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Endocrine Sys (Sites of Hormones production (Hypothalamus (Hypothalamic…

- - - - Bony struct= sella turcica
    - - 2 lobes
        
        Anterior
        
        Func: in general: Growth n reproduction
        
        Hormones production
        
        Growth hormone
        
        Func: 1) increases in physical size 2)Regulate fats n sugar metabolism
        
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        Req: cofactor-somatomedin C (ICF-1)
        
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        Regulation of its release
        
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        Adrenocorticotrophic hormone/adrenocorticotropin (ACH)
        
        Func: tells adrenal cortex => release its metabolsim-controlling hormones
        
        Sig: not epinephrine
        
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        Thyroid-stimulating hormone (TSH)
        
        Func: tells thyroid gland to produce & release thyroid hormones
        
        Prolactin
        
        Func: tells mammary glands to make milk => release it in response to suckling (n other things)
        
        Follicle-stimulating hormone (FSH)
        
        Func: tells
        
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        Luteinizing hormone (LH)
        
        Func:
        
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        Partially controls metabolism
        
        Where: adrenal cortex n thyroid
        
        why: endocrine pancreas has other triggers as well
        
        Does not control:
        
        1) Parathyroid gland
        
        2) Adrenal medulla
        
        3) hormones of digestive sys
        
        Loc: in front of posterior pituitary
        
        Charac: not attached to the brain
        
        Sig: not embryologically/histologically related to the brain
        
        Looks like the rest of endocrine sys
        
        Posterior
        
        Loc: behind anterior pituitary
        
        Charac: attached to the hypothalamus by a neural stalk
        
        Sig: embryologically/histologically related to the brain (especially hypothalamus)
        
        General func: 1) Kidney 2)some reproductive funcs
        
        Hormone production
        
        Antiduiretic hormone (ADH)
        
        Func: tells kidney to retain salt n H2O
        
        Oxytocin
        
        Func:
        
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      - General func: each subs secreted has its own cell type w/in the gland
      - General struct: actually 8 glands in 1
        
        Especially in: anterior pituitary (more of a typical endocrine gland)
      - Controlled by: Hypothalamus
        
        How: Hormones
        
        Types
        
        Inhibitory hormone
        
        Hypothalamic releasing hormone
        
        Func: tell pituitary what to do
  - - - A portion of info sent up/down through brain's integrative centers
        
        Relayed to pituitary as: Hormones
        
        2 types
        
        Hypothalamic releasing hormones
        
        Inhibitory hormones
    - - GH releasing hormone & GH inhibitory hormone
        
        Func: control the production of GH
        
        Big enough deal to get 2 controllers
      - Thyrotropin-releasing hormone
        
        Func: tells anterior pituitary to release TSH
      - Corticotropin-releasing hormone
        
        Func: tells anterior pituitary to release ACH
      - Gonadotropin-releasing hormone
        
        Func: tells anteriorir pituitary
        
        Release FSH & LH
        
        Sig: have other triggers for these 2
      - Prolactin-inhibitory hormone
        
        Func: inhibits prolactin production.
        
        Why only inhibit?
        
        Prolactin isnt' a hormone you want on board
      - Regulation
        
        Most: negative feedback loops w/ their pituitary hormones
        
        Few: products released by pituitary target organs
        
        Ex: GnRH feed backs not only w/ FSH & LH but also estrogen, progesterone, hCG (during pregnancy
  - - - Below larynx & anterior to trachea
    - - Epithelial cells (innermost)
        
        What: cuiboidal & secretory
        
        Func: make thyroid hormones
      - Colloid
        
        What: proteinaceous fluid of epithelial cells face
        
        Func: Storage of hormone
      - Follicles (outermost)
        
        What: ring of epithelial cells & colloid inside the ring
    - - General charac
        
        Hormones = amine class
        
        What: circulate bound to plasma prots (including albumin)
        
        Sig: the blood always = large reserve of hormone
      - Controlled by
        
        Thyroid-stimulating hormone
        
        Trigger/Control
        
        Thyroglobulin
        
        Func: acts as a scaffold for hormone synthesis
        
        Charac: inactive in & of itself
        
        Struct: big prot w/ lots of tyrosines
        
        Produced by epithelial cells
        
        Thyroxine (T4)
        
        Struct: 4 iodines on it
        
        Sig: majority of the hormone produced by the thyroid
        
        Triodothyronine (T3)
        
        Struct: 3 iodines on it
        
        Charac; most active hormone
        
        Produce fr anterior pituitary
        
        Regulated by: hypothalamic thyrotropin-releasing hormone
        
        Stimuli
        
        1)Cold weather
        
        2) Low lvls of circulating thyroid hormone
        
        3) Sympathetic n.sys
        
        Inhibitors
        
        High lvls of circulating thyroid hormone
      - Making thyroid hormones
        
        1) From nutrients
        
        Sig: no other tissue body does
        
        What: Iodine
        
        Obtained as iodide
        
        How: eating
        
        Why: no natural stores of iodide like it does for chloride/bicarb
        
        Amount: small = 50mg/yr
        
        Where:
        
        1) Plants
        
        Why: most places- plants take up sufficient iodine fr soil
        
        2) iodine-rich Seafood
        
        3) Iodized salt
        
        What: Potassium iodide added to table salt
        
        Sig: solve iodine deficiency
        
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        Process
        
        Where: epithelial cells
        
        1) What: Na+/K+ exchange pump
        
        Export Na+ fr cell
        
        2)What: Iodine trapping
        
        How: cotransport w/ Na+
        
        Drag Iodine in cells
        
        3) Produce thyroglobulin
        
        what: high-tyrosine prot
        
        At apical membr => close to thyroglobulin secretion site
        
        Produce: pendrin
        
        what: protein
        
        Func: exports iodide in exchange for chloride
        
        Sig: oxidized iodine coupled w/ thyroglobuline's tyrosines
        
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        Out in the colloid
        
        What: peroxidase
        
        Func: Iodide (I-) convert to elemental iodine
        
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      - Funcs
        
        In cell
        
        acts by
        
        1) direct coupling to an intracellular, nuclear receptor
        
        2) Receptor = transcription factor directly
        
        Sig: similar to steroid hormones
        
        Generally act to
        
        Increase metabolic rate
        
        Molecular/Genetic changes
        
        1) Increased ATP production
        
        Where: glycolysis, beta-oxidation, other source of acetyl CoA
        
        How: thyroid hormones increase # of mitochondria & their activity
        
        2) increased transport of nutrients into the cells
        
        How: thyroid hormones increases activity of transporters
        
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        3) Increased carrying away of heat n CO2
        
        How: transporters = ATP-powered
        
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        Common E stores = metabolized rapidly
        
        What: fats and carbs
        
        Funcs:
        
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        Side effects of increased metabolic rate
        
        1) Weight
        
        WHat: encourage weight loss
        
        why: body = using E
        
        2) Cardiovascular sys
        
        what: increased blood flow = supply O2 & remove CO2 & dissipate heat
        
        Conseque: cardiac output, contractility, heart rate = increase
        
        3) Respiratory sys
        
        What: sys produces excess CO2
        
        Conseque: respitory rate = up => remove waste
        
        4) Gut
        
        What: increases motility 2)nutrient uptake
        
        Sig: major way for distinguish fr sympathetic n.sys stimulation vs thyroid stimulation
        
        5) Nervous sys
        
        what: increases processing speed n power
        
        Sig: makes person feels sharper
        
        6) Musculoskeletal sys
        
        what: increases activity of muscles & strength or rxn to action potentials
- - - - Endocrine/neuroendocrine
        
        Released by: glands/ modified neurons behave like glands
        
        Action: circulate in the bloodstream
        
        Destiny: get at a variety of targets
      - Autocrine
        
        Released by: cells
        
        Action: Circulate through extracellular fluid
        
        Destiny to other cells of same kind, including the producing cell
      - Neurotransmisson
        
        Released by: neuron
        
        Action: push across a synapse
        
        Destiny: another neuron or muscle
      - Paracrine
        
        Released by: cells
        
        Action: circulate through EC fluid
        
        Destiny: other cells nearby
      - Cytokines
        
        Released by: cells into EC fluid
        
        Action: circulate in EC fluid
        
        Destiny: act on the immune sys
    - - Polypeptides/Proteins
        
        Classification:Proteins as messenger
        
        Why use them
        
        Adv: 1) easy to synthesize 2)water-soluble 3)Variety 4)Secreted in an inactive form
        
        Disadv: 1)too big to enter the target cell 2)subject to degradation
        
        Made: like other proteins
        
        Where: on rough ER/ribosomes
        
        How: using mRNA as a template
        
        Mechanism
        
        Secreted as: Prohormones
        
        What: inactive form => must be cleaved to become active
        
        Action at target cell: interact w/ receptor on cell surface
        
        Sig: can't get into cell
        
        Ex: Growth hormone, ADH, Insulin
      - Steroids
        
        Classification: Lipid as messenger
        
        Why use them
        
        Disadv: not water-soluble
        
        why: hard to store & transport
        
        Adv: can cross cell membr
        
        Made: fr Cholesterol
        
        Synthetic pathway = complex
        
        Mechanism
        
        Secreted as: synthesize on the spot
        
        Why: cannot be store inside the cell
        
        Action at target cell: diffuse into the cell across the membrane
        
        Why: lipid soluble
        
        Ex: most sex hormones, cortisol, aldosterone
      - "Amine" hormone
        
        Classification: small + hydrophilic molecule as messenger
        
        Why use them
        
        Disadv: not a lot
        
        Adv: 1)easier to synthesize than a prot 2)can be carried along by proteins
        
        Made from: amino acid tyrosine
        
        Mechanism
        
        Secreted as: bound to prot carriers in the blood
        
        Why: can be a circulating "background pool"
        
        Action at target cell: interact w/ receptors on cell surface
        
        Ex: most neurotransmitters: epinephrine, norepinephrine; thyroid hormones
    - - Target cells
        
        Effects:
        
        Few
        
        Alter something about cell's physiology
        
        Ex: such as its resting membr potential
        
        Most
        
        Regulation of gene transcription in cells
        
        Once in cells
        
        Note: hormones essentially no activity
        
        Biochem usefulness: func of what's downstream
        
        Func: set off intracellular signaling cascade
        
        How
        
        1/ Control ion channels
        
        Mechanisms
        
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        2/ Activation of 2nd messenger sys
        
        Mechanism
        
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        3/ Direct gene regulation
        
        Mechanism
        
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      - Regulation
        
        Negative feedback
        
        What: a change caused by hormone = inhibition of hormone's release/action
        
        Counterhormones: feedback loop bet 2 hormones
        
        Ex: GnRH & FSH
        
        Positive feedback
        
        what: a change caused by hormone = greater release of hormone
        
        Req: spike in hormone conc
        
        Common: female reproductive sys
        
        Ultimately convert to
        
        Negative feedback loops
        
        When: once the pike = over
        
        goes back to negative control
        
        Cyclical variation
        
        What: 1)production lvl of some hormones varies w/ other physiological process 2)w/ triggers like time of day
        
        Background lvls
        
        What: if it can be bound to a prot => circulating "pool" of it that keeps concs effectively steady
        
        Regulation of receptors
        
        What: some hormones cause their own receptors to be downregulated/destroyed/sequestered