Introduction to Pathology Quiz

Introduction to Pathology

• Pathology is the study of disease and suffering.
• Oral and Maxillofacial Pathology is a specialization within pathology.

Course Structure

• Quizzes are mostly on Mondays.
• Most online classes are on Wednesday and Monday.
• Class times: 8:00 am - 10:00 am (Mondays and Wednesdays)
• 3 partial exams (45%); final exam (20%)
• In-class cases/histology (15%)
• Quizzes (15%)
• Professionalism & Class Participation (5%)

Pathology of Disease

• General pathology examines the basic cellular and tissue responses to disease.
• Systemic pathology focuses on the effects of disease across specialized organs and tissues.

The Cell (Cell Structure)

• The cell contains many organelles including: 
  • Chromatin
  • Nucleus
  • Nucleolus
  • Nuclear envelope
    • Plasma membrane
    • Smooth endoplasmic reticulum
  • Rough endoplasmic reticulum
    • Ribosomes
    • Golgi apparatus
    • Lysosome
    • Mitochondrion
    • Centrioles
    • Glycosomes
    • Cytosol
    • Peroxisome
    • Microfilament - Microtubule
  • Intermediate filament
    • microvilli
• Cell processes:
  • Exocytosis: Secretion of materials out of the cell

Noncoding DNA

• The human genome contains roughly 3.2 billion DNA base pairs, 80% are non-coding DNA.
• These regions include promoters, enhancers, binding sites for transcription factors, regulatory RNAs, transposons, and telomeres (chromosome ends) and centromeres (chromosome "tethers").
• These regions are essential for gene expression and “architectural planning".

Genetic Variations

• Many genetic variations (polymorphisms) are associated with diseases.
• Variations in gene regulation can be more crucial than structural protein changes.
• Sequencing analysis of any two people shows >99.5% similarity.
• Variations are primarily in SNPs and CNVs within a few regions in the DNA.

DNA Single Nucleotide Polymorphisms (SNPs)

• SNPs are variations in a single nucleotide in a DNA base pair.
• Over 6 million SNPs have been located in humans' genomes, including exons, introns, and intergenic regions.
• SNPs in noncoding areas can affect gene expression,
• SNPs can potentially be linked with diseases.

Copy Number Variations (CNVs)

• CNVs are variations in the DNA sequences involving the number of larger contiguous DNA sequences.
• They range from 1000 base pairs to millions of base pairs.
• They can be duplicated or deleted in individuals. CNVs vary between individuals by millions of base pairs.

Epigenetics Factors

• Epigenetics refers to heritable changes in gene expression. 
• They are not caused by modifications in the DNA sequence. 
• Common types of epigenetic changes are:
  • Histone acetylation
  • Histone methylation
  • Histone phosphorylation
    • DNA methylation
    • Chromatin organization

Histones

• Histones are specialized proteins important for chromatin dynamics
• The DNA and histone complex is called chromatin.
• Chromatin is found in two forms:
  • Heterochromatin
  • Euchromatin

MicroRNAs and Long Noncoding RNAs (lncRNAs)

• miRNAs are noncoding RNAs that regulate gene expression by modulating the translation of target mRNAs.
• siRNAs (small interfering RNAs) are also noncoding RNAs, which regulate multiple genes and can be introduced into cells experimentally to silence target genes.
• lncRNAs are noncoding RNAs exceeding coding mRNAs. They modulate gene expression. 
• Example: XIST, regulates X-chromosome inactivation in females.

Cell Housekeeping

• Cell housekeeping involves many vital functions to maintain cell health.
• The cell membrane protects against its surroundings.
• Nutrients arrive and are processed by cells.
• Internal communication and movement of cells are vital functions.
• Cell compartments like the endoplasmic reticulum and Golgi are important for synthesizing molecules.
• Energy production happens inside the mitochondria.

Cell Death

• Two major pathways of cell death are necrosis and apoptosis.
• Necrosis follows cellular damage from toxins, ischemia, or trauma. 
• Apoptosis is a programmed cell death that is essential for development and normal tissue turnover.

Cell Signaling

• Cells receive and respond to several signals.
• Some cell signals lead to differentiation, some lead to cell specialization, and others induce proliferation and cell division.
• Types of cell signaling: 
  • Autocrine
  • Paracrine
  • Endocrine
  • Synaptic

Growth Factors

• Growth factors are signaling molecules that stimulate the activities of signaling pathways and genes.
• They stimulate cellular functions like survival, growth, and division.
• Growth factors bind to specific receptors to regulate cellular processes.
• Growth factors can also promote cell replication and prevent apoptosis.

Extracellular Matrix (ECM)

• ECM consists of a network of proteins.
• It provides structural support, regulates cell signaling, and contributes to tissue development, healing, and maintenance.
• The interstitial matrix fills spaces between cells and the basement membrane surrounds epithelial cells and some connective tissues.
• Cells have ECM receptors and integrins that facilitate cell adhesion and signaling. 
• Forms of ECM:
  • Fibrillar collagens
  • Elastin
  • Proteoglycans, including chondroitin sulfate, dermatan sulfate, keratan sulfate, and hyaluronan (HA).
  • Adhesive proteins including fibronectin.

Tissue Repair and Regeneration

• Tissue repair involves either full tissue regeneration or repair by scarring.
• Labile tissues regenerate readily, while stable tissues can regenerate, and permanent tissues cannot, leading to scarring.
• Steps in scar formation include inflammation, formation of granulation tissue, and scar formation to repair the injury.

Stem Cells

• Stem cells are cells that have the ability to differentiate into specialized cell types.
• They are crucial components of tissue homeostasis, especially in the repair of damaged tissues. 
• There are different types of stem cells: totipotent (embryos only), pluripotent, multipotent, and lineage-committed stem cells.
• Stem cells play central roles in all organs and tissues involved in normal function.

Three Types of Tissue

• Labile Tissues: these are tissues that constantly renew themselves (such as skin, bone marrow, GI epithelium).
• Stable Tissues: these are tissues that renew themselves only when there is an injury and are able to heal. (examples include: Liver, Kidney, Pancreas)
• Permanent tissues: These tissues cannot regenerate (such as the heart and brain).

Cytokines

• Cytokines are proteins involved in inflammation and immune system functions.
• They regulate several bodily processes.

Regenerative Medicine

• Regenerative medicine focuses on restoring damaged tissues or organs using stem cells, cellular therapy or induced pluripotent stem cells (iPSCs).
• Regenerative approaches offer solutions and opportunities in treating diseases.

Objectives and Summary

• This section covers specific objectives and topics, useful for further understanding of the subject matter.