Please enable JavaScript.
Coggle requires JavaScript to display documents.
Biological Aspects of COVID-19, Biological aspects of COVID19 pt 2 -…
Biological Aspects of COVID-19
what is COVID-19
infectious disease
How do infectious disease work?
illness caused by pathogens or toxic products
Bacteria- rapidly dividing single celled organisms
Viruses- tiny capsules containing genetic material
Fungi- primitive single or multi-cellular plant like organisms
Parasites- organism that lives with or on another organism
Functional immune system protects host
Symptoms arise when: immune system is compromised ; infectious agent overwhelms the immune system
respiratory illness
What is the structure of COVID-19?
Large; single stranded DNA
surface spike glycoproteins
What is the mechanism of transmission?
respiratory droplets from close contact
spread by asymptomatic, presymptamatic, and symptamatic carriers
average exposure of 5 days
What are covids early infection?
attacks epithelial cells lining airways- nasal cavity; bronchioles; alveoli
viral spike S protein enable anchoring to host cells
binds ACE2 receptor
entry enabled through activation of surface enzyme- TMPRSS2
What are covids late stage infection?
accelerated viral replication
infects epithelial and pulmonary capillary endothelial cells
inflammation promotes
vascular permeabililty, thickenning of interstitium, pulmonary edema, hyaline membrane deposition
diffuse thickening of aveloar wall and endothelial walls - acute respitory distress syndrome
ULTIMATE SYPMTOM: endothelial barrier disruption- impaired oxygen diffusion capacity
How is the disease presented?
incubation period is 5 days
fever/ dry cough/ shortness of breath
diagnosis through PCR testing
Complications such as: pneumonia, respitory distress, liver injury;
more serious include
cytokine storm and macrophage activation syndrome (MAS)
; systematic inflammation of organs followed by organ failure
How is COVID-19 treated?
supportive management of acute hypoxic respiratory failure
heated high flow nasal canula oxygen - maximizes O2 delivery
most ICU patients require mechanical ventilation
What is the immune system?
network of organs, cells, proteins, and substances that defend against pathogen
What are the major organs and tissues associated with immune system?
Skin and Mucous Membranes: first line defenses; physical barrier; produces substances- sebum, mucus, enzymes; contain cilia which remove pathogens/debris
White Blood Cells: circulates in bloodstream or resides in tissue until it is needed
Bone Marrow: source of immune cells
Lymphoid tissue: thymus, spleen, lymph nodes, tonsils- resident immune system
What are the functions of the immune cells
Defense:
House keeping- remove damage tissue and debris
3, Surveillance
What are the types of immunity?
Innate immunity
primitive- does not require presence of foreign antigen & immediate
involves neutrophils, macrophages, mast cells,
no immunological memory
Adaptive immunity
precise- recognizes unique antigens
slow response
involves lymph node
leads to immunological memory
includes B and T cells
Biological aspects of COVID19 pt 2
What is innate immunity?
primitive- non specific
response to pathogen associate molecular patterns(PAMPS)
immediate
involves neutrophils, macrophages, mast cells
no immunological memory
What are the mechanisms for innate immunity?
Mechanical barriers: skin/nose/airways
Chemical barriers: sweat, tears, saliva- promote inhospitable pH environment for pathogens
Fever- adaptive response to increase body temp; kill pathogens sensitive to extreme temperature
Inflammation- Non-specific immune response initiated by phagocytic white blood cells (WBC); release of cytokines that facilitate destruction of foreign pathogens
What is adaptive immunity?
precise- recognizes unique pathogen antigens
slower response
involves small lymphocytes
leads to immunological memory
What are the mechanisms of adaptive immunity?
Cell Mediated Immunity: presentation of cell surface antigens to T-lymphocytes
Helper T cells relay information to other immune cells to aid in killing pathogens
cytotoxic T cell directly kill foreign pathogens
Humoral Immunity
Involves production of antibodies- immunoglobulins in the cell
plasma proteins produce b lymphocytes in response to recognition of a specific foreign antigen
Antibodies functions include
neutralize the pathogens toxins and host entry
facilitate phagocytosis
promote pathogen demise via complement system
What are three important terms to know?
Vaccine: stimulate the body's response against a specific pathogen or disease
What are the kinds of vaccines?
Protein Subunit- uses pieces of virus
contains recombinant CoV-2 spike protein
Pros: Safety; logistically good
Cons: weaker immune response; needs booster
Novavax
Viral Vector Vaccine- harmless virus thats altered to contain part of target virus genetic codee
modified to enter host but not have viral replication
acts as delivery system- vector
Johnson & Johnsonn
Pros: cost effective; good logistics
cons: existing levels of immunity to virus vector
RNA-Based Vaccine- contains synthetic version of part of target virus genetic code
enncapsulated strand of RNA encodes for productionn of S protein
Pfizer and Moderna vaccine
Pros: safety; cost effective; specificc
cons: logistics
Vaccination: act of introducing a vaccine into the body to produce protection
what are the principles of vaccination?
Leverage the adaptive immune response- create immunological memory; reduces symptomatic illlness
Induce primary response without direct exposure
Widespread vaccination within a community protects everyone- aka herd immunity (reduces people able to spread)
Immunization: process by which a person becomes protected against a disease through vaccination