Biochemistry Exam 3: Hemostasis and Clotting
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Questions and Answers

What is the primary function of desmosine in elastin?

  • Facilitating mineralization in bone
  • Providing unique chemical properties to elastin (correct)
  • Enhancing the flexibility of collagen
  • Acting as a growth factor binding site

    • Which protein provides a scaffold for elastin deposition?

  • Collagen
  • Fibrillin (correct)
  • Hydroxyapatite
  • Desmosine

    • What is the role of pyrophosphate in bone mineralization?

  • Promotes hydroxyapatite formation
  • Enhances osteocyte activity
  • Inhibits hydroxyapatite crystallization (correct)
  • Stimulates collagen synthesis

    • Which type of bone is described as dense and provides structural support?

    <p>Cortical bone</p> Signup and view all the answers

    What is the primary function of osteoblasts in bone?

    <p>Building new bone</p> Signup and view all the answers

    Which disease is associated with defects in fibrillin?

    <p>Marfan syndrome</p> Signup and view all the answers

    How is collagen organized within bone?

    <p>In brick-like shapes</p> Signup and view all the answers

    What role does hydroxyapatite play in the composition of bone?

    <p>Offers hardness to bone</p> Signup and view all the answers

    What condition is indicated by petechia on the lower extremities and gumline along with a super deficient platelet count?

    <p>Thrombocytopenia</p> Signup and view all the answers

    What is the main difference between direct and indirect bilirubin?

    <p>Indirect bilirubin is bound to proteins, whereas direct bilirubin is not.</p> Signup and view all the answers

    What is the role of estrogen in bone health?

    <p>It decreases the production of interleukin-6.</p> Signup and view all the answers

    How does calcium contribute to signal transduction?

    <p>As a messenger conveying signals within the cell.</p> Signup and view all the answers

    Which specimen type is NOT commonly used in clinical testing?

    <p>Bone marrow</p> Signup and view all the answers

    What factor can have the largest impact on laboratory results?

    <p>Time of collection</p> Signup and view all the answers

    Which hormone is responsible for promoting calcium reabsorption in the kidneys?

    <p>Parathyroid hormone (PTH)</p> Signup and view all the answers

    What is NOT included in a basic metabolic panel?

    <p>Total Protein</p> Signup and view all the answers

    What triggers the release of parathyroid hormone (PTH)?

    <p>Low blood calcium levels.</p> Signup and view all the answers

    Which of the following can occur if a patient eats before a fasting lab test?

    <p>Lipemia</p> Signup and view all the answers

    What role does calcium play in muscle contraction?

    <p>It activates cellular processes necessary for contraction.</p> Signup and view all the answers

    Which cells are responsible for bone resorption?

    <p>Osteoclasts</p> Signup and view all the answers

    Which test is NOT part of liver function tests?

    <p>Serum glucose</p> Signup and view all the answers

    What can imply a significant laboratory error due to sample collection issues?

    <p>High levels of potassium and magnesium</p> Signup and view all the answers

    What effect does calcitonin have on calcium levels in the body?

    <p>It inhibits calcium reabsorption in the kidneys.</p> Signup and view all the answers

    Which factor is NOT associated with promoting osteoclastic activity?

    <p>Increased weight-bearing exercise</p> Signup and view all the answers

    What is a common characteristic of oral precancerous lesions?

    <p>They are usually asymptomatic.</p> Signup and view all the answers

    Which of the following is considered a sign of advanced oral cancer?

    <p>Pain radiating to the ear.</p> Signup and view all the answers

    What appearance is most concerning for oral cancer?

    <p>Erythroplakia.</p> Signup and view all the answers

    What is considered the gold standard for diagnosing oral cancer?

    <p>Biopsy.</p> Signup and view all the answers

    Which condition is a clear sign of hypophosphatasia?

    <p>Loss of hydroxyapatite.</p> Signup and view all the answers

    Which alternative method is NOT scientifically backed for the diagnosis of oral lesions?

    <p>Biopsy.</p> Signup and view all the answers

    In which area of the mouth is there a higher concern for abnormalities indicative of oral cancer?

    <p>Sides of tongue.</p> Signup and view all the answers

    What lesser-known condition can resemble oral cancer and is caused by friction?

    <p>Frictional hyperkeratosis.</p> Signup and view all the answers

    Which cells are primarily responsible for bone resorption?

    <p>Osteoclasts</p> Signup and view all the answers

    What role do osteoblasts play in bone maintenance?

    <p>They differentiate from stroma.</p> Signup and view all the answers

    How does estrogen influence bone density in postmenopausal women?

    <p>It reduces osteoclast numbers.</p> Signup and view all the answers

    Which process occurs on the pressure side of moving teeth during orthodontic treatment?

    <p>Increased osteoclast activity.</p> Signup and view all the answers

    What is the primary component of enamel that contributes to its hardness?

    <p>Hydroxyapatite</p> Signup and view all the answers

    What happens to bone density with age, particularly in women?

    <p>It decreases more significantly in women post-menopause.</p> Signup and view all the answers

    Which two factors are crucial for osteoclast differentiation?

    <p>RANKL and m-CSF</p> Signup and view all the answers

    What is one consequence of increased osteoclast activity in conditions like osteoporosis?

    <p>Bone erosion</p> Signup and view all the answers

    What is the primary component of plaque polysaccharides?

    <p>Glucose polymers</p> Signup and view all the answers

    What happens to the anaerobic environment within dental plaque as it develops?

    <p>It becomes increasingly anaerobic, favoring anaerobic bacteria.</p> Signup and view all the answers

    How does fluoride contribute to dental health?

    <p>It increases the rate of remineralization of enamel.</p> Signup and view all the answers

    Which of the following is a major type of oral cancer?

    <p>Squamous cell carcinoma</p> Signup and view all the answers

    What are common risk factors for developing oral cancer?

    <p>Tobacco use, HPV, alcohol</p> Signup and view all the answers

    At what sites is oral cancer typically found?

    <p>Tongue and floor of the mouth</p> Signup and view all the answers

    How does the access to oxygen change for bacteria in the interior of plaque?

    <p>Bacteria have reduced access to oxygen.</p> Signup and view all the answers

    Which statement accurately describes fluoride levels in nature?

    <p>Fluoride levels vary depending on the environment.</p> Signup and view all the answers

    Study Notes

    Biochemistry Exam 3 Study Notes

    • Hemostasis and Blood Clotting:

      • Clotting begins with platelet aggregation, triggered by contact with the sub endothelium, resulting in a prothrombotic response.
      • Platelets are activated by collagen, thromboxane A2 (TXA2), and ADP.
      • This process activates secondary messengers, IP3, leading to calcium release and platelet activation.
      • Inactive platelets have receptors for PGI2, which antagonizes activation and inhibits calcium release.
      • PGI2 and cyclic AMP decrease platelet aggregation, while TXA2 and ADP increase it.
      • Blood clotting occurs through vasoconstriction, platelet plug formation (adhesion, activation, aggregation), and coagulation cascade.
      • Blood clotting can be triggered by external or internal injury to the endothelial cell layer.
      • Clotting factors (like II, VII, IX, X) rely on vitamin K (in their synthesis).
      • Calcium plays a crucial role in the coagulation cascade.
      • Inhibitors like antithrombin III and others help regulate clotting.

    • Roles of Calcium and Vitamin K:

      • Clotting factors that bind calcium have modified amino acids.
      • Vitamin K is a cofactor for the enzyme that carboxylates glutamic acid residues in clotting factors.
      • These carboxylated residues are critical for binding calcium, an essential step in the clotting process.
      • Citrate and EDTA are calcium chelators, that can block clotting.

    • Heme Biosynthesis:

      • Heme is a prosthetic group found in hemoglobin and myoglobin.
      • It's composed of a porphyrin ring with an iron ion (Fe2+) at the center.
      • Critical steps of heme synthesis occur in mitochondria and cytoplasm.
      • The synthesis pathway includes the formation of d-amino levulinic acid (d-ALA).
      • The rate-limiting step in heme synthesis is the reaction catalyzed by d-ALA synthase.
      • Enzymes like d-amino levulinic acid dehydratase and ferrochelatase are very sensitive to lead poisoning.
      • Heme synthesis is regulated differently in liver and bone marrow. It can be regulated by feedback inhibition, by free heme, in the liver, through transcriptional and translational regulation of δ-aminolevulinate synthase. And in the bone marrow, heme synthesis is stimulated by erythropoietin and by iron.

    • Hemostasis Tests:

      • PT (prothrombin time) tests the extrinsic pathway (factors VII, X,V).
      • PTT (partial thromboplastin time) tests the intrinsic pathway (factors XII, XI, IX, VIII, X, V).

    • Blood Clotting Factors:

      • Factors 8 and 9 are Vitamin K dependent.
      • Factor Va is blocked by protein C in coagulation.

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    Biochemistry Exam 3 PDF

    Description

    Prepare for your Biochemistry Exam 3 with this study guide focused on hemostasis and blood clotting mechanisms. Understand the roles of platelets, clotting factors, and the calcium-dependent cascade that leads to successful clot formation. Key concepts include the interaction of various molecules in the clotting process and the physiological responses to injury.

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