BIO 205 Lymphatic and Respiratory System Exam 4

What are the functions of the lymphatic system

1. Fluid Balance- excess interstitial fluid enters capillaries

2. Lipid Absorption- fat is absorbed via lacteals and is called chyle

3. Defense- foreign substances are filtered by nodes and spleen

Chyle

fat and lymph fluid

Lacteals

small lymphatic vessels in the intestine that absorb dietary fats and transport them to the bloodstream.

Lymphatic capillaries

small vessels that absorb interstitial fluid, fats, and proteins from tissues and transport them into the lymphatic vessels

lymphatic vessels

large vessels that carry lymph away from tissues with a one way flow valve structure

Mechanisms of movement of lymphatic vessels

1. Contractions of lymphatic vessels by using valves as pumps that contain pacemaker cells

2. Contraction of skeletal muscle by body movement

3. Thoracic pressure change that causes lymph to move toward heart

Lymph nodes

distributed along vessels and filter lymph

Lymphatic trunk

large lymphatic vessels that drain from specific body areas

• connect to large veins in thorax or to lymphatic ducts

Jugular trunk

drains from head and neck

Subclavian trunk

drains upper limbs, superficial thoracic wall and mammary glands

Bronchomediastinal trunk

drains from deep thoracic organs and deep thoracic wall

Intestinal trunk

drains abdominal organs

Lumbar trunk

drains lower limbs, pelvic and abdominal walls, pelvic organs

Lymphatic ducts

move lymph into major veins

Right lymphatic duct

drains right side of the head, right upper limb and right thorax

thoracic duct

drains the remainder of the body

Primary lymphatic organs

sites where lymphocytes are produced and mature, including the bone marrow and thymus. capable of launching an immune response

Pre B cells

become immunocompetent in red bone marrow

Pre T cells

become immunocompetent in the thymus

Secondary Lymphatic tissues/organs

include lymph nodes, spleen, and mucosa-associated lymphoid tissue (MALT), where lymphocytes interact with each other to produce an immune response

Lymphatic tissues

are specialized connective tissues involved in the production and maturation of lymphocytes. These tissues include lymph nodes, spleen, and mucosa-associated lymphoid tissues (MALT).

Lymphatic organs

are specialized structures that play a crucial role in the immune system by filtering lymph and producing immune cells. They include lymph nodes, the spleen, and the thymus.

Nonencapsulated lymphatic tissues

are lymphatic tissues that lack a connective tissue capsule but have reticular fibers, has mucus membranes called mucosa-associated lymphatic tissue (MALT) Use mucus to defend against pathogens and play a role in immune response. Examples include tonsils and Peyer's patches.

Diffuse lymphatic tissue

dispersed lymphocytes and macrophages that blends in with other tissues

Lymphatic nodules

dense, connective tissue with Peyer patches and MALT, referred to as lymphatic follicles

Tonsils

A large group of lymphatic nodules, provides protection against bacteria, forms a ring around oral cavity and pharynx

3 groups of tonsils

Palatine (tonsils)

Pharyngeal (adenoids)

Lingual (on the tongue)

Lymph node structure

• superficial and deep

• structures that filter lymph, containing a capsule, cortex, and medulla.

• Afferent and Efferent Vessels

• substances removed by phagocytosis or stimulated to proliferate in germinal centers

• Cancer often migrates here

Spleen structure

• can rupture

• White pulp tissue is associated with arteries

• Red pulp tissue is associated with veins

• Lymphatic sheath and nodules (white)

• Splenic cords and venous sinus (red)

Spleen blood flow

• Fast, slow and intermediate

• slow flow is open circulation

Spleen function

destroys defective RBCs, detects and responds to foreign substances and has a limited reservoir for blood

Thymus

an organ where T lymphocytes mature and differentiate, playing a crucial role in the immune response. secretes thymosin

thymus anatomy

• lobes surrounded by capsules that divide it into distinct lobules, each containing a cortex and medulla.

• epithelial cells

• cortex has many lymphocytes

• medulla has thymic corpuscles that dev t cells

Immunity

the ability to resist damage from foreign substances such as microorganisms and harmful chemicals

Innate or nonspecific resistance

is the body's first line of defense against pathogens and present at birth, involving physical barriers like skin and mucous membranes, as well as immune responses like chemicals and cell phagocytosis

Adaptive or specific immunity

immune response that needs to be exposed first or develops over time

• specificity and memory

Specificity adaptive immunity

the ability to recognize a particular substance

Memory adaptive immunity

the ability to remember previous encounters with a particular substance and respond rapidly

Examples of innate immunity

skin, mucous membranes, tears, saliva, urine, cilia in respiratory tract, coughing and sneezing

Chemical mediators

molecules/substances responsible for aspects of innate immunity

surface chemicals in innate immunity

lysozymes in tears and saliva

Histamine and kinins in innate immunity

vasodilation and increased vascular permeability during inflammation

Interferons in chemical mediators

proteins that inhibit viral replication and modulate the immune response.

Complement in innate immunity

a group of proteins that work with antibodies to promote inflammation and lyse cells.

Prostaglandins and leukotrienes in chemical mediators

lipid compounds that promotes inflammation

pyrogens in chemical mediators

promotes fever

Cytokines

proteins secreted by cells that bind to receptors on cell surfaces, stimulating a response

Complement

A group of 20 proteins that circulate in the blood in an inactive form until activated

Become activated through the complement cascade

Two pathways

Complement cascade

A series of reactions involving the complement proteins that enhance the ability of antibodies and phagocytic cells to clear pathogens from an organism.

Alternative pathway

part of the innate immunity, C3 binds with a foreign substance. attracts macrophages

Classical pathway

part of adaptive immunity that is triggered by the binding of antibodies to an antigen, leading to the activation of complement proteins.

Result of activated complement proteins

1. membrane attack complex

2. Opsonization

3. Inflammation

Membrane attack complex

makes channels through plasma membranes of microbes resulting in cell lysis

Opsonization

compliment proteins attach to surface of bacterial cell which stimulates phagocytosis

Interferon

a protein that protects against viral infections and some forms of cancer

spread of viruses

Enter the host cell and use the host cells protein making organelles to make and assemble a new viruses that are released to infect other cells

How interferons work

Virus-infected cells produce interferons, which bind to the surfaces of neighboring cells, signaling them to produce antiviral proteins that will stop replication

White Blood Cells

are a key component of the immune system, helping to identify and eliminate pathogens such as viruses and bacteria.

Actions of white blood cells

Chemotaxis- movement toward the source

Phagocytosis- the process of engulfing and digesting pathogens, active transport

Neutrophils

• phagocytic and the first cell to enter the infected tissue

• Release chemical signals such as cytokines and chemotactic factors that increase inflammatory response and activate other cells

• Release lysosomal enzymes that kill microorganisms and cause tissue damage

• cross wall of gastrointestinal tract providing protection

Monocytes

• macrophages that leave the blood to enter tissues

• produce chemicals like interferons, prostaglandins and complement

• found beneath free surfaces such as the skin, membranes, and tissues and within sinuses

Reticuloendothelial cells

Monocytes found in the sinuses

Dust cells

Monocytes in the lungs

Kupffer cells

monocytes in the liver

Microglia

monocytes in the central nervous system

Basophils

promotes inflammation when activated by the innate or adaptive system, releases histamine and leukotrienes

• Basophils = motile, leave blood to tissue

• Mast cells = non motile, in CT

Eosinophils

• leaves blood and enters tissues by reducing inflammation by breaking down the chemicals produced by basophils

• Secrete enzymes that kill some parasites

Natural killer cells

• type of lymphocyte that lyses tumors and virus-infected cells

• recognize whole class of cells, not just one

Inflammatory Response

response initiated by chemicals that produce vasodilation, chemotactic attraction, and an increase in vascular permeability. fibrinogen and complement enter the tissue

Local inflammation

confined to a specific area of the body, systems are redness, heat, swelling, pain or loss of function

Systemic inflammation

inflammation that affects the entire body, characterized by fever, increased heart rate, and elevated neutrophil numbers

• fever due to the production of pyrogens by various kinds of cells

• A large volume of plasma enters spaces, leading to death

Foreign antigens

not produced by the body, introduced from outside

• bacteria, viruses, pollen, feces, food, drugs

Self Antigens

molecules produced by the body that trigger an immune response in others but are usually tolerated by the individual's own immune system.

Adaptive Antibody mediated

immune response involving B cells that produce antibodies specific to antigens.

Adaptive Cell Mediated

immune response involving T cells that directly attack infected cells.

• cytotoxic and helper t cells

Cell mediated Cytotoxic T cells

are a type of T cell that directly kill infected or cancerous cells by recognizing specific antigens presented by MHC I molecules.

Cell Mediated Helper/regulatory T cells

promotes or inhibits both antibody mediated and cell mediated immunity

Antigenic determinants and receptors

• lymphocytes must interact and recognize an antigen for a response to occur

• Lymphocytes interact with specific antigens called antigenic determinants or epitopes

• given an identical antigen receptors so they can combine

Major histocompatibility complex molecules

are molecules that present peptide fragments derived from pathogens on the surface of cells for recognition by T cells, playing a crucial role in immune system signaling.

-immune cells must be able to distinguish between self and foreign antigens

Endogenous antigens

antigens produced in the cell, from genetic expression and protein synthesis

Exogenous antigens

antigens that originate from outside the body and are taken up by antigen-presenting cells, usually by phagocytosis

MHC I

molecules display endogenous antigens, found on nucleated cells, function as a red flag to prompt immune cells to destroy displaying cells

MHC II

molecules display exogenous antigens, primarily found on professional antigen-presenting cells like dendritic cells and macrophages, facilitating T-cell activation. Not destruction!!!

Clonal selection

A mechanism that results in a large population of identical lymphocytes

• occurs when lymphocytes proliferate and become specialized when exposed to a antigen

Stem cell derive

• all blood cells including lymphocytes come from red bone marrow

• some stem cells rise to pre t cells in thymus

• other stem cells rise to pre b cells in red bone marrow

Positive selection

ensures survival of lymphocytes that react against antigens, these then proliferate and form clones

Negative selection

eliminates lymphocytes that bind too strongly to self-antigens, preventing autoimmunity.

Activation of lymphocytes

is the process by which lymphocytes are stimulated to proliferate and differentiate in response to specific antigens, leading to an immune response.

In order for B or T cells to produce a response

binding of the MHC II, which presents processed antigens to T cells that wants to activate more cells

• and costimulation

Costimulation

is the second signal required for T cell activation, ensuring that T cells respond appropriately to antigens.

Costimulation by cytokines

released by macrophage of a cytokine, tells t-cell what type of response to become

Costimulation by surface molecules

binding of two molecules, sends signal to t - cell, confirms response and helps cell stay alive and proliferate.

Lymphocyte Proliferation

is the process by which helper t cells undergo rapid cell division after activation, expanding their population to effectively respond to an antigen.

Inhibition of lymphocytes

1. deletion of self-reactive lymphocyte

2. Preventing activation of lymphocytes that encounter self-antigens

3. Activation of regulatory t cells to maintain tolerance and prevent autoimmune reactions.

Tolerance of lymphocytes

is the ability of the immune system to recognize and ignore self-antigens, preventing unnecessary immune responses against the body's own tissues.

Antibody mediated immunity

involves the production of antibodies in response to antigens, primarily by B cells

Structure of antibodies

Y shaped consisting of four polypeptide chains, two identical heavy chains and two identical light chains

Variable region of antibody

is the part of an antibody that binds to specific antigens

Constant region of antibody

is the part of an antibody that determines its class and effector functions.

IgG

activates complement and promotes phagocytosis, can cross the placenta and provide immune protection, rh factor

80 to 85