Chapter 11: Endocrine

Question 1

11.1-11.7

Answer 1

1. Hormones and Endocrine Glands

• Exocrine glands secrete products through ducts (eventually → outside)
• Endocrine glands secrete hormones into the blood (inside)
• Hormones are chemical messengers
  
  • Bind to their receptors on target tissues
  • Specificity (lock and key)
  • Affinity
• Major endocrine glands
  
  • Hypothalamus
  • Pituitary
  • Pineal gland
  • Thyroid gland
  • Parathyroid glands
  • Adrenal glands
  • Pancreas (Islets of Langerhans)
  • Gonads
    a. Ovaries
    b. Testes
• Additional hormone-producing organs/tissues
  
  • Adipose (fat) tissue
  • Gastrointestinal tract
  • Heart
  • Kidneys
  • Liver
  • Placenta
  • Thymus
  • Blood

2. Hormone structures and synthesis

• Three major chemical classes of hormones:
  
  • Amines
  • Peptides and proteins
  • Steroids
• Amine Hormones
  
  • Derived from the amino acid tyrosine
  • Thyroid hormones
    a. T3 & T4 (thyroxine)
    b. From the thyroid gland
  • Catecholamines
    a. Epinephrine & Norepinephrine
    b. From adrenal gland (medulla)
  • Dopamine
    a. From hypothalamus
• Peptide and Protein Hormones
  
  • Synthesized as a preprohormone
  • Cleaved to a prohormone in rough ER
  • Cleaved to active hormone in Golgi
  • Hormone and other fragments secreted together
  • One prohormone may produce many active hormones
    a. Ex: Proopiomelanocortin (POMC)
  • Protein Hormone Examples
    a. adrenocorticotropic hormone (ACTH)
    b. melanocyte-stimulating hormone (MSH)
    c. follicle-stimulating hormone (FSH)
    d. luteinizing hormone (LH)
    e. prolactin
    f. oxytocin
    g. thyroid-stimulating hormone (TSH)
    h. thyrotropin-releasing hormone (TRH)
    i. insulin
    j. glucagon
    k. growth hormone (GH)
    l. somatostatin (SST)
    m. parathyroid hormone (PTH)
    n. calcitonin
    o. vasopressin
    p. renin
    r. angiotensin
    s. atrial natriuretic peptide (ANP)

know all of these hormones

• Steroid Hormones
  
  • From a cholesterol precursor (lipid)
  • Stimulated by anterior pituitary hormones
  • Via G-protein coupled receptor
• Steroid Hormone Synthesis
  
  • Series of enzymatic conversions
  • Synthesis starts in the inner mitochondrial membrane
  • Further processing happens in smooth ER

live off the membrane of the mitocrhondia in pink
after first noncholesterol steriod hromone it gets back to AER, and wall ofsmooth er has tons of enzymes, so the wayyou express those enzymes changes the way those enzymes there are presetn
salt sugar sex scary

• Adrenal Gland Hormones Sources
  
  • Cortex
    a. Zona glomerulosa
    → Aldosterone
    b. Zona fasciculata
    → Cortisol (primarily)
    c. Zona reticularis
    → Androgens (primarily)
  • Medulla
    a. Epinephrine
    b. Norepinephrine

** salt sugar sex scary **

• Adrenal Gland Hormones
  
  • Aldosterone
    a. Regulates in kidney
    b. Na+ & H2O retention
    c. K+ & H+ excretion
  • Cortisol
    a. Regulates glucose metabolism
  • Androgens
    a. Reproduction & Growth
• Gonadal Hormones
  
  • Androgens
    a. Spermatogenesis
    b. Growth
    c. Secondary sexual characteristics
  • Estrogens
    a. Oogenesis – egg development
    b. Breast development
    c. Ovulation
  • Progesterone
    a. From corpus luteum in ovary
    b. Promotes secretion from endometrium
    c. Matures breasts for lactation
• Calcitriol Synthesis
  
  • Cholesterol-derived precursor
  • Converted to Vitamin D3 in skin
    a. Energy from UV light
  • Hydroxyl groups added in liver and kidneys
  • Active hormone is 1,25-dihydroxyvitamin D3
    a. AKA Calcitrol

only choeteriol based hormones are steriods

recognie basic biochemical structures and kno them and know which is peptide steriod and amine hormones; know hormones for each group an which group they fall into

3. Hormone Transport in the Blood

• Peptide & Catecholamine Hormones
  
  • Hydrophilic
  • Water-soluble
  • Dissolved in plasma
• Steroid and thyroid hormones
  
  • Poorly soluble
  • Mostly bound to plasma proteins
  • Small concentrations dissolved in plasma (“free hormones”)
  • Only free hormones interact with target cells

review lipid soluble and water soluble second messenger pathways

4. Hormone Metabolism and Excretion

• Blood concentration depends on:
  
  • Rate of secretion
  • Rate of removal
• Clearance rates
  
  • Peptides & Catecholamines
    a. minutes to an hours
  • Steroids (bound to carrier)
    a. Hours to days
• Liver and kidneys work together to metabolize and excrete hormones
• Enzymes in the blood break down proteins and catecholamines
• Steroid hormones are modified to be soluble without a carrier protein

5. Mechanisms of Hormone Action

• Receptors
  
  • Lock-and-key
  • Specificity
  • Affinity
• Action only on target tissues
• Proteins & Catecholamines
  
  • Bind to extracellular receptors
  • Activate
    a. Receptor enzyme activity
    b. Receptor-associated janus kinase
    c. G-protein coupled receptor activity leading to a second messenger cascade
  • Non-genomic & genomic activity
• Up-regulation
  
  • More receptors
  • Prolonged, low exposure to hormone
  • Increases target cell responsiveness
• Down-regulation
  
  • Fewer receptors
  • High exposure to hormone
  • Decreases responsiveness
• Permissive Actions of Steriods
  
  • Synergistic effects of hormones acting in concert
    a. Hormone A can up- or down-regulate receptors for Hormone B
  • Permissiveness
    a. Hormone A is necessary for Hormone B to exert its full effect

mechanicss f steriod: can ge tout of plasma wth carrier proteins, find receptor on the membrane brougt in by receptor mediated endocytosis, in the lysossome, it breaks down the bidnign protein and releases the steriod from the carrying protein adn then we can have intracellular metabolism and interaction; some steriods actually have membrane bound receptors (non genomic activity of steriods); latest research: tehre can be quick acting effects of steriods through membrane bound receptors

6. Inputs that control hormone secretion
7. Types of endocrine disorders
8. Control systems involving the hypothalamus & pituitary gland