Human Biology - immunity

Immunity lecture 4

define pathogen?

A pathogen is any microorganism, such as bacteria, viruses, fungi, or parasites, that can cause diseases

define infection

invasion of the body tissues by pathogens

define disease

any harmful change from the normal structure and function of the body.

define immunity

Immunity is the body's ability to resist or fight off infection and disease through specific defenses, such as antibodies or immune cells.

what are the two types of immunity

innate defence

adaptive defence

what is the difference between innate defence (non-specific) and adaptive (specific)defence

Innate defense refers to the body's initial, non-specific response to pathogens, including physical barriers and immune cells, while adaptive defense involves a targeted immune response that develops over time, creating memory of specific pathogens for faster responses in the future.

what does non specific innate defence consist of? how many line of defence are there and what is in those line of defence?

first line of defence is the Skin

second line of defence is the inflammatory response and phagocytic cells.

what is phagocytosis?

A process where immune cells, such as macrophages and neutrophils, engulf and digest pathogens and cellular debris to help eliminate infections and maintain tissue health.

what is the process of phagocytosis?

first step

the Macrophages detects the pathogens

step two

the phagocyte cell engulfs the pathogen forming a phagosome

step three

it then creates a vacuole that contains that digest the pathogen, breaking it down into smaller components for removal.

what are antigens?

generates an immune response

describe the structure and function of an antigen?

Antigens are molecules structures that are recognised by the immune system.

There function is that through the process of phagocytosis it keeps a small amount of that pathogen and binds it to a specialized cell surface receptor which makes it only specific to pathogens, activating immune responses that target and eliminate them.

therefore antigens are used to trigger the immune responses, enabling the body to identify and combat foreign invaders.

describe where white blood cells come from?

White and red blood cells are made in the bone marrow from stem cells, (cells which can change into any other types of cells

like macrophages, neutrophils, T cells and B cells

identify the bodies main non specific defence cells?

the bodies main non specific cells defence is

macrophages, which eats ANY pathogens

Natural killer cells, which target infected or cancerous cells.

Neutrophils, which comes out of the blood and into the area that detects pathogens, and helps form a extra barrier to injured parts and kill pathogens

then there are

cytokines, which signals where the injured area is and used for tissue repair

mast cells, which triggeres inflammation to injured areas releasing histamine

platlets, that form clots to the wounds

how white blood cells recognise an antigen?

white blood cells recognise antigens through specific receptors on their surfaces that bind to the unique structures on pathogens.

(lock in key)

This binding initiates an immune response to target and eliminate the invader.

discuss the role of inflammation?

Inflammation is a key protective response to injury or infection.

these 4 symptoms consist of

pain- signals that there is injury

redness- which tells us that’s there is more blood flow going to that area allowing more o2 diffusion and nutrients needed

swollen- tells us that there is more cells increasing in that area (vasodilation) , increasing the blood vessels flow to ensure more cells

hot- chemicals released by the immune cells increases the rate of diffusion like o2 to sped up the healing process

what are the negative side effects of inflammation?

reduced mobility, not being able to efficiently move

can trigger allergies, like asthma

can cause depression

explain the role of fever in fighting infections?

when the body is infected immune cells like macrophages send signals to the brain which increases the body temperature, reason being

is that pathogens are most likely to die in higher temps

certain cells like T cells are able to work better

inc rates of diffusion for faster transportation of nutrients and o2 is better

Explain the role of T cells in cell immediate immunity?

antigens presenting cells like a macrophages or Dentric cells eats the bacteria and takes some of it which..

it binds with a T cell which is a specific cell and makes a receptor specific for that pathogen.

the T cells makes cytokines to activate other immune cells

the unactivated cytotoxic T cell becomes activated which grows and kill pathogens these T cells are called t killer cells specific to those antigens

it is then split into two which are memory cells and cytotoxic cells

explain the role of B cells in antibody mediated immunity

antigens presenting cells like macrophages and dentric cells kills pathogens in which they keep little..

they then bind to a T cell receptor

b cells are then activated, and replicate due to the cytokines

the inactivated b cell then becomes activated which creates b cells specific to that antigen receptor.

these then split into two which is the plasma cells and memory B cells that produce antibodies to neutralize pathogens.

describe how antigens and antibodies are related?

Antigens are foreign substances that trigger an immune response, while antibodies are proteins produced by B cells that specifically bind to antigens to neutralize or eliminate pathogens.

what are the first white blood cells that come out to eliminate pathogens, then the second?

macrophages signal neutrophils to come kill pathogens

what is the cells process of non specific immune system?

Macrophages eats pathogen

cytokines signals more cells to come (which tells the blood to open up and bone marrow)

inflammation happens due to the mast cells producing hesrtamine

the blood becomes sickly and leaky which neutrophils come and helps eliminate pathogens (phagocytosis)

the swelling due to inflammation is caused by?

the build up of histamine from the mast cells

explain how the non specific immune system will respond to a pathogen step by step?

1. Pathogen enters the body.

2. Macrophages recognize and engulf the pathogen.

3. Cytokines are released, signaling more immune cells.

4. Blood vessels dilate and become leaky, allowing more cells to reach the infection site.

5. Neutrophils arrive to assist in phagocytosis and inflammation produces by mast cells.

the effects of this can cause a fever, due to the increase temp this is because pathogens are unlikely to survive in high heats and better for certain cells to follow through their duties.

explain how the specific immune system will respond to a pathogen step by step?

Q

1. Antigen presenting cells like macrophages and dendritic cells presents antigen to a helper T cells.

   2 Helper T cells activate B cells to produce antibodies. (plasma B cells) (and T killer cells)

   3. Antibodies target the pathogen for destruction.

   4. Cytotoxic T cells kill infected cells directly.

   5. Memory cells are created for future immunity.

explain the antibody mediated immunity step by step?

1. antigen presenting cells like macrophages and dendritic cells gives the antigens which binds to B cell receptor, activating the B cell.

   2 B cell differentiates into plasma cells that produce antibodies.

   3. Antibodies bind to the antigen, marking it for destruction. 4. Helper T cells enhance the antibody response.

   5. Memory B cells are formed for rapid response in future infections.

For neutralising Antigens!!

explain the cell mediated immunity step by step?

1. Antigen presenting cells, such as macrophages gives the antigens to T helper cell

2. ,which activates the Cytotoxic T cells and proliferate.

3. Activated T cells then split into two which are the T killer cells killing cells that are infected and memory cells created for quicker responses against future infections.

Direct Attack on antigens!!

how are antibodies able to bind to specific antigens?

Antibodies are able to bind to specific antigens due to their unique structure, which includes a variable region that fits precisely with the shape of the antigen. This specificity is a result of the genetic recombination of antibody genes during B cell development.