Download Adaptive immune system

Basic Immunology
•
The immune system is the body’s natural defense in combating
organisms.
•
The immune system can be thought of as having two “lines of
defense”:
1. Innate immune system: Non-specific (no memory)
response to antigen (substance to which the body regards as
foreign or potentially harmful).
2. Adaptive immune system: which displays a higher degree
of memory and specificity.
Basic Immunology
 Innate immune system:
• It is what we are born with and it represents the first line of defense to
an intruding pathogen.
• The response is rapid, and is unable to “memorize” the same pathogen
in the future.
 Adaptive immune system:
• Although cells and molecules of the adaptive system possess slower
dynamics, they possess a high degree of specificity.
• It is genetically based and we pass it on to our offspring.
• It frequently incorporates cells and molecules of the innate system in its fight
against harmful pathogen.
Basic Immunology
Components of the immune system
Innate immune system
Adaptive immune system
Response is non-specific
Pathogen and antigen specific response
Exposure leads to immediate maximal
response
Lag time between exposure and maximal
response
Cell-mediated and humoral components Cell-mediated and humoral components
No immunological memory
Exposure leads to immunological memory
Found in nearly all forms of life
Found only in jawed vertebrates
Basic Immunology
Basic Immunology
• The immune system protects human from infection (bacteria, viruses,
etc..) with layered defenses of increasing specificity.
• Physical barriers prevent pathogens from entering the body.
• If a pathogen breaches these barriers, the innate immune system will
provide an immediate, but non-specific response.
• If pathogens successfully evade the innate response, a third layer of
protection will take an action, which is the adaptive immune system.
• The adaptive immune system will adapt its response during an
infection to improve its recognition of the pathogen.
• This improved response is then retained after the pathogen has been
eliminated, in the form of immunological memory.
Basic Immunology
Surface barriers :
1. The first most important barrier is the SKIN. The skin cannot be penetrated
by most organisms unless it already has an opening, such as a cut or
scratch.
2. Mechanically, pathogens can be expelled from the lungs by cilliary action of
mobility, also by coughing or sneezing. Also the flushing action of tears,
saliva and urine will force out pathogens as does sloughing off skin.
3. Sticky mucus in respiratory and gastrointestinal tracts traps many
microorganisms.
4. pH acidity (<7.0) of skin secretions inhibits bacterial growth as well as hair
follicles secretions.
5. Saliva, tears and nasal secretion contain lysozome (an enzyme that
destroys bacterial wall causing cell lysis).
6. The stomach is a formidable obstacle as its mucous secrete hydrochloric
acid (pH <3.0) and protein-digesting enzymes that kill many pathogens.
Lymphatic System
Lymphatic System
• The lymphatic system is involved in the
immune system, i.e. in phagocytosis and
by maintaining the immune system.
 The lymphatic system is a complex
network consisting of:
 Lymphoid organs
 lymph nodes
 lymph ducts
Lymph tissues
 lymph capillaries
 lymph vessels
Lymphatic System
•
Lymphatic system functions:
1. Filtering out organisms that cause diseases.
2. Absorption of fatty acids and subsequent transport of fat to the
circulatory system.
3. Production of immune cells (such as lymphocytes, monocytes, and
plasma cells).
4. Distribution of fluids and nutrients in the body, because it drains
excess fluids and protein.
Lymphatic System
LYMPH: originates as blood plasma that
leaks from the capillaries of the circulatory
system, becoming interstitial fluid, and filling
the spaces between cells.
• plasma is forced out of the capillaries
(filtration) and forced back in (absorption) due
to interactions of hydrostatic pressure and
oncotic pressure.
• while out of the capillaries, the fluid mixes
with the interstitial fluid.
• most of the fluid is returned to the
capillaries.
• the excess interstitial fluid is collected by
the lymphatic system by diffusion into the
lymph capillaries and is processed by the
lymph nodes then returned to the circulatory
system.
• once within the lymphatic system the fluid is
called lymph, and has almost the same
composition as the original interstitial fluid.
Lymphatic System
Lymph nodes:
• Act as filters, with an internal reticular
connective tissue filled with
lymphocytes that collect and destroy
bacteria and viruses.
• when the body is fighting an infection,
lymphocytes multiply rapidly and
produce a characteristic swelling of the
lymph nodes.
Lymphatic System
Lymphatic Circulation:
• The lymphatic system acts as a secondary circulatory system, except that it
collaborates with white blood cells in lymph nodes to protect the body from
infection.
• Unlike the circulatory system, the lymphatic system is not closed and has no
central pump.
• Like veins, lymph vessels have one-way, smilunar valves and depend mainly
on the movement of the muscles to squeeze fluid through them to the
lymphatic capillaries.
• The fluid is then transported to a larger lymphatic vessels terminating in the
lymphatic duct; these ducts drain into the circulatory system.
Lymphatic System
Lymphatic vessels:
• lymph capillaries are thin-walled tubes that carry lymph from the tissue spaces
to other large lymphatic vessels.
• lymphatic vessels have valves to prevent the backflow of fluid.
• lymph fluid always flow toward the thoracic cavity, where it empties into veins in
the upper thoracic region.
Lymphatic System
Lymphoid organs:
 Tonsils: are masses of lymphatic tissues located in the upper portions of the
nose & throat, where they form a protective ring of lymphatic tissue:
 Nasopharyngeal tonsils.
 Palatine tonsils.
 Lingual tonsils.
Lymphatic System
 Spleen: is the largest of the lymphoid organs, present in the left
upper quadrant of the abdomen, just below the diaphragm and
behind the stomach.
Functions of the spleen:
1. Producing lymphocytes & monocytes.
2. It filters microorganisms & other debris which are not destroyed by
the lymphatic system.
3. Storage of red blood cells.
4. Maintaining balance between cells & plasma in the blood.
5. Removing non-viable red blood cells.
Lymphatic System
Head and Neck lymph nodes:
 Cervical lymph nodes:
 Anterior cervical lymph nodes.
 Posterior cervical lymph nodes.
Tonsillar lymph nodes.
 Submandibular lymph nodes.
 Submental lymph nodes.
 Supraclavicular lymph nodes.
The Skin
The Skin
• The skin is the body’s first line of defense against diseases.
• Sometimes is called the integumentary system.
Functions of the skin
 It helps to regulate body temperature.
 It provides a barrier against bacteria from entering the body.
 It excretes liquids and salts.
 It provides sensitivity to touch.
 It uses ultraviolet rays from the sun to convert chemicals into the
vitamin D necessary for absorption of Calcium.
The Skin
Skin structure:
• The skin is composed of different layers:
 Epidermis.
 Dermis.
 Subcutaneous fat.
The Skin
The epidermis:
• Is the outer layer of the skin.
• It has NO blood supply of its own, the cells receive their nutrients from vessels
underlying tissues.
• As new cells are pushed to the surface, the older cells die and sloughed off.
• Hair and skin color are determined by the melanin produced in the epidermis.
The Skin
The dermis:
• Is a thick connective tissue layer that gives bulk to the skin.
• It contains many free nerve endings and receptors, which allow for detection of
touch, temperature and pain.
• With age, the connective tissue becomes less elasticized and wrinkles develop.
The Skin
The subcutaneous fat layer:
• Is a layer of loose connective tissues that anchors the skin to the underlying
organs.
• It insulates against heat loss and cushions underlying organs.
• The distribution of subcutaneous fat is responsible for the difference in body
contours between individuals.
The Skin
Skin appendages:
• The skin has a number of appendages including:
 Hair.
 Nails.
 Glands.
The Skin
Hair
• Is found on almost ALL skin surfaces.
• It is enclosed in a follicle and consists of a root and a shaft.
• The bulk of the shaft is made of dead material and protein.
The Skin
Nails
• It primarily consists of non-living matter.
• It has a root and body. The body is the visible portion, and the root is covered by
skin called the cuticle.
• The extensive blood supply in the underlying dermis gives nails their pink color.
The Skin
Glands
 Three types of glands in the skin are:
1. Sebaceous glands.
2. Sweat glands (sudoriferous).
3. Apocrine sweat glands.
The Skin
Sebaceous glands:
• found in all areas of the body except for the pals of the hands and the sole of
the feet.
• they are oil glands that keep the hair and skin soft.
• they are also associated with sex hormone and become active during puberty.
• Sebaceous activity decreases with age, which is why hair and skin become
dry as aging occurs.
The Skin
Sweat (sudoriferous) glands:
• They are distributed all over the body and provide heat regulation by
secreting sweat.
• Sweat is also produced in response to stress.
The Skin
Apocrine sweat glands
• Are the largest skin glands and are found under the arms, around the nipples
and in the genital region.
• Bacterial action causes the secretions to break down, producing body odor.
The Skin