Lymphatic System Flashcards
What are pathogens?
disease-causing organisms, like viruses, bacteria, fungi, and parasites
What is immunity?
The ability to defend against infection and resist disease
What is the immune system?
All the cells and tissues involved in producing immunity
What does the lymphatic system include?
The lymphatic system (AKA lymphoid system) includes the cells, tissues, and organs responsible for defending the body.
What does the lymphatic system consist of? (4x)
(1) an array of lymphatic tissues and organs scattered throughout the body;
(2) a network of lymphatic vessels, which begin in peripheral tissues and connect to veins;
(3) lymph, a fluid that resembles plasma but contains a much lower concentration of dissolved proteins, flowing in the lymphatic vessels; and
(4) lymphoid cells, including lymphocytes and smaller numbers of phagocytes and other cells.
What are the primary lymphatic tissue/organs?
Primary lymphatic tissues and organs are sites where lymphocytes are formed: red bone marrow and the thymus.
What are the secondary lymphatic tissue/organs?
Secondary lymphatic tissues and organs are where lymphocytes are matured/activated: the tonsils, MALT (mucosa-associated lymphatic tissue), lymph nodes, and spleen.
What is MALT
MALT (mucosa-associated lymphatic tissue),
What are lymphoid tissues?
connective tissues dominated by lymphocytes.
In a lymphoid (or lymphatic) nodule, the lymphocytes are ___________ in an area of ____________ next to the ____________
densely packed; areolar tissue (loose connective tissue); epithelial lining.
What are Peyer’s patches?
clusters of lymphoid nodules along the intestine
Where are large lymphoid nodules located?
tonsils; Peyer’s patches, on the wall of the appendix.
Where are lymphoid nodules located?
within lymphoid organs, i.e., lymph
nodes and the spleen.
What are Lymph nodes?
small lymphoid organs
Where are lymph nodes located? And what do they do?
The greatest number of lymph nodes is located in the neck, axillae, and groin, where they defend us against bacteria and other invaders.
_____ flows through lymph nodes before it reaches the _____
Lymph flows through lymph nodes before it reaches the veins.
What are the functions of lymph nodes? (2x)
1) functions like a kitchen water filter: It purifies lymph before it returns to the veins.
2) an early-warning defense system
How does lymph nodes function as a filter/purifier?
As lymph flows through a lymph node, at least 99% of antigens (i.e., foreign substances) in the lymph are removed by macrophages within the lymph nodes that engulf debris or pathogens in lymph as it flows through.
How does lymph nodes function as an early warning defense system?
Any infection or other abnormality in a peripheral tissue puts antigens into the interstitial fluid, and thus into the lymph. Lymph then carries these antigens to nearby lymph nodes, where macrophages and lymphocytes are activated.
How do lymph nodes function as an early warning defense system?
Any infection or other abnormality in a peripheral tissue puts antigens into the interstitial fluid, and thus into the lymph. Lymph then carries these antigens to nearby lymph nodes, where macrophages and lymphocytes are activated.
What is the function of the Thymus?
primary lymphoid organ. It is necessary in early life for immunity,
Is the Thymus necessary later in life?
later in life atrophies and becomes inactive
Where is the thymus located?
located in the mediastinum, just posterior to the sternum
What is the function of the Spleen in the lymphatic system? (3x)
(1) removing abnormal blood cells and other blood components by phagocytosis, (2) storing iron recycled from old red blood cells, and (3) initiating immune responses by B cells
and T cells in response to antigens in circulating blood
When is the spleen important? Why?
all throughout your life because they help get rid of damaged cells. (Ex: red blood cells, recycle the RBCs to make more RBCs.)
The adult spleen contains the ________ collection of lymphoid tissue in the body.
largest
the spleen performs the same functions for blood that ____________ for the __________
lymph nodes perform for lymph.
What is the function of lymphatic vessels?
carry lymph from peripheral tissues to the venous system.
Where does the lymphatic network begin?
lymphatic capillaries, which branch through peripheral tissues.
How do lymphatic capillaries differ from blood capillaries? (3x)
(1) are closed at one end rather than forming
continuous tubes, (2) have larger luminal diameters, (3) have thinner walls.
Lymph is interstitial fluid that first enters _______ and then drains into ___________
Lymph is interstitial fluid that first enters lymphatic capillaries and then drains into larger major lymph-collecting vessels, known as trunks and ducts.
Lymphatic capillaries (desc)
lined by endothelial cells, but their
the basement membrane is incomplete or absent.
The endothelial cells of a lymphatic capillary are _____________
not bound tightly together, but they do overlap.
How do the unique features of lymphatic capillaries aid in its function?
The endothelial cells of a lymphatic capillary are not bound tightly together, but they do overlap. The region of overlap acts as a one-way valve. It permits fluids and solutes (including proteins) to enter, along with viruses, bacteria, and cell debris, but it prevents them from returning to the intercellular spaces.
From the lymphatic capillaries, lymph flows into _________.
From the lymphatic capillaries, lymph flows into larger lymphatic vessels (trunk) that lead toward the even greater lymphatic vessels (ducts).
How are lymphatic vessels different from blood vessels?
in size, general appearance, and branching patterns.
Most arteries are bright red, veins are dark red (usually illustrated as blue to distinguish them from arteries), and lymphatic vessels
are a
pale golden color.
What do lymphoid cells consist of?
immune system cells found in lymphoid tissues.
Immune cells include
phagocytes and lymphocytes.
What do Phagocytes include? What are their func?
Phagocytes include macrophages and microphages (neutrophils, eosinophils). These cells are the first line of defense against pathogens (bacteria/viruses).
What do lymhocytes respond to? What do they do to them?
specific invading pathogens, as well as to abnormal body cells (such as virus-infected cells or cancer cells). They eliminate these threats through a combination of physical and chemical attacks.
What are the 3 types of lymphocytes?
(1) T (thymus-dependent) cells,
(2) B (bone marrow-derived) cells, and
(3) NK (natural killer) cells.
Circulating lymphocytes are only a small fraction of the total lymphocyte population. (T/F)
True
Where are the majority of lymphocytes?
distributed in tissues throughout the body.
What is one of the functions of the lymphatic system? (involves capillaries)
Capillaries normally deliver more fluid to peripheral tissues than they carry away. The lymphatic vessels return excess tissue fluid (lymph) to the bloodstream (via the venous system) to maintain normal blood volume & tissue fluid level.
What does the continuous circulation of fluid helps with? (3X)
1) transport lymphocytes and white blood cells from one organ to another.
2) distributes hormones, and nutrients to tissue,
3) carries wastes from their tissues of origin to the general circulation.
primary function of the lymphatic system is
to produce, maintain, and distribute lymphocytes and other lymphoid cells that provide defense against infections and foreign substances.
To provide an effective defense, lymphocytes must ________ problems and ____________ site of injury or infection
detect problems; reach the
Lymphocytes are able to enter or leave the capillaries/lymphatic vessels as needed. (T/F)
True
Why do Lymphocytes and other cells circulate within the blood?
Because they must be able to detect problems and reach the site of injury to provide an effective defense
The body’s reaction to these infectious agents and other abnormal substances is known as
immune (immune, protected) response.
What is resistance in relation to immunity?
The closely associated process is resistance, which is the ability of the body to maintain its immunity.
What are the two types of immunity humans have?
innate (natural and “one-size-fits all”) immunity and adaptive (acquired and specific) immunity.
What is the general difference between the two types of immunity?
Each immunity employs specific lymphocytes and mechanisms and both work together to defend us against foreign organisms or substances.
What does innate immunity include?
physical barriers and defense processes that either (a) prevent or slow the entry of infectious organisms or (b) attack them.
What is an example of innate immunity?
The skin (physical barrier, and phagocytes attack invading bacteria.)