very young children 2. In pregnant women 3. In the course of some diseases
Posterior Lobe of the Pituitary Gland • Neurohypophysis o Contains axons of hypothalamic neurons o Supraoptic manufacture antidiuretic hormone o Paraventricular nuclei manufacture oxytocin • Hormones travel by means of axoplasmic transport
Posterior lobe Hormones • Antidiuretic hormon (ADH) o Vasopressin o Stimulates through the increase of solute concentration in the blood or fall in blood volume or blood pressure o Osmoreceptors respond to a change in the osmotic concentration of body fluids which in return stimulates neurosecretory neurons
Posterior lobe Hormones • Oxytocin (OXT) o Stimulates smooth muscle contraction in the wall of uterus during labor o After delivery, promotes ejection of milk
Hypothalamus 1. Secretes regulatory hormones - Anterior lobe of pituitary gland 2. Releases hormones into the blood stream - Posterior lobe of pituitary gland 3. Exerting direct control over adrenal medullae endocrine cells
Thyroid Gland - Two lobes connected by the isthmus - 34g, deep red color - When something goes wrong, it enlarges and distorts the surface of the neck.
Thyroid Gland - ďťż Follicle Cavity - Thyroid follicles - Follicle cavity - Follicle cells
- Thyroglobulin
Thyroid Hormones - Affect almost every cell in the body - Enter target cells by means of an energy dependent transport system - Bind to receptors (1) in cytoplasm, (2) on the surface of mitochondria, and (3) in the nucleus (1) Storage (2) Increase the rates of ATP production (3) Activates genes that control the synthesis of enzymes - Activates genes that code for the synthesis of enzymes involved in glycolysis and ATP production - Calorigenic effect
- C cells (Clear cells) - Calcitonin (CT) - Regulates calcium concentrations in body fluids -direct endocrine regulation Childhood: - bone growth - mineral deposition - reduce loss of bone mass -sodium permeability (high Ca) - convulsions, muscular spasms (low Ca) - constipation, weight gain, goiters, thyroid cancer, fatigue, dementia, hypothyroidism,
Parathyroid Gland • Primarily responsible for regulating calcium ions in the human body
• Increases Ca2+ levels in body fluids http://www.becomehealthynow.com/image s/organs/endocrine/parathyroid_glands.jpg
Adrenal Glands
http://www.mayoclinic.com/images/imag e_popup/mcdc7_adrenal_glands.jpg http://iahealth.net/wp-content/uploads/2008/12/adrenal_gland.jpg
Adrenal Cortex • Releases corticosteroids
http://www.vet.uga.edu/vpp/clerk/groover/Fig1.jpg
Zona glomerulosa Hormone: Mineralcorticoids Function: Involved in salt and water regulation Regulatory control: stimulated by angiotensin II and decreased levels of Na+ Deficiency: Decrease of sodium levels and increase in potassium levels
Zona fasiculata Hormone: Glucocorticoids Function: important in immunological and metabolic processes as well as fetal development Regulatory control: stimulated by ACTH by anterior lobe of pituitary gland Deficiency: compromised immuno and metabolic processes
Zona reticularis Hormone: Androgen Function: involve in muscle and bone growth as well as blood formation in children and women Regulatory control: stimulated by ACTH by anterior lobe of pituitary gland Deficiency: compromised bone growth and blood formation
Medulla Hormone: Epinephrine and norephinephrine Function: increases cardiac activity, blood pressure and blood glucose levels Regulatory control: stimulated by sympathetic activation Deficiency: results in low blood glucose levels
Pineal Gland • Responsible for melatonin production via pinealocytes. • Inhibits reproductive functions, and prevents free radical damage http://www.crystalinks.com/pinealbrainstem.jpg
Pancreas
• Exocrine gland o Pancreatic Acini
Pancreas
Endocrine gland • Islets of Langerhans: o Alpha cells – glucagon o Beta cells – insulin o Delta cells o F cells – Pancreatic Polypeptide
Production of Glucagon • Glucose concentrations fall below normal levels (70-110mg/L) • When glucagon binds to the receptors in the cells, they produce adenylate cyclase
Effects of Adenylate Cyclase • Stimulates the breakdown of Glycogen in skeletal muscles and liver cells • Stimulates the breakdown of trigylcerides in adipose tissue • Stimulates the production and release of glucose by the liver
Production of Insulin • Glucose levels exceed the normal levels (70110mg/L) • Insulin binds to receptor proteins on the plasma membranes of target cells
• Receptor functions as a kinase where it attaches phosphate groups to intracellular enzymes • Autonomic activity influences the production of Insulin
http://www.happyhealthybalance.net/2010/05/insulin-sugar-fat.html
Illness
Diabetes Mellitus • Sugar accumulates in the blood and urine – faulty glucose metabolism • Genetic abnormalities o Insulin dependent (Type o Non-Insulin dependent
(Type 2)
1)
Insulin Problems • Insulin dependent – depend on the absorption of insulin to absorb and utilize glucose in the body • Insulin independent – no need for insulin absorption
Effects of Insulin to target cells • Accelerates glucose uptake (facilitated diffusion) • Accelerate glucose utilization and enhancement in ATP production • Stimulating glycogen production
• Stimulating amino acid absorption and protein synthesis • Stimulating triglyceride formation in adipose tissue
Kidney • Calcitriol • Erythropoietin • Renin
Calcitriol steroid hormone secreted in response to the parathyroid hormone (PTH) o Stimulate calcium and potassium ion absorption in the digestive tract o Stimulate formation of different osteoprogenitor cells and osteoclasts o
o Stimulate o Stimulate
bone reabsorption of osteoclasts calcium reabsorption of Ca+ ions in kidneys o Suppressing PTH production o Cholecalciferol
Erythropoietin o Response
of kidneys tissues to low levels of
oxygen o Stimulate bone marrow to produce more red blood cells
http://www.empowerthepatient.com/red-blood-cells.htm
Renin • Response of kidneys to sympathetic stimulation or decline in renal blood flow • Converts angiotensinogen to angiotensinogen I which is then modified to angiotensinogen II
Heart • secrete natriuretic peptides when the blood volume becomes too great • Promote the loss of Na+ and water • Inhibit renin release and secretion of ADH and aldosterone
• Suppress thirst • Prevent angiotensin II and norephinephrine from elevating the blood pressure • Reduction of blood volume and blood pressure o reduces the stretching of the cardiac muscles
Thymus •Thymosin •originally
http://catalog.nucleusinc.com/generateexhibit.php?I D=14932
named to an extract of the thymus that promotes the maturation of lymphocytes which are white blood cells responsible for immunity • Produces hormones that develop and maintain immune defenses
Gonads • Males o Interstitial tissues in the testes Testosterone o Nurse cells support differentiation and physical maturation of the sperm Under FSH Stimulation, they secrete the hormone Inhibin Inhibits the secretion of Inhibin at the anterior lobe of the pituitary gland Suppresses GnRH release at the hypothalamus
http://www.vetmed.lsua.edu/eiltslotus/theriogenology-5361/male%20reprod_2.htm
• Females Steroid hormones such as estrogens (produced in the ovary under FSH and LH stimulation) Estradiol – primary estrogen Circulating FSH stimulates secretion of inhibin by ovarian cells Inhibin – suppresses FSH release
http://klikphirtual.blogspot.com/2010/05/menstruation.html
• remaining follicle cells reorganize into a corpus luteum that releases a mixture of estrogens and progestins • placenta and uterus o pituitary gland and the ovary o promote normal fetal development and delivery
Adipose Tissue • Produces the peptide hormone leptin o Feedback control of appetite o Binds hypothalamic neurons involved in emotions and appetite control http://www.nature.com/nature/journal/v459/n7245/fig_tab/45934 0a_F1.html
Interaction of Hormones •Antagonistic effect –Results are weaker than those produced by either hormones acting individually Ex. PTH and calcitonin, glucagon and insulin • Synergistic effect –Net result is greater than the effect of each hormone acting alone Ex. Glucose-sparing action of GH and glucocorticoids
Interaction of Hormones •Permissive effect –First hormone is needed for the second one to produce its effect Ex. Epinephrine and thyroid hormones •Integrative effect –Hormones may produce different but complementary results Ex. Calcitriol and parathyroid hormones
Growth • Growth Hormone (GH) o children: support muscular and skeletal development o adults (not primary hormone involved): maintain normal blood glucose concentration mobilize lipid reserves in adipose tissue • Thyroid Hormones o required during fetal development for the normal development of the nervous system
Growth • Insulin o helps in the passage of glucose and amino acids across the plasma membrane • Parathyroid hormone (PTH) and Calcitrol o promotes the absorption of calcium salts from the bloodstream for the deposition in bones
Growth • Reproductive Hormones  o males: androgens o females: estrogens o stimulate cell growth and differentiation in their target tissues accounts for gender-related differences in skeletal proportions and secondary sex characteristics
Stress -a physical or emotional condition that affects homeostasis -Homeostatic adjustments oppose many stresses
General Adaptation Syndrome
General Adaptation Syndrome
General Adaptation Syndrome
Behavior • Behavioral effects can be seen in individuals whose endocrine glands are either oversecreting or undersecreting
Aging and Hormone Production • Changes in normal mixture of hormones can affect intellectual capabilities, memory, learning and emotional states • Undergoes few functional changes with advanced age • Decline in concentration of growth hormone and reproductive hormones