NCMC101 Endocrine System PDF

Summary

This document provides an overview of the endocrine system, focusing on the development, structure, function, and clinical correlations of various glands. It includes details on the pituitary, thyroid, parathyroid, adrenal, pineal, and thymus glands, with descriptions of their components and functions. Information on blood supply, location, and clinical aspects (e.g., thyroglossal duct cysts) is also presented.

Full Transcript

NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM DEVELOPMENT OF PITUITARY GLAND Hypophyseal pouch/ Rathke- u...

NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM DEVELOPMENT OF PITUITARY GLAND Hypophyseal pouch/ Rathke- upgrowth from ROOF of 1.0 ENDOCRINE SYSTEM primitive mouth- ANT. PITUITARY Neurohypophysial bud- downgrowth from the forebrain Complex network of glands and organs (diencephalon)- POST. PITUITARY Regulates all biological processes in the body LOBES Uses hormones to control and coordinate our body’s metabolism, energy level, reproduction, growth and ANTERIOR POSTERIOR development, response to injuries, stress and mood THE MAJOR ENDOCRINE ORGANS Glandular epithelium Consists of Nervous Tissue 3 PARTS: Extension of the Pituitary PARS DISTALIS- largest, Hypothalamus Thyroid responsible for hormone PARS NERVOSA Parathyroid secretion INFUNDIBULUM PARS INTERMEDIA Adrenal PARS TUBERALIS- upward Pineal extension of the Pars Thymus gland Distalis that surrounds the Pancreas Infundibulum GONADS BLOOD SUPPLY: ○ Ovaries Anterior Pituitary Gland receives arterial supply from the ○ Testes SUPERIOR HYPOPHYSEAL ARTERY which is a branch of 1.0 PITUITARY GLAND INTERNAL CAROTID ARTERY Posterior Pituitary Gland and Infundibulum receive arterial supply from the: Also called as HYPOPHYSIS CEREBRI ○ SUPERIOR HYPOPHYSEAL ARTERY “Master” Endocrine gland, about the size of a PEA ○ INFUNDIBULAR ARTERY Protrusion off the bottom of the hypothalamus at the base ○ INFERIOR HYPOPHYSEAL ARTERY of the brain LODGED in an arca called as PITUITARY FOSSA or SELLA TURCICA which is part of sphenoid bone PINEAL GLAND Also called as EPIPHYSIS CEREBRI Typically measures around 7x6x3 mm in size situated in a groove between the laterally placed thalamic bodies (OUTWARD of the ROOF of the THIRD VENTRICLE) PEA sized, mean weight is around 172 mg Produces MELATONIN which plays a role in regulating sleep patterns Known as the “THIRD EYE” because of its location deep in the center of the brain and its connection to light GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 1 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM THYROIDEA IMA ARTERY ○ In up to 12% of individuals, a small midline artery, called the Thyroidea Ima artery, arises from the aortic arch or brachiocephalic trunk and reaches the thyroid isthmus ineriorily THYROID GLAND Right and Left lobes connected by a narrow ISTHMUS (second, third and fourth tracheal rings) Each lobe is pear shaped, apex directed upward- lamina of thyroid cartilage; Base at the level of the fourth or fifth tracheal rings Surrounded by Pretracheal layer of deep fascia 20 gms PYRAMIDAL LOBE is often present; projects upward from the isthmus, usually to the LEFT of the midline Fibrous of Muscular band frequently connects the pyramidal lobe to the hyoid bone- LEVATOR GLANDULAE THYROIDEA CLINICAL CORRELATION: THYROGLOSSAL DUCT CYST AND SINUS Normally thyroglossal duct atrophies & disappears, but a remnant may persists forming a cyst Painless, progressively enlarging movable mass; asymptomatic unless becomes infected Following infection- perforation of the skin forming a thyroglossal duct sinus that opens in the median plane of the neck THYROGLOSSAL DUCT CYST BRANCHIAL CLEFT CYST Midline Lateral to midline Near hyoid bone Anterior to SCM Moves up w/ swallowing or tongue Does not move w/ swallowing or tongue protrusion protrusion PARATHYROID GLAND Ovoid bodies, measuring about 6mm long in diameter Four (4) in number; closely related to the posterior border of the Thyroid gland lying within its fascial capsule GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 2 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM system in early life but continues to grow until puberty and then it undergoes gradual involution in which the thymic tissue is replaced by fat 10 gms (birth); 20 gms(1 year); 25-35 gms (7-25) Supplied by the Inferior Thyroid and Internal Thoracic arteries Produces THYMOSIN which promotes T lymphocyte differentiation and maturation SUPERIOR PARATHYROID GLAND Constant in position Lie at the level of the middle of the posterior border of the Thyroid gland INFERIOR PARATHYROID GLAND Lie close to the inferior poles of the Thyroid gland; may lie within the fascial sheath, embedded in the Thyroid substance or outside the fascial sheath BLOOD SUPPLY: from the superior and inferior thyroid arteries VENOUS DRAINAGE: into the superior, middle and inferior thyroid veins LYMPH DRAINAGE: deep cervical and paratracheal lymph node ADRENAL GLAND Adrenal gland- normal 4 gms Three zones of Adrenal cortex: ○ Zona Glomerulosa- aldosterone ○ Zona Fasciculata- cortisol; 75% of the cortex ○ Zona Reticularis- androgens Adrenal cortex- ESSENTIAL to life and produces steroid hormones, including Mineralocorticoids (Aldosterone), Glucocorticoids (ex. Cortisone) and sex hormones Adrenal medulla- secretes Epinephrine and Norepinephrine Adrenal Cortex Zones Glomerulosa- “salty” (aldosterone) Fasciculata- “sweet” (cortisol) Reticularis- “sex” (androgens) THYMUS RELATIONS: Bilobed structure, attains its greatest size in the neonate, ○ Right Triangular playing a key role in the development of the immune Anteromedially- IVC GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 3 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM Anterolaterally- Liver Body- to the left of SMA and SMV Post- Diaphragm Tail- closely related to the hilum of spleen and left colic ○ Left: Crescent (Lunar) flexure Anterior- Spleen, Stomach, Pancreas PANCREATIC DUCTS Post- Diaphragm Main pancreatic duct: ○ Extends through the entire length of pancreas ○ Joins bile duct to form the hepatopancreatic ampulla ○ Empties into duodenum Accessory pancreatic duct ○ Lies in head of pancreas ○ Drains into the main duct BLOOD SUPPLY Suprarenal arteries arise from 3 sources: ○ Superior from Inferior Phrenic ○ Middle from Abdominal aorta ○ Inferior from Renal VENOUS DRAINAGE: Right Adrenal vein drains into IVC Left Adrenal vein- drains into Left renal vein- IVC LYMPHATICS BLOOD SUPPLY: Lateral aortic Superior pancreaticoduodenal artery from Gastroduodenal PANCREAS (Hepatic- Celiac) Exocrine & Endocrine gland Inferior pancreaticoduodenal from SMA ○ Pancreatic Acinar- Exocrine Pancreatic arteries from Splenic ○ Islets of Langerhan- Endocrine VENOUS DRAINAGE: Elongated accessory digestive gland: lies retroperitoneally Pancreatic veins which are tributaries of the Splenic and and transversely across the posterior abdominal wall Superior mesenteric; most of them empty into the Splenic Normal weight- 60 to 100 gm vein Head- expanded part: is embraced by the C shaped curve of the Duodenum ○ Uncinate process- projection from the inferior part of head; extends medially to the left post. To SMA Neck- short and overles the superior mesenteric vessels GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 4 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM ○ Represents the remains of the upper part of the gubernaculum, connects the lateral margin of the uterus to the ovary OVARIES Germinal epithelium- simple cuboidal ○ Modified area of peritoneum covering ovary ○ Thin fibrous capsule (Tunica albugina) beneath ○ Oval shaped measuring 4x2 cm Outer Cortex ○ Contains ovarian follicles Inner Medulla BLOOD SUPPLY: Ovarian (Gonadal) from the Abdominal aorta at the level of 1st lumbar vertebra VENOUS DRAINAGE: Ovarian (Gonadal) RIGHT side- IVC; Left side- LEFT RENAL LYMPHATIC DRAINAGE: Para Aortic nodes at level of 1st lumbar NERVE SUPPLY: Aortic plexus ATTACHMENTS Mesovarium ○ Each ovary is attached to the back of the Broad ligament Suspensory Ligament ○ Extending between the attachment of mesovarium and lateral wall of the pelvis ○ CONTAINS THE OVARIAN VESSELS Round Ligament GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 5 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM TESTES CHEMISTRY OF HORMONES Firm, mobile organ lying within the scrotum HORMONES- is defined as the chemical substances secreted by LEFT usually lies at LOWER than the right cells into the extracellular fluids that regulate the metabolic activity Surrounded by fibrous capsule- TUNICA ALBUGINEA of other cells in the body. TUNICA VAGINALIS COMES FROM A GREEK WORD WHICH MEANS “TO AROUSE” or ○ Serous sac of the peritoneum that covers the front “TO EXCITE” and sides of the testes and epididymis Hormones are produced by specialized cells ○ Consists of the parietal layer that forms the Cells secrete hormones into extracellular fluid innermost layer of the scrotum and visceral layer Blood transfers hormones to target sites adherent to the testis and epididymis These hormones regulate the activity of other cells Hormones are classified chemically as: 1. Amino acid-based, which includes a. Proteins b. Peptides c. Amines 2. Steroids made from cholesterol 3. Prostaglandins- made from highly active lipids MECHANISMS OF HORMONE ACTION Hormones affect only certain tissues or organs (target cells or target organs) Target cells must have specific protein receptors Hormone-binding alters cellular activity EFFECTS CAUSED BY HORMONES 1. Changes in plasma membrane permeability or electrical state 2. Synthesis of proteins, such as enzymes 3. Activation or inactivation of enzymes 4. Stimulation of mitosis 5. Promotion of secretory activity Two mechanisms in which hormones act A. Direct gene activation B. Second-messenger system DIRECT GENE ACTIVATION (STEROID HORMONE ACTION) 1. Diffuse through the plasma membrane of target cells 2. Enter the nucleus 3. Bind to a specific protein within the nucleus 4. Bind to specific sites on the cell’s DNA 5. Activate genes that result in synthesis of new proteins 1.0 ENDOCRINE SYSTEM PHYSIOLOGY Second-messenger system of the body Coordinates and directs the activity of the body cells Uses chemical messengers (hormones) that are released into the blood MAJOR PROCESSES CONTROLLED BY HORMONES 1. Reproduction 2. Growth and development 3. Mobilization of body defenses 4. Maintenance of much of homeostasis 5. Regulation of metabolism SECOND-MESSENGER SYSTEM (NONSTEROID HORMONE ACTION) 1. Hormones binds to a membrane receptor 2. Hormone does not enter the cell GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 6 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM 3. Sets off a series of reactions that activates an enzymes 4. Catalyzes a reaction that produces a second-messenger molecule 5. Oversees additional intracellular changes to promote a specific response OVERVIEW OF HORMONES CONTROL OF HORMONE RELEASE Hormone levels in the blood are mostly maintained by negative feedback A stimulus or low hormone levels in the blood triggers the release of hormone GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 7 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM Hormone release stops once an appropriate level in the 2 KINDS OF GLANDS blood is reached 1. ENDOCRINE- ductless glands that empty their hormonal The stimuli that activates the endocrine organs fall into products directly into the blood three major categories 2. EXOCRINE- glands that have ducts through which their 1. Hormonal secretions are carried into a particular site. 2. Humural PITUITARY GLAND 3. Neural Size of a pea HORMONAL STIMULI OF ENDOCRINE GLANDS Hangs by a stalk from the hypothalamus in the brain Most common stimuli Protected by the Endocrine glands are activated by other hormones sphenoid bone Examples: Has two functional ○ Anterior pituitary hormones lobes ○ Anterior pituitary- glandular tissue ○ Posterior pituitary- nervous tissue Often called the “master endocrine gland” HORMONES OF THE ANTERIOR PITUITARY Six anterior pituitary hormones Two affect non-endocrine targets ○ Growth hormone ○ Prolactin HUMORAL STIMULI OF ENDOCRINE GLANDS Four stimulate other endocrine glands (tropic hormones) Changing blood levels of certain ions stimulate hormone ○ Thyroid-stimulating hormone (thyrotropic release hormone) Humoral indicates various body fluids such as blood and ○ Adrenocorticotropic hormone bile ○ Two gonadotropic hormones (FSH & LH) Example: Parathyroid hormone Calcitonin Insulin NEURAL STIMULI OF ENDOCRINE GLANDS Nerve impulses stimulate hormone release Most are under the control of the sympathetic nervous system Examples include the release of norepinephrine and epinephrine by the adrenal medulla LOCATION OF MAJOR ENDOCRINE ORGANS CHARACTERISTICS OF ALL ANTERIOR PITUITARY GLAND Proteins (or peptides) Act through second-messenger systems Regulated by hormonal stimuli, mostly negative feedback GROWTH HORMONE General metabolic hormone GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 8 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM Major effects are directed to growth of skeletal muscles and long bones Plays a role in determining final body size Causes amino acids to be built into proteins Causes fats to be broken down for a source of energy GROWTH HORMONE (GH) DISORDERS Gigantism results from hypersecretion of GH during childhood ○ Proportion are normal ○ The person is extremely tall Acromegaly- results from hypersecretion of GH during adulthood ○ The facial bones particularly the lower jaw and the bony ridges underlying the eyebrow enlarged tremendously, as well as the feet and the hand Dwarfism ○ Pituitary dwarfism results from hyposecretion of GH during childhood ○ Body proportion are normal but they are miniature in size Prolactin (PRL) Stimulates and maintains milk production following PITUITARY-HYPOTHALAMUS RELATIONSHIP childbirth Hormonal release is regulated by releasing and inhibiting Function in males is unknown hormones produced by the hypothalamus Adrenocorticotropic hormone (ACTH) Hypothalamus produces two hormones Regulates endocrine activity of the adrenal cortex ○ These hormones are transported to Thyroid-stimulating hormone (TSH) neurosecretory cells of the posterior pituitary Influences growth and activity of the thyroid gland Oxytocin CHARACTERISTICS OF ALL ANTERIOR PITUITARY GLAND Antidiuretic hormone Proteins (or peptides) The posterior pituitary is not strictly an endocrine gland, but Act through second-messenger systems does release hormones Regulated by hormonal stimuli, mostly negative feedback HORMONES OF THE POSTERIOR PITUITARY Gonadotropic hormones Oxytocin - Regulate hormonal activity of the gonads ○ Stimulates contractions of the uterus during labor, Follicle-stimulating hormone (FSH) sexual relations, and breastfeeding (letdown ○ Stimulates follicle development in ovaries reflex) ○ Stimulates sperm development in testes ○ Causes milk ejection in a nursing woman Luteinizing hormone (LH) Antidiuretic Hormone (ADH) ○ Triggers ovulation of an egg in females ○ Inhibits urine production by promoting water ○ Stimulates testosterone production in males reabsorption by the kidneys HOMEOSTATIC IMBALANCE ○ In large amounts, causes vasoconstriction leading Hyposecretion of FSH and LH leads to sterility in both male to increased blood pressure and females ○ Also known as vasopressin Hypersecretion does not appear to have caused any ○ Drinking alcoholic beverages inhibits ADH problems. secretion and results in the output of a large Some drugs used to promote fertility stimulates the release amount of urine. of the Gonadotropic hormone, and multiple births ○ Hyposecretion of ADH— leads to a condition of (indicating multiple ovulation at the same time) excessive urine output called diabetes insipidus ○ Continually thirsty and drink large amount of water GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 9 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM THYROID HORMONE Major metabolic hormone Composed of two active iodine-containing hormones ○ Thyroxine (T4)- secreted by thyroid follicles ○ Triiodothyronine (T3)- conversion of T4 at target tissues HISTOLOGY OF THE THYROID GLAND ○ 1.0 THYROID GLAND PHYSIOLOGY Found at the base of the throat Consists of two lobes and a connecting isthmus Produces two hormones ○ Thyroid hormone ○ Calcitonin Thyroxine (T4) is the major hormone secreted by the thyroid follicles Most T3 are formed at the target tissue by conversion of T4 to T3 Thyroxine has 4 bound iodine atoms– thus it is called T4 GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 10 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM Triiodothyronine has 3 bound iodine atoms– thus it is also ○ Cretinism results in dwarfism in which adult body referred to as the T3 proportion remain childlike Thyroid hormone controls the rate at which glucose is ○ The head and trunk are about 1 ½ times the length “burned” or oxidized and converted to heat and body of the legs energy ○ Untreated cretins are mentally retarded Target cell since all cells in the body depend on the ○ Scanty hair and the skin is dry continuous supply of chemical energy to power their ○ If hyposecretion is detected and treated early activities. mental retardation will be prevented Without IODINE functional hormones cannot be made ○ If hyposecretion occurred in adults— results to Source of IODINE is the diet myxedema— in which there is both mental and Food richest in iodine are the SEAFOODS physical sluggishness (mental retardation does THYROID HORMONE DISORDERS not occur) Goiters Myxedema ○ Thyroid gland enlarges due to lack of iodine - Caused by hypothyroidism in adults ○ Salt is iodized to prevent goiters - Results in physical and mental sluggishness ○ Iodine deficiency- developed GOITER OTHER SIGNS OF MYXEDEMA ○ GOITER- is an enlargement of the thyroid gland - Puffiness of the face ○ Classified in 2 ways - Fatigue Endemic- caused by lack of iodine in the - Poor muscle tone diet - Low body temperature (person is always cold) Sporadic- related to ingestion of food or - Obesity drugs and occurring randomly - Dry skin ○ Nontoxic goiter is most common in females- Hyperthyroidism specially during adolescence, pregnancy and ○ Generally results from a tumor of the thyroid gland menopause. At these times the demand for iodine ○ Extreme overproduction of thyroxine results in a increases. high metabolic basal rate ○ Toxic goiter arises from long standing nontoxic ○ Intolerance of heat goiter and occurs in elderly people ○ Rapid heart beat ○ Nontoxic goiter occurs when thyroid gland can’t ○ Weight loss secrete enough thyroid hormone o meet metabolic ○ Nervous and agitated behavior needs— as a result the thyroid mass increases to ○ General inability to relax compensate Grave’s disease ○ Endemic goiter- results from inadequate iodine in ○ Caused by hyperthyroidism the diet– leads to inadequate synthesis of ○ Results in increase metabolism, heat intolerance, hormone– deficiency rapid heartbeat, weight loss, and exophthalmos ○ Sporadic goiter- too much of a good thing; results ○ Can be treated surgically by removal of part of from too much ingestion of goitrogenic foods or thyroid use of goitrogenic drugs— these foods and drugs ○ Chemically by administering thyroid blocking contain agents that decrease T4 production. drugs or radioactive iodine which destroys some GOITROGENIC FOODS GOITROGENIC DRUGS of the thyroid cells 1. Cabbage 1. Propylthiouracil 2ND MOST IMPORTANT HORMONE OF THYROID GLAND 2. Soybean 2. Iodides Calcitonin or Thyrocalcitonin 3. Peanuts 3. Phenylbutazone Decreases blood calcium levels by causing its deposition 4. Peaches 4. Amino salicylic acid on bone 5. Strawberries 5. Cobalt Antagonistic to parathyroid hormone 6. Peas 6. Lithium Produced by parafollicular cells 7. Spinach Parafollicular cells are found between the follicles 8. Radishes It is released directly to the blood in response to increasing Cretinism levels of blood calcium - Caused by hyposecretion of thyroxine Calcitonin production ceases in elderly adults - Results in dwarfism during childhood ○ Lack of TH stimulation in early childhood will result to cretinism GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 11 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM applied to the upper arm from an in-flated 1.0 PARATHYROID GLAND PHYSIOLOGY sphygmomanometer cuff ○ Chvostek sign - twitching of facial muscles in Tiny masses (pea-sized) on the posterior of the thyroid response to tapping over the area of the facial Secrete parathyroid hormone (PTH) nerve ○ Stimulates osteoclasts to remove calcium from bone ○ Stimulate the kidneys and intestine to absorb more calcium ○ Raise calcium levels in the blood During surgery surgeon left a portion of the parathyroid containing tissue for Blood Ca Homeostasis Severe hyperparathyroidism causes massive bone destruction. HORMONAL REGULATION OF CALCIUM IN BLOOD 1.0 ADRENAL GLANDS (SUPRARENAL GLANDS) Sit on top of the kidneys Two regions ○ Adrenal cortex Composed of regular endocrine tissue ○ Adrenal medulla Made up of neuro-secretory tissue ADRENAL CORTEX Composed of three distinct layers or zones of secreting cells: ○ Zona glomerulosa ○ Zona fasciculata ○ Zona reticularis Cells of the outer zone secrete a class of hormone called mineralocorticoids (salt) Cells of the middle zone secrete glucocorticoids (sweet) Cells of the inner zone secrete a small PTH is known as a HYPERCALCEMIC hormone (acts to amount of glucocorticoids and increase calcium in the blood) gonadocorticoids (sex) On the other hand CALCITONIN is HYPOCALCEMIC All cortical hormones are steroid- together they are known ABNORMALITY as CORTICOSTEROID If blood Ca falls too low neurons become extremely irritable and overactive They deliver impulses at such a rapid rate that the muscle goes into an uncomfortable spasm (tetany) which may be fatal. ○ Trousseau sign - carpopedal spasm that results from ischemia, such as that induced by pressure GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 12 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM MINERALOCORTICOIDS Important role in regulating how mineral salts (electrolytes) are processed in the body Human body---ALDOSTERONE---the only physiologically important mineralocorticoid ○ Main function: maintenance of sodium homeostasis in the blood Increase Na+ reabsorption in the kidney Na+ ions are reabsorbed from the urine back into the blood in exchange for potassium or hydrogen ions In this way aldosterone not only adjusts blood sodium levels but also can influence K+ levels and pH levels in the blood. Reabsorption of Na+ ions causes water to be reabsorbed (partly by triggering ADH) aldosterone promotes water retention by the body =aldosterone=can increase Na+ and H2O retention and 1.0 RENIN-ANGIOTENSIN-ALDOSTERONE SYSTEM promote loss of K+ and H+ ions Aldosterone secretion is controlled mainly by the A critical regulator of blood volume, electrolyte balance, ans renin-angiotensin-aldosterone system (RAAS) systemic vascular resistance Sequence on how RAAS operates 1. When incoming BP in the kidneys drops below a certain level, a piece of tissue near the vessels (juxtaglomerular apparatus) secrete renin into the blood. 2. Renin, an enzyme, causes angiotensinogen (a normal constituent of blood) to be converted to angiotensin I. 3. Angiotensin I circulates to the lungs, where converting enzymes in the capillaries split the molecule, forming angiotensin II. 4. Angiotensin II circulates to the adrenal cortex, where it stimulates the secretion of aldosterone. (Some aldosterone is also synthesized in the heart and blood vessels) 5. Aldosterone causes increased reabsorption of sodium which causes increased water retention. As water is retained the volume of the blood increases. The volume of blood creates higher BP– which causes the renin-angiotensin-aldosterone system to stop. RAAS is a negative feedback mechanism that helps maintain the homeostasis of BP. GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 13 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM Affects every cell in the body Precise mechanism on how they work is unknown but there are some generalizations: ○ Glucocorticoids accelerate the breakdown of protein into amino acid (except in liver cells) Move out of the tissue cells and into the blood---changed into glucose via the process called gluconeogenesis Prolonged high blood concentration of glucocorticoids results in the loss of proteins (“tissue wasting”) and hyperglycemia Glucocorticoid tend to accelerate mobilization of both lipids from adipose cells and lipid catabolism by nearly every cell in the body Angiotensinogen- Sole precursor of all angiotensin Glucocorticoids are essential for maintaining a normal BP peptides, chiefly produced by the live High concentrations of glucocorticoids rather quickly Renin- enzyme that converts angiotensinogen to causes a marked decrease in the number of WBC called angiotensin I. Main source are the JGC (juxtaglomerular eosinophils in the blood (eosinopenia) and marked atrophy cells of the kidneys) of the lymphatic tissue, thymus gland and lymph nodes are Angiotensin I- physiologically inactive form of angiotensin affected Angiotensin Converting Enzyme Converts Ang-I to Normal amount of glucocorticoid act with epinephrine that physiologically active Ang-II promotes recovery during injury produced by the Angiotensin II- very potent vasoconstrictor inflammatory agents HORMONES OF THE ADRENAL CORTEX Glucocorticoid secretion increases as part of the stress response GONADOCORTICOIDS (SEX HORMONES) The normal adrenal cortex secretes small amounts of male hormones (androgens)---not enough to give women masculine appearance but sufficient to influence the appearance of pubic and axillary hair in both boys and girls ADRENAL CORTICAL HORMONE ABNORMALITIES Hypersecretion of cortisol from the adrenal cortex often produces a collection of symptoms called Cushing’s Syndrome ○ Hypersecretion of glucocorticoids results in redistribution of body fat---moon face and reddened skin GLUCOCORTICOIDS The chief glucocorticoid secreted by the zona fasciculata is the cortisol (a.k.a hydrocortisone) GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 14 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM ADVANCE CUSHING'S SYNDROME Hypersecretion of Aldosterone--Aldosteronism ○ Leads to increase water retention, muscle weakness due to K+ loss Hypersecretion of Androgens can result from tumors of the adrenal cortex---called virilizing tumors ○ Increase blood levels of male hormone (↑testosterone) ○ In women it can cause acquisition of male characteristics Hyposecretion of Mineralocorticoids and Glucocorticoids---Addison’s Disease Drop in blood Na+ and Blood Glucose, increase in Blood K+ level, dehydration and weight loss ABNORMAL STRIAE Bronze skin tone, muscles are weak, burnout, susceptibility to infection BUFFALO HUMP Other common undesirable effects are: 1. High BP 2. Hyperglycemia 3. Possible diabetes 4. Weakening of the bones (as the protein is withdrawn to be converted into glucose) 5. Severe depression of the immune system 6. Hypersecretion of sex hormones lead to masculinization--masculine pattern of hair distribution GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 15 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM 1.0 ADRENAL MEDULLA Composed of neuro-secretory tissue---that is, tissue composed of neuron specialized to secrete products into the blood rather than across the synapse Secretes 2 important hormones ○ Epinephrine or Adrenaline (accounts for 80% of the medulla’s secretion) ○ Norepinephrine or Noradrenaline (accounts for 20% of the medulla’s secretion) Both are nonsteroid hormones called CATECHOLAMINES When you feel threatened physically or emotionally---the sympathetic NS brings about the “fight or flight” reaction to help cope with the stressful situation One of the organ it stimulates is the adrenal medulla which pumps its hormones into the bloodstream to enhance and Glucagon prolong the effects of the neurotransmitters of the NS ○ Tend to increase blood glucose---stimulate Catecholamines---increase HR, BP and blood glucose level conversion of glycogen to glucose in the liver cells and dilate the small passageway of the lungs ○ Stimulates gluconeogenesis---transformation of Results in more oxygen and glucose in the blood and a fatty acids and amino acids into glucose faster circulation of blood into the organ (most importantly Insulin to the brain, heart and muscles) ○ Promote movement of the fatty acids, amino acid Thus body is able to respond better to short term stressors and glucose out of the blood and into the tissue Damage or destruction of the adrenal medulla has no major cells effects as long as the sympathetic NS continues to function normally. Hypersecretion of the CATECHOLAMINES leads to symptom of typical excessive sympathetic NS activity: rapid beating of the heart, high BP and tendency to perspire and be very irritable Solution: surgically remove adrenal gland 1.0 PANCREATIC ISLETS Structure of the Pancreatic Islets ○ Pancreas is an elongated gland (12 to 15 cm), weighing up to 100 g (3.5 ounces) ○ Each of the 1 to 2 million pancreatic islets in the pancreas contains 9 combinations of 4 primary types of endocrine cells ○ Each type of cell secrete a different hormone Alpha cells---secrete glucagon Beta cells---secrete insulin Delta cells---secrete somatostatin Pancreatic polypeptide cells---secrete polypeptide Without insulin blood levels of glucose rise Some instances they spill into the urine because the kidney tubule cells cannot reabsorb fast enough As glucose flushes out of the body water follows and dehydration occurs GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 16 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM DIABETES MELLITUS—WHICH LITERALLY MEANS SOMETHING SWEET. 1.0 GONADS BECAUSE CELLS CANNOT USE GLUCOSE, fats and even protein are broken down to meet the energy requirements Ovaries Results to decline in body weight ○ Produce eggs When large amounts of fats instead of sugars are used for ○ Produce two groups of steroid hormone energy the blood becomes very acidic (ACIDOSIS) Estrogens Diabetic Ketoacidosis Progesterone Results to appearance of ketones in the blood Testes (intermediate product of fats breakdown) ○ Produce sperm Unless corrected this will result in coma or death. ○ Produce androgens, such as testosterone 3 CARDINAL SIGNS OF DIABETES MELLITUS(3P’S) 1. Polyuria- excessive urination to flush out the glucose and ketones 2. Polydipsia- excessive thirst due to dehydration 3. Polyphagia- hunger due to inability to use glucose and the loss of fats and protein from the body Somatostatin ○ Primary role is the regulations of other endocrine cells of the pancreatic islets ○ Inhibits secretion of glucagon, insulin, and pancreatic polypeptide Hormones of the Ovaries ○ Inhibits secretion of the growth hormone Estrogens (somatotropin) ○ Stimulate the development of secondary female Pancreatic polypeptide characteristics ○ It influences the digestion and distribution of food ○ Mature female reproductive organs molecules. ○ With progesterone, estrogens also Promote breast development 1.0 PINEAL GLAND Regulate menstrual cycle Progesterone Found on the third ventricle of the brain ○ Acts with estrogen to bring about the menstrual Secretes melatonin cycle ○ Helps establish the body’s wake and sleep cycles ○ Helps in the implantation of an embryo in the ○ Believed to coordinate the hormones of fertility in uterus humans ○ Helps prepare breasts for lactation Levels of melatonin rise and fall during the course of the Hormones of the Testes day Produce several androgens Peak levels occur at night feel drowsy Testosterone is the most important androgen Lowest level is daylight around noon. ○ Responsible for adult male secondary sex characteristics 1.0 THYMUS GLAND ○ Promotes growth and maturation of male reproductive system Located posterior to the sternum ○ Required for sperm cell production Largest in infants and children Produces thymosin ○ Matures some types of white blood cells ○ Important in developing the immune system GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 17 NCMC101 S.Y. ‘24 - ‘25 | MR. IAN BENEDICT V. BETITO ENDOCRINE SYSTEM Endocrine Function of the Placenta Produces hormones that maintain the pregnancy Some hormones play a part in the delivery of the baby Produces human chorionic gonadotropin (hCG) in addition to estrogen, progesterone, and other hormones Other Hormone-Producing Tissues and Organs Parts of the small intestine Parts of the stomach Kidneys Heart Many other areas have scattered endocrine cells GELYN B. AZURIN | BSN / LEVEL 1 | SEMESTER 1 PAGE 18

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