Module 15: The Lymphatic and Immune Systems Flashcards Preview

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Flashcards in Module 15: The Lymphatic and Immune Systems Deck (41):
1

Lymphatic trunks

Collect lymph from large regions of the body into two specific lymphatic ducts

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Lymphatic ducts

Right lymphatic duct
Thoracic duct

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Right lymphatic duct

Receives lymph from the vessels in the right upper
regions of the body
Drains into the right subclavian vein and then into the superior vena cava

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Thoracic duct

Receives lymph from the rest of the body
Drains into the left subclavian vein and then into the superior vena cava
Cisterna chyli forms the beginning of the thoracic duct

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Lymph nodes

~600, in clusters along lymphatic vessels
Filter and clean lymph (Phagocytic cells remove and destroy microorganisms, cellular debris, cancerous cells, etc.)
Contain lymphocytes that provide protection from foreign invaders and other substances

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Structure of lymph nodes

Usually bean shaped and about 2.5 cm (1 inch) in length
Capsule
Cortex
Medulla
Trabeculae
Sinuses
Germinal centers of the follicles (nodules)
Afferent vessels
Efferent vessels

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Cortex

Outer region
Contains T cells and B cells

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Medulla

Inner region
Contains B cells and plasma cells

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Trabeculae

Divide nodes into compartments

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Germinal centers

Contain dividing lymphocytes

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Afferent vessels

Transport lymph into the node

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Efferent vessels

Transport lymph out of the node

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Spleen

Largest lymphatic organ in the body
Surrounded by a thin capsule
Consists of two areas of tissue called white pulp (contains mostly lymphocytes)
and red pulp (where old red blood cells are destroyed)
Forms blood cells during fetal development
Filters and stores blood
Destroys old red blood cells and foreign material
Stores lymphocytes

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Thymus

Within the mediastinum, behind the sternum
Pinkish gray colour during childhood and yellowish in old age as the tissue is replaced with fat
Composed of two lobes
Provides a source of lymphocytes before birth
Secretes hormones that stimulate T cells to attack pathogens

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Tonsils

Clusters of lymphatic with structures called crypts that
trap foreign substances
Protect the body against bacteria and other pathogens from entering the area around the openings to the nasal and oral cavities

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Palatine tonsils

On each side of the throat near the opening of
the oral cavity into the pharynx

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Pharyngeal tonsils (adenoids)

Near the opening of the nasal cavity into the pharynx

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Lingual tonsils

At the base of the tongue near the opening of the oral
cavity into the pharynx

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Peyer’s patches and appendix

Peyer’s patches - in the small intestine
Appendix - in the large intestine
Prevent bacteria from penetrating the intestinal wall
Mucosa-associated lymphatic tissue (MALT)

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Lymphoid tissue in the respiratory tract

Prevents bacteria and other foreign substances from penetrating the walls of the bronchial tubes
Mucosa-associated lymphatic tissue (MALT)

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First line of defence (nonspecific resistance general defence)

Skin
Mucous membranes
Tears
Saliva
Urine
Vaginal secretions
Defecation
Vomiting

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Second line of defence

Interferon (protective chemical)
Complement (protective chemical)
Natural killer cells (NKCs)
Phagocytosis
Inflammation
Fever

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Third line of defence (immunity, specific resistance)

Cell-mediated (T cells)
Antibody-mediated (B cells)

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Interferon

Protein produced by virus-infected cells
Released to protect surrounding cells
Infected cells that produced the interferon do not survive

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Complement (complement system)

Group of proteins found in blood plasma
Remains inactive until it comes in contact with microorganisms or foreign particles
Enhances phagocytosis, triggers inflammation, and/or destroys bacteria by “drilling” holes in their cell walls

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Natural killer cells (NKCs)

Class of lymphocytes known as the “pit bulls” of the non-specific defence system
Found in the blood, spleen, bone marrow, and lymph nodes
Directly attack and kill virus-infected cells and cancer cells before the immune system is involved
Secrete specific chemicals that enhance the inflammatory response

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Heat and redness

Damaged tissues immediately release chemicals that cause the blood vessels in the area of the injury to dilate which increases temperature and blood flow

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Pain and swelling

Phagocytic WBCs squeeze through the blood vessel walls The plasma and proteins that accompanied the squeezing phagocytes cause swelling (edema), and the swelling stimulates nerve receptors (pain)

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Antigens (Ags)

Foreign bodies that are capable of generating a specific response
Found on the surface of pathogens

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B cells

Also called B lymphocytes
Develop from stem cells in bone marrow
Mature in bone marrow

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T cells

Also called T lymphocytes
Develop from stem cells in bone marrow
Mature in the thymus

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Humoral (Antibody-mediated) immunity

Involves the production of antibodies (immunoglobulins) that are secreted into body fluids
Both T cells and B cells are involved
Invading antigens are recognized by macrophages and helper T cells
Helper T cells present the antigens to the B cells
B cells divide and become plasma cells and memory B cells

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Plasma cells

Produce antibodies (Abs)

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Cell-mediated immunity

T cells cannot bind to free antigens, need help from APCs
T cells respond by dividing and forming a variety of T cells:
• Cytotoxic T cells
• Helper T cells
• Regulatory T cells
• Memory T cells

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Antigen-presenting cells (APCs)

Mainly macrophages
Present the antigens to the T cells for destruction

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Cytotoxic T cells

Destroy the cell membrane of foreign antigens

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Helper T cells

Produce chemicals called lymphokines, which attract
macrophages to the antigens

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Regulatory T cells

Stop the immune response after the antigens have been
destroyed

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Buboes

Infected lymph nodes
The nodes do not always win the battle and become very swollen

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AIDS

Destroys helper T cells and the immune system slowly collapses

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Hapten

Incomplete antigen