- Hypothalamus

• Thymus

  Lungs

  Heart

  Liver

  Stomach

  Pancreas

  Kidney

  Small Intestine

  Seminal Vesicles

  Prostate

  Adipose Tissue

  Skin


  What are the organs with hormone-secreting cells?
• Hypothalamus

  Pituitary Gland

  Pineal Gland

  Thyroid Gland

  Parathyroid Glands

  Adrenal Glands

  Ovaries

  Testes


  What are the Major Endocrine Glands
• Hypothalamus (Endocrine Gland)


  Secreted Hormones:

  
  

  Antidiuretic Hormone (ADH)

  Oxytocin (OT)

  Regulatory Hormones
• Pituitary Gland (Endocrine Gland)


  Secreted Hormones:

  
  

  Anterior Pituitary = Adrenocorticotropic Hormone (ACTH), Follicle-Stimulating Hormone (FSH), Growth Hormone (GH), Luteinizing Hormone (LH), Melanocyte-Stimulating Hormone (MSH), Prolactin (PRL), Thyroid-Stimulating Hormone (TSH)

  
  

  Posterior Pituitary = ADH & OT
• Adrenal Glands (Endocrine Gland)

  Secreted Hormones:

  
  

  Cortex = Corticosteroids

  Medulla = Epinephrine (E) & Norepinephrine (NE)
• Pineal Gland (Endocrine Gland)

  Secreted Hormones:

  
  

  Melatonin
• Thyroid Gland (Endocrine Gland)

  Secreted Hormones:

  
  

  Calcitonin (CT)

  Thyroid Hormone (TH)
• Parathyroid Glands (

  Secreted Hormones:

  
  

  Parathyroid Hormone (PTH)
• Thymus (Endocrine Gland)

  Secreted Hormones:

  
  

  Thymopoietin and Thymosin
• Pancreatic Islets (Endocrine Gland)

  Secreted Hormones:

  
  

  Glucagon

  Insulin

  Somatostatin

  Pancreatic Polypeptide
• Heart (Endocrine Gland)

  Secreted Hormones:

  
  

  Atriopeptin
• GIT (Endocrine Gland)

  Secreted Hormones:

  
  

  Cholecystokinin (CCK)

  Gastric Inhibitory Peptide (GIP)

  Gastrin

  Secretin

  Vasoactive Intestinal Peptide (VIP)
• Kidney (Endocrine Gland)

  Secreted Hormones:

  
  

  Calcitriol

  Erythropoietin (EPO)

  Renin
• Ovaries (Endocrine Gland)

  Secreted Hormones:

  
  

  Estrogen

  Inhibin

  Progesterone
• Testes (Endocrine Gland)

  Secreted Hormones:

  
  

  Androgen and Inhibin
• Endocrine Glands

  Secrete signaling molecules called hormones into a neighboring vascularized compartment for uptake by capillaries and distribution throughout the body, rather than directly into an epithelial duct like exocrine glands

  
  

  Although function in different ways, the endocrine system and the nervous system interact to modulate and coordinate the metabolic activities of the body
• Ductless Glands

  Distinct clusters of cells with certain organs of the body -e.g. pituitary gland, thyroid and parathyroid gland, adrenal gland, pineal gland
• Endocrine Cells


  E.g. islets of Langerhans in the pancreas, corpus luteum of the ovary and the interstitial cells of Leydig in the testis
• Major Endocrine Glands (Parts of the Endocrine System)


  In which the sole or major function of the organ is the synthesis, storage, and secretion of hormones.
• Endocrine Components Within Other Solid Organs (Parts of the Endocrine System)


  For example, the endocrine components of the pancreas, ovary, testis and kidney, in the form of clusters of endocrine cells within other tissues
• The Diffuse Endocrine System (Parts of the Endocrine System )

  Scattered individual hormone cells (or small clumps), usually within an extensive epithelium, e.g. the gastrointestinal and respiratory tract.
• Specialized Cells/Endocrine Cells (Components of Endocrine Glands)

  Are always very close to blood capillaries, which receive the secreted hormones and distribute them throughout the body.

  
  

  Usually aggregate as endocrine glands, where they typically arrange themselves as cords of cells.

  
  

  Many endocrine cells however produce hormones or other molecules through different modes of secretion.

  
  

  §e.g. APOP cells

  
  

  Isolated endocrine cells in the body, such as:

  §Endocrine cells of the digestive tract

  §Cells of the placenta

  §Cells of the heart that produce the ANP

  §Juxtaglomerular cells of the kidney

  ​
• Endocrine Tissues or Organs (Components of the Endocrine Glands)


  Pertains to endocrine glands

  
  

  Components of endocrine system that secrete chemicals directly into the bloodstream.

  
  

  e.g. Pancreas, endocrine components - Islet of Langerhans
• Secretory Organs (Components of the Endocrine Glands)

  Any of various organs that synthesize substances needed by the body and release it through ducts or directly into the bloodstream

  
  

  e.g. pituitary, thyroid, pineal gland
• Embryonic Origin


  All three embryonic germ layers (endoderm, mesoderm, and ectoderm) contribute to the development of the endocrine glands.

  
  

  All secretory glands, whether exocrine or endocrine, develop from epithelia.
• Ectoderm (Germ Layer)


  Hypothalamus, Pituitary, Gland, Pineal Gland, Adrenal Medulla (Endocrine Organ)
• Mesoderm (Germ Layer)

  Adrenal Cortex (Endocrine Organ)
• Endoderm (Germ Layer)

  Thyroid Gland, Parathyroid Glands, Pancreas, Thymus (Endocrine Organ)
• Hormones


  Are frequently hydrophilic molecules such as proteins, glycoproteins, peptides, or modified amino acids

  
  

  receptor proteins are on the surface of target cells

  
  

  hydrophobic steroid and thyroid hormones must circulate on transport proteins but can diffuse through the membrane of cells and activate cytoplasmic protein receptor in target cells
• Paracrine (Types of Endocrine Secretion)


  Localized dispersal in interstitial fluid or through short loops of blood vessels o hormones produced act very quickly but only at a short distance

  
  

  e.g. gastrin
• Juxtacrine (Types of Endocrine Secretion)


  A signaling molecule remains on the secreting cell's surface or adjacent extracellular matrix

  
  

  effects target cells when the cells make contact

  
  

  important in developmental tissue interactions
• Autocrine (Types of Endocrine Secretion)


  Cells may produce molecules that act on themselves or on cells of the same type

  
  

  e.g. IGF
• Hormonal Control Mechanisms


  In endocrine control, the hormone is discharged from a cell into the bloodstream and is transported to the effector cells

  
  

  In paracrine control, the hormone is secreted from one cell and acts on adjacent cells that express specific receptors

  
  

  In autocrine control, the hormone responds to the receptors located on the cell that produces it
• Pituitary Gland (Hypophysis)


  Small bean-shaped gland, about 1 cm across, at the base of the brain beneath the third ventricle, sitting in a bony cavity in the base of the skull (the sella turcica).

  
  

  Weight: about 0.5g in adults

  
  

  Develops from oral ectoderm and developing brain

  
  

  Neural component: arises as a bud growing down from the floor of the diencephalon and caudally as a stalk or infundibulum still attached to the brain

  
  

  Oral component: arises as an out pocketing of ectoderm from the roof of the primitive mouth; grows cranially, forming the Rathke's (hypophyseal) pouch

  
  

  The base of this pouch constricts and separates it from the pharynx

  
  

  Pituitary-dependent endocrine glands

  
  

  thyroid gland

  adrenal cortex

  gonads
• Adenohypophysis (Anterior Pituitary)


  Develops from an evagination of the oral ectoderm (Rathke's Pouch) that lines the primitive oral cavity (stomadeum)

  
  

  a. Pars distalis (pars anterior)

  b. Pars intermedia

  c. Pars tuberalis
• Neurohypophysis (Posterior Pituitary)


  Develops from neural ectoderm as a downgrowth of the diencephalon

  
  

  a. Median eminence

  b. Infundibulum

  c. Pars nervosa
• Development of the Pituitary Gland

  The pituitary gland develops from two different structures an ectodermal diverticulum of the roof of the oropharynx (Rathke's Pouch) and a downward extension of the neuroectoderm at the floor of diencephalon

  
  

  The pituitary gland at 10 weeks in development shows ectodermal issue from the oropharynx in close proximity to neural tissue. The Rathke's Pouch is about to lose connection with the oropharynx

  
  

  Cells from Rathke's Pouch divide and differentiate rapidly into the pars distalis and encircle the infuncibulum, which with pars nervosa forms the neuroectodermally derived posterior lobe of the pituitary gland
• Pituitary Gland Hormones (Directly on Non-Endocrine Tissues)

  Growth hormone (GH)

  Prolactin (PRL)

  Antidiuretic hormone (ADH)

  Oxytocin

  Melanocyte stimulating hormone (MSH)
• Pituitary Gland Hormones (Trophic Hormones/Modulate the Secretory Activity of Other Endocrine Glands)

  Thyroid stimulating hormone (TSH)

  Adrenocorticotrophic hormone (ACTH)

  Gonadotrophic hormones

  Follicle stimulating hormone (FSH)

  Luteinizing hormone (LH)
• Adenohypophysis (Anterior Pituitary Gland)


  Derived from oral ectoderm

  
  

  Has three parts:

  1. A large pars distalis/anterior lobe

  2. Pars tuberalis (wraps around the infundibulum)

  3. The thin pars intermedia

  
  

  The three parts of the adenohypophysis are derived from the hypophyseal pouch off the embryonic pharynx