endocrinology

• What is homeostasis?


  the stable state of the internal environment
• Does the endocrine system maintain all homeostasis ?

  No
• What does the endocrine system maintain? (5)


  -metabolism ( of blood glucose, lipid, protein)

  -Adipose energy stores

  - stress response

  - blood & bone calcium

  - ECF osmolarity
• What is a hormone?

  a chemical produced in specific cells
• How is a hormone transported?


  Blood or extracellular fluid
• What does a hormone regulate?


  Signaling in specific targets
• Hormone function in endocrine pathways (4)


  1. input

  2. endocrine tissue --> release hormone

  3. travels to target tissue ( receptor -> signal -> response)

  4. triggers feedback
• hormone communication (3)


  endocrine, neuroendocrine, RARELY paracrine
• hormone communication involves...


  hormones that are secreted into the blood
• a cell without a receptor causes...

  no response
• neuroendocrine communication involves....


  neurons releasing hormones into the blood
• paracrine communication involves...


  hormones traveling through interstitial fluid
• endocrine glands (classic) (6)


  -anterior pituitary

  -thyroid gland

  -parathyroid gland

  -pancreas (endocrine)

  -adrenal cortex

  -adrenal medulla
• neurons (2)


  -hypothalamus

  -posterior pituitary
• Most active endocrine tissue of them all is the...

  placenta
• specialized cells in other tissues (6)


  -stomach

  -adipose

  -skin

  -ovaries

  -testes

  -blastocyst
• Two major types of hormones


  -proteins (peptide hormones)

  -steroids
• proteins are made of _________and can be ______ or ________

  amino acids, small, large
• are proteins hydrophilic or hydrophobic?

  hydrophilic
• what are steroids derived from?

  cholesterol
• cholesterol is modified by ____________ to create different hormones

  enzymes
• are steroids hydrophilic or hydrophobic?

  hydrophobic
• what is the cells and ECF membrane made of?


  Lipids
• Can steroids or proteins pass through this lipid membrane?


  steroids can, proteins cannot
• Hoe can steroids travel through ECF?

  bonding proteins
• most of the steroids is bound but only the_______ hormone can result in a response or be metabolized

  free
• protein synthesis steps (3)

  transcription --> translation --> exocytosis
• how is protein synthesis regulated?

  at transcription and exocytosis
• steroid synthesis


  step wise enzymatic reactions starting with cholesterol
• how is steroid synthesis regulated?

  by transcription and modification of those enzymes
• transcriptional regulation can _________ or __________ transcription

  activate, repress
• translation results in (2)

  protein hormones, synthesis of "steroidogenic" enzymes
• protein hormones are synthesized by.....

  translation on membrane bound ribosomes
• exocytosis of protein hormone release (4)


  -input

  -specific release signal

  -fast release (seconds)

  -"pulsatile release"
• what dictates pulse amplitude?


  stimulus frequency and strength
• proteases


  enzymes that cut proteins
• pro hormone convertases (2)


  - amino acid sequence specific

  -tissue specific
• POMC is a precursor for...


  hormones and neurotransmitters depending on the origin
• prohormones processes to (2)

  active hormones + other peptide fragments
• pro-opimelanocortin (POMC) in the anterior pituitary covertases into (4)


  -ACTH

  -lipotropin

  -endorphin

  -fragment