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 (C)</p> Signup and view all the answers

    What is the primary function of osteoblasts in bone?

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

    Which disease is associated with defects in fibrillin?

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

    How is collagen organized within bone?

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

    What role does hydroxyapatite play in the composition of bone?

    <p>Offers hardness to bone (D)</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 (C)</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. (D)</p> Signup and view all the answers

    What is the role of estrogen in bone health?

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

    How does calcium contribute to signal transduction?

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

    Which specimen type is NOT commonly used in clinical testing?

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

    What factor can have the largest impact on laboratory results?

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

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

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

    What is NOT included in a basic metabolic panel?

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

    What triggers the release of parathyroid hormone (PTH)?

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

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

    <p>Lipemia (D)</p> Signup and view all the answers

    What role does calcium play in muscle contraction?

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

    Which cells are responsible for bone resorption?

    <p>Osteoclasts (A)</p> Signup and view all the answers

    Which test is NOT part of liver function tests?

    <p>Serum glucose (A)</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 (D)</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. (B)</p> Signup and view all the answers

    Which factor is NOT associated with promoting osteoclastic activity?

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

    What is a common characteristic of oral precancerous lesions?

    <p>They are usually asymptomatic. (D)</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. (B)</p> Signup and view all the answers

    What appearance is most concerning for oral cancer?

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

    What is considered the gold standard for diagnosing oral cancer?

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

    Which condition is a clear sign of hypophosphatasia?

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

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

    <p>Biopsy. (C)</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. (B)</p> Signup and view all the answers

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

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

    Which cells are primarily responsible for bone resorption?

    <p>Osteoclasts (A)</p> Signup and view all the answers

    What role do osteoblasts play in bone maintenance?

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

    How does estrogen influence bone density in postmenopausal women?

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

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

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

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

    <p>Hydroxyapatite (A)</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. (A)</p> Signup and view all the answers

    Which two factors are crucial for osteoclast differentiation?

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

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

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

    What is the primary component of plaque polysaccharides?

    <p>Glucose polymers (B)</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. (B)</p> Signup and view all the answers

    How does fluoride contribute to dental health?

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

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

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

    What are common risk factors for developing oral cancer?

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

    At what sites is oral cancer typically found?

    <p>Tongue and floor of the mouth (D)</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. (C)</p> Signup and view all the answers

    Which statement accurately describes fluoride levels in nature?

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

    Flashcards

    Thrombocytopenia

    A condition where the platelet count is below the normal range.

    Direct Bilirubin

    Water-soluble bilirubin processed by the liver, ready for excretion.

    Indirect Bilirubin

    Unconjugated, insoluble bilirubin, bound to albumin in the blood.

    Pre-analytical variables

    Factors affecting lab results from order to analysis, account for up to 75% of errors.

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    Lipemia

    Milky serum or plasma due to eating before a fasting lab test.

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    Hemolysis

    Rupture of red blood cells during collection, leading to elevated potassium, magnesium, and phosphate.

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    Lipid Panel

    Tests cholesterol (total, HDL, LDL) and triglycerides.

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    Basic Metabolic Panel (BMP)

    Group of chemistry tests measuring kidney function and electrolytes.

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    Desmosine's role in elastin

    Desmosine is a unique amino acid found only in elastin, formed from lysine reactions.

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    Elastin's structure

    Elastin has large hydrophobic domains and is highly elastic and flexible.

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    Fibrillin's function

    Fibrillin is an extracellular matrix protein that provides a scaffold for elastin deposition and limits growth factor availability.

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    Bone composition

    Bone is composed of collagen microfibrils and hydroxyapatite crystals.

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    Collagen's role in bone

    Collagen provides bone shape and strength by offering sites for hydroxyapatite crystal nucleation.

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    Hydroxyapatite's role in bone

    Hydroxyapatite crystals provide bone hardness and strength, filling spaces between collagen pieces.

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    Osteoblasts

    Cells that help build bone.

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    Osteons

    Structural units in compact bone that provide support for nerves and blood supply passage

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    Osteoblast function

    Osteoblasts create new bone and regulate osteoclast activity.

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    Osteoclast role

    Osteoclasts break down bone.

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    RANKL and m-CSF

    These proteins stimulate osteoclast formation and require calcium.

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    Bone resorption and remodeling

    The continuous process of bone breakdown and rebuilding, essential for tooth movement and maintaining bone structure.

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    Enamel composition

    Enamel is primarily hydroxyapatite (90%) and lacks collagen.

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    Bone Density and Age

    Bone density naturally decreases with age, more significantly for women during menopause.

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    Menopause and Osteoporosis

    Decreased estrogen levels during menopause lead to increased osteoclast activity and bone loss, increasing risk of osteoporosis.

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    Bone loss in orthodontics

    Tooth movement alters bone tension: pressure side increases osteoclast activity, tension side increases osteoblast activity.

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    Estrogen's effect on bone

    Estrogen helps reduce bone breakdown by decreasing the production of interleukin-6 (IL-6).

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    Calcium's role in signal transduction

    Calcium acts as a messenger, carrying signals from the cell surface to the cell's interior.

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    Calcium's structural role

    Calcium, in the form of calcium phosphate, is a major component of bone and teeth.

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    Calcium homeostasis

    The process of maintaining calcium levels in the blood within a specific range.

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    Bone remodeling

    The continuous process of breaking down and rebuilding bone tissue, using osteoclasts and osteoblasts.

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    Parathyroid Hormone (PTH)

    A hormone that increases blood calcium levels by promoting calcium reabsorption and inhibiting phosphate excretion.

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    Vitamin D role in Calcium Homeostasis

    Vitamin D is needed for calcium absorption in the intestine.

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    Osteoporosis's effect on teeth

    Osteoporosis weakens the jaw, potentially leading to gum recession and tooth loss.

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    Dental Plaque

    A sticky film of bacteria that forms on teeth, creating an anaerobic environment that promotes acid production.

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    Anaerobic Microenvironment

    An environment lacking oxygen, favoring the growth of anaerobic bacteria in dental plaque.

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    Dextrans

    The most abundant glucose polymers in dental plaque, contributing to its sticky nature.

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    Fluoride's Role

    Fluoride strengthens enamel, increasing remineralization rates and preventing tooth decay.

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    Dental Calculus

    Hardened plaque caused by calcium phosphate precipitation, often forming on teeth.

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    Squamous Cell Carcinoma

    The most common type of oral cancer, originating from the surface lining of the mouth and throat.

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    Oral Cancer Risk Factors

    Tobacco use, alcohol consumption, sun exposure, HPV infection, and iron deficiency are major risk factors for oral cancer.

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    Oral Cancer Etiology

    Mutations in genes controlling cell growth lead to uncontrolled cell division, creating tumors.

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    Oral Precancer

    A condition where cells in the mouth show changes that might lead to cancer. It's often asymptomatic but can appear as a white or red patch.

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    Leukoplakia

    A white patch in the mouth caused by abnormal cell growth, a potential precancerous condition.

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    Erythroplakia

    A red patch in the mouth, a more serious precancerous condition than Leukoplakia.

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    Hypophosphatemia

    Low levels of phosphate in the blood. Can be caused by insufficient intake, increased excretion, or impaired absorption.

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    Hypophosphatasia

    A rare genetic disorder where the body cannot produce enough alkaline phosphatase, affecting bone and teeth development.

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    TNSALP

    The enzyme tissue nonspecific alkaline phosphatase, essential for bone mineralization. A deficiency leads to Hypophosphatasia.

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    Hydroxyapatite

    The mineral component of bone, formed from calcium and phosphate, essential for bone strength.

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    PPi (Pyrophosphate)

    An inhibitor of bone mineralization, accumulation leads to weak bones in Hypophosphatasia.

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    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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