Biochemistry Exam 3: Hemostasis and Clotting
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Questions and Answers

What unique amino acid is found in elastin and results from lysine modifications?

  • Hydroxyapatite
  • Collagen
  • Desmosine (correct)
  • Fibrillin

What primary function do fibrillin microfibrils serve in the body?

  • Facilitate chemical signaling
  • Store calcium for bone health
  • Assist in the elastic fiber formation (correct)
  • Provide structural strength in bones

Which disease is associated with defects in elastin-related components?

  • Ehlers-Danlos syndrome
  • Scurvy
  • Osteoporosis
  • Marfan syndrome (correct)

What is the role of osteoblasts in bone formation?

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

What is a major component that provides hardness to bones?

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

How are the collagen fibers organized in bone structure?

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

What prevents the formation of hydroxyapatite crystals in bones?

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

What is the primary role of heparin in the blood coagulation process?

<p>Binds to antithrombin to enhance its action (A)</p> Signup and view all the answers

What type of bone is focused on structural support and contains osteons?

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

Which test evaluates the extrinsic pathway in the coagulation process?

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

What does a prolonged prothrombin time indicate?

<p>Deficiency in extrinsic pathway factors or vitamin K (A)</p> Signup and view all the answers

What is the effect of warfarin on blood coagulation?

<p>Acts on liver cells to reduce clotting factors (C)</p> Signup and view all the answers

What effect does lead have on heme synthesis?

<p>Replaces Fe2+ in ferrochelatase (B)</p> Signup and view all the answers

Which condition is characterized by a deficiency of platelets?

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

What is the role of calcium chloride in the PT test?

<p>To start the coagulation process (B)</p> Signup and view all the answers

What happens to d-ala levels in the case of lead poisoning?

<p>d-ala is overproduced (A)</p> Signup and view all the answers

Which factor primarily regulates the transfer of iron from intestinal cells into the bloodstream?

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

Which of the following describes fibrinolysis?

<p>The breakdown of vascular clots (C)</p> Signup and view all the answers

Why is the bleeding time test not commonly used anymore?

<p>It has high variability in results (B)</p> Signup and view all the answers

What is the outcome of high hepcidin levels in the body?

<p>Decreased iron uptake (D)</p> Signup and view all the answers

What is bilirubin a product of?

<p>Conversion of hemoglobin (B)</p> Signup and view all the answers

How is iron stored within cells?

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

What occurs to bilirubin when it accumulates in the body?

<p>It leads to jaundice (B)</p> Signup and view all the answers

Which condition leads to low heme production due to depressed d-ala synthesis?

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

What role does estrogen play in bone density regulation?

<p>Decreases interleukin-6 production (D)</p> Signup and view all the answers

What is the primary role of calcium in bone and teeth?

<p>Forms calcium phosphate, a structural component (D)</p> Signup and view all the answers

Which hormone is primarily responsible for stimulating bone resorption?

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

Which statement best describes the function of osteoblasts?

<p>They are involved in bone formation. (D)</p> Signup and view all the answers

How does calcitonin affect calcium levels in the body?

<p>It inhibits osteoclastic activity. (B)</p> Signup and view all the answers

What triggers the release of parathyroid hormone (PTH)?

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

What is the role of vitamin D in calcium homeostasis?

<p>It promotes calcium reabsorption in the kidney. (C)</p> Signup and view all the answers

What cellular effect does Ca2+ have regarding muscle function?

<p>Activates blood platelets (D)</p> Signup and view all the answers

What is the immediate response of parathyroid glands to low serum calcium levels?

<p>Release parathyroid hormone (PTH) (A)</p> Signup and view all the answers

How does hyperparathyroidism primarily affect bone health?

<p>Stimulates osteoclast activity to degrade bone (C)</p> Signup and view all the answers

What role does calcitonin play in calcium homeostasis?

<p>Inhibits bone resorption and stimulates calcium excretion (B)</p> Signup and view all the answers

What occurs when plasma calcium levels are high?

<p>Osteoclast activity is decreased (A)</p> Signup and view all the answers

Which of the following is NOT a consequence of hypoparathyroidism?

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

What effect does excessive vitamin D intake have on calcium homeostasis?

<p>Increases calcium resorption from bones (D)</p> Signup and view all the answers

What happens during chronic low extracellular calcium levels?

<p>Increased production of PTH mRNA (D)</p> Signup and view all the answers

What is the primary function of vitamin D in relation to calcium homeostasis?

<p>Stimulates calcium absorption from the gut (C)</p> Signup and view all the answers

What is the primary component of the polysaccharides found in dental plaque?

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

Which of the following statements accurately describes the anaerobic environment in fully developed dental plaque?

<p>It limits access to oxygen for bacteria. (D)</p> Signup and view all the answers

Which cancer is the most common type of oral cancer?

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

What is a major risk factor associated with the development of oral cancer?

<p>Tobacco use (B)</p> Signup and view all the answers

How does fluoride contribute to dental health?

<p>It inhibits demineralization. (B)</p> Signup and view all the answers

Which area is NOT typically associated with the development of squamous cell carcinoma?

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

What is the consequence of metabolic acids not diffusing out of dental plaque quickly?

<p>Acidic environment contributing to tooth demineralization (B)</p> Signup and view all the answers

How is oral cancer occurrence related to age and gender?

<p>More common in older people than younger people (B)</p> Signup and view all the answers

Flashcards

Platelet Activation

Platelets become active when they come into contact with damaged blood vessels.

Clotting Cascade

A series of chemical reactions that lead to blood clotting.

Calcium in Blood Clotting

Calcium is needed for many clotting factors to function properly.

Vitamin K in Blood Clotting

Vitamin K helps activate clotting factors.

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Antithrombin III

A natural anticoagulant that helps prevent blood clots.

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Prothrombin Time (PT)

A blood test that measures the time it takes for the extrinsic pathway of the coagulation cascade to form a clot.

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Heme Synthesis

A process producing heme, a component crucial for oxygen transport.

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Bilirubin

A byproduct of hemoglobin breakdown that is eventually excreted in bile.

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Neonatal Jaundice

A condition where bilirubin accumulates in a newborn, potentially causing toxicity.

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What does Heparin do?

Heparin is an anticoagulant that prevents blood clots by enhancing antithrombin's action against thrombin and factor Xa.

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What is Warfarin?

Warfarin is a vitamin K antagonist that slows down blood clotting by interfering with the liver's production of clotting factors.

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What does 'Fibrinolysis' mean?

Fibrinolysis is the breakdown of blood clots, both in blood vessels and during wound healing.

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What is the function of Aspirin?

Aspirin inhibits platelet aggregation, preventing platelets from sticking together and forming clots.

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What is Thrombocytopenia?

Thrombocytopenia is a condition where the number of platelets in the blood is too low, leading to increased bleeding.

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What is Glanzmann's Thrombasthenia?

Glanzmann's Thrombasthenia is a rare genetic disorder where platelets lack functional fibrinogen receptors, leading to poor platelet aggregation and bleeding problems.

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What are Petechiae?

Petechiae are small reddish hemorrhages (bleeding spots) on the skin, often caused by platelet deficiency.

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What does the bleeding time test measure?

The bleeding time test assesses primary hemostasis by measuring how long it takes for a small wound to stop bleeding.

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Desmosine

A unique amino acid found only in elastin, formed by the chemical modification of lysine residues.

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Elastin

A protein that gives tissues like skin and blood vessels their elasticity.

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Fibrillin

An extracellular matrix protein that acts as a scaffold for elastin deposition.

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Marfan Syndrome

A genetic disorder caused by mutations in the fibrillin gene (FBN1), leading to defects in connective tissue.

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Hydroxyapatite

A mineral found in bones and teeth, providing hardness and strength.

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Collagen

A protein that gives bones their shape and strength, acting as a scaffold for hydroxyapatite.

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Osteoblasts

Cells responsible for building bones, depositing collagen and hydroxyapatite.

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Osteoclasts

Cells responsible for breaking down bone, removing old or damaged tissue.

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Lead Poisoning and Heme Synthesis

Lead poisoning disrupts heme synthesis by interfering with specific enzymes, ultimately leading to microcytic anemia (small red blood cells with low hemoglobin).

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D-Ala Overproduction

Lead poisoning inhibits heme synthesis, which normally inhibits D-ala synthase. Without this inhibition, D-ala is overproduced, leading to neurotoxicity, particularly in developing brains.

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Hereditary Defects in Heme Synthesis

Porphyrias are genetic disorders that interfere with heme synthesis, often due to deficiencies in specific enzymes. This results in low heme production.

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Iron Uptake and Transport

Iron, essential for heme synthesis, is absorbed inefficiently in the intestines. Transferrin, a protein in the blood, carries iron to cells. The liver controls iron storage and uptake.

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Hepcidin Regulation of Iron Uptake

Hepcidin, a hormone secreted by the liver, regulates iron absorption by controlling ferroportin, a protein that helps iron enter the blood. High hepcidin means low iron intake.

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Iron Deficiency and Overload

Iron deficiency leads to anemia. Iron overload can lead to tissue damage, as excess iron can be harmful.

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Hemoglobin Degradation and Bilirubin Production

Hemoglobin breaks down in macrophages, releasing bilirubin, a yellow pigment. Bilirubin is insoluble in water, so it's transported bound to albumin. Excess bilirubin causes jaundice.

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Bilirubin Metabolism

Bilirubin is excreted in bile after being conjugated in the liver. This conjugation makes it water-soluble and easier to eliminate.

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Calcium's Roles

Calcium serves two main roles: as a messenger conveying signals within cells and as a structural component of bones and teeth.

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Calcium in Signal Transduction

Calcium ions activate cells by triggering various processes like muscle contraction, neurotransmitter release, and T cell activation.

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Calcium Homeostasis

Maintaining a stable level of calcium in the blood involves a complex interplay between bones, the digestive tract, and kidneys.

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Parathyroid Hormone (PTH)

PTH is released when blood calcium levels are low, increasing calcium absorption in the gut and reabsorption in the kidneys.

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Vitamin D's Role

Vitamin D enhances calcium absorption in the intestine, working in synergy with PTH.

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Calcitonin's Function

Calcitonin is released when blood calcium levels are high, inhibiting bone resorption and promoting calcium deposition in bones.

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Bone Remodeling

A continuous process of bone resorption by osteoclasts and bone formation by osteoblasts ensures bone strength and adaptation.

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Osteoclasts and Osteoblasts

Osteoclasts break down bone, while osteoblasts rebuild it, tightly coupled to maintain bone health.

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Dental Plaque

A thin, sticky film of bacteria that forms on teeth, leading to an anaerobic environment in the interior, where they primarily utilize anaerobic glycolysis to generate energy.

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Dental Calculus

Hardened dental plaque formed by the precipitation of calcium phosphate in the plaque, often occurring due to inhibited precipitation by salivary proteins.

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Fluoride's Role in Teeth

Fluoride enhances tooth remineralization by increasing the rate at which calcium phosphate is deposited on the enamel surface, helping to prevent tooth decay.

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Oral Cancer: The Main Type

Squamous cell carcinoma is the most common type, arising from the epithelial lining of the mouth and throat.

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Where is Oral Cancer Typically Found?

Oral cancer frequently occurs on the tongue and the floor of the mouth.

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Oral Cancer: Men vs. Women

Oral cancer is more common in men than women and is also more prevalent in older people.

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How Does Oral Cancer Develop?

Oral cancer arises from genetically damaged cells that continue to divide uncontrollably. This can be caused by the inactivation of tumor suppressor genes or the activation of oncogenes.

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Major Risk Factors for Oral Cancer

Primary risk factors include tobacco use (especially smoking), alcohol consumption, sun exposure, HPV infection, and iron deficiency.

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Parathyroid Hormone (PTH) Role

PTH is a hormone that regulates calcium levels in the blood. It increases calcium levels by stimulating calcium absorption from the gut, inhibiting calcium excretion from the kidneys, and promoting bone resorption (breaking down bone to release calcium).

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Calcium Regulation: Low Levels

When blood calcium levels are low, the parathyroid glands release PTH. This triggers a cascade of events to increase calcium levels in the blood, ultimately restoring balance.

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Calcium Regulation: High Levels

High blood calcium levels lead to a decrease in PTH release and suppression of osteoclast activity. This helps prevent excessive bone resorption and the release of calcium.

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Vitamin D's Role in Calcium

Vitamin D is crucial for calcium absorption from the gut. It also helps regulate calcium balance in the bones.

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Calcitonin's Role

Calcitonin is a hormone that lowers blood calcium levels. It inhibits bone resorption and promotes calcium excretion by the kidneys, acting as a protective mechanism against excessive bone loss.

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Hyperparathyroidism

Excessive production of PTH leads to hyperparathyroidism. This causes increased bone resorption, leading to bone fragility, kidney stones, and other complications as calcium levels are abnormally high.

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Hypoparathyroidism

Hypoparathyroidism is characterized by low PTH levels. This results in decreased calcium levels in the blood, causing symptoms like muscle cramps, neurological issues, and heart problems.

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Vitamin D Deficiency

Insufficient vitamin D intake can lead to impaired calcium absorption, weakening bones over time, and potential for low blood calcium levels.

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Study Notes

Biochemistry Exam 3 Study Notes

  • Hemostasis and Blood Clotting:

    • Clotting begins with physical aggregation of platelets, which are small, non-nucleated cells circulating in the blood.
    • Platelet activation occurs upon contact with subendothelium and is triggered by several molecules (collagen, thromboxane A2, ADP).
    • Platelet activation involves a cascade of events including the production of second messengers, such as IP3, leading to calcium release, and platelet activation.
    • Inactive platelets have surface receptors for molecules like PGI2, which antagonizes platelet activation by inhibiting calcium release, and TXA2 and ADP, which facilitate aggregation and coagulation.
    • Blood clotting is triggered by external or internal injury to the endothelial cells.
    • The main processes of hemostasis include: vasoconstriction, platelet plug formation (adhesion, activation, and aggregation), and the coagulation cascade.
    • Platelet aggregation is a fragile process, relying on non-covalent bonds to hold platelets together.
    • The coagulation cascade is complex, involving various clotting factors that interact in a specific sequence.
    • Calcium, and vitamin K, play critical roles in the clotting cascade; they are cofactors for specific clotting factors, including factors II, VII, IX, and X.

  • Calcium and Vitamin K in Blood Clotting:

    • Clotting factors require calcium for proper functioning.
    • Vitamin K is crucial in several steps of the blood coagulation cascade. It converts specific amino acids into carboxylated forms to allow them to bind calcium properly allowing clotting to occur.

  • Natural and Pharmacological Anticoagulants:

    • Antithrombin III is a natural anticoagulant. Heparin works by accelerating the action of antithrombin III.
    • Aspirin and warfarin are pharmacological inhibitors of coagulation that interfere with platelet aggregation and coagulation pathways respectively.
    • Heparin is an anticoagulant which helps with fibrinolysis, preventing blood clots.

  • Blood Clotting Tests:

    • Prothrombin time (PT) tests for the extrinsic pathway. Activated partial thromboplastin time (PTT) tests for the intrinsic pathway. Bleeding time measures primary hemostasis.

  • Heme Biosynthesis:

    • Heme is a prosthetic group for several proteins, including hemoglobin and myoglobin, crucial for oxygen transport.
    • Heme synthesis involves sequential steps in mitochondria and cytoplasm in cells.
    • Heme synthesis is regulated depending on the need level for the cell needing it.
    • Lead poisoning can interfere with the synthesis of heme. This is very harmful as it affects the bone marrow specifically where red blood cells and blood cells are produced.

  • Iron Metabolism:

    • Iron is an essential component for heme synthesis, and plays an important part in the absorption, transport and storage of iron.
    • Iron balance is maintained by regulatory mechanisms involving peptides such as hepcidin, transferrin and ferritin

  • Bilirubin Metabolism:

    • During heme degradation, bilirubin is produced from hemoglobin breakdown (as byproduct).
    • Bilirubin is further processed and excreted in the bile, where it is eventually converted to stercobilin and excreted in feces.

  • Neonatal Jaundice and UV light:

    • Bilirubin is toxic to infants who lack a blood-brain barrier. Accumulating bilirubin in fatty tissues of newborns can be treated through phototherapy, using UV light.

  • Other Details:

    • Hemoglobin is broken down to cause the breakdown of biliverdin, which is further reduced to bilirubin.
    • Bilirubin is a yellow pigment and is excreted in the urine.

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Prepare for Biochemistry Exam 3 with this focused quiz on hemostasis and blood clotting. Explore the intricate processes of platelet activation, aggregation, and the coagulation cascade essential for understanding blood function. Test your knowledge and ensure you're ready for the exam!

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