Endocrine Histology Flashcards
General Observations of Endocrine Glands:
No ducts, rich vascularization, epithelially derived cells, release hormones that act by binding hormone receptors.
What two types of hormone receptors exist?
Intracellular and Cell surface receptors
What do hormones require?
Receptors in target cells. They are effective at low concentrations and regulated by feedback loops.
What are examples of Hormones?
Pituitary, Thyroid, Parathyroids, Adrenals, Pancreatic islets, Pineal, Gastrointestinal tract, Kidneys and others
What are two hormone categories?
Amino acid derivatives and Steroids (cholesterol derivatives)
What are Amino Acid Derivatives?
From pituitary, thyroid, parathyroids and pancreatic islets. Cells typically endodermally or ectodermally derived.
What are Steroids?
From gonads, adrenal cortex. Cells are mesodermally derived.
What are Intracellular Receptors?
Receptors located in cytoplasm or nucleus of target cell. Hormones are lipid soluble. Steroid hormones or thyroid hormones.
What are Cell surface receptors?
Amino acid-derived hormones. Hormones are hydrophilic. Activation of second messenger cascades.
What are three types of tissues with Endocrine Functions?
Discrete glands, Glands with Endocrine and Exocrine functions, DNES cells (diffuse neuroendocrine)
What are examples of discrete glands?
Pituitary, pineal, thyroid, parathyroids, adrenals
What are examples of glands with endocrine and exocrine functions?
Kidney, pancreas, gonads (testis, ovary), placenta
What is autocrine signaling?
Hormones target sites on the same cell
What is paracrine signaling?
Cell secretes hormones that target an adjacent target cell.
What is endocrine signaling?
Hormone is secreted into the blood by an endocrine gland and the hormone travels through blood stream until it reaches distant target cells.
What is another name for the Pituitary Gland?
Hypophysis
What two components come together during development to make the pituitary gland?
Oropharynx ectoderm (Rathkes pouch) and Neuroectoderm
What bone does the pituitary develop within?
Sphenoid bone
What is the precursor tissue to the posterior lobe of the pituitary?
Neuroectoderm
What is the precursor tissue to the anterior lobe of the pituitary?
Oropharynx ectoderm (Rathkes pouch)
What is another name for Neuroectoderm?
Floor of the diencephalon
What is another name for Ectoderm?
Roof of the stomatodeum
What does the neuroectoderm form?
Pars nervosa
What does the Oropharynx ectoderm form?
Pars tuberalis, Pars distalis, Pars intermedia
What part of the oropharynx ectoderm encircles the infundibular stalk?
Pars tuberalis