Lymphatic System And Immunity Flashcards
Lines of defense
Pathogens- environmental agents capable of producing disease. They can be a range of thing, infection organisms, toxic chemicals and radiation
They use lines of defence to fight against these pathogens
1. First line of defense- external barriers like skin and mucous membranes( so anything that physically try’s and keep a pathogen out)
Sometimes pathogens are going to get past that first line of defense so then it goes to
2. Second line of defense: where we have several nonspecific defense mechanisms. The general self defense mechanism include white blood cells ( leukocytes) and macrophages, anti microbial proteins, immune surveillance, inflammation and fever all helping to fight against a broad range of pathogens
3. Third line of defense: the adaptive immune defense. Your body not only defeats the pathogen but remembers it so it can defeat it faster in the future as well as more efficiently
Immune system consists of:
- cells that inhabit most organs
- chemicals they produce neutralise and destroy pathogens
- physical barriers eg. Skin.
- physiological processes: inflammation and fever
Immune system is more of a collection of defensive cells and mechanisms tht try and fight against pathogens
2 types : innate and adaptive
Innate= 1st and 2nd
Adaptive = 3rd
Characteristic of of innate that make it different to adaptive
- local effect
- non specific
- lack memory
External barriers
3 ‘Ps’ of innate immunity:
1. Protective proteins- keratin
2. Protective cell
3. Protective processes
Skin
• Makes it mechanically difficult for microorganisms to enter the body
• Toughness of keratin
• Too dry and nutrient-poor to support microbial growth
• Mucous membranes
• Digestive, respiratory, urinary, and reproductive tracts are open to the exterior and protected by mucous membranes
Subepithelial areolar tissue
• Viscous barrier of hyaluronic acid
However, some organisms (snake venom) break it down.
Leukocytes and Macrophages
Phagocytes-phagocytic cells with a voracious appetite for foreign matter
( cell that eats other cell)
Five types of leukocytes (innate and adaptive)
1. Neutrophils
• Wander in connective tissue killing bacteria
• Create a killing zone due to role of lysosomes
2. Eosinophils
• Found especially in the mucous membranes
• Stand guard against parasites, allergens (allergy-causing agents), and other pathogens
• Kill tapeworms and roundworms by producing superoxide, hydrogen peroxide, and toxic proteins
- Lymphocytes
• Circulating blood contains
80% T cells
15% B cells
5% NK cells
• Many diverse functions
•Immune surveillance and specific immunity - Basophils
• Secrete chemicals that aid mobility and action of other leukocvtes
• Leukotrienes: activate and attract neutrophils and eosinophils
• Histamine: a vasodilator, which increases blood flow
Speeds delivery of leukocytes to the area
• Heparin: inhibits clot formation - Monocytes
•Emigrate from blood into connective tissue and transform into macrophages
Antimicrobial Proteins
• Proteins that inhibit microbial reproduction and provide short-term, nonspecific resistance to pathogenic bacteria and viruses. Act as first line of defense
Two families of antimicrobial proteins (interferons & compliment system)
1. Interferons - secreted by certain cells infected by viruses
• Bind to surface receptors and activate 2nd messenger system and synthesis of anti-viral proteins
- Complement system - a group of 30 or more globular proteins that make contributions to both innate and adaptive immunity
• 4 methods of destroying pathogens; inflammation, immune clearance, phagocytosis and cytolysis
Immune surveillance
Immune Surveillance
• Is a phenomenon in which natural killer (NK) cells continually patrol the body “on the look out” for pathogens or diseased host cells
• Destroy and attack bacteria, cells infected with viruses, and cancer cells
• Once recognised the NK cells bind to the enemy cell and releases proteins called perforins (put a hole in PM) and secretes granzymes (an enzyme) which induces apoptosis
Attack mechanisms of natural killing cells is that they need to be able to recognise what they are going to go after they have receptors that enables them to distinguish between healthy and compromised cells. Once they release a cell is an enemy cell they attach to it and release perforins that make a small whole in the enemy cell and they secrete granzymes into the cell. Once granzymes are in the target cell they initiate a cascade of reactions that lead to apoptosis. The enemy cell is going to result in program cell death, cell does itself. Then macrophages engulf and digest dying cell.
Fever
An abnormal elevation of body temperature
• Results from trauma, infections, drug reactions, brain tumors,
and other causes like hormone imbalance
Normal temp is around 37
Fever is an adaptive defense mechanism that, in moderation, does more good than harm
• Promotes interferon activity
• Inhibits reproduction of bacteria and viruses - all have optimal growth temperatures and if a fever shifts body temperature it’s slowing down reproduction of those bacteria and viruses.
• Elevates metabolic rate and accelerates tissue repair
• Very high temperatures are dangerous; metabolic discoordination and cellular dysfunction. > 40.5°C = convulsions/ coma, brain damage/ death 44 - 46°C
The course of a fever
Hypothalamic thermostat is reset to higher set point
Onset
(body temperature rises)
Stadium
(body temperature oscillates around new set point)
Infection ends, set point returns to normal
Defervescence (body temperature returns to normal)
Inflammation
Inflammation
Local defensive response to tissue injury of any kind,
including trauma and infection
Purposes of inflammation
• Limits spread of pathogens, then destroys them
• Removes debris from damaged tissue- cleanses the area
• Initiates tissue repair
Four cardinal signs of inflammation
• Redness, swelling, heat, pain
• 5th by some is impaired use, but goes hand in hand with pain
Cytokines- important in inflammation
Many of the chemicals that regulate inflammation are classed as cytokines
• Small proteins that act as a chemical communication network among immune cells
Paracrine effects - short range -> to neighbouring cells. Direct cell to cell communication in close proximity
Autocrine effects - on the same cell that secretes the cytokines.
Cytokines include interferons, interleukins, tumor necrosis factor and chemotactic factors
3 major processes of inflammation
3 major processes of inflammation
1. Mobilisation of Defenses
• Most immediate requirement for tissue injury by getting defensive leukocytes to the site quickly
• Increase blood flow (hyperemia) leases to increase immune cell delivery to injured site which can facilitate faster immune response
- Containment and Destruction of Pathogens
• Prevent pathogens from spreading through the body
• Fibrinogen - filters into tissue forming a sticky mesh traps pathogens and any other debrie
• Heparin - anticoagulant that prevents unwanted blood clotting at effected area
• Phagocytes - antibodies that fight the infection- i gulf and digest pathogens - Tissue Clean-up and Repair
• Monocytes - agents of tissue cleanup and repair
NEUTROPHILS
• Macrophages - engulf and destroy bacteria
• Edema - swelling compresses veins and reduces drainage and force lymphatic valves to open
What is a pathogen
So a pathogen is just a term that’s used for any environmental agent that’s capable of producing disease. there’s kind of 3 lines of defense that we have. First, this like an external barrier, something that stops that pathogen. Getting in second is non specific responses. So things like, if you have a fever. it’s obviously not targeting one specific type of pathogen, it’s targeting anything. And then the third line of offense is the adaptive immune system, where you’ll have a memory of the the pathogen, so that you can defeat it faster in the future.
Forms of immunity
forms of immunity that can be broken into 2 types. They can be either a innate which is just what your immune system already has. It’s inherent defense that you already have to to protect against the wide range of diseases. So something that’s innate is something like that external barrier. You have already got that it doesn’t really matter what disease is and u have some localised effect. So your skin is going to go through a localized effect. If you have something that tries to get through in that one area, so you might get inflammation of your skin in a place where pathogen sitting, you might get a rash or something like that. That’s that’s specific to that area. You have that localized effect. But you don’t have any memory of the the thing that’strying to hurt you, the pathogen
and then you have adaptive, which is that third line of defense which is remembering what is happening.
Cells for immunity
in both innate and adaptive immune system..
Phagocytes is just the cell that eats and other cells. Phagocytes are something that has an appetite for foreign matter, and it’s something that is going to fully engulf another cell.
you have 5 types of cells
First, you’ve got neutrophils which are primarily trying to kill bacteria. They’re wandering around inconnective tissue, and they kill things in 2 ways.
They can either do that. So where they’re trying to swallow up another cell, or they can create like a chemical killing zone where they transform oxygen into toxic chemicals, and they kill things around it, and that can be helpful. But it also kills the neutrophil itself, but and it also harms tissue. That’s around. So it’s wandering around and connected tissue. Some of that connective tissue also gets harm. So when you have something like rheumatoid arthritis. One of the reasons is these neutrophils are creating these toxic environments for your own cells. And creating some issues there.
- Eosinophils : predominantly mucus membrane and there guarding against parasites and particularly important during allergies. So once an allergy comes in you might have a response from an Eosinophils but also they respond to things like take tape worm etc. Sodifferent types of parasites by producing a few toxic chemicals so similar to the neutral fills in creating those toxic chemicals like superoxide, hydrogen, peroxide, and toxic proteins.
- Lymphocytes :
They circulate around the blood, and they we’ve got. And then particularly long lasting as well, they lost a long period of time. We’ve got 3 types
We’ve got 80% of them at T cells. So there the ones that mature in the thymus and 15% are B-cells which mature in the bone marrow - Basophils:
they’re essentially they’re helping out other some of these other cells that we’re talking about. So that help out other Leucocytes -white blood cells. So then, they’re kind of helping out. And they do a few different things. They secret some chemicals. That attract neutrophils They also create these histamines. So they increase blood, flow and secrete efferents. Which inhibit clot formation. - Now last one to monocytes:
particularly important to us, because they turn into macrophages and macrophages are cell that eat up other cells.
Interferons
Interferons are proteins produced by cells in response to viral infections. They help to activate the immune system and inhibit viral replication.
An example of interferons in action is when a cell gets infected by a virus. The infected cell releases interferons to signal nearby cells to activate their antiviral defenses. This helps limit the spread of the virus throughout the body. 🦠🚫💪
