Physio Exam 6 21-24

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  1. 1. Explain the process of fat digestion and absorption in detail.
    In the lumen of the small intestines bile salts from the liver coat fat droplets-->Pancreatic lipase and coliapse are broken down into monoglycerides and fatty acids stored in micelles-->Since fats are lipophilic, many are absorbed by simple diffusion, monoglycerides and fatty acids leave the micelles and diffuse across the apical membrane into the enterocyte, cholesterol is transported through the cell separately into the cell-->monoglycerides and fatty acids are recombined in the SER to form triglycerides-->cholesterol+triglycerides+protein=large droplets called chyomicrons-->their size requires them to be packaged into secretory vesicles by the Golgi apparatus and leave the cell by exocytosis-->the size the chylomicrons prevent it from entering capillaries and instead are absorbed into the lymph vessels of the villi to be filtered, some fatty acid not assembled with chylomicrons cross the basement membrane and enter enter the blood.
  2. 2. Of the six cell types in the gastric mucosa pick four of them, and name the cell type, describe the substance they secrete, the function of that secretion and the stimulus for its release.
    • SS(substance secreted)
    • SfR(stimulus for release)
    • FoS(function of secretion)

    G cells-(SS-gastrin)-(SfR-acetylcholine, peptides, and amino acids)-(FoS-stimulates gastric acid secretion)

    D cells-(SS-somatostatin)-(SfR-acid in stomach)-(FoS-inhibits gastric acid secretion)

    Chief cells-(SS-pepsin/gastric lipase)-(SfR-acetylcholine, acid secretion)-(FoS-digest proteins/digests fats)

    Mucus neck cell-(SS-mucus/bicarbonate)-(SfR-tonic secretion; with irritation of mucosa/secreted with mucus)-(FoS-physical barrier between lumen and epithelium/buffers gastric acid to prevent damage to epithelium)
  3. Explain how insulin behaves in the Fed state (reference figure 22.15).
    • When we eat a meal, β cells of the pancreas can be influenced by a few ways:
    •    1. distension of GI tract wall-->stretch receptors-->↑ sensory neuron input-->CNS-->↑
    • parasympathetic output

       2. presence of carbohydrates in GI lumen-->endocrine cells of small intestine-->GLP I and GIP

       3. nutrient digestion and absorption-->↑ plasma amino acids

       4. nutrient digestion and absorption-->↑ plasma glucose

    ↑ in insulin secretion tigers the liver, muscles, adipose, and other cells to ↑ glocolysis, glyconeogenesis, lipogenesis, protein synthesis, and ↑ glucose transport-->results in ↓ plasma glucose.
  4. Describe the body’s adaptations to maximize heat loss and minimize the production and then describe the adaptations to minimize heat loss and maximize heat production.
    • To maximize heat loss:
    •    -vasodilation of blood vessels
    •    -increased sweating
    •    -behavioral responses;
    •       fans
    •       immersion in water
    •       stay out of the sun
    •       remove clothes

    • To minimize heat production:
    •    -diminish food intake
    •    -behavioral response
    •       decrease physical activity

    • To minimize heat loss
    •    -vasoconstriction of blood vessels
    •    -lack of sweating
    •    -behavioral responses
    •       add layers of clothing
    •       curling up to minimize surface exposure
    •       standing near a heat source

    • To maximize heat production
    •    -shivering
    •    -behavioral responses
    •       increase voluntary activity(stamping feet, etc)
  5. Describe the production of thyroid hormone (reference figure 23.4).
    Na-I symporter brings I into the cell. The pedrin moves I into the colloid-->follicular cell synthesis enzymes and thyroglobulin for colloid-->thyroid peroxidase adds iodine to make tyrosine to make Tand T4.-->thyroglobulin is taken into the cell in vesicles-->Intracellular enzymes separate Tand Tfrom the protein-->Free  Tand T4 enter the circulation.
  6. Describe the three main hormones involved in calcium regulation. Be sure to include where they are produced and what actions each hormone has.
    • parathyroid hormone-secreted by the parathyroid glands,
    •    -main function is to increase Ca concentrations
    •    -mobilizes Ca from bone
    •    -enhances renal absorption of Ca
    •    -indirectly increases intestinal absorption of Ca

    • calcitriol (vit D) obtain through diet or made from the skin form sunlight. Also regulated by kidney by PTH.
    •    enhances Ca uptake
    •    facilitates renal reabsorption of Ca
    •    helps mobilize Ca out if bone

    • Calcitonin-peptide produced by C cells of thyroid gland.
    •    opposite of PTH
    •    when Ca increases calcitonin decreases bone resorption and increases renal calcium excretion
  7. Compare the primary and secondary immune responses (reference figure 24.8).
    During a primary immune response, antigen activates the appropriate  naive cells reproduce--->clonal expansion create more cells of the clone. The new clones become effector cells that carry out an immediate response(effector cells-->plasma cells that secrete antibodies), effector cell have a short life span. Or they become memory cells that live long and reproduce. 

    When memory cells are reexposed to the same antigen, the response is much quicker and produce more antibodies

    clonal expansion leads to immunologic memory
  8. Describe four of the seven functions of antibodies.
    • Activating mast cells-when IgE antibodies detect an antigen, the mast cells degraulates, releasing chemicals for an inflammatory response
    • acts as opsonins-soluble antibodies coat antigens to flag down phagocytes
    • make antigen clump-this enhances recognition of antigens so phagocytes find then easier

    activates B lymphocytes- these antibodies are bound to B lymphocytes on their Fc region. with as many as 1000. when antigens are detected, the cell differentiates into plasma cell to and make more antibodies and some turn into memory cells.
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Physio Exam 6 21-24
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