1. adrenaline insulin glucagon oestrogen testosterone Glands & Hormones

2. Syllabus reference:

3. This symbol in the corner of a slide indicates a picture, diagram or table taken from your text book

4. Glands Covering and lining most surfaces in the body are epithelial cells. Glands are structures formed from epithelial cells simplestratified columnar cuboidalsquamous Types of epithelial cells

5. Some epithelial cells are specialized by having cilia; others are capable of secreting complex molecules.

6. exocrineendocrine Glands of the body are classified as either exocrine or endocrine types.

7. Glands; summary so far:  Glands are multicellular epithelial structures that specialize in synthesizing and secreting complex molecules including hormones and enzymes.  Glands are classified as either exocrine or endocrine glands.  Exocrine glands have ducts to body surfaces or body cavities.  Endocrine glands are small isolated blocks of tissues with no ducts to surfaces. They are therefore referred to as "ductless" glands.  The products of exocrine glands collect in the duct of the gland and flow toward the surface through the duct.  Since endocrine glands lack ducts, their product is released across the cell membrane into interstitial spaces around the cells. They then diffuse into capillaries.

8. Types of gland

9. Exocrine Glands Most glands of the body are exocrine glands with ducts connecting to body surfaces or body cavities. For example, your salivary glands open into the oral cavity and sweat glands deposit their product on the skin surface. Types of exocrine gland structure: Simple tubeCoiled tubeBranched tube

10. Exocrine Glands secretion mechanism Exocrine glands can also be classified by their secretion mechanism. Merocrine glands 1. Merocrine glands: these secrete substances by the process of exocytosis. Vesicles fuse with the plasma membrane resulting in the release of their contents into the extracellular space. Examples include most sweat glands, the salivary glands and the goblet cells lining of the respiratory and digestive tracts. secretory product Most exocrine glands release their products in this way.

11. Section through a sweat gland of the skin; a coiled tube exocrine gland Example of a merocrine gland: sweat glands

12. Example of a merocrine gland: salivary glands

13. Exocrine Glands secretion mechanism Exocrine glands can also be classified by their secretion mechanism. Apocrine glands 2. Apocrine glands: Glands that secrete by shedding a portion of their cytoplasm, containing the secretory product, into a duct pinched off portion of the cell Examples include the mammary glands and sweat glands in the armpits.

14. Normal alveoli in lactating mammary gland look like bunches of grapes. Example of an apocrine gland: mammary glands Simplified diagram of a mammary gland Each one is a functional unit [alveolus] of epithelial cells that secretes milk into its centre.

15. Exocrine Glands secretion mechanism Exocrine glands can also be classified by their secretion mechanism. Holocrine glands 3. Holocrine glands: Glands that secrete by shedding entire cells from the lining of a duct. Examples include the sebaceous glands associated with hair follicles. disintegrating cell and its released contents mitotic divisions to replace lost cells

16. Sebaceous gland associated with a hair follicle; a branched exocrine gland Example of a holocrine gland: Sebaceous glands

17. Endocrine Glands NOTE: the pancreas has both exocrine and endocrine gland cells

18. Endocrine Glands hormone producing structuresEndocrine glands are the hormone producing structures of the body. Some, like the thyroid are large and obvious. Others, for instance the Islets of Langerhans found in the pancreas, are small islands of endocrine cells embedded within the larger exocrine portion of this organ. Endocrine cells release their secretory products into the interstitial spaces around the cells. The hormones then diffuse into nearby capillaries and are carried to all parts of the body. target tissueOnly when the hormones encounter a target tissue do they exert an effect.

19. Secretory cell in endocrine gland Hormone diffuses into the blood Only cells in the target tissue or target organ have the correct membrane receptors for this hormone Cells without the appropriate membrane receptors remain unaffected by this hormone Endocrine Glands

20. Key terms: Exocrine glandExocrine gland: a gland that secretes externally through a duct Endocrine glandEndocrine gland: a gland that secretes hormones internally directly into the bloodstream HormoneHormone: the secretion of an endocrine gland that is transmitted by the blood to the tissue(s) on which it has a specific effect Target tissueTarget tissue: cells of an organ that are affected by specific hormones

21. Hormones There are 2 major types of hormones: Lipid-based Hormones Protein-based Hormones

22. Lipid-based hormones The commonest type of lipid-based hormones are the steroids Examples include aldosterone and the sex hormones such as oestrogen and testosterone Aldosterone: hormone produced in the adrenal gland, regulating salt and water balance in the kidney testosterone

23. Lipid-based hormones Lipid based hormones are hydrophobic which means they are lipid soluble. They can diffuse through the cell membrane without the need for a receptor on the membrane. These hormones bind to receptor proteins in the cytoplasm or nucleus. This steroid-protein complex then binds to DNA and either starts or inhibits transcription of a particular gene. This means it coordinates which genes should be transcribed as mRNA, to make a protein.

24. How steroid hormones work: 1.Steroid hormone diffuses across the plasma membrane 2.Steroid hormone binds with protein receptor 3.Steroid-protein complex diffuses into the nucleus 4.Steroid-protein complex binds to a specific gene 5.Gene is transcribed to produce a section of mRNA 6.mRNA is translated by ribosomes in the cytoplasm to produce the required protein 

25. Protein-based hormones These include: –Polypeptides e.g. insulin; ADH –Glycoproteins e.g. FSH; LH –Catecholamines e.g. adrenaline; noradrenaline ADH – anti diuretic hormone FSH – follicle stimulation hormone LH – luteinizing hormone adrenaline

26. Protein-based hormones Protein based hormones are hydrophilic and are not lipid soluble. That means they cannot diffuse across a membrane. first messengerThe protein hormone acts as a first messenger by binding to receptors in the plasma membrane. This causes an enzyme to be activated. cyclic AMPThis enzyme causes the formation of cyclic AMP from ATP. second messengerCyclic AMP acts as a second messenger to activate a particular reaction pathway in the cytoplasm.

27. hormone hormone receptor in plasma membrane ATP cyclic AMP an enzyme activated another enzyme activated or direct effect on a biochemical reaction in the cytoplasm How protein-based hormones work – outline of mechanism: first messenger second messenger

28. adenosine cyclic adenosine monophosphate [cAMP] adenosine monophosphate [AMP] What is cyclic AMP?

29. How protein-based hormones work – detailed mechanism: 1.Protein hormone binds to a protein in the plasma membrane of a target cell 2.G-Protein activated 3.Cyclase enzyme activated. This catalyses the conversion of ATP to cyclic AMP (cAMP) 4.cAMP activates an enzyme in the cytoplasm. This enzyme will catalyse the required reaction in the target cell. 

30. How adrenaline affects target tissues: adrenaline FIRST MESSENGER receptor protein G protein adenylyl cyclase ATP cAMP inactive enzyme active enzyme inactive enzyme active enzyme inactive glycogen phosphorylase active glycogen phosphorylase glycogen glucose phosphate SECOND MESSENGER      

31. How adrenaline affects target tissues      

32. The pancreas Both endocrine and exocrine functions can be found in the same organ. The pancreas simultaneously produces exocrine secretions like digestive enzymes and endocrine secretions like insulin and glucagon that are released into the blood to exert their effects throughout the body.