lymphatic and immune

Question 1

what is the composition of the blood?

Answer 1

water, proteins, ions, nutrients, gases, waste, WBC, RBC, platelets

Question 2

what are the main plasma proteins?

Answer 2

Albumin: This is the most abundant protein in blood plasma, 55% of total plasma proteins. Albumin is crucial for maintaining colloid osmotic pressure, which helps regulate fluid balance between the bloodstream and tissues. It also acts as a carrier molecule, transporting various substances like fatty acids, hormones, and certain medications throughout the body.

Globulins: about 38% of plasma proteins. They can be further classified into different types:
Immunoglobulins (antibodies): These are produced by white blood cells and play a vital role in the immune system by recognizing and neutralizing pathogens like bacteria and viruses.
Transport globulins: These carry various substances in the bloodstream, such as hormones, lipids (fats), and metal ions like iron and copper.
Other globulins: This category includes various proteins involved in blood clotting, inflammation, and other physiological processes.

Fibrinogen: 4% it is a large, complex protein present in blood plasma. It plays a critical role in the blood clotting process, essential for preventing excessive bleeding from wounds

Question 3

what is a buffy coat?

Answer 3

A buffy coat is a thin, yellowish-beige layer that appears in centrifuged anticoagulated blood. It’s composed primarily of Leukocytes (white blood cells).

Question 4

define hematopoiesis

Answer 4

Hematopoiesis is the process by which the body produces all the different types of blood cells.
All blood cells originate from hematopoietic stem cells (HSCs). These are immature, self-renewing cells found primarily in the bone marrow of adults. HSCs have the remarkable ability to differentiate into various types of progenitor cells, which further mature into specific lineages of red blood cells, white blood cells, or platelets.

Question 5

define hemocytoblasts

Answer 5

Hemocytoblasts, also known as hematopoietic stem cells (HSCs), are the foundation of the blood cell production system. They are immature cells found in the bone marrow.

Question 6

do WBC have hemoglobin? nucleus?

Answer 6

Hemoglobin - no
Nucleus - yes

Question 7

define ameboid movement

Answer 7

when WBCs leave the blood.
Certain types of white blood cells, like neutrophils and monocytes, utilize ameboid movement to migrate through tissues, squeeze between cells, and engulf pathogens during immune responses.

Question 8

can RBCs leave the blood? can WBCs leave?

Answer 8

RBC - no
WBC - yes, essential for immune function, uses diapedesis and ameboid movement

Question 9

what are the 2 functions of WBC?

Answer 9

1. protect the body against pathogens
2. remove dead cells and debris from the tissue

Question 10

what are the kinds of WBCs? explain

Answer 10

Neutrophils: 10-12um. These are the most abundant WBCs and are the first responders to infections. They are particularly effective at engulfing and digesting bacteria through phagocytosis. their nuclei are lobed (2-4).

Basophils: 10-12 um. These are the least common WBC type and are involved in allergic reactions (release histamine) and inflammation. contain large cytoplasmic granules. have blue color.

Eosinophils: 11-14 um. These WBCs are involved in allergic reactions and defense against parasitic infections. their nuclei are lobed. they are involved in allergic reactions, asthma, inflammation and destroying worms.

Monocytes: 12-20 um. These versatile WBCs can leave the blood and differentiate into macrophages, which are powerful phagocytes that reside in tissues and eliminate pathogens and debris. can break down phagocytized foreign substances and present that to lymphocytes.

Lymphocytes: 6-14 um. These are critical for adaptive immunity, which involves the body’s ability to recognize and target specific pathogens. There are two main types:
B lymphocytes (B cells): These produce antibodies, specialized proteins that can bind to and neutralize pathogens or mark them for destruction by other immune cells.
T lymphocytes (T cells): These orchestrate various immune responses. Some T cells directly kill infected cells or cancer cells, while others regulate the immune response.

Question 11

what are the 2 types of WBCs?

Answer 11

the presence or absence of cytoplasmic granules, which are compartments containing enzymes and other molecules, gives two main categories:

Granulocytes: These WBCs have visible granules in their cytoplasm that contain proteins and enzymes specialized for various immune functions.
Neutrophils, Eosinophils, Basophils.

Agranulocytes: These WBCs lack visible granules.
Lymphocytes, Monocytes.

Question 12

define cytoplasmic granules

Answer 12

Cytoplasmic granules, also known as secretory granules or intracellular granules, are small, membrane-bound sacs found within the cytoplasm of some cells. They act like tiny storage compartments for various molecules that the cell needs to release at specific times.

the contents of cytoplasmic granules vary depending on the cell type and its function. They can store a diverse range of molecules, including: Enzymes, Signaling molecules, Pigments, Precursors

Question 13

what is the difference between macrophages and monocytes?

Answer 13

Monocytes are like immune system scouts in the bloodstream, while macrophages are tissue-resident assassins. Monocytes become macrophages when they enter tissues and specialize in gobbling up foreign invaders.

Question 14

define chemotaxis (explain in WBCs)

Answer 14

Chemotaxis is the movement of an organism or cell in response to a chemical stimulus. immune cells can use chemotaxis to migrate towards sites of infection or inflammation, where chemicals released by damaged tissues or pathogens attract them.

Question 15

what are the 3 main functions of the lymphatic system?

Answer 15

1. fluid balance - The lymphatic system collects excess fluid that seeps out of blood vessels and tissues throughout the body. This fluid, called lymph, doesn’t return to the bloodstream directly. Instead, the lymphatic system acts like a drainage network, filtering the lymph and returning it to the bloodstream near the collarbone. that prevents swelling.
2. defense - The lymphatic system is a key player in the immune system. It houses structures called lymph nodes, which act as filters and battlegrounds for immune cells like lymphocytes (including B and T cells). Lymph nodes trap antigens (foreign substances) from the lymph fluid, allowing lymphocytes to launch immune responses against pathogens like bacteria and viruses.
3. lipid absorption - In the lining of the small intestine, dietary fats are absorbed into lacteals, which are specialized lymphatic vessels. These fats are then transported through the lymphatic system to the bloodstream for delivery to various tissues throughout the body for energy storage or use.

Question 16

what does the lymphatic system include?

Answer 16

lymph, lymphocytes, lymphatic vessels, lymph nodes, tonsil, spleen, thymus.

Question 17

define lymph

Answer 17

Lymph is a pale yellow fluid that flows through the lymphatic system. Lymph is similar to blood plasma, the liquid portion of blood, but with some key differences (less concentrated with proteins than in blood plasma).
derived from the plasma ( substances such as ions, nutrients…) and tissues (substances such as hormones, enzymes and waste).

Question 18

do the lymphatic system circulate fluid?

Answer 18

no, unlike the circulatory system, the lymphatic system carries fluid in 1 direction - from the tissues to the circulatory system.

Question 19

describe the lymphatic capillaries (and compare with blood capillaries)

Answer 19

These are tiny, thin-walled vessels. Lymphatic capillaries are found extensively throughout almost all tissues in the body.
Compared to blood capillaries, lymphatic capillaries have a slightly higher permeability due to looser junctions between their endothelial cells (simple squamous) and their lack of basal lamina. This allows them to take up larger molecules and fluid more readily.
Unlike blood capillaries, which are continuous tubes, lymphatic capillaries have a unique blind-ended structure. Imagine a dead-end alley – fluid can enter the capillary but can’t flow back out.

Question 20

describe the lymphatic vessels

Answer 20

Lymphatic vessels are the conduits of the lymphatic system, forming a network of thin tubes responsible for transporting lymph throughout the body.
they resemble small veins.
They have thin walls composed of endothelial cells and smooth muscle fibers.
lymphatic vessels possess valves that prevent backflow of lymph. These valves are similar to tiny flaps that open only towards the direction of lymph flow.

Question 21

what are the 3 factors causes compression of the lymphatic vessels?

Answer 21

1. contraction of skeletal muscle
2. contraction of smooth muscle in the wall
3. pressure changes in the thorax during breathing

Question 22

to what locations in the body do the lymphatic vessels converge and empty into?

Answer 22

Thoracic Duct: This is the larger and longer of the two main lymphatic ducts. It receives lymph from most of the body, including the lower limbs, abdomen, left chest, left arm, and head (except the upper right portion). The thoracic duct empties lymph into the left subclavian vein , a large vein near the left collarbone.

Right Lymphatic Duct: This duct is smaller than the thoracic duct and receives lymph from the upper right portion of the body, including the right chest, right arm, and upper right head and neck. The right lymphatic duct drains lymph into the right subclavian vein , mirroring the thoracic duct on the opposite side.

Question 23

define reticular fibers (in lymphatic tissue)

Answer 23

Reticular fibers form a branching network (reticulum) throughout lymphatic tissue organs like lymph nodes and the spleen. This network acts as a delicate scaffold, providing structural support and adhesion sites for various immune cells, including lymphocytes (B and T cells), macrophages, and antigen-presenting cells (APCs).
Their intricate network creates a specialized microenvironment that allows immune cells to efficiently identify, interact with, and eliminate pathogens or foreign particles.

Question 24

define pathogens

Answer 24

Pathogens are biological agents that can cause disease in an organism. They come in various forms (Bacteria, Viruses, Fungi….) and can invade humans, animals, and even plants.

Question 25

define tonsils (and kinds)

Answer 25

Tonsils are lymphoid tissues located in the back of the throat, forming part of the lymphatic system’s first line of defense against pathogens.
they form a protective ring of lymphatic tissue around the openings between the nasal and oral cavities and the pharynx.

Palatine Tonsils: These are the most familiar type, visible at the back of the throat on either side of the uvula (the small fleshy projection hanging down from the soft palate).

Lingual Tonsils: Located at the base of the tongue, these tonsils are usually not visible without special techniques.

Pharyngeal tonsil - located near the internal opening of the nasal cavity.

Question 26

define lymph nodes ( and structure)

Answer 26

Lymph nodes, also sometimes called lymph glands, are small, bean-shaped organs that are a crucial part of the lymphatic system. They act as filters for the fluid that travels through the lymphatic vessels.

structure:
Each lymph node is surrounded by a fibrous capsule (dense connective tissue) that provides support and structure.
Trabeculae (thin, finger-like extensions of connective tissue that project inwards from the lymph node’s capsule) originate from the fibrous capsule that surrounds the entire lymph node.
The inner region of the lymph node is filled with fluid-filled spaces called sinuses. Lymph fluid carrying immune cells and other substances flows through these sinuses.
lymph enters through afferent vessels and exits through efferent vessels.

Question 27

what are the functions of lymph nodes?

Answer 27

1. activate the immune system - pathogens in the lymph stimulate lymphocytes in the tissue to divide.
   the new lymphocytes are released to the lymph and then the blood - they are part of the adaptive immunity.
2. eliminate pathogens from the lymph through the action of macrophages.

Question 28

what are the locations of lymph nodes?

Answer 28

Lymph nodes are found throughout the body, particularly in clusters around the neck, armpits, groin, chest, and abdomen. They are strategically positioned along the pathways of lymphatic vessels.
inguinal nodes - groin
axillary nodes - armpit
cervical nodes - neck

Question 29

define germinal centers

Answer 29

lymphatic nodules (the basic functional units) that contain rapidly dividing lymphocytes.

Question 30

describe the spleen (and structure)

Answer 30

The spleen is a soft, fist-sized organ located in the upper left portion of the abdomen, just below the diaphragm and behind the stomach. It’s a vital component of the lymphatic system.

Structure:
-Capsule: The spleen is surrounded by a tough, fibrous capsule (dense connective tissue and smooth muscle) that provides external support and structure. trabeculae originate from the fibrous capsule that surrounds the spleen and divide the spleen into 2 compartments:
-Red Pulp: This inner region is rich in red blood cells and contains structures called splenic cords, which are filled with red blood cells and macrophages (phagocytic cells that engulf debris and pathogens).
-White Pulp: Scattered throughout the red pulp are clusters of white blood cells, primarily lymphocytes (B and T cells), forming lymphatic tissue.

Question 31

what are the functions of the spleen?

Answer 31

-the spleen filters BLOOD instead of lymph. the spleen detects and respond to foreign substances in the blood and destroy worn out RBCs.
-lymphocytes in the white pulp are stimulated and divide.
-The spleen acts as a storage unit for red blood cells and platelets. During times of blood loss or increased need, the spleen can release these stored cells back into circulation to maintain proper blood cell levels.

Question 32

describe the thymus

Answer 32

It’s a specialized gland located in the upper chest area, just behind the breastbone and above the heart. The thymus is divided into 2 lobes each surrounded by a connective tissue capsule that is providing external support and structure. trabeculae divide each lobe into lobules. The inner region is divided into two distinct areas:
Cortex: The outer cortex is densely packed with immature T lymphocytes (thymocytes).
Medulla: The inner medulla contains a network of epithelial cells, macrophages, and mature T lymphocytes.

This is the site where T cells are maturing.
Once mature T lymphocytes have passed the selection process and completed their training, they migrate from the thymus to populate the lymph nodes and other lymphoid organs. These mature T cells are now ready to participate in immune responses throughout the body.

Question 33

can you live without a spleen?

Answer 33

You can live without a spleen, but it does affect your immune function (increased Risk of Infections)

Question 34

define antigen

Answer 34

An antigen (Ag) is any molecule that can trigger an immune response in the body.

Question 35

define immunity

Answer 35

immunity is the ability to resist damage from pathogens, chemicals and internal threats.
it is subdivide into innate immunity and adaptive immunity.

Question 36

specify and memory are characteristics of the ______ immunity

Answer 36

adaptive

Question 37

define specify (immunity)

Answer 37

the ability of the immune system to recognize and respond to specific pathogens or antigens (foreign molecules on pathogens).

Question 38

define memory (immunity)

Answer 38

memory refers to the ability of the adaptive immune system to “remember” specific pathogens it has encountered previously. This immunological memory allows the body to respond more quickly, stronger, longer-lasting and more effectively upon re-exposure to the same pathogen, preventing or minimizing illness.

Question 39

when exposed to a substances for the 2nd time, the response is the same in the adaptive immunity? in the innate immunity?

Answer 39

innate immunity - the same (no memory and specify)
adaptive immunity - faster, stronger, longer-lasting and more effective (with memory and specify)

Question 40

define innate immunity

Answer 40

Innate immunity is the body’s first line of defense, present at birth and non-specific. It acts as a general barrier against a broad range of pathogens through physical barriers, immune cells, and inflammatory responses.

Question 41

define adaptive immunity

Answer 41

Adaptive immunity is the body’s developed defense system, creating targeted responses to specific pathogens. It has memory, allowing for a faster and stronger response upon future encounters with the same threat.

Question 42

how innate immunity is accomplished?

Answer 42

-Physical Barriers:
These are the front lines, acting as the first hurdle for pathogens trying to enter the body. They include:
Skin, Mucous membranes, Tears, hair and more.

• Chemical Mediators:
  *interferons - Interferons are signaling proteins primarily known for their potent antiviral activity. When a virus infects a cell, the infected cell produces interferons. These interferons then bind to receptors on neighboring cells, inducing an antiviral state. This essentially creates a defensive barrier around the infected cell, making it more difficult for the virus to spread to healthy cells.
  *Complement: A group of proteins that can coat pathogens, making them easier for phagocytes to engulf, and can also directly kill some pathogens.

-Cellular Defenses:
Special white blood cells play a crucial role in innate immunity:
*Phagocytes: These cells (macrophages, DCs and neutrophils) engulf and destroy foreign particles.
*cells of inflammation - (basophils, eosinophils and mast cells) the cells located at point where pathogen might enter the body. activate by either innate or adaptive and release chemicals (like histamine) that produce inflammatory response
*Natural killer (NK) cells: recognize the class of cells and not a specific one (innate without memory). These cells can directly attack and kill virus-infected cells or tumor cells.

-Inflammatory response: When tissues are damaged or infected, inflammatory chemicals are released, causing redness, swelling, and heat. This localized inflammation helps isolate the infection and attracts immune cells to the area.

Question 43

what is the first kind of WBC that enter infected tissue? what are they doing?

Answer 43

Neutrophils (and in large number)
they send chemical signals that increase the response. they often die after phagocytizing.

Question 44

define pus

Answer 44

Pus is a thick usually yellowish-white fluid matter formed at the site of inflammation during infections, regardless of the cause.
The primary cellular component of pus is dead white blood cells, particularly neutrophils.

Question 45

define Dendritic Cells (DCs)

Answer 45

Dendritic cells (DCs) are specialized immune cells that play a critical role in bridging the innate and adaptive immune systems. They act as sentinels, constantly scanning tissues for signs of danger and orchestrating a targeted immune response against invaders. DCs are professional antigen-presenting cells (APCs). Their primary function is to capture, process, and present antigens to T lymphocytes (T cells), a key component of the adaptive immune system.

Question 46

what are the effects of the chemical mediators?

Answer 46

-vasodilation increases blood flow and brings phagocytes and other WBCs.
-phagocytes enter the tissue
- increased vascular permeability allows fibrinogen and complement proteins to enter the tissue.

Question 47

define vasodilation

Answer 47

Vasodilation is the widening of blood vessels, allowing more blood to flow through.

Question 48

define complement proteins

Answer 48

Complement proteins are a group of about 30 blood proteins that work together like a tag team. They help the immune system fight infection by:

Marking invaders: They tag pathogens for destruction by immune cells.
Direct attack: In some cases, they can directly kill certain pathogens.
Inflammation: They trigger inflammation to isolate the infection.

Question 49

define fibrinogen and why it is important to the immune system

Answer 49

Fibrinogen is a glycoprotein complex, a large molecule with both protein and sugar components, produced by the liver. It plays a critical role in the blood clotting process, but it also has some indirect connections to the immune system.

Physical Barrier: A fibrin clot can act as a physical barrier, preventing the spread of pathogens (disease-causing organisms) from the site of injury to other parts of the body.

Question 50

what are the 2 types of inflammation?

Answer 50

Local Inflammation:
Involves a confined area of the body.
The classic signs of inflammation (redness, swelling, heat, pain) are typically present at the specific site of injury, infection, or irritation.
Examples: A sprained ankle, a pimple, or a bee sting.

Systemic Inflammation:
Involves a widespread response throughout the body.
The classic signs of inflammation might be present in various locations or the person might experience more general symptoms like fever (pyrogens), fatigue, and malaise. bone marrow produces and releases large numbers of neutrophils.
Example: Sepsis

Question 51

define pyrogens (and what temperature-regulation mechanism it affects)

Answer 51

Pyrogens are substances (chemicals) that cause an increase in body temperature, leading to a fever.
In the hypothalamus, these pyrogens act on specific brain cells, causing them to reset the body’s temperature set point to a higher level.

Question 52

what’s is the difference between acute inflammation and chronic inflammation?

Answer 52

duration
Acute Inflammation: This is a short-term response, typically lasting from hours to a few days. It’s a rapid and well-coordinated process aimed at quickly eliminating a threat and initiating healing.

Chronic Inflammation: This is a long-term inflammatory response that can persist for weeks, months, or even years. It often becomes a self-perpetuating cycle where the body continues to fight a perceived threat, even if the initial trigger is gone.

Question 53

what are the 4 signals of inflammation?

Answer 53

Rubor (Redness): This arises due to the dilation of small blood vessels in the inflamed area. Increased blood flow (vasodilation) brings more immune cells and healing factors to the site, causing the redness.

Calor (Heat): The increased blood flow (vasodilation) and metabolic activity at the site of inflammation lead to a localized rise in temperature, making the area feel hot to the touch.

Tumor (Swelling): Inflammation often involves fluid accumulation in the affected tissues due to increased vascular permeability (leakage from blood vessels) and the influx of immune cells. This fluid buildup causes swelling. (neutrophils emigration)

Dolor (Pain): Tissue damage, the release of chemicals by immune cells, and pressure from swelling can all stimulate pain receptors, leading to discomfort in the inflamed area.

Question 54

what are the 2 types of antigens?

Answer 54

foreign - exogenous antigens: these are antigens that originate outside the body and enter from the environment. They are perceived as foreign by the immune system and trigger an immune response. Examples: bacteria, viruses, fungi, parasites, toxins…

self - endogenous antigens: these antigens are produced within the body by our own cells. In a healthy state, the immune system tolerates these self-antigens and doesn’t attack them. However, under certain conditions, the immune system can malfunction and start reacting to self-antigens, leading to autoimmune diseases. Examples of endogenous antigens include: dead or dying cells, mutated proteins…

Question 55

how the adaptive immunity can be divided?

Answer 55

antibody-mediated immunity:
Involves the production of antibodies (Y-shaped proteins) by B lymphocytes (B cells -PC).
Antibodies can specifically bind to antigens (foreign molecules), neutralizing them and marking them for destruction by immune cells.
Provides long-term immunity through immunological memory, allowing the body to respond more effectively to previously encountered pathogens.

Cell-mediated immunity:
Involves the action of T lymphocytes (T cells) and other immune cells. Cytotoxic T cells can directly kill infected cells or tumor cells.
Helper T cells orchestrate the immune response by activating other immune cells and antibody production by B cells.
Plays a crucial role in defending against intracellular pathogens (viruses that live inside cells), viruses in general, and some cancers.

Question 56

where do T cells mature? where B cells?

Answer 56

both cells originate in the bone marrow from hematopoietic stem cells.
T cells migrate from the bone marrow to a specialized organ called the THYMMUS.
B cells mature within the BONE MARROW.

Question 57

define clones

Answer 57

A group of genetically identical cells.
clonal expansion of lymphocytes (B or T cells) in response to an antigen. Upon encountering a specific antigen, B or T cells that recognize that antigen are stimulated to proliferate rapidly, creating a large population of identical daughter cells. These daughter cells share the same antigen receptor as the parent cell, allowing them to specifically target the antigen.
each clone for one antigen.

Question 58

define proliferation

Answer 58

Proliferation refers to the rapid growth or multiplication of cells.

Question 59

how the lymphocytes recognize the antigen?

Answer 59

Lymphocytes, both B cells and T cells, recognize antigens through specific molecules on their surface called antigen receptors.
They cannot directly recognize free-floating antigens in the body. Instead, they rely on antigen presentation by specialized cells called antigen-presenting cells (APCs).

Question 60

define APCs (types and function)

Answer 60

Antigen-Presenting Cells. They are a specialized group of immune cells that play a critical role in the adaptive immune system by capturing, processing, and presenting antigens (foreign molecules) to lymphocytes. This antigen presentation is essential for activating cells and initiating a targeted immune response.

**Dendritic Cells (DCs): DCs are considered the most potent APCs due to their high efficiency in antigen presentation and T cell activation. They have specialized processes for capturing antigens and migrating to lymphoid organs.
**Macrophages: These are versatile immune cells found in various tissues throughout the body. They can phagocytose (engulf) pathogens and other foreign particles, process antigens, and present them to the cells. Macrophages also play a role in inflammation and tissue repair.
***B Cells: While B cells are primarily known for their role in antibody production, they can also function as APCs under certain conditions. They can internalize antigens, process them, and present them on their surface molecules (MHC class II) to T cells. This function is particularly important for activating helper T cells, which play a crucial role in coordinating the immune response.

Question 61

define MHC ,molecule

Answer 61

Major Histocompatibility Complex molecules, are protein structures found on the surface of most cells in the body. combined MHC and processed antigen can bind to antigen receptor.
MHC molecules play a critical role in self-tolerance, preventing the immune system from attacking the body’s own healthy cells.

MHC Class I:
Found on the surface of most nucleated cells in the body.
They present antigen fragments derived from cytosolic proteins (proteins within the cytoplasm of the cell) to cytotoxic T lymphocytes (CTLs).
CTLs recognize these MHC class I-antigen complexes and can directly kill infected cells or tumor cells that display the specific antigen on their surface.

MHC Class II:
Primarily found on professional antigen-presenting cells (APCs) such as dendritic cells, macrophages, and B cells.
They present antigen fragments derived from exogenous antigens (foreign molecules) that have been engulfed by the APC to helper T cells.
Helper T cells, upon recognizing the MHC class II-antigen complex, do not directly kill cells but instead orchestrate the immune response by activating other immune cells and B cells to produce antibodies.

Question 62

define cytokines

Answer 62

Cytokines are a broad category of small proteins that act as chemical messengers.

Question 63

define Th cells

Answer 63

short for T helper cells, are a specific type of T lymphocyte (T cell) crucial for the adaptive immune system.
Th cells don’t directly attack pathogens themselves. Instead, they secrete cytokines (signaling molecules) that activate and regulate other immune cells, such as B cells (antibody-producing cells) and cytotoxic T lymphocytes (CTLs) that can directly kill infected cells.

Question 64

define plasma cells (PCs)

Answer 64

Plasma cells are a specialized type of white blood cell derived from B lymphocytes (B cells) in the immune system. They play a critical role in the adaptive immune response by producing large quantities of antibodies, which are proteins that can specifically bind to and neutralize antigens.
they are short-lived but can churn out massive quantities of antibodies specific to the antigen that triggered their activation.

Question 65

is the antibody mediated immunity effective against intracellular or extracellular antigens?

Answer 65

Antibody-mediated immunity is primarily effective against extracellular antigens.
Antibodies circulate in the bloodstream and extracellular fluids. They can readily bind to and neutralize antigens present outside the cells.

Question 66

what is the structure of antibody

Answer 66

a Y-shaped protein molecule.
Two Heavy Chains: Longer polypeptide chains that determine the antibody class (IgG, IgA, IgM, etc.) and influence its function and effector mechanisms.
Two Light Chains: Shorter polypeptide chains identical to each other.

Variable Regions: These hypervariable regions determine the antibody’s antigen specificity. The variable regions of the heavy and light chains come together to form the unique antigen-binding site. This allows each antibody molecule to bind to a specific antigen with high affinity.
Constant Region: This region is identical within a specific antibody class. can activate complement or attach the antibody to cells.

Question 67

another name for antibody (explain the name)

Answer 67

immunoglobulin (Ig) - a globulin protein involved in immunity.

Question 68

how can antibody effect antigens?

Answer 68

direct - binds to an antigen and inactivates it.
indirect - binds and then the constant region activate other mechanism to destroy the antigen.

Question 69

how antibodies are produced at primary response?

Answer 69

Antigen Presentation:
The antigen enters the body and is taken up by antigen-presenting cells (APCs). Inside the APC, the antigen is broken down into smaller fragments (peptides). These peptide fragments are then loaded onto MHC class II molecules on the APC surface.

B cell Activation:
B cells that have not yet encountered their specific antigen are called naive B cells. They circulate throughout the body and express unique B cell receptors (BCRs) on their surface. Each BCR is a membrane-bound antibody with a specific antigen-binding site. A naive B cell with a BCR that matches the specific antigen fragment presented on the MHC class II molecule of an APC can bind to the MHC. This binding triggers B cell activation.

B cell Proliferation and Differentiation:
Once activated, the B cell undergoes clonal expansion. It rapidly divides through mitosis, giving rise to a large population of identical daughter cells.
These daughter cells then differentiate into two main types:
Plasma cells (antibody-producing cells) and Memory B cells (remain in a resting state within the body’s lymphoid organs for long periods, serving as a memory of the encountered antigen).

Antibody Secretion:
Plasma cells actively produce large amounts of antibodies with the same antigen-binding site as the original BCR that recognized the antigen. These antibodies are secreted into the bloodstream and extracellular fluids, where they can encounter and bind to the antigen.

Immune Response:
The secreted antibodies can then exert their effects on the antigen through various mechanisms like neutralization, opsonization, and complement activation (as explained previously).

Question 70

how long will it take to the PCs to produce enough antibodies at first response? at secondary response?

Answer 70

In the primary immune response it takes 3-14 days.
the secondary immune response is much faster.

Question 71

why secondary response to an antigen is better protection than first response?

Answer 71

speed:
the secondary response is much faster, with sufficient antibodies produced within a few days of re-exposure to the antigen. This rapid response is crucial for quickly controlling infections and preventing them from becoming severe.

Antibody Quantity and Quality:
secondary response produces a much higher quantity of antibodies. Additionally, the antibodies are predominantly of IgG class, which are more versatile and effective.

Question 72

define memory cells

Answer 72

memory cells are a specific type of long-lived lymphocyte that play a critical role in immunological memory. There are two main types of memory cells:

Memory T cells: These develop from T lymphocytes (T cells) that have been activated by encountering a specific antigen (foreign molecule) during a primary immune response.
Memory B cells: These arise from B lymphocytes (B cells) that have been activated by an antigen in the primary response.

They express receptors (T cell receptors for memory T cells and B cell receptors for memory B cells) that can recognize the same antigen they encountered previously. Upon re-exposure to the same antigen, memory cells can rapidly differentiate into effector cells (cytotoxic T lymphocytes for memory T cells and plasma cells for memory B cells) that can directly combat the pathogen.

Question 73

is the cell mediated immunity effective against intracellular or extracellular antigens?

Answer 73

Cell-mediated immunity is primarily effective against intracellular antigens.
Intracellular antigens reside within infected host cells. Antibodies cannot directly access the interior of cells. Cell-mediated immunity utilizes specialized immune cells like cytotoxic T lymphocytes (CTLs) to target and eliminate cells harboring intracellular pathogens.

Question 74

How does Cell-mediated Immunity works?

Answer 74

Antigen Presentation: antigen-presenting cells (APCs) take up the pathogen and break it down into fragments (peptides).

MHC Class I Presentation: These peptide fragments are then loaded onto MHC class I molecules on the APC surface. MHC class I molecules are present on almost all nucleated cells in the body, allowing for broad antigen presentation.

Cytotoxic T lymphocyte (CTL) Activation: CTLs, a type of T lymphocyte, circulate throughout the body and express T cell receptors (TCRs) on their surface. When a CTL encounters an APC presenting a specific antigen fragment on its MHC class I molecule that matches the TCR, the CTL becomes activated.

CTL Activation and Attack: The activated CTL undergoes proliferation, generating a population of CTLs specific to the infected cells. These CTLs recognize and bind to infected cells presenting the same antigen-MHC class I complex. They then release cytotoxic molecules (perforin and granzymes) that create pores in the infected cell membrane, leading to programmed cell death (apoptosis) of the infected cell.

Question 75

how can cytotoxic T cells distinguish between infected cells and uninfected cells?

Answer 75

almost all nucleated cells in the body express MHC class I molecules. When a cell becomes infected with a virus or intracellular pathogen, the antigen processing machinery within the cell breaks down the pathogen into peptides. These peptides are then loaded onto MHC class I molecules and displayed on the cell surface.
CTLs express TCRs (T cell receptors) on their surface that are specific for recognizing a particular antigen peptide presented on an MHC class I molecule.

Question 76

define cytotoxic T cells (and their 2 main effects)

Answer 76

Cytotoxic T lymphocytes (CTLs), also sometimes called killer T cells or cytotoxic T cells, are a specialized type of white blood cell that plays a critical role in cell-mediated immunity. CTLs are specifically designed to eliminate infected cells harboring intracellular pathogens like viruses, bacteria, and parasites.

Direct Killing: CTLs express T cell receptors (TCRs) on their surface that can recognize a specific antigen peptide fragment presented on an MHC class I molecule (explained below) on the surface of an infected cell. Once a CTL recognizes and binds to an infected cell presenting the specific antigen-MHC class I complex, it becomes activated. The activated CTL releases potent cytotoxic molecules, such as perforin and granzymes, that create pores in the infected cell membrane. These pores allow the entry of granzymes, which induce programmed cell death (apoptosis) of the infected cell. This eliminates the pathogen residing within the cell and prevents its further replication and spread.

Cytokine Secretion: CTLs can also secrete cytokines, signaling molecules that influence other immune cells. These cytokines can activate other immune cells, such as macrophages and natural killer (NK) cells, to enhance the immune response against the pathogen, help to recruit and direct other immune cells to the site of infection.
that contribute to the development of immunological memory for future encounters with the same pathogen.

Question 77

what are the first, second and third lines of defense (of the immune system)?

Answer 77

1. Physical and Chemical Barriers (First Line of Defense)
2. Innate Immune System (Second Line of Defense)
3. Adaptive Immune System (Third Line of Defense)

Question 78

what are the 4 ways immunity can be acquired?

Answer 78

**active natural - Acquired through natural exposure to a pathogen.
**active artificial - Vaccination, Simulated natural infection using weakened/inactive pathogens or components
**passive natural - antibodies from the mother are transfer at the placenta and in milk.
**passive artificial - injected antibodies

active= the body’s own immune system is stimulated to produce antibodies.
passive = antibodies from another source without the person’s own immune system being actively stimulated.

Question 79

What is the origin of red blood cells .

Answer 79

All blood cells originate from hematopoietic stem cells (HSCs).

Question 80

What are HSCs (hematopoietic stem cells )?

Answer 80

All blood cells originate from hematopoietic stem cells (HSCs).
These are immature, self-renewing cells found primarily in the bone marrow of adults. HSCs have the remarkable ability to differentiate into various types of progenitor cells, which further mature into specific lineages of red blood cells, white blood cells, or platelets.