General Concepts of Disease

General Concepts of Disease

• Disease is a disturbance of the body's structure or function
• Asymptomatic: Disease without symptoms

Principles of Diagnosis

• The study of diseases is Pathology
• Bacteria are a pathogen
• Diagnosis determines the nature and cause of illness
• Diet history is not part of a patient’s clinical history
• Prognosis refers to the eventual outcome of a disease
• A physical examination involves a systematic examination of the body

Diagnostic Tests

• A screening test helps to detect diseases early
• A biopsy is an invasive diagnostic procedure
• A test with high specificity excels at detecting individuals without the disease
• A test with high sensitivity is useful at detecting individuals with the disease

Imaging Techniques

• MRI does not use radiation
• MRI is best for detecting soft tissue abnormalities
• Ultrasound's primary advantage is that it is non-invasive and safe for pregnancy
• A PET scan primarily assesses metabolic activity of tissues
• EEG measures electrical activity in the brain

Types and Classifications of Diseases

• Endoscopy is used for viewing the interior of organs
• Infectious diseases are caused by microorganisms
• Degenerative diseases are caused by a deficiency
• Neoplastic is the disease classification that includes cancer
• Disease with unknown cause is Idiopathic

Treatment

• Specific treatment targets the underlying cause of a disease
• Symptomatic treatment relieves symptoms without curing the disease
• Pain relievers for headaches are an example of symptomatic treatment

Basic Structure and Organization of Cells

• The cell is the fundamental structural and functional unit of the body
• The nucleus directs metabolic functions of the cell
• The cytoplasm is surrounded by the cell membrane

Organelles and Their Functions

• Mitochondria are responsible for energy production
• The golgi apparatus modifies and packages proteins
• Lysosomes are responsible for digesting cellular waste
• The rough endoplasmic reticulum (RER) is associated with protein synthesis
• Centrioles help move chromosomes during cell division

Tissues and Their Functions

• Plasma is not a type of tissue
• Epithelial tissue primarily functions to cover and protect body surfaces
• Connective tissue includes blood, bones and cartilage
• Cardiac muscle is the muscle found in the heart

Cellular Transport

• Diffusion is the movement of molecules from high to low concentration
• Osmosis refers to water moving through a selectively permeable membrane
• Active transport requires energy to move molecules against a concentration gradient
• Phagocytosis refers to Cell eating

Cell Adaptations and Injury

• Hypertrophy refers to an increase in cell size
• Hyperplasia refers to the increase in both cell size and number
• Metaplasia is the process of a cell changing from one type to another

Cell Death and Aging

• Apoptosis is programmed cell death
• Sodium diffusion into a cell is called Cell swelling
• All necrotic cells are dead
• Damage to DNA and organelles leads to aging and cell damage
• Apoptosis is controlled while necrosis is uncontrolled
• Genetic makeup, environmental factors and the efficiency of repair mechanisms play a role in cell longevity;

Genes and Inheritance

• A gene expressed in both homozygous and heterozygous states is Dominant
• A gene expressed only in the homozygous state is Recessive
• Sex-linked genes are located on a sex chromosome

Chromosomes and DNA Structure

• In females, one of the two X chromosomes is inactivated; this structure is called a Barr body
• Humans have 22 pairs of autosomes
• DNA controls cell activities and inheritance
• The nucleotide is the basic structural unit of DNA
• Uracil is found in RNA but not in DNA

Protein Synthesis

• Transfer RNA carries the genetic instructions from DNA to the ribosome
• The ribosome is responsible for protein synthesis
• The process of copying DNA into mRNA is called Transcription
• Converting mRNA into a protein is called Translation

Cell Division

• Mitosis results in two identical daughter cells
• Chromosomes line up in the center of the cell during Metaphase
• Chromatids separate and move to opposite poles during Anaphase
• Human Cells have 46 chromosomes after mitosis

Meiosis and Gametogenesis

• Meiosis reduces the chromosome number by half
• Germ cells undergo meiosis
• Four functional sperm are produced from one spermatogonium
• One functional ovum is produced from one oogonium

Mitochondrial DNA and Gene Technology

• Mitochondria contains its own DNA
• Mitochondrial DNA is inherited only from the mother
• Recombinant DNA technology studies gene structure and function
• Gene therapy repairs or replaces defective genes
• CRISPR-Cas9 edits genes precisely.

Congenital vs. Hereditary Diseases

• Congenital diseases are present at birth, but not necessarily inherited
• Hereditary Disease result from a chromosome abnormality or defective gene
• Vaccination during pregnancy is not a cause of congenital malformations
• The period when an embryo is most vulnerable to injury is the third to eighth week

Causes of Congenital Malformations

• Known causes of intrauterine injuries include harmful drugs/chemicals, maternal infection and radiation exposure
• Zika virus is a maternal infection known to cause brain defects in a fetus
• Thalidomide caused limb deformities in babies
• Cytomegalovirus infection in a pregnant woman can cause severe fetal brain and lung infection

Chromosomal Abnormalities

• Nondisjunction occurs when homologous chromosomes fail to separate during cell division
• Monosomy is a condition in which there is one missing chromosome
• Trisomy is the presence of an extra chromosome in a cell
• Turner syndrome involves a missing X chromosome

Specific Chromosomal Disorders

• Klinefelter syndrome is a sex chromosome disorder
• The genotype of Klinefelter syndrome is 47, XXY
• Downsyndrome is the most common chromosomal abnormality in newborns
• Down syndrome is caused by nondisjunction of chromosome 21

Genetic Inheritance

• An autosomal dominant disorder means that only one copy of the defective gene is needed to have the disease
• Tay-Sachs disease is inherited in an autosomal recessive manner
• X-linked disorders primarily affect males
• Mutation is a permanent change in genetic material.

Prenatal Diagnosis

• Amniocentesis involves collecting a sample of amniotic fluid to check for genetic abnormalities
• A major advantage of chorionic villus sampling over amniocentesis is that it can be done earlier in pregnancy
• High alpha-fetoprotein (AFP) levels in amniotic fluid may suggest neural tube defects
• Ultrasound is non-invasive and detects structural abnormalities
• Age of the mother is a major risk factor for chromosomal abnormalities in babies