AnP Chapter 17 (LO1) Flashcards
Lymphatic system
consist of lymphatic vessels, length, lymphatic tissues, and lymphatic organs
The tissues and organs of the lymphatic system include
lymph nodes, thymus, tonsils, spleen and red bone marrow
The lymphatic system has three functions:
The maintenance of fluid balance: absorb this fluid and return it to the bloodstream
Absorption of fats: specialized lymphatic vessels in the small intestines absorb fat and fat soluble vitamins
Immunity: lymph nodes and other lymphatic organs filter lymph to remove cellular waste, microorganisms and foreign particles
Lymph
A clear, colorless fluid similar to plasma but with a lower protein content
Originates in the tissues as the fluid left behind after Capillary exchange
Lymphatic Vessels
Also called lymphatic capillaries
carry fluid in one direction only away from the tissue
lymphatic vessel structure
Have thin walls made of epithelial and valves to prevent backflow
lymphatic vessels overlap loosely
Valves prevent backflow, ensuring that length move steadily away from the tissues and toward the heart
The lymphatic system has two collecting ducts:
The right lymphatic duct: drains lymph from the upper right quadrant of the body into the right subclavian vein
Thoracic duct: drains limbs from the rest of the body into the left subclavian vein
Macrophages
phagocytize bacteria and foreign matter
Dendritic cells
which engulf foreign substances and help activate T cells
Mucosa-associated lymphatic tissue (MALT)
Passages that open to the exterior of the body contain scattering of lymphocytes throughout their mucous lining
Tonsils
Masses of lymphoid tissue that forms a protective circle at the back of the throat
Guard against pathogens entering the body through the nose or throat
Tonsillar crypts
deep pits covered with epithelium
3 sets of tonsils
A singular Pharyngeal tonsil (adenoids): sits on the wall of the pharynx just behind the nasal cavity
A pair of Palatine tonsils: lies in the posterior of the oral cavity
Numerous lingual tonsils: are concentrated in patches on each side of the base of the tongue
Appendix
A narrow pouch that projects off the lower end of the large intestine
Densely populated with lymphocytes
May serve as a reservoir for beneficial gut bacteria
Payer’s patches
Small masses of lymphatic tissue scattered throughout the small intestine just beneath the intestinal mucosa
Part of the gut associated lymphatic tissue (GALT)
Lymphatic organs
have connective tissue capsules that separate the organ from neighbouring tissues
lymphatic organs are divided into two categories: primary and secondary
primary lymphatic organs
include the famous in Redbone Marrow
Provide a location for stem cells to divide and mature into T and B lymphocytes
immunocompetence
Immunocompetence:
Where lymphocytes learn to recognize and attack foreign invaders
secondary lymphatic organs
include lymph nodes in the spleen; this is where mature lymphocytes become activated and begin to protect the foreign pathogen’s
Thymus
Produces T cells
Located in the mediastinum
Produces a hormone called thymosin
After enlarging through childhood, it slowly shrinks
Divided into Lobules that extend in word from a fibrous outer capsule
thymosin
Promotes the development of lymphocytes
Steps on how the thymus works
- Immature T lymphocytes travel from Redbone Merrill to the outer cortex of the thymus protecting them and giving them a chance to divide and mature
- The developing T lymphocytes migrate toward the inner medulla
a) They encounter other lymphoid cells which trains the new lymphocytes to distinguish between its own cells and foreign cells - Once the training is complete the lymphocytes are immunocompetent and released into the bloodstream
Lymph nodes
serve as sites for final maturation of some types of lymphocytes and monocytes
removed pathogens in foreign material from lymph as it passes through
The body contains more than 600 lymph nodes
Trabeculae
connective tissue that extends to the node dividing it into compartments
Cortical nodules
compartments filled with lymphocytes
Germinal centers
a less dense area at the center of the compartments that form and release lymphocytes when an infection is present
Sinuses
lined with macrophages which separate the compartments and filter lymph as it flows through the sinuses
Afferents lymphatic vessels
Channel fluid into a node
Efferent lymphatic vessel
after slowly filtering through the node lymph leaves through single
Cervical lymph nodes
found in the neck, monitor limbs coming from head and neck
Axillary lymph nodes
classic in the armpit, receive them from arm and breast
Inguinal lymph nodes
occur in the groin, they receive lymph from legs
Sentinel lymph node
the first lymph node reached by metastasizing cancer cells
Lymphadenopathy
enlargement of one or more lymph nodes
Stony hard nodes
Very firm, rubbery nodes
Softer nodes
typically indicate metastic cancer
suggest lymphoma (cancer involving lymphocytes)
suggest infection or inflammatory condition
Postauricular lymph nodes
located behind the ear, main large as a result of infections of the head, neck, sinuses, ears, scalp or pharynx
Suboccipital lymph nodes
which reside where the back of the neck meets the head
Main large as a result of localized infection of the scalp or head
Preauricular lymph nodes
located behind the ear, main large as a result of infections of the head, neck, sinuses, ears, scalp or pharynx
Submandibular lymph nodes
suggest an infection of the head, neck, sinus, ears, eyes, scalp, or pharynx
Axillary lymph nodes
made in large as a result of an infection, cat scratch disease, lymphoma or breast cancer
Inguinal lymph nodes
may occur from infection of the leg or foot, a sexually transmitted disease or lymphoma
Spleen
About the size of a fist
The body’s largest lymphatic organ
Resides in the upper left quadrant of the abdomen inferior to the diaphragm protected by the lower ribs
The spleen contains two types of tissue: red pulp and white pulp
White pulp
contains compact masses of lymphocytes, surrounds the arteries leading into each compartment
Red pulp
exist along the edges of the compartments
Consist of a network of erythrocyte filled sinuses supported by a framework of reticular fibers and phagocytic cells
Blood collects in the venous sinuses after passing through the reticular fibers
it then returns to the heart through the veins
The spleen fulfils many functions:
Immunity
destruction of old red blood cells
blood storage
hematopoiesis
Immunity
lymphocytes and macrophages in the white pulp screen passing blood for foreign antigens while phagocytic cells in the sinuses ingest and destroy any microorganisms
Destruction of old red blood cells
macrophages in the sinuses digest worn out red blood cells and imperfect platelets
They also recycle haemoglobin from destroyed red blood cells salvaging the iron and globin and returning it to the bone marrow and liver for later use
Blood storage
the spleen store is 20% to 30% of the bodies platelets
it can help stabilize blood volume by rapidly adding blood back into general circulation
Hematopoiesis
the spleen produces red blood cells in the fetus
After birth it does so only in cases of severe anaemia
Throat life the spleen provides a location for monocytes and lymphocytes to mature
immune system: The body has —– lines of defense for taking care of threats it encounters on a daily basis
3
First line of defence
External barriers such as the skin and mucous membranes keep most of the pathogens we encounter at bay
Second line of defence
If a pathogen penetrates the first line of defence the body launches several mechanisms geared at repelling a wide variety of threats
Nonspecific immunity (innate immunity)
Protects against a broad range of pathogen’s using a variety of mechanisms such as external barriers, phagocytosis, antimicrobial proteins, natural killer cells, inflammation and fever
Third line of defence
specific immunity
If exposed to the same pathogen in the future the body can quickly recognize it targeting a response at this one specific invader
Specific immunity
this occurs when the body retains a memory of a pathogen after defeating it
External barriers
The skin is composed of tough protein, repels most pathogens and its surface is dry and lacking nutrients making it a hostile environment for bacteria
Mucous membranes line the digestive, respiratory, urinary and reproductive tract which produces mucus and traps pathogens
lysozomes
Acid mantle
a thin layer of acid produced by sweat that inhibits bacterial growth
Lysozyme
an enzyme which destroys bacteria that is found in mucus, tears, and saliva
Phagocytosis
If a pathogen makes its way past the skin or mucous membranes and enters the body it will be confronted by phagocytes
how phagocytosis works
- phagocytes are small cells whose sole job is to ingest and destroy micro organisms and other small particles
- When a phagocyte encounters of microorganism it sends out a membrane projection called pseudopods
- The pseudopods envelop a complete sac called phagosome
- The phagosome travels to the interior of the cell and fuses with a lyzome which contains digestive enzymes
- The digestive enzymes from the lysosome destroy the micro organism
- The waste products are then released from the cell
Types of phagocytes
Most important phagocytes are macrophages and neutrophils
Macrophages evolve from monocytes and congregate in areas where microbial invasion is likely to occur such as the Alviolus of the lungs, the liver, nerve tissue, bone and the spleen
Neutrophils around the body seeking out bacteria
How phagocytosis it works
Chemotaxis: Neutrophils travel to site of infection after being summoned by a chemical released from inflamed cells
Once they’re the neutrophils anchor themselves to the inside of blood Capillary
Diapedesis: they use enzymes to digest a portion of the basement membrane which allows them to squeeze out of the vessel and enter the inflamed tissue
Antimicrobial proteins
Two types of proteins help provide non-specific resistance against bacterial and viral invasion: interferons and the complement system
Interferons
a protein produced by cells to respond to viral invasion
The interferon is released and binds to surface receptors on cells that triggers production of enzymes that would prevent the virus from replicating
Complement system
more than 20 different proteins circulate in the blood stream in an in active form waiting to assist in the immune response
The release of complement also starts a process that kills certain bacteria
how the complement system works
The process begins when a bacteria or antibodies against the bacteria, activate the complement causing a cascade of chemical reactions
Membrane attack complex: A group of complement proteins embedded themselves into the bacterium’s plasma membrane in the ring like circles effectively punching a hole in the bacterium
Fluid and sodium ration to the bacterium through the opening
Bacterium swells and bursts
Natural killer cells
a unique group of them for sites that continually roam the body seeking a pathogens or disease and destroying any foreign cells
They use several methods to destroy the cells most of them involve the secretion of chemicals
Inflammation
Tissue injury produces inflammation
Inflammation stimulates the body’s defense system to begin fighting the infection while instigating measures to contain the pathogen
The inflammatory response includes processes at cleanup and repair the damaged tissue
how inflammation works
- Injured cells secrete chemicals causing blood to rush in (hyperemia) bringing necessary leucocytes and flush out toxins/wastes
- The same chemicals that trigger vasodilation also causes the cells in the capillary walls to separate allowing fluid, leucocytes and plasma proteins to leak through into the injured tissue
- —Fibrinogen that leaks into the area formed a sticky cloth to help keep the infection from spreading - Neutrophils which have been drawn to the area by chemotaxis actively phagocytize pathogens
4 classic signs of inflammation:
Swelling: results from fluid leaking out of the capillaries
Redness: results from hyperemia
Heat: results from hyperemia
Pain: may result from injured nerves, pressure on the nerves from swelling, or stimulation of nerves by bacterial toxins
Signs of inflammation also facilitate healing:
Swelling compress veins reducing venous drainage while forcing the Capillary valves open to promote
Capillary drainage
Hyperemia: brings materials necessary for healing including oxygen and amino acids
Heat in the area increases the metabolic rate and the rate of tissue repair
Pain signals that an injury has occurred and serves as a reminder to rest the area to allow healing
Words ending in -itis denote
inflammation
Pyrexia (fever)
Febrile
Pyrexia (fever): is an abnormal elevation of body temperature
Febrile: a person with a fever
The sequence of events during a fever
- As neutrophils and macrophages phagocytize bacteria, they secrete pyrogen
- PGE resets the bodys set point for temp
- When the set point rises the body needs to generate heat by shivering and constricting blood vessels
- The temperature rises until it reaches its new set point where it remains as long as the pathogen is present
- When the pathogen is no longer a threat, the phagocytes stop producing the pyrogen and the bodys set point for temperature returns to normal
- —The body needs to lose the excess heat by sweating and dilating blood vessels
Temperatures over —– can cause convulsions
Temperatures greater than — to — typically result in irreversible brain damage or death
Temperatures over 105 (40.5) can cause convulsions
Temperatures greater than 111 to 115 (44 to 46) typically result in irreversible brain damage or death
Two mechanisms of specific immunity
cellular (cell mediated) immunity
humoral (antibody mediated) immunity
cellular (cell mediated) immunity
aims to destroy foreign cells or host cells that have become infected with a pathogen
humoral (antibody mediated) immunity
focuses on pathogens outside the host cells, sends out antibodies to “mark” a pathogen for later destruction
active immunity
body routinely makes its own antibodies or T cells against a pathogen
permanent
passive immunity
possible to achieve immunity after receiving an injection of antibodies from another person or animal
lasts only a few months
natural active immunity
the type of immunity occurs when the body produces antibodies or T cells after being exposed to a particular antigen
artificial active immunity
this results when the body makes T cells and antibodies against a disease as a result of a vaccination
natural passive immunity
this form of immunity results when a fetus acquires antibodies from the mother through the placenta, or when a body acquires them through breastfeeding
artificial passive immunity
this form of immunity involves obtaining serum from a person or an animal that has produced antibodies against a certain pathogen and then injecting it into someone else
Lymphocytes
fight invading pathogens
3 classes: natural killer cells, T lymphocytes and B lymphocytes
T Lymphocytes
T cells
Develop from stem cells in red bone marrow
Before they fully mature they leave the bone marrow and go to the thymus until they are fully functional
Once the cells are immunocompetent they go to the lymphatic organs and tissues ( lymph nodes, spleen, peyer’s patches and tonsils)
B Lymphocytes
B cells
Begin as stem cells in red bone marrow
Remain in bone marrow until fully functional
Once mature they leave bone marrow and go to lymphatic organs and tissues
Antibodies
gamma globulin proteins formed by B cells and found in plasma and body secretions
Immunoglobulins (Ig)
chains of proteins joined together in a way that resembles a capital Y or T
Antigen
any molecule that triggers an immune response
5 classes of antibodies
IgA, IgD, IgE, IgG and IgM
IgA:
populates mucous membranes in the intestines, respiratory tract, and urinary tract
Also found in saliva, tears and breast milk
IgD
exists in the blood in very amounts may activate basophils and mast cells
IgE
involved in allergic reactions
IgG
is the primary antibody of the secondary immune response: also the most abundant of all the immunoglobulins, making up 80% of all circulating antibodies
IgM
active in the primary immune response also involved in agglutination of incompatible blood types
3 classes of T cells:
Cytotoxic T cells (killer T cells): carry out the attack
Helper T cells: play a supportive role
Memory T cells: remember the pathogen in case of future invasion
how cellular immunity works
- The immune process begins when a phagocyte ingests an antigen
- Antigen-presenting cell: a phagocyte that displays fragments of the antigen on its surface
a) Antigen presentation: alerts the immune system to the presence of a foreign antigen
b) When the T cell spots the foreign antigen it binds to it
3. This activates the T cell which begins dividing repeatedly to form clones: some will become effector cells (such as cytotoxic T cells) which will carry out the attack others will become memory cells
4. cytotoxic T cells binds to the surface of the antigen and delivers a toxic dose of chemicals that will kill it
5. interleukin: a chemical secreted from helper T cells which attract neutrophils, natural killer cells and macrophages
a) It stimulates the production of T and B cells
Humoral Immunity
Focusses on pathogens outside the cell
It uses antibodies to mark the antigen for the later destruction
How Humoral Immunity works
- The surface of a B cell contains thousands of receptors for a specific antigen which binds to it
- The best so that engulfs the antigen digest it and display some of the antigens fragments on its surface
a) A helper T cell binds to the present antigens and secretes interleukins which activate the B cell - The best cell begins to rapidly reproduce creating a clone or family of identical B cells that are programmed against the same antigen
- Some of these cloned P cells become effective by cells or memory B cells most become plasma cells
Antibodies use a range of tactics to defeat antigens including the following
Binding to antigens attachment points, preventing it from attaching to a human cell
Triggering agglutination helping to contain the antigen and make it easier for phagocytes to work
Promoting the binding of complement proteins to the invading cell setting of the complement cascade destroying the invading microorganism
Antibody titer
the amount of time between exposure to a new antigen and the rising level of blood antibodies against that antigen
Secondary response
rapid production of memory and plasma cells which can then create large numbers of antibodies against the antigen
Hypersensitivity
Immunodeficiency disorder
Hypersensitivity: When the immune system overreacts to an antigen
Immunodeficiency disorder: when the immune system fails to react
Allergy
a condition in which the immune system reacts to environmental substances that most people can tolerate
Anaphylaxis
a severe immediate allergic reaction that affects the whole body
The release of a huge amount of histamine causes constriction of the airways and vasodilation causing blood pressure to drop
Autoimmune diseases
When the bodies immune system fails to differentiate between self antigens and foreign antigens the body produces antibodies that attack it’s on tissue resulting in an autoimmune disease
There are more than 100 auto immune diseases
Systemic lupus erythematosus
affects the kidneys, skin, heart, and joints
Scleroderma
affects the skin, intestines and lungs
Grave’s disease
affects the thyroid gland
Ulcerative colitis
affects GI tract
Immunodeficiency diseases
The immune system fails to adequately protect the body against pathogens
Severe combined immunodeficiency disease
children have few to no T and B cells and can’t fight off pathogens forcing them to live in a protected environment
Aquired immunodeficiency syndrome (aids)
results from infection with the human immunodeficiency virus (HIV)
Human immunodeficiency virus (HIV)
the virus invades helper T cells eventually destroying them
Autograft
Allograft
Autograft: tissue is taken from one part of the body and transplanted to another
Allograft: tissue taken from a donor and transplanted in the recipient
Aging and the immune system
The body produces fewer haemopoietic stem cells, disease fighting white blood cells, and antigen presenting cells
Lymphocytes the body does produce after failed to mature and become immunocompetent
T cells respond less quickly to antigens previously encountered
The bodies macrophages destroy bacteria cancer cells and antigens more slowly
