Endocrine System


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-Endocrine System
-Major Endocrine Parts

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Endocrine System

  2. 2. INTRODUCTION The endocrine system is made up of the endocrine glands that secrete hormones. Although there are scattered throughout the body, they are still considered to be one system because they have similar functions, similar mechanisms of influence, & many important interrelationships. Some glands also have non-endocrine regions that have functions other than hormone secretion. For example, the pancreas has a major exocrine portion that secretes digestive enzymes & an endocrine portion that secretes hormones. The ovaries & testes secrete hormones & also produce the ova & sperm. Some organs, such as the stomach, intestines, & heart, produce hormones, but their primary function is not hormone secretion.
  3. 3. TERMS 1) Glands – Are special secreting organs which pour their secretions either directly or indirectly into the bloodstream. Kinds of Glands: a) Duct Glands or Exocrine Glands – Have ducts or canals through which they pour out their secretions. These include lacrimal (tear) glands, sebaceous (sweat), salivary, gastric, mammary glands. b) Ductless or Endocrine Glands – Pour their secretions called hormones directly into the bloodstream. 2) Endocrine System - A set of glands that produce hormones-chemical messengers that circulate in the blood. One of the body’s two communication systems (Nervous & Endocrine System). Derives its name from the fact that various glands release hormones directly into the blood, which in turn transports the hormones to target tissues via ducts. Secretes hormones that coordinate slower but longer-acting responses including reproduction, development, energy metabolism, growth, & behavior.
  4. 4. TERMS 3) Hormone - Chemical messengers produced by the endocrine glands & circulated in the blood. Chemical messengers carried by blood. May stimulate other glands. Regulate growth, development, metabolism, sex processes. “Messenger Molecules.” Reach all parts of the body, but only target cells are equipped to respond. Classification of Hormones: a) Protein Hormones – (comprising small peptides, proteins & glycoproteins) Are water-soluble thus (1) they don’t require carrier proteins for circulatory system transport but (2) do require cell membrane receptors to enter their target cells. b) Steroid Hormones – Are cholesterol-derived compounds. They are water insoluble thus (1) don’t require cell membrane receptors but (2) do require carrier proteins for transport through the circulatory system. c) Amino Acid Analogues & Derivatives – Include (1) catecholamines that act like the protein hormones & (2) thyroid hormones that act like steroids.
  5. 5. TERMS Actions of Hormes: (based on target cells & working distance) a) Autocrine – Hormone acts locally on the releasing cell & adjacent like-members. b) Paracrine – Hormone acts locally or within an organ system on nonlike cells. c) Endocrine – Hormone acts distantly via fluid transport on non-like cells.
  6. 6. TERMS Mechanisms of Hormone Release: a) Humoral - In response to changing levels of ions or nutrients in the blood. b) Neural - Stimulation by nerves. c) Hormonal - Stimulation received from other hormones. 4) Target Cells – Are cells responding to the hormones for which they have receptors. Only cells possessing the proper receptors will respond to hormones; this is what gives the endocrine system its specificity. 5) Homeostasis – Is the (unconscious) maintenance of a constant internal environment by the organism. Homeostasis is accomplished by two interconnected systems: (1) the Autonomic Nervous System (sympathetic, parasympathetic & enteric) which communicates via nerve impulses resulting in rapid, but typically short-lived responses; & (2) the Endocrine System which communicates via hormones resulting in a slower, but more prolonged response.
  7. 7. ELEMENTS OF ENDOCRINE SYSTEM 1) Endocrine cells & glands 2) Hormones – 100+ chemical messengers secreted by endocrine cells into the intercellular (extracellular) space where they may act locally (autocrine & paracrine) or be transmitted by adjacent circulatory systems to act distantly (endocrine). 3) Target cells
  8. 8. HYPOTHALAMUS A part of the forebrain that sits below (hypo) the thalamus & is responsible for orchestrating several behaviors that are considered "maintenance" behaviors such as eating, drinking, sleeping, & body temperature. In addition, the hypothalamus helps govern the endocrine system (glands that produce hormones) using the pituitary gland, & is also involved in feeling emotions & perceiving things are rewarding (for example, being in love is perceived as a good & rewarding feeling/emotion & something worth trying to obtain more of). All vertebrate brains contain a hypothalamus. In humans, it is roughly the size of an almond.
  9. 9. HORMONES SECRETED HORMONE EFFECT Thyrotropin-releasing hormone Stimulate thyroid-stimulating (Prolactin-releasing hormone) hormone (TSH) release from anterior pituitary (primarily). Stimulate prolactin release from anterior pituitary. Corticotropin-releasing hormone Stimulate adrenocorticotropic hormone (ACTH) release from anterior pituitary. Dopamine hormone) (Prolactin-inhibiting Inhibit prolactin release from anterior pituitary.
  10. 10. HORMONES SECRETED HORMONE EFFECT Growth hormone-releasing Stimulate Growth hormone (GH) hormone release from anterior pituitary. Gonadotropin-releasing hormone Stimulate follicle-stimulating hormone (FSH) release from anterior pituitary. Stimulate luteinizing hormone (LH) release from anterior pituitary. Somatostatin (growth hormone- Inhibit Growth hormone (GH) inhibiting hormone) release from anterior pituitary. Inhibit (moderately) thyroidstimulating hormone (TSH) release from anterior pituitary.
  11. 11. HORMONES SECRETED HORMONE EFFECT Oxytocin Uterine contraction & Lactation (letdown reflex). Vasopressin (antidiuretic hormone) Increase in the permeability to water of the cells of distal tubule & collecting duct in the kidney & thus allows water reabsorption & excretion of concentrated urine
  12. 12. PITUITARY GLAND (HYPOPHYSIS/CEREBRI) Known as the master gland because part of its function is to control the endocrine glands. Located near the hypothalamus, the pituitary gland secretes the most number of hormones. It is divided into two parts: the posterior pituitary & the anterior pituitary. As its names suggests, the hypophysis is found beneath the brain resting within a bony crypt formed by the sphenoid bone. Anatomically & functionally it is divided into an posterior neurohypophysis & anterior adenohypophysis.
  13. 13. HORMONES SECRETED HORMONE EFFECT Oxytocin Causes the uterus to contract during childbirth. Vasopressin/Anti-Diuretic Hormone (ADH) Regulates the amount of urine being released by the bladder. Growth hormone or Somatotropin Regulates the amount & tiring of Hormone body growth.
  14. 14. HORMONES SECRETED HORMONE Thyroid-stimulating hormone Follicle-stimulating hormone Prolactin EFFECT Is a hormone that stimulates the thyroid gland to produce thyroxine, & then triiodothyronine which stimulates the metabolism of almost every tissue in the body. Regulates the development, growth, pubertal maturation, & reproductive processes of the body. Is a protein that in humans is probably best known for its role in enabling female mammals to produce milk.
  15. 15. THYROID GLAND Arguably the phylogenetically oldest of the endocrine organs, the thyroid gland is a bi-lobed gland lying ventral to the (gasp!) thyroid cartilage of the larynx. It is a compound gland containing 2 sets of endocrine producing cells: (1) Follicular cells that produce thyroid hormones & (2) parafollicular cells that secrete calcitonin. The thyroid gland is a very vascular organ that is located in the neck. It consists of two lobes, one on each side of the trachea, just below the larynx or voice box. The two lobes are connected by a narrow band of tissue called the isthmus. Internally, the gland consists of follicles, which produce thyroxine & triiodothyronine hormones. These hormones contain iodine.
  16. 16. HORMONES EFFECT Triiodothyronine It affects almost every physiological process in the body, including growth & development, metabolism, body temperature, & heart rate. Thyroxine Increases cardiac output. Increases heart rate. (Tetraiodothyronine) Increases ventilation rate. Increases basal metabolic rate. Potentiates the effects of catecholamines. Potentiates brain development. Thickens endometrium in females. increase metabolism of proteins & carbohydrates. Calcitonin This protein hormone acts via membrane receptors to lower blood calcium levels by (1) suppressing osteoclast activity (bone resorption & release of calcium) & (2) promoting osteoid mineralization. Calcitonin secretion is regulated by serum levels of calcium. SECRETED HORMONE
  17. 17. ADRENAL GLANDS (SUPRARENAL GLANDS) The suprarenal glands are bilateral, triangular shaped glands positioned over the superior pole of the kidneys. A thick connective tissue capsule invests each gland & the parenchyma is divided into two regions, cortex & medulla. The orange-colored 2 adrenal glands are located just above both kidneys. It consists of two parts: the outer cortex & the inner medulla. The adrenal cortex produces steroids that plays important role in maintenance of blood pressure & regulation of the breakdown of secretes hormones that help in the body’s reaction to stress.
  18. 18. ADRENAL CORTEX (SUPRARENAL CORTEX) Situated along the perimeter of the adrenal gland, the adrenal cortex mediates the stress response through the production of mineralocorticoids & glucocorticoids, including aldosterone & cortisol respectively. It is also a secondary site of androgen synthesis. The suprarenal cortex is divided into 3 zones based on the arrangement of their cells. The zona glomerulosa is the most superficial & its cells are arranged in ovoid clusters surrounded by sinusoidal capillaries. The zona fasciculata is the middle cortical layer & its cells are arranged in long straight cords surrounded by sinusoidal capillaries. The zona reticularis is the deepest layer of the cortex & its cells are arranged in interwoven cords separated by capillaries.
  19. 19. ADRENAL MEDULLA (SUPRARENAL MEDULLA) The adrenal medulla (Latin: suprarenal medulla) is part of the adrenal gland. It is located at the center of the gland, being surrounded by the adrenal cortex. It is the innermost part of the adrenal gland, consisting of cells that secrete epinephrine (adrenaline), norepinephrine (noradrenaline), & a small amount of dopamine in response to stimulation by sympathetic preganglionic neurons.
  20. 20. HORMONES SECRETED HORMONE EFFECT Mineralocorticoids These hormones, such as Aldosterone (Aldosterone) controls the body’s sodium, potassium & water level. Glucocorticoids Are steroids, like cortisone & cortisol, which aids carbohydrates, fat & protein metabolism in the body. Androgen Are responsible for the secondary sex characteristics. Epinephrine/Adrenaline Regulates the sympathetic nervous system, such as making the heart beat fast, increase blood pressure, dilation of pupils & other involuntary body functions during stress.
  21. 21. HORMONES SECRETED HORMONE EFFECT Norepinephrine Maintains normal blood circulation & increases blood pressure by constricting the blood vessels.
  22. 22. GONADS (OVARIES & TESTES) The gonad is the organ that makes gametes. The gonads in males are the testes, & the gonads in females are the ovaries. The product, gametes, are haploid germ cells. For example, spermatozoon & egg cells are gametes. Are the reproductive glands – testes or testicles in male & ovaries in female. The testes & ovaries have the main function of stimulating the reproductive organs to become mature & produce the sperm cells for males & egg cells for females.
  23. 23. HORMONES SECRETED HORMONE EFFECT Testosterone/Androgen The principal male hormone which is responsible for the appearance of secondary sex characteristics such as growth of beard & public hair, deepening of voice & increased in height. Estrogen Female sex hormone that regulates the secondary sex characteristics – development of the breast, widening of pelvic bones & growth of public hair. Progesterone Another female sex hormones, which regulates or controls menstruation & lactation in pregnant women.
  24. 24. DISORDERS/AILMENTS GLAND DISORDERS DESCRIPTION Hypothal- Hypopituitar Hypothalamic disease may cause insufficient amus -ism or inhibited signalling to the pituitary leading to deficiencies of one or more of the following hormones: thyroid-stimulating hormone, adrenocorticotropic hormone, beta-endorphin, luteinizing hormone, follicle-stimulating hormone, & melanocyte– stimulating hormones. Neurogenic Neurogenic diabetes insipidus may occur Diabetes due to low levels of ADH production from Insipidus the hypothalamus. Insufficient levels of ADH result in increased thirst & urine output, & prolonged excessive urine excretion increases the risk of dehydration.
  25. 25. DISORDERS/AILMENTS GLAND DISORDERS/A DESCRIPTION ILMENTS Hypothalamus Tertiary Secondary hypothyroidism occurs Hypothyroidism when TSH secretion from the pituitary is impaired, whereas tertiary hypothyroidism is the deficiency or inhibition of TRH. Developmental Insufficient GH production may Disorders cause poor somatic growth, precocious puberty or gonadotropin deficiency, failure to initiate or complete puberty, & is often associated with rapid weight gain, low T4, & low levels of sex hormones.
  26. 26. DISORDERS/AILMENTS GLAND Pituitary Gland DISORDERS/A DESCRIPTION ILMENTS Diabetes A condition where there is Insipidus excessive amount of urine excreted in the body making the individual dehydrated & weak, which increased thirst & urination Syndrome of A condition cause by the water inappropriate intoxication due to the retention of anti-diuretic fluid in the body. hormones (SIADH)
  27. 27. DISORDERS/AILMENTS GLAND Pituitary Gland DISORDERS/A DESCRIPTION ILMENTS Dwarfism A condition when there is too little growth of hormones during childhood characterize by being miniature. It is mark by abnormally short bone development. Acromicria Occurs when the deficiency of growth hormones is after puberty resulting to having small bones of the extremities.
  28. 28. DISORDERS/AILMENTS GLAND Pituitary Gland DISORDERS/A DESCRIPTION ILMENTS Giantism Cause by excessive growth hormones during childhood that leads to over growth of skeletal system. Acromegaly A condition due to excessive production of growth hormone in adults mark by overgrowth of extremities (hands, feet & face).
  29. 29. DISORDERS/AILMENTS GLAND DISORDER Thyroid Gland Hyperthyroidism DESCRIPTION Hyperthyroidism, or overactive thyroid, is due to the overproduction of the thyroid hormones T3 & T4, which is most commonly caused by the development of Graves' disease, an autoimmune disease in which antibodies are produced which stimulate the thyroid to secrete excessive quantities of thyroid hormones The disease can result in the formation of a toxic goiter as a result of thyroid growth in response to a lack of negative feedback mechanisms. Hypothyroid- Hypothyroidism is the underproduction of ism the thyroid hormones T3 & T4.
  30. 30. DISORDERS/AILMENTS GLAND DISORDERS Thyroid Gland Thyroid neoplasm Thyroid cancer Thyroiditis Goitre DESCRIPTION Thyroid neoplasm is a neoplasm or tumor of the thyroid. Thyroid cancer is a malignant neoplasm originating from follicular or parafollicular thyroid cells. Inflammation of the thyroid. A goitre or goiter, is a swelling of the neck or larynx resulting from enlargement of the thyroid gland, associated with a thyroid gland that is functioning properly or not.
  31. 31. DISORDERS/AILMENTS GLAND DISORDERS Adrenal Gland Cushing’s Syndrome DESCRIPTION It is characterize by moon-shaped face, obesity, easily bruised skin & poor healing of wounds. Adrenogenital Cause by excessive adrenal androgen & Syndrome more mark in women than in men symptoms include hirsutism, amenorrhea, deepening of voice & decrease breast size. Addison’s Undersection of glucocorticoids could Disease result to this disorder. The symptoms exhibited are weakness, fatigue, weight less, low blood pressure & tanning without exposure to the sun or hyperpigmentation.
  32. 32. DISORDERS/AILMENTS GLAND Gonads DISORDERS DESCRIPTION Precocious Puberty A syndrome characterize by accelerated sexual development. Sterility, Diminishes Sexual drive & Amenorrhea Failure of sexual characteristics to develop Infertility