The Lymphatic System Flashcards
Parts of lymphatic system
Lymphatic vessels
Lymphoid tissues and organs
Functions of lymphatic system
- Transports escaped fluids from cardiovascular system back to blood
2.Body defense and resistance to disease
Lymph is made of
Excess tissue fluid
Plasma proteins carried by lymphatic vessels
What happens if excess fluids are not picked up?
Edema occurs as tissues accumulate in tissues
Lymphatics
Lymphatic vessels
What do lymphatics do?
Pick up and return excess fluid to blood
Lymph in lymphatic vessels only flows toward
The heart
One way system
Lymph capillaries location
Interwoven between tissue and blood capillaries
Connected by filaments
Why do lymph capillaries have flap-like mini valves?
To let fluid leak in
How do lymph capillaries work?
Higher pressure inside closes mini-valves
Fluid is forced along the vessel
Function of lymphatic collecting vessels
1.Collect lymph from lymph capillaries
2.Carry lymph to and away from lymph nodes
- Return fluid to circulatory veins near the heart
Right lymphatic duct function
Drains lymph from right arm and right side of the head and thorax
Thoracic duct function
Drains lymph from rest of body
Similarities between lymphatic vessels and veins of CV system
1.Thin walled
2.Larger vessels have valves
3. Low pressure pumpless system
Lymph transport is aided by
- Milking action of skeletal muscles
- Pressure changes in thorax during breathing
- Smooth muscle in walls of lymphatics
Function of lymph nodes
Filter lymph before it is returned to blood
Harmful materials that lymph nodes filter
1.Bacteria
2. Viruses
3. Cancer cells
4. Cell debris
Which defense cells are inside of the lymph nodes
Macrophages
Lymphocytes
Lymphocytes in lymph
Respond to foreign substances
Macrophages in lymph
Engulf and destroy bacteria, viruses and other foreign substances in lymph
Appearance of lymph node
Kidney shaped
Less than one inch
Buried in connective tissue
Surrounded by capsule, separated in compartments by trabeculae
Cortex (outer part of lymph nodes)
- Has follicles (collection of lymphocytes)
- Germinal centers enlarge when bodies are released by plasma cells
Medulla (inner part of lymph nodes)
contains phagocytic macrophages
Afferent lymphatic vessels
Carry lymph towards lymph node
Efferent lymphatic vessels
Carry lymph out of lymph nodes
Describe the flow of lymph through lymphatic vessels
- Lymph enters convex side through afferent lymphatic vessels
- Lymph flows through a number of sinuses inside of the node
- Lymph exits through efferent lymphatic vessels
- Because there are fewer efferent than afferent vessels, flow is slowed. (Slow flow helps screen for pathogens)
Other lymphoid organs
Spleen (curves around left side of stomach)
Thymus (In thorax)
Tonsils
Peyer’s patches (in intestine)
Appendix
Spleen location
Left side of abdomen
Function of spleen
- Cleans blood
- Lymphocyte reproduction and immune surveillance
- Destroys worn out blood cells
4.makes fetal blood cells
5. Acts as blood reservoir
Overlies the heart
Functions at peak levels only during youth. Decreases in size after growing
Thymus
Tonsils
Small masses of lymphoid tissues deep to mucosa surrounding pharynx (throat)
Tonsils function
- Trap & remove bacteria/ pathogens
Cause of tonsillitis
Tonsils congested with bacteria
Peyer’s patches location
Found in wall of small intestine
Similar lymphoid follicles are found in the appendix
Peyer’s patches function
Macrophages capture and destroy bacteria in the intestine
Mucosa Associated Lymphoid tissues (MALT) include
Peyer’s patches
Tonsils
Appendix
Acts as sentinel to protect respiratory and digestive tracts
MALT
Immunity
Specific resistance to disease
______ system is a functional system instead of organ system in anatomical sense
Immune system
Innate (nonspecific) defense mechanisms
1st & 2nd lines of defense
1st line of defense parts
1.Skin
2.Mucous membranes
3. Secretions of skin and mucous membranes
2nd line of defense parts
1.Phagocytic cells
2.Natural killer cells
3.Antimicrobial proteins
4.inflammatory response
5.Fever
6. Chemicals that kill pathogens
Adaptive (specific) defense mechanisms
Third line of defense
Third line of defense parts
1.Lymphocytes
2. Antibodies
3. Macrophages and other antigen presenting cells
Innate (nonspecific) defense system
1.Protect against variety of invaders
2.Responds immediately to protect body from foreign materials
Adaptive (specific) defense system
- Fights invaders that get past the innate system
2.Specific defense is required for each type of invader - Highly specific resistance to disease is immunity
Natural killer cells
Promote cell lysis by direct cell attack against infected or cancerous cells
Inflammatory response
1.Prevents spread of harmful agents
2. Disposes pathogens and dead tissue cells
3.Promotes tissue repair
4. Attracts phagocytes
What do acidic skin secretions do?
Inhibit bacterial growth
How does sebum protect?
Sebum is toxic to bacteria
How does mucus protect
Mucus traps microorganisms
How do gastric juices protect
Acidic gastric juices kill pathogens
How do saliva and tears protect
Saliva and tears have lysozyme (enzyme that destroys bacteria)
Fever
High body temperature stops bacteria replication
Enhances body repair
Release chemicals called perforin and granzymes to degrade Target cell contents
NK natural killer cells
Triggered when body tissues are injured
Inflammatory response
Cardinal signs of acute inflammation
- Redness
- Heat
3.Pain - Swelling (edema)
Damaged cells release
Histamine
Kinin
Effects of histamine and kinin
1.Dilated blood vessels
2. Leaky capillaries
3.Phagocytes and white blood cells move into area (positive chemotaxis)
Process of inflammatory response
- Neutrophils migrate to inflammation area by rolling along vessel wall (following scent of chemicals from inflammation)
- Neutrophils squeeze through capillary walls by diapedesis to inflammation sites
- Neutrophils gather in precise site of tissue injury (positive chemotaxis) and consume foreign material present
Neutrophils and macrophages engulf foreign material through
Phagocytosis
Phagocytes
Phagocytic vesicle is fused with lysosome,
Enzymes digest cell’s contents
Steps of phagocytosis in a macrophage
- Phagocyte adheres to pathogens
2.Phagocyte engulfs the particles, forming a phagosome
- Lysosome fuses with phagocytic vesicle forming a phagolysosome
4.Lysosomal enzymes digest pathogens or debris, leaving a residual body
- Exocytosis removes indigestible and residual material
Antimicrobial proteins enhance innate defenses by
Attacking microorganisms directly
Hindering reproduction of microorganisms
Most important types of antimicrobial proteins
Complement proteins
Interferon
Group of at least 20 plasma proteins that circulate in the plasma
Complement
Complement is activated when
Complement proteins encounter and attach to cells (complement fixation)
Membrane attack complexes (MACs) produce holes or pores in cells
Allow water to rush into cells
Cell bursts (lyses)
Complement proteins attach, make pore, let water in, cell bursts
Enhances inflammatory response
Activated complement
Interferons
Small proteins secreted by virus infected cells
Function of interferons
Bind to membrane receptors
Interfere with viruses multiplying ability
Hypothalamus regulates body temperature at
37 C
98.6 F
Hypothalamus thermostat can be reset by
Pyrogens (secreted white blood cells)
High temperatures inhibits the release of
Iron and zinc (needed by bacteria) from the liver and spleen.
Fever increases the speed of
Repair processes
Antibodies
Target and destroy antigens
Immune system’s response to a threat
Immune response
Aspects of adaptive defense
- Antigen specific
- Systemic
- Memory
Adaptive defense system recognizes and acts against particular foreign substances
Antigen specific
Immunity is not restricted to initial infection site
Systemic
Adaptive defense system recognizes and mounts a stronger attack on previously encountered pathogens
Memory
Two arms of adaptive defense system
Humoral immunity
Cellular immunity
Antibody mediated immunity
Humoral immunity
Provided by antibodies in body fluids
Targets virus infected cells, cancer cells and cells of foreign grafts
Cell-mediated immunity
Substances capable of exciting immune system and provoking immune response
Antigen
Foreign proteins
Nucleic acids
Large carbohydrates
Some lipids
Pollen grains
Microorganisms (bacteria, fungi, viruses)
Examples of non-self antigens
Presence of our cells in another person’s body can trigger immune response because
They are foreign
What restricts donors for transplants
Self antigens
Our own antigens don’t trigger response unless there is an autoimmune disorder
Haptens
Incomplete antigens
How do haptens work?
When they link up with our proteins, immune system may recognize the combination as foreign and attack
Haptens are found in
Poison ivy
Animal dander
Detergents
Hair dyes
Cosmetics
Produce antibodies and oversee humoral immunity. Respond to specific antigens
B lymphocytes (B cells)
Constitute cell-mediated arm of the adaptive defenses; do not make antibodies
T Lymphocytes (T cells)
Help the Lymphocytes, but don’t respond to specific antigens
Antigen presenting cells (APCs)
Lymphocytes arise from
Hemocytoblasts of bone marrow
Whether a Lymphocyte matures into a B or T cells depends on
Where it becomes immunocompetent
Immunocompetence
Responding to a specific antigen because antigen binds to specific receptors on the Lymphocyte’s surface
T cells develop immunocompetence in
Thymus
B cells develop immunocompetence in
The bone marrow
What happens to T cells that bind self antigens
They are destroyed,
Self tolerance is important part of Lymphocyte education
Immunocompetent T and B cells migrate to
Lymph nodes and spleen,
Here they encounter different antigens
Naive cells vs mature cells differentiation
Mature cells bind recognized antigens
Motion of mature Lymphocytes
Circulate continuously throughout the body
Engulf antigens and then present fragments of them on their own surfaces where they can be recognized by T cells
Antigen presenting cells APCs
Major types of cells behaving as APCs
Dendritic cells
Macrophages
B Lymphocytes
What happens when APCs present antigens
Dendritic cells and macrophages activate T cells, which release chemicals
What triggers clonal selection
Binding between B Lymphocyte and a specific antigen
Clonal selection (primary humoral response)
Large number of clones produced
Descendants
B cell clone members
Most of the B cell clone members become
Plasma cells
Plasma cells
Produce antibodies to destroy antigens
Activity lasts 4-5 days
Plasma cells begin to die
Some B cells become long lived memory cells meaning
Capable of mounting rapid attack against the same antigen in subsequent meetings (secondary humoral response)
Secondary humoral response
B cells become long lived memory cells
Active immunity
B cells encounter antigens and produce antibodies
How can you acquire active immunity
Naturally through infections
Artificially through vaccines
Passive immunity
Get antibodies from someone else
Breast milk
Immune serum
Gamma globulin (donated antibodies)
Short lived protection
2-3 weeks
Immunological memory doesn’t occur
Monoclonal antibodies
Prepared for clinical for diagnostic services
Produced from descendants
Exhibit specificity from one antigen
Examples of uses for monoclonal antibodies
Cancer treatment
Diagnosis of pregnancy
Treatment after exposure to hepatitis and rabies
Gamma globulin part of blood proteins
Antibodies
Immunoglobulins, Igs
Antibodies
What is the structure of antibodies
- 4 polypeptides ( 2 heavy and 2 light) linked by disulfide bonds to form T or Y
Variable regions
Form antigen binding sites, one on each arm of the T or Y
Constant regions
Determine type of antibody formed (antibody class)
Each polypeptide chain has 2 regions
Variable region
Constant region
Antibody classes
Antibodies of each class have slightly different roles and differ structurally and functionally
Five major immunoglobulin classes
M
A
D
G
E
IgM
Can fix complement
IgA
Found mainly in secretions, such as mucus and tears
IgD
Helps activate B cells
IgG
Cross placental barrier and fix complement; most abundant antibody in plasma
IgE
Involved in allergies
Chief antibody ammunition used against cellular antigens
Complement fixation
Neutralization
Antibodies bind to specific sites on bacterial exotoxins or on viruses that can cause cell injury
Precipitation
Cross-linking reaction in which antigen antibody complex settles out of solution
Main difference between B and T cells
B cells secrete antibodies
T cells fight antigens directly
Like B cells, immunocompetent T cells are activated to
form a clone by binding with a recognized antigen
Unable to bind to free antigens
T cells
Antigens must be presented by a
Macrophage, and double recognition must occur
APC engulfs and presents the processed antigen in combination with
A protein from the APC
Antigen presentation
Cells must recognize non-self and self
Non-self
Antigen fragment presented by APC
Self
Coupling with a specific glycoprotein on the APCs surface at the same time
Helper T cells
Recognize foreign antigens
Secrete cytokines (activate T & B cells)
Cytotoxic T cells
Kill cancerous, infected and damaged cells
Cytotoxic ( killer) T cells
Insert toxic chemicals (perforin or granzyme)
How do killer T (cytotoxic cells work?)
1.T cell attaches and inserts a toxic chemical like perforin or granzyme
2.Perforin & granzyme enters foreign cell’s plasma membrane
3.perforin makes pores.Pores now appear in target cell’s membrane
4.Granzymes (protein digesting enzymes) enter and kill the foreign cell
- Cytotoxic T cell detaches and seeks other targets
Perforin
Causes cell lysis
Granzymes
Protein digesting enzymes
Which cells recruit other cells to fight invaders?
Helper T cells
Directly interact with B cells bound to an antigen , prodding the B cells into clone production
Helper T cells
Cytokines
Chemicals that act directly to rid the body of antigens
Regulatory T cells
Release chemicals to suppress the activity of T & B cells
Stop immune response to prevent uncontrolled activity
Few members of each clone are memory cells
Tumor necrosis factor
Causes cell killing, attracts granulocytes; activates T cells and macrophages
Complement
Activate after binding to antibody covered antigens, when active, complement causes lysis of microorganism and enhanced inflammatory response
What percent of blood group and tissue must match to attempt a graft?
75%
Immunosuppressive therapy
Therapy after transplant. Helps prevent rejection
Most important disorders of the immune system
- Allergies
- Autoimmune diseases
3.Immunodeficiencies
Hypersensitivities,
Abnormal, vigorous immune responses. Immune system overreacts to a harmless antigen
Allergies, tissue damage occurs
Immediate (acute allergies) cause
IgE antibodies and histamine
Hives and anaphylaxis are symptoms of
Immediate acute hypersensitivity
What kind of allergy is anaphylactic shock (Systemic)?
Acute allergic response
Delayed hypersensitivity
Reflects activity of T cells, macrophages, cytokines
Symptoms appear 1-3 days after coming in contact with the antigen
Delayed hypersensitivity
Allergic contact dermatitis (poison ivy, cosmetics) is caused by
Delayed hypersensitivity
Allergy mechanism
- Antigen invades body
2.Plasma cells produce large amounts of class IgE antibodies against allergen
3.IgE antibodies attach to mast cells in body tissues (and to circulating basophils).
4.More of same allergen invades body
5.Allergen binding to IgE on mast cells triggers release of histamine and other chemicals
6. Histamine causes blood vessels to dilate and become leaky, which promotes edema, large amounts of mucus, smooth muscles contract
Autoimmune diseases occur when
Occurs when body’s self tolerance breaks down
Body produces auto antibodies and sensitized T lymphocytes that attack its own tissues
Auto immune diseases
The body produces autoantibodies and sensitized lymphocytes that attack its own tissues
Autoimmune diseases
Body produces Auto antibodies and sensitized T lymphocytes that attack its own tissues
Autoimmune disease
Most autoimmune diseases result from
1.Formerly hidden self antigens
2. Changes in structure of self antigens
3.antibodies formed against foreign antigens that resemble self antigens
Rheumatoid arthritis
Myasthenia gravis
Multiple sclerosis
Graves disease
Autoimmune disorder examples
Rheumatoid arthritis
Destroys joints
Myasthenia gravis
Impairs communication between nerves and skeletal muscles
Multiple sclerosis
White matter of brain and spinal cord is destroyed
Graves disease
Thyroid gland produces excess thyroxine
Destroys pancreatic beta cells, deficient insulin production
Type I diabetes mellitus
Systemic Lupus erythematous (SLE)
Affects kidney, heart, lungs and skin
Glomerulonephritis
Severe impairment of kidney function due to acute inflammation
Types of immunodeficiencies
Congenital or acquired
SCID severe combined immunodeficiency disease is a type of
Congenital disease
Can be present at birth, children have very little immune function
AIDS (acquired immune deficiency syndrome,) is caused by
Virus that attacks and cripples helper T cells
Immunodeficiencies result from
Abnormalities in any immune element
Production or function of immune cells or complement is
Abnormal
Proteins secreted by activated B cells
Antibodies
Formed in response to large number of antigens
Antibodies
