Bio 105 Lecture 9
Incompatibility of human cells and pathogens specific for
different species (eg. plant/animal/fungal viruses)
• May stem from host range for attachment and infection
• Human body may not present acceptable environment for pathogen’s survival
Species Resistance
is external and non-specific (eg. skin, mucous membranes) physical barriers
First Line
is internal and somewhat-specific chemical and cellular defenses (WBCs)
Second Line
is internal and very-specific chemical and cellular defenses: adaptive immunity
Third Line
Make up our innate defenses: host immune responses that don’t require exposure to the pathogen beforehand for maximum efficiency
First Two Lines
In the ____, shedding keratinocytes remove pathogens by degerming, and underneath dendritic cells patrol, performing immune surveillance
Epidermis
The _____ is primarily composed of (irregular dense) collagen, which gives skin its physical resistance to injury
Dermis
secrete antimicrobial peptides including dermicidins and lysozyme, as well as salts to the surface
– Sebaceous (oil) glands secrete sebum, lowering surface pH
Sweat glands
Physical barriers are also present in the ____that line cavities
Mucous Membranes
One portion of the mucous membranes is the___
lacrimal apparatus
Group of structures that produce and drain away tears
• Defenses include movement of tears(degerming)and lysozyme • Also provides a portal of entry into respiratory tract and gut!
Lacrimal Apparatus
Mostlycompetingwith pathogens for nutrients/habitats
• Can also create a hostile environment for pathogens (eg. deploying antibiotics)
Microbioal Anatagonism
is a group of plasma proteins that bind foreign bodies and perform three actions...
1. Opsonize them to encourage
phagocytosis
2. Trigger inflammation by attracting and activating leukocytes (cytokine activity)
3. Destroy (gram- negative) pathogens by membrane attack
Complement
are proteins secreted by cells infected by a pathogen (often virus)
– trigger nearby cells to increase cellular defenses like anti-viral proteins (AVPs), and recruit immune cells (cytokine function)
Interferons
are the dispatchers of the immune system – Generally small proteins/peptides secreted as chemotactic
factors or stimulators
Cytokines
are mostly secreted by leukocytes to regulate lymphocyte activity
Interleukins
are secreted in response to viral infection
Interferons
stimulate leukocyte cell division
Growth Factors
Are pyrogens that stimulate apoptosis and inflammation
Tumour Necrosis Factors
Are potent host-produced chemotactic factors (chemoattractants)
Chemokines
The cellular element of the innate defenses are blood cells (also called formed elements), and they come in three varieties:
Erthroycytes, Leukocytes, platelets
All blood cells are born from stem cells in the
Red Marrow: Hematopoiesis
make up a small but important fraction of blood cells
– Outnumbered 700:1 by erythrocytes (5-10k cells/microliter)
Leukocytes
innate leukocytes full of secretable chemicals
stored in large vesicles known as granules
Granulocytes
leukocytes that make up the NK cells, T cells and
B cells (mostly adaptive)
Lymphocyte
innate leukocytes that patrol tissues for pathogens and damaged host cells, to consume them by phagocytosis
Monocyte
50-70% of all leukocytes, first-responders at the site of infections where they release chemicals by degranulation to damage pathogens (and host cells alike!) and/or phagocytose pathogens: formation of pus
Neutrophils
2-4% of leukocytes, specialized to defend against
helminths (worms); involved in allergies
Eosinophil
1% of leukocytes, release histamine by degranulation in response to infections, which causes inflammation; involved in allergies
Basophil
make up 25- 40% of circulating leukocytes
Lymphocyte
make up 5% of leukocytes and are the ‘patrolmen’ phagocytes of the immune system
Monocytes
develops quickly, is short-lived and is typically beneficial
• Allowsmigrationofimmunecellsandchemicalmediatorsinto infected/damaged tissue
Acute Inflammation
is long-lasting, causing continuing damage to tissues and disease on its own
• Prolongedimmuneresponse=widespreadcelldeathandthe formation of granulomas
Chronic Inflammation
Is caused by dysregulation of the body’s thermostat: the hypothalamus
Fever