Notes, summaries, assignments, exams, and problems for Biology

Response to Orthodontic Pressure

Light Pressure (<1 second to Hours)

• Less than 1 second: PDL fluid is incompressible; alveolar bone bends, and a piezoelectric signal is generated.
• 1-2 seconds: PDL fluid is expressed; the tooth moves within the PDL space.
• 3-5 seconds: Blood flow within the PDL is partially compressed on the pressure side and dilated on the tension side.
• Minutes: Blood flow is altered, and oxygen tension begins to change.
• Hours: Metabolic changes and chemical messengers affect cellular activity.
• Less than 4 hours: Cellular differentiation begins within the PDL.
• 2 days: Tooth movement occurs as osteoclasts and osteoblasts remodel bone.

Heavy Pressure (<1 second to 7-14 days)

• Less than 1 second: PDL fluid is incompressible; alveolar

Aggressive Periodontitis: Localized vs. Generalized

This section outlines the key similarities and differences between Localized Aggressive Periodontitis (LAP) and Generalized Aggressive Periodontitis (GAP).

Localized Aggressive Periodontitis (LAP)

• Circumpubertal onset.
• Robust serum antibody response to infecting agents.
• Localized first molar/incisor presentation with interproximal attachment loss on at least two permanent teeth, one of which is a first molar.
• Lack of clinical inflammation.
• Presence of deep periodontal pockets.
• Amount of plaque inconsistent with the amount of periodontal destruction.
• Plaque forms a thin biofilm, rarely mineralizing into calculus.
• Distolabial migration and diastema formation.
• Increasing mobility of first molars.
• Sensitivity

First Line of Defense:

• 1) Mechanical Barriers & Surface Secretions:
  • A) Skin
  • B) Mucus Membrane:
    • 1) Sticky Mucus Membrane
    • Cilia
    • Mechanical Cleansing Action: Saliva, Tears, Urine
    • Low pH Stomach
    • Tears & Saliva: Lysozyme
    • Peristalsis in GIT
• 2) Normal Bacterial Flora
• 3) Naturally Occurring Antimicrobial Substances:
  • A) Type I Interferon: Antiviral Effect
  • B) Lysozyme: Lysis of Bacteria
  • C) Complement System: Responsible for Lysing Microorganisms
• 4) Body Hormones
• 5) Genetic Predisposition
• 6) Body Temperature: Pyrexia
• 7) Oxygen Tension
• 8) Inflammation

Serum Soluble Proteins:

• 1) C-Reactive Protein: Binds bacteria, activates complement, causes bacterial lysis (opsonin)
• 2) Ceruloplasmin: Oxidizes iron, inhibiting microbe iron uptake
• 3) Haptoglobin: Binds hemoglobin, inhibiting

Mineral Trioxide Aggregate (MTA) Applications

Pulp Therapy

• Pulp capping
• Furcation repair
• Strip perforation repair
• Root resorption repair
• Immature teeth
• Root end filling material

Elements of Pulp Regeneration

Therapy for exposed dental pulps using stem cells and a biofunctional scaffold, inhibiting or eliminating infection to facilitate pulp generation.

Nickel-Titanium (NiTi) Rotary Instruments

Advantages of NiTi Reciprocation

• Mimics manual movement
• Reduces risks associated with continuous rotation in curved canals

Types of Posts

1. Carbon fiber epoxy resin posts
2. Zirconia posts
3. Glass fiber reinforced posts
4. Ultra-high strength polyethylene fiber reinforced posts

Advantages of NiTi Rotary

• Gradual, evenly tapered radicular preparation
• Fewer instruments required
• Reduced

Metabolic and Biochemical Processes

BMI Calculation: BMI = Kg/M². Interpretation: <25 = Normal, 25-30 = Overweight, >30 = Obese. Ethanolamine (Ethan-NH₃), Choline = N(CH₃)₃

Leptin and Adipose Tissue

Leptin is released from adipose tissue when mass is high. It travels through the blood to the arcuate nucleus, binds to neuronal cells, and activates the JAK-STAT pathway. This increases gene expression of POMC, which produces alpha-MSH (a neurotransmitter). Alpha-MSH reaches neurons connected to adipose tissue, releasing norepinephrine. Norepinephrine binds to beta-adrenergic receptors on adipose tissue, promoting an increase (via the G-protein coupled receptor pathway and activation of PKA). This leads to upregulation of UCP1 expression and... Continue reading "Metabolic Pathways and Liposome Drug Delivery" »

Digestive System Vocabulary

1. Bile – a digestive fluid that helps digest fats
2. Appendix – a small organ attached to the large intestine
3. Celiac disease – an autoimmune disease caused by gluten
4. Defecation – feces / the process of passing stool
5. Weight gain – putting on weight / an increase in body weight
6. Palpate – to examine by touch
7. Stool – solid waste eliminated from the body
8. Bowel – the intestines (small or large)

Digestive Functions and Pathologies

• The pancreas produces and contains digestive enzymes.
• Peptic ulcers may affect the lining of the stomach.
• The last part of the digestive tract is in the large intestine/colon.
• Bile is produced by the liver and released into the duodenum.
• Adverse reaction – reakcja niepożądana
• Autoimmune disorder

Synaptic Transmission Fundamentals

• Synapse: The gap between neurons (synaptic cleft).
• Synaptic Knob: The terminal structure containing vesicles.
• Neurotransmitters: Chemicals that transmit signals.
  • Acetylcholine: Activates muscles.
  • Monoamines: Involved in cognitive processes (emotion, arousal, memory).
  • Amino Acids, Peptides, and Estrogen.
• Vesicles: Store neurotransmitters.
• Axon Hillock: Essential for initiating the firing of a neuron (action potential generation).

Postsynaptic Potentials (EPSP and IPSP)

• EPSP (Excitatory Postsynaptic Potential): Moves the membrane potential toward the threshold.
• IPSP (Inhibitory Postsynaptic Potential): Moves the membrane potential away from the threshold.

Vision and Refractive Errors

• Nearsightedness (Myopia):
  • The eyeball

Cotrimoxazole and Therapeutic Uses

Cotrimoxazole (also known as trimethoprim-sulfamethoxazole or TMP-SMX) is a broad-spectrum antibiotic that combines two antimicrobial agents:

• Trimethoprim (TMP)
• Sulfamethoxazole (SMX)

These two components work synergistically to block two steps in the bacterial synthesis of folic acid, which is essential for bacterial growth and replication.

Mechanism of Action

• Sulfamethoxazole: Inhibits dihydropteroate synthase, blocking the conversion of PABA to dihydrofolic acid.
• Trimethoprim: Inhibits dihydrofolate reductase, blocking the conversion of dihydrofolic acid to tetrahydrofolic acid.

By combining both, cotrimoxazole effectively prevents bacterial DNA synthesis.

Therapeutic Uses of Cotrimoxazole

Cotrimoxazole is used to... Continue reading "Cotrimoxazole: Mechanism, Therapeutic Uses, and Safety" »

Atherosclerosis: Pathogenesis & Complications

A chronic inflammatory disease of medium and large arteries, caused by endothelial injury and lipid accumulation.

Key Risk Factors:

• Hypertension
• Hyperlipidemia
• Smoking
• Diabetes

Lesions evolve from fatty streaks → fibrous plaques → complicated plaques.

Common Complications:

• Myocardial Infarction (MI)
• Stroke
• Aneurysm
• Peripheral Artery Disease

Histologically, it shows lipid cores, calcification, and fibrous caps.

Hypertensive Disease: Organ Damage & Malignant Forms

Chronic blood pressure (BP) elevation causes vascular and organ damage.

Consequences Include:

• Arteriolosclerosis
• Left Ventricular (LV) hypertrophy
• Stroke
• Chronic Kidney Disease

Malignant hypertension (diastolic BP >120 mmHg) causes fibrinoid necrosis... Continue reading "Essential Pathology Topics: Systemic Diseases & Neoplasms" »

First Stage: Gum Pad (Birth to 2 Years)

This stage lasts from birth until the completion of the deciduous maxillary gum pad.

• Maxillary Gum Pad: Horseshoe shape.
• Mandibular Gum Pad: U shape.
• Transverse Division: Elevated ridges are divided into segments for future deciduous teeth.
• Lateral Sulcus: Located distal to the canine area.

Gum Pad Occlusion

Gum Pad at Rest: The pads are not in contact, and the tongue is projecting.

Occlusal relationships are described in three dimensions:

1. Anteroposteriorly (Overjet): Anterior overjet; the mandibular lateral sulcus is posterior to the maxillary.
2. Vertically: Anterior open bite; posterior segments (Segment D) touch.
3. Transversely: The maxillary gum pad is wider than the mandibular (resulting in overjet).

Second Stage: