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Sir M.Farooque Soomro

DIN,PBPsy:, Bsc Nursing(UOL), BCom (UOS)

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Endocrine System

UNIT-V

Anatomy & Physiology

BSN (Gen) 1^st year, 2^st semester

Objectives

At that the end of this unit, the students will be able to:

1. Define Endocrine system
2. Identify Endocrine glands and Endocrine tissues present in the body
3. Discuss types of Hormones, target cells, target organ
4. Briefly discuss Mechanism of Action of Hormone (protein and steroids)
5. Discuss the location and structure of pituitary gland.
6. Discuss the role of hypothalamic hormones in the regulation of pituitary gland secretions
7. Discuss the function of the hormones secreted by anterior and posterior pituitary gland.
8. Briefly discuss the structure, function & hormones of the following glands;

1. Thyroid 4. Adrenal

2. Para Thyroid 5. Pancreas

3. Pineal

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1. Define Endocrine system

• The endocrine system, consisting of glands and tissues that produce hormones, works in coordination with the nervous system to maintain optimal functioning of the body's various systems and organs.

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• Endocrine gland: A ductless gland that secretes hormones into the blood stream.
• Exocrine gland: A gland that secretes its products through a duct.

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2. Identify Endocrine glands and Endocrine tissues present in the body

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The human body contains several endocrine glands, Here are some of the major endocrine glands in the body:

• Pineal Gland
• Pituitary Gland
• Thyroid Gland
• Parathyroid Glands
• Thymus Gland
• Adrenal Glands
• Pancreas
• Ovaries (in Females) & Testes (in Males).

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Endocrine tissues in other organs also produce hormones, though they're not considered traditional endocrine glands. These include:

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Adipose Tissue: Releases hormones called adipokines that regulate metabolism and appetite.

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Thymus: Produces hormones that play a role in immune function and development.

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Gastrointestinal Tract: Releases hormones like gastrin, secretin, and cholecystokinin, which regulate digestion and appetite.

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Placenta: During pregnancy, it produces hormones such as estrogen, progesterone, and human chorionic gonadotropin (hCG), which support fetal development and pregnancy maintenance.

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3. Discuss types of Hormones, target cells, target organ

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• Hormones are chemical messengers produced by various glands and tissues in the body. They are secreted into the bloodstream and travel to target tissues or organs where they exert their effects, regulating physiological processes and maintaining homeostasis, e.g. metabolism, growth and development, reproduction, mood regulation, and responses to stress.

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• The main types of hormones based on their chemical structure and mode of action.

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1. Steroid Hormones
2. Peptide and Protein Hormones
3. Amino Acid-Derived Hormones

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The main types of hormones along with their typical target cells and organs:

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1. Steroid Hormones:

• Types: Estrogen, progesterone, testosterone, cortisol, aldosterone.
• Target Cells/Organs: These hormones often target cells throughout the body but have specific effects on particular organs:
• Estrogen and progesterone: Target reproductive organs such as the uterus and ovaries in females and the testes in males.
• Testosterone: Targets reproductive organs, secondary sexual characteristics, and muscle tissue in males.
• Cortisol: Acts on various cells, particularly in the liver, muscle, and adipose tissue, to regulate metabolism and stress response.
• Aldosterone: Acts on the kidneys to regulate electrolyte balance and blood pressure.

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2. Peptide and Protein Hormones:

• Types: Insulin, glucagon, growth hormone, thyroid-stimulating hormone (TSH), Prolactin.
• Target Cells/Organs: These hormones typically act on specific target organs or tissues:
• Insulin and glucagon: Act on liver, muscle, and adipose tissue to regulate blood sugar levels.
• Growth hormone: Acts on bones, muscles, and other tissues to stimulate growth and metabolism.
• Thyroid-stimulating hormone (TSH): Acts on the thyroid gland to regulate thyroid hormone production.

Prolactin: Acts on the mammary glands to stimulate milk production in females.

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3. Amino Acid-Derived Hormones:

• Types: Thyroid hormones (T3 and T4), adrenaline (epinephrine), noradrenaline (norepinephrine).
• Target Cells/Organs: These hormones target various organs and tissues:
• Thyroid hormones: Act on cells throughout the body to regulate metabolism, growth, and development.
• Adrenaline and noradrenaline: Act on the cardiovascular system, respiratory system, and other tissues to prepare the body for "fight or flight" responses.

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4. Briefly discuss Mechanism of Action of Hormone (protein and steroids)

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• The mechanism of action of hormones involves complex interactions between hormones, receptors, and target cells, leading to specific physiological responses. These are just a few examples of protein hormones;

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• Insulin and Glucagon: Secreted by the pancreas.
• Growth Hormone (GH): Secreted by the anterior pituitary gland.
• Thyroid Stimulating Hormone (TSH): Secreted by the anterior pituitary gland.
• Follicle-Stimulating Hormone (FSH) and Luteinizing Hormone (LH): Secreted by the anterior pituitary gland.
• Adrenocorticotropic Hormone (ACTH): Secreted by the anterior pituitary gland.
• Prolactin: Secreted by the anterior pituitary gland.
• Parathyroid Hormone (PTH): Secreted by the parathyroid glands.
• Calcitonin: Secreted by the thyroid gland.
• Erythropoietin (EPO): Secreted by the kidneys.
• Leptin: Secreted by adipose (fat) tissue.

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• Protein Hormones are synthesized and released by endocrine glands. They typically bind to receptors located on the surface of target cells. The activation of intracellular signaling pathways leads to changes in cellular function, such as gene expression, enzyme activity, or ion transport across the cell membrane. The cellular responses by protein hormones contribute to various physiological processes, including metabolism, growth and development, stress response, and immune function.

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• Steroid hormones are primarily secreted by the adrenal cortex and the gonads:
• Adrenal Cortex: Glucocorticoids: Such as cortisol, which regulates metabolism and stress responses. Mineralocorticoids: Such as aldosterone, which regulates electrolyte balance and blood pressure.
• Gonads: Testes (in Males):
• Testosterone: The primary male sex hormone responsible for the development of male reproductive tissues and secondary sexual characteristics. Ovaries (in Females): Estrogens: which regulate the menstrual cycle, promote the development of female reproductive tissues, and contribute to secondary sexual characteristics. Progesterone: Involved in the menstrual cycle, pregnancy, and embryogenesis.
• In addition to the adrenal cortex and gonads, small amounts of steroid hormones are also produced in other tissues, such as the placenta during pregnancy and adipose (fat) tissue.

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• Steroid Hormones are synthesized from cholesterol primarily in the adrenal cortex and gonads. Steroid hormones are lipid-soluble and can diffuse across the cell membrane. Once inside the cell, steroid hormones bind to specific intracellular receptors, often located in the cytoplasm or nucleus. The altered protein synthesis by steroid hormones results in changes in cellular function, such as the production of enzymes, structural proteins, or regulatory factors. The overall physiological effects of steroid hormones include regulation of metabolism, immune response, reproductive functions, and stress adaptation.

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• Both protein and steroid hormones play critical roles in maintaining homeostasis and coordinating various physiological processes in the body, albeit through different mechanisms of action.

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5. Discuss the location and structure of pituitary gland.

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• The pituitary gland, also known as the the "master gland“.
• The pituitary gland is a small, pea-sized gland.
• The pituitary gland is located at the base of the brain, just below the hypothalamus.
• The pituitary gland consists of two main parts, each with distinct functions:
• Anterior Pituitary
• Posterior Pituitary

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6. Discuss the role of hypothalamic hormones in the regulation of pituitary gland secretions.

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The hypothalamus plays a crucial role in regulating the secretion of hormones from the pituitary gland through the release of its own hormones, known as hypothalamic-releasing hormones and hypothalamic-inhibiting hormones.

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These hormones control the function of the anterior pituitary gland through a system of blood vessels known as the hypophyseal portal system. A network of blood vessels connecting the hypothalamus and anterior pituitary gland.

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The hypothalamic hormones act as master regulators of the anterior pituitary gland,

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7. Discuss the function of the hormones secreted by anterior and posterior pituitary gland.

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• The hormones secreted by the anterior and posterior pituitary glands have distinct functions and play crucial roles in regulating various physiological processes in the body.

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• Anterior Pituitary Hormones:
• Growth Hormone (GH): Stimulates growth, particularly in bones and muscles. Regulates metabolism, including the breakdown of fats and the synthesis of proteins.
• Thyroid-Stimulating Hormone (TSH): Stimulates the thyroid gland to produce and release thyroid hormones (thyroxine and triiodothyronine), which regulate metabolism, growth, and energy expenditure.
• Adrenocorticotropic Hormone (ACTH): Stimulates the adrenal cortex to produce and release glucocorticoid hormones, such as cortisol, which regulate metabolism and the body's response to stress.

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• to be continue..

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• Follicle-Stimulating Hormone (FSH): In females, stimulates the growth and development of ovarian follicles and the production of estrogen. In males, stimulates spermatogenesis (sperm production).
• Luteinizing Hormone (LH): In females, triggers ovulation and stimulates the production of progesterone by the corpus luteum. In males, stimulates the production of testosterone by the interstitial cells of the testes.
• Prolactin (PRL): Stimulates milk production (lactation) in mammary glands after childbirth. Also involved in reproductive function and behavior.

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Posterior Pituitary Hormones:

• Oxytocin: Stimulates uterine contractions during childbirth. Promotes milk ejection (letdown reflex) during breastfeeding. Also involved in social bonding, trust, and emotional regulation.
• Vasopressin (Antidiuretic Hormone, ADH): Regulates water balance by increasing water reabsorption in the kidneys, reducing urine output, and conserving body fluids. Constricts blood vessels, raising blood pressure in response to low blood volume or high osmolality.

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• These hormones work together to maintain homeostasis, regulate growth and development, control metabolism, respond to stress, and coordinate reproductive functions.

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8. Briefly discuss the structure, function & hormones of the following glands; Thyroid, Adrenal, Para Thyroid, Pancreas & Pineal

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1. Thyroid Gland is a butterfly-shaped endocrine gland located in the front of the neck, just below the larynx. It consists of two lobes. It produces hormones, primarily thyroxine (T4) and triiodothyronine (T3), which regulate metabolism and Affects the body's energy levels.
2. Adrenal Glands are two adrenal glands, one on top of each kidney. They produce two hormones such as Cortisol (which regulates stress and metabolism) & Adrenaline (which initiates the "fight or flight" response).
3. Parathyroid Glands are small glands located on or near the thyroid gland. They produce parathyroid hormone (PTH), which regulates calcium and phosphate levels in the blood, important for bone health.
4. The pancreas is a leaf shaped organ. The pancreas is located in your entire body just behind your stomach. It is part of both the digestive and endocrine systems. Pancreas functions as both an endocrine and exocrine gland. It produces two hormones such as Insulin (regulating blood sugar levels) & Glucagon (raising blood sugar levels).
5. Pineal Gland This small gland in the brain produces melatonin. Melatonin hormone that regulates sleep patterns and circadian rhythms.

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If you have any…!

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Questions…?

or

Confusion…?

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THANK YOU...�