biola

The big Three

HIV, Tuberculosis, Malaria

Epidemiology

Finding the causes of disease; helps determine what causes infectious diseases and how they spread

Epidemic

Outbreak of an infectious disease that later subsides

Pandemic

An epidemic that is geographically widespread

Endemic

Continually present in a region

A Plague

Serious disease afflicting a population

The Plague (Black Death)

Specific disease caused by Yersinia pestis

Innate Immunity

Limits pathogen spread during initial infection and activates the adaptive immune system

Adaptive Immunity

Eliminates specific pathogens and develops memory for faster future responses

Virus

Cannot replicate on its own; requires a host cell

Phagocytes

White blood cells that engulf and destroy invading pathogens; first line of defense

First line of defense

Phagocytes of the innate immune system

Types of phagocytes of the innate immune system

Neutrophils, macrophages, dendritic cells

Macrophage and dendritic cell lifespan

2–3 weeks

Location of macrophages and dendritic cells

Virtually every tissue; increase during inflammation or damage

Functions of macrophages and dendritic cells

Engulf and kill bacteria, orchestrate wound repair, remove old red blood cells, induce apoptosis in old cells, detect pathogens using PRRs, present antigens to activate adaptive immunity

Dendritic cells

Detect PAMPs in tissues, migrate to lymph nodes, and activate T cells

Neutrophils (PMNs, granulocytes)

Granule

Most common white blood cell

Neutrophil

Phagocytosis

Endocytosis in which cells engulf large particles or cells; lysosomal enzymes degrade the material

Ways phagocytes kill engulfed bacteria

Acidification, toxic oxygen products, toxic nitrogen oxides, antimicrobial peptides, enzymes, nutrient competition

Primary role of innate immunity

Activate acute inflammation

Do most animals have adaptive immunity?

No; most rely only on innate immunity

Benefits of acute inflammation

Recruits innate immune cells, cleanses infection site with fluid, delivers antibodies, activates adaptive immunity

Trigger of inflammation

Tissue damage or presence of pathogens

Inflammation also damages

Uninfected cells

Major symptom of infectious disease

Inflammation

Classic symptoms of acute inflammation

Redness, pain, swelling, heat

Chronic inflammation can lead to

Tissue destruction

Pattern Recognition Receptors (PRRs)

Receptors that bind PAMPs and trigger immune responses in macrophages and dendritic cells

Pathogen

Associated Molecular Patterns (PAMPs)

Cytokines

Secreted proteins that signal immune cells to increase innate and adaptive immune responses

Too much cytokine

Cytokine storm; fluid

Too little cytokine

Insufficient immune activation; infection is not contained

Tumor Necrosis Factor (TNF)

Cytokine important in inflammation; excess TNF can cause Crohn's disease or rheumatoid arthritis

Antibodies

Proteins that specifically bind and neutralize pathogens

Organs of the immune system

Spleen, lymph nodes, thymus, bone marrow

Blood's role for immune cells

Circulates immune cells throughout the body

All innate immune system cells

White blood cells

Plasma

Fluid portion of blood containing proteins; diffuses into tissues and is collected by the lymphatic system

Lymph nodes

Filter lymph fluid and contain white blood cells

DNA

• sequence of nucleotides (A,G,T,C) with instructions that determine organisms biological properties,

• double helix with complementary strands

RNA

• sequence of nucleotides (A,G,U,C)

• extra oxygen atom in each, chemically unstable and more difficult to repair

• used in viruses, greater capacity for genetic mutation

DNA replication

separate strands, create complementary strands for each one

Central Dogma

• explains how genetic information flows

• DNA transcribed(T to U)→ RNA translate→ Protein

• RNA used as temporary messenger, translated to protein sequence by making certain amino acids in triplets

• PROTEINS CAN NEVER BE TRANSFERRED BACK TO NUCLEIC ACID

Protein

• linear sequence of amino acids, 20 different

• variable structure, many different shapes

Exception to central dogma

• retroviruses can make DNA from RNA (reverse transcription)

• RNA viruses can do RNA replication

gene

segment of DNA or RNA that gives rise to a protein

genome

• composed of all nucleic acids passed from parent to progeny

• almost every cell has a complete copy of its genome