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U4-endocrine system.pdf

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Hormones are chemical messengers that are secreted into the bloodstream by endocrine glands and target specific organs. The endocrine system regulates bodily functions through hormones, while the nervous system uses nerves. There are two main types of hormones - lipid-soluble hormones like steroids which diffuse through cell membranes, and water-soluble hormones like peptides which bind to surface receptors. Major endocrine glands include the pituitary, thyroid, parathyroids, pancreas, adrenals, ovaries/testes, which regulate growth, metabolism, sexual development, and other processes. Hormones bind to receptors on target cells and trigger physiological responses through various mechanisms of action.

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ENDOCRINE SYSTEM Hormones Unit 4
Concept of Hormone A hormone --chemical substance --secreted into the interstitial fluids by one specialized cell or a group of cells --exert physiological control effect on other cells of the body by binding to receptors on or in their target cells.
Endocrine vs. Nervous System
Nervous system exerts point-to-point control through nerves, similar to sending messages by conventional telephone. electrical in nature and fast.
Hormones travel via the bloodstream to target cells broadcasts its hormonal messages to essentially all cells by secretion into blood and extracellular fluid. requires a receiver to get the message cells bear a receptor
TYPES OF GLAND Exocrine glands : secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ, or to The outer surface of the body sudoriferous (sweat), sebaceous (oil), mucous, and digestive glands Endocrine glands: secrete their products (hormones) into the interstitial fluid surrounding the secretory cells From the interstitial fluid, hormones diffuse into blood capillaries and blood carries them to target cells throughout the body. Pituitary, thyroid, parathyroid, adrenal, and pineal glands SEVERAL ORGANS AND TISSUES ARE NOT EXCLUSIVELY CLASSIFIED AS ENDOCRINE GLANDS BUT CONTAIN CELLS THAT SECRETE HORMONES. THE HYPOTHALAMUS, THYMUS, PANCREAS, OVARIES, TESTES, KIDNEYS, STOMACH, LIVER, SMALL INTESTINE, SKIN, HEART, ADIPOSE TISSUE, AND PLACENTA.
7 Circulating Vs Local Hormones circulating hormones: Endocrine, or telecrine:
Transportation of Hormones Local hormones: Paracrine and Autocrine
Chemical Classes of Hormones Lipid-soluble Hormones Water-soluble Hormones Steroid Hormones Thyroid Hormones Nitric Oxide Amine Hormones Peptide Hormones Eicosanoid Hormones
LIPID-SOLUBLE HORMONES 1. Steroids -derived from cholesterol Secreted by Adrenal cortex (cortisol and aldosterone), Ovaries (estrogen and progesterone), Testes (testosterone), Placenta (estrogen and progesterone) 2. Thyroid hormone T3 & T4 synthesized by attaching iodine to the amino acid tyrosine 3. The gas nitric oxide (NO) is both a hormone and a neurotransmitter. Its synthesis is catalyzed by the enzyme nitric oxide synthase
WATER-SOLUBLE HORMONES 1. Proteins and polypeptides, including hormones Small protein hormonesa are 3 to 49 amino acids; larger protein hormones include 50 to 200 amino acid secreted by anterior and posterior pituitary gland Pancreas (insulin and glucagon) Parathyroid gland (parathyroid hormone) Many others. 2. Amine hormones : derivatives of the amino acid The catecholaminesepinephrine, norepinephrine, and dopamine from tyrosine Histamine is synthesized from the amino acid histidine by mast cells and platelets. Serotonin Melatonin are derived from tryptophan 3. The eicosanoid hormones derived from arachidonic acid, a 20-carbon fatty acid. Prostaglandins and leukotrienes.- Circulatory hormones
HORMONE TRANSPORT IN THE BLOOD Water soluble free Lipid soluble transport protein [ synthesized in liver] Function og transport protein: 1. They make lipid-soluble hormones temporarily water-soluble, thus increasing their solubility in blood. 2. They retard passage of small hormone molecules through the filtering mechanism in the kidneys, thus slowing the rate of hormone loss in the urine. 3. They provide a ready reserve of hormone, already present in the bloodstream
Properties of the hormone effect 1. Specificity
The receptors may be present on the plasma membrane in the cytoplasm in the nucleus are protein in nature may contain carbohydrate or phospholipid moieties
2. Signal Transmission The role of the hormones is to transit the regulatory signals from the control (endocrine) system to the target cells (organs or glands). enhance or inhibit some function of the target. 3. High Biological Efficiency Low plasma concentration (nmol pmol/L) great regulatory function
MECHANISMS OF HORMONAL ACTION First step: to bind to specific receptors at the target cell. Locations for the different types of hormones: 1) on the surface of the cell membrane. Protein, peptide, and catecholamine hormones 2) in the cell cytoplasm. Steroid hormones 3) in the cell nucleus. Thyroid hormones (t3 and t4)
List of Ductless Glands and their function
1. Thymus Located: Gland like structure situated in front of the trachea behind the top of the breastbone. Function: In early childhood plays some part in building resistance (immunity) to disease and physical development. 2. Thyroid Located: A two-lobed gland found in all vertebrates located in front of and on either side of the trachea. Secretion: It secretes thyroxine which contains 65% iodine. Rate of production is regulated by the pituitary gland. Function: It regulates metabolism. Deficiency causes dwarfness in children called cretinism and myxodema or gills disease in adults. Its deficiency also causes goitre which is the enlargement of thyroid gland. 3. Para-Thyroid Located: Four, small kidney-shaped glands that lie in pairs near or within the lateral lobes of the thyroid glands. Secretion: It secretes parathormone. Function: Raise the level of calcium in the blood. Its deficiency causes tetany. It regulates calcium in blood and helps in growth. Removal of these glands may cause death.
4. Prostrate Located: A gland present in males surrounding urethra at the neck of the bladder. The urine passes through it. Secretion: Prostatic secretion is mixed up with sperms and other fluids to make up the semen. Function: Secretion is essential to the general functions of the human body related to blood pressure and sexual potency. In men above 50 enlargement of this gland is common but if disorder exists then surgical removal is required. 5. Gonads: Located: These are the reproductive glands present in the ovaries of female and testes in males. Secretion: Gonadotrophins Function: Relates to the reproductive system of the body, increases secretion of sex hormones. 6. Adrenal Located: Two small dissimilar glands, one above each kidney, consisting of cortex and medulla. Secretion: Cortex secretes corticosteroid and medulla secretes sex hormones including adrenaline and cortisone. Function: Causes acceleration of the breath, contraction of small blood vessels, dilation of the pupil and increases metabolic rate. Also causes heightened emotion and a sudden increase in physical strength, as during fear or anger, controls sexual growth and almost all functions of the human body. It also regulates blood pressure and function of the heart. Its rise causes Addisons disease.
7. Pancreas: Located: Soft irregular 15 cm long gland lying near the stomach. Secretion: Secretes pancreatic juice into the duodenum and contains the Islets of Langerhans, produces insulin, a clear secretion alkaline in nature containing enzymes. Function: Aids in digestion of proteins, carbohydrates and fats. Its failure results in diabetes 8. Pituitary Located: A small oval shaped gland attached to the base of the vertebrae in the brain which is also known as hypophysis. Secretion: The anterior pituitary gland produces the following hormones and releases them into the bloodstream: adrenocorticotropic hormone, which stimulates the adrenal glands to secrete steroid hormones, principally cortisol, growth hormone, which regulates growth, metabolism and body composition. Function: It is also known as Master Gland which controls the endocrine glands and influences growth and metabolism. The hormones secreted by it control mental, sexual and physical growth of the body. Deficiency causes dwarfism. An excess of it results in much increased body growth called Acromegaly. From this article we come to know about the various ductless glands, their secretions, locations and functions.

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U4-endocrine system.pdf

  • 2. Concept of Hormone A hormone --chemical substance --secreted into the interstitial fluids by one specialized cell or a group of cells --exert physiological control effect on other cells of the body by binding to receptors on or in their target cells.
  • 4. Nervous system exerts point-to-point control through nerves, similar to sending messages by conventional telephone. electrical in nature and fast.
  • 5. Hormones travel via the bloodstream to target cells broadcasts its hormonal messages to essentially all cells by secretion into blood and extracellular fluid. requires a receiver to get the message cells bear a receptor
  • 6. TYPES OF GLAND Exocrine glands : secrete their products into ducts that carry the secretions into body cavities, into the lumen of an organ, or to The outer surface of the body sudoriferous (sweat), sebaceous (oil), mucous, and digestive glands Endocrine glands: secrete their products (hormones) into the interstitial fluid surrounding the secretory cells From the interstitial fluid, hormones diffuse into blood capillaries and blood carries them to target cells throughout the body. Pituitary, thyroid, parathyroid, adrenal, and pineal glands SEVERAL ORGANS AND TISSUES ARE NOT EXCLUSIVELY CLASSIFIED AS ENDOCRINE GLANDS BUT CONTAIN CELLS THAT SECRETE HORMONES. THE HYPOTHALAMUS, THYMUS, PANCREAS, OVARIES, TESTES, KIDNEYS, STOMACH, LIVER, SMALL INTESTINE, SKIN, HEART, ADIPOSE TISSUE, AND PLACENTA.
  • 7. 7 Circulating Vs Local Hormones circulating hormones: Endocrine, or telecrine:
  • 8. Transportation of Hormones Local hormones: Paracrine and Autocrine
  • 9. Chemical Classes of Hormones Lipid-soluble Hormones Water-soluble Hormones Steroid Hormones Thyroid Hormones Nitric Oxide Amine Hormones Peptide Hormones Eicosanoid Hormones
  • 10. LIPID-SOLUBLE HORMONES 1. Steroids -derived from cholesterol Secreted by Adrenal cortex (cortisol and aldosterone), Ovaries (estrogen and progesterone), Testes (testosterone), Placenta (estrogen and progesterone) 2. Thyroid hormone T3 & T4 synthesized by attaching iodine to the amino acid tyrosine 3. The gas nitric oxide (NO) is both a hormone and a neurotransmitter. Its synthesis is catalyzed by the enzyme nitric oxide synthase
  • 11. WATER-SOLUBLE HORMONES 1. Proteins and polypeptides, including hormones Small protein hormonesa are 3 to 49 amino acids; larger protein hormones include 50 to 200 amino acid secreted by anterior and posterior pituitary gland Pancreas (insulin and glucagon) Parathyroid gland (parathyroid hormone) Many others. 2. Amine hormones : derivatives of the amino acid The catecholaminesepinephrine, norepinephrine, and dopamine from tyrosine Histamine is synthesized from the amino acid histidine by mast cells and platelets. Serotonin Melatonin are derived from tryptophan 3. The eicosanoid hormones derived from arachidonic acid, a 20-carbon fatty acid. Prostaglandins and leukotrienes.- Circulatory hormones
  • 12. HORMONE TRANSPORT IN THE BLOOD Water soluble free Lipid soluble transport protein [ synthesized in liver] Function og transport protein: 1. They make lipid-soluble hormones temporarily water-soluble, thus increasing their solubility in blood. 2. They retard passage of small hormone molecules through the filtering mechanism in the kidneys, thus slowing the rate of hormone loss in the urine. 3. They provide a ready reserve of hormone, already present in the bloodstream
  • 13. Properties of the hormone effect 1. Specificity
  • 14. The receptors may be present on the plasma membrane in the cytoplasm in the nucleus are protein in nature may contain carbohydrate or phospholipid moieties
  • 15. 2. Signal Transmission The role of the hormones is to transit the regulatory signals from the control (endocrine) system to the target cells (organs or glands). enhance or inhibit some function of the target. 3. High Biological Efficiency Low plasma concentration (nmol pmol/L) great regulatory function
  • 16. MECHANISMS OF HORMONAL ACTION First step: to bind to specific receptors at the target cell. Locations for the different types of hormones: 1) on the surface of the cell membrane. Protein, peptide, and catecholamine hormones 2) in the cell cytoplasm. Steroid hormones 3) in the cell nucleus. Thyroid hormones (t3 and t4)
  • 17. List of Ductless Glands and their function
  • 18. 1. Thymus Located: Gland like structure situated in front of the trachea behind the top of the breastbone. Function: In early childhood plays some part in building resistance (immunity) to disease and physical development. 2. Thyroid Located: A two-lobed gland found in all vertebrates located in front of and on either side of the trachea. Secretion: It secretes thyroxine which contains 65% iodine. Rate of production is regulated by the pituitary gland. Function: It regulates metabolism. Deficiency causes dwarfness in children called cretinism and myxodema or gills disease in adults. Its deficiency also causes goitre which is the enlargement of thyroid gland. 3. Para-Thyroid Located: Four, small kidney-shaped glands that lie in pairs near or within the lateral lobes of the thyroid glands. Secretion: It secretes parathormone. Function: Raise the level of calcium in the blood. Its deficiency causes tetany. It regulates calcium in blood and helps in growth. Removal of these glands may cause death.
  • 19. 4. Prostrate Located: A gland present in males surrounding urethra at the neck of the bladder. The urine passes through it. Secretion: Prostatic secretion is mixed up with sperms and other fluids to make up the semen. Function: Secretion is essential to the general functions of the human body related to blood pressure and sexual potency. In men above 50 enlargement of this gland is common but if disorder exists then surgical removal is required. 5. Gonads: Located: These are the reproductive glands present in the ovaries of female and testes in males. Secretion: Gonadotrophins Function: Relates to the reproductive system of the body, increases secretion of sex hormones. 6. Adrenal Located: Two small dissimilar glands, one above each kidney, consisting of cortex and medulla. Secretion: Cortex secretes corticosteroid and medulla secretes sex hormones including adrenaline and cortisone. Function: Causes acceleration of the breath, contraction of small blood vessels, dilation of the pupil and increases metabolic rate. Also causes heightened emotion and a sudden increase in physical strength, as during fear or anger, controls sexual growth and almost all functions of the human body. It also regulates blood pressure and function of the heart. Its rise causes Addisons disease.
  • 20. 7. Pancreas: Located: Soft irregular 15 cm long gland lying near the stomach. Secretion: Secretes pancreatic juice into the duodenum and contains the Islets of Langerhans, produces insulin, a clear secretion alkaline in nature containing enzymes. Function: Aids in digestion of proteins, carbohydrates and fats. Its failure results in diabetes 8. Pituitary Located: A small oval shaped gland attached to the base of the vertebrae in the brain which is also known as hypophysis. Secretion: The anterior pituitary gland produces the following hormones and releases them into the bloodstream: adrenocorticotropic hormone, which stimulates the adrenal glands to secrete steroid hormones, principally cortisol, growth hormone, which regulates growth, metabolism and body composition. Function: It is also known as Master Gland which controls the endocrine glands and influences growth and metabolism. The hormones secreted by it control mental, sexual and physical growth of the body. Deficiency causes dwarfism. An excess of it results in much increased body growth called Acromegaly. From this article we come to know about the various ductless glands, their secretions, locations and functions.