CHAPTER 21 - A7P II

Immune system is NOT an ________ ________ but the lymphoid system is

organ system

a cell population that inhabits all organs and defends the body from agents of disease

immune system

Immune system is NOT an ________ ________ but the lymphoid system is

organ system

a cell population that inhabits all organs and defends the body from agents of disease

immune system

what is the function of the vein like vessels in the lymphoid system

recover fluids to return to blood stream

why doe the lymphoid system inspect fluid

to check for disease agents

what happens when the lymphoid system detects disease agents

it activates the immune responses

human microbiome

archaea, bacteria, viruses, fungi, parasites

what are the components of the lymphoid system

lymphatic vessels, lymphoid tissues, and organs that produce immune cells

how does fluid enter the lymphatic vessels

fluid filters from blood capillaries into tissue spaces, with 15% entering the lymphatic vessel

what is the role of lymphatic capillaries

capillaries reabsorb 85% of the filtered fluid and 15% enters lymphatic vessels

excess filtered fluid picks up foreign cells and chemicals from tissues

immune surveillance

what happens to the filtered fluid during immune surveillance

it passes through lymph nodes of immune cells

what is the result of the filtered fluid passing through lymph nodes of immune cells during immune surveillance

it activates an immune response

lacteals in small intestine absorb dietary lipids not absorbed by blood capillaries

lipid absorption

swelling from blocked lymphatic drainage

lymphedema

recovered fluid

lymph

transport lymph

lymphatic vessels

aggregates of lymphocytes and macrophages, populate many body organs

lymphoid tissue

where lymphoid cells are concentrated; surrounded by connective tissue capsules

lymphoid organs

colorless, clear fluid, like plasma, but low in protein

lymph

originates as tissue fluid taken up by lymphatic vessels

lymph

chemical composition varies indifferent places (intestines)

lymph

general term used to designate the lymphatic vessels that collect and transport lymph

lymphatics

what are lymphatic capillaries also known as

terminal lymphatics

where do lymphatic capillaries penetrate in the body

nearly every body tissue, except cartilage, cornea, bone, and bone marrow

what is the structure of the capillary wall in lymphatic capillaries

endothelium with simple squamous cells that overlap to form one way valves

what happens to the lymphatic capillaries when the interstitial fluid pressure is high

they open

what anchors one end of a lymphatic capillary

anchoring filaments

what can enter lymphatic capillaries through gaps between cells

bacteria and cells

what prevents back flow of lymph

valves in lymphatic vessels

what is the first step in the lymph flow process

lymphatic capillaries merge

what do lymphatic collecting vessels do in the lymph flow process

collecting vessels converge

what is the final destination of lymph in the lymph flow process

lymphatic trunks which drain major portions of the body (intestinal trunk, jugular, subclavian, bronchomediastinal, intercostal, and lumbar trunks)

what are the two collecting ducts where lymphatic trunks converge

right lymphatic duct, thoracic duct

what regions does the right lymphatic duct receive lymph form

right arm, right side of head, and thorax

where does the right lymphatic duct empty into

right subclavian vein

where does the thoracic duct begin

as a sac in the abdomen, cistern chyli

what regions does the thoracic duct receive lymph from

below the diaphragm, left arm, left side of head, neck, and thorax

subclavian veins collect from

collecting ducts

T or F? the circulatory and lymphatic system have an interrelationship

TRUE

what are the components of the lymphatic system

lymphatic capillaries, collecting vessels, lymphatic trunks, collecting ducts, subclavian veins

what is the pathway of lymph in the lymphatic system

lymphatic capillaries —> collecting vessels —> lymphatic trunks —> collecting ducts —> subclavian veins

what structure does lymph pass through in the lymphatic system

lymph nodes

how does lymph flow differ from venous return

lymph flows without a pump and at low pressure and slower speed than venous blood

what stimulates the contraction of lymphatic vessels

stretching of vessels stimulates their contraction

what helps move lymph along in the body

lymph is moved along by rhythmic contractions of lymphatic vessels, squeezing of skeletal muscles, rhythmic pulsations of nearby arteries, the thoracic and respiratory pump, and the rapid flow of blood in subclavian veins drawing lymph in

what is the function of the lymphatic system

provides delivery of nutrients and drains waste, most functional during sleep

how is the CSF-ISF composition regulated in the lymphatic system

regulated by astrocytes

How are veins in the glymphatic system drained?

Drains via lymphatic vessels of meninges & arachnoid granulations into bloodstream

What is the role of arterial pulsations in the glymphatic system?

Help drive fluid mix into brain tissue

What is the significance of the glymphatic system in Alzheimer's disease?

Removal of beta-amyloid protein associated with Alzheimer's disease

What are the functions of Neutrophils?

Antibacterial

What is the role of Natural Killer (NK) cells?

attack & destroy infected host cells and cancerous cells

Where do T lymphocytes (T cells) mature

thymus

What happens when B lymphocytes (B cells) are activated?

They proliferate and differentiate into plasma cells that produce antibodies

What are the functions of Macrophages?

Phagocytosis; Antigen-presenting cells (APCs); Alert other immune cells

Where are Dendritic cells found?

Skin, mucous membranes, and lymphoid organs

What are lymphoid tissues?

Aggregations of lymphocytes in connective tissues of mucous membranes and various organs

What is diffuse lymphoid tissue?

Lymphocytes are scattered in the tissue.

Where is mucosa-associated lymphoid tissue (MALT) found?

In mucous membranes.

What are lymphoid nodes?

Structures that house lymphocytes and macrophages.

What are aggregated lymphoid nodules (formerly Peyer's patches)?

Large clusters of nodules found in the small intestine.

What are the primary lymphoid organs?

Red bone marrow & thymus

Where do T & B cells become immunocompetent?

Primary lymphoid organs (red bone marrow & thymus)

What are the secondary lymphoid organs?

Lymph nodes, tonsils, & spleen

Where do immunocompetent cells migrate and populate?

Secondary lymphoid organs (lymph nodes, tonsils, & spleen)

What separates lymphatic tissue from neighboring tissues?

Connective tissue capsule

primary lymphoid organs

red bone marrow and thymus

secondary lymphoid organs

lymph nodes, spleen, tonsils

What is the primary function of red bone marrow?

Hematopoiesis

How are blood-forming cells in red bone marrow stimulated to produce formed elements?

Colony-stimulating factors secreted by reticular cells and stroma stimulate stem cells

What happens to mature blood cells in red bone marrow before entering the circulatory system?

they push through reticular and endothelial cells, then enter sinus and flow through the circulatory system

What are the main systems associated with the thymus?

Endocrine, lymphoid, and immune systems

How is the thymus structured?

Bilobed and divided by septa into several lobes

What is the function of thymic epithelial cells in the thymus?

Involved in T cell development

What forms the blood-thymus barrier in the thymus?

Cortical epithelial cells and pericytes

involution, degeneration, shrinkage occurs by?

by age 65
- unable to make new T cells (immunosenescence vulnerable to infections & cancer)

What are the main functions of lymph nodes?

Cleanse lymph and serve as lymphocyte activation sites

How many lymph nodes are there in a young adult?

Approximately 450

How is the interior of a lymph node divided?

Into compartments by trabeculae

What are the two main parts of a lymph node's parenchyma?

Cortex and medulla

Where do B cells multiply and differentiate into plasma cells within a lymph node?

In the germinal centers of the cortex

How does lymph enter a lymph node?

Through several afferent lymphatic vessels along the convex surface

How does lymph leave a lymph node?

Through 1 to 3 efferent lymphatic vessels exiting the hilum

Where are axillary lymph nodes located?

Armpit

Where are thoracic lymph nodes located?

Thoracic cavity, especially mediastinum

Where are abdominal lymph nodes located?

Posterior abdominopelvic wall

Where are intestinal & mesenteric lymph nodes located?

Mesenteries, appendix & intestines

Where are inguinal lymph nodes located?

groin

Where are popliteal lymph nodes located?

back of knee

Lymphadenitis

swollen, painful lymph node responding to foreign antigen

Lymphadenopathy

collective term for all lymph node diseases

What is metastasis in cancer?

when cancerous cells break free from the original primary tumor, travel, and establish new tumors.

How do metastasizing cells enter the lymphatic system?

Metastasizing cells easily enter lymphatic vessels.

What is a sentinel lymph node (SLN) in cancer?

the first lymph node encountered by metastasizing cells, where they multiply and eventually destroy the node.

How do cancerous lymph nodes typically appear?

Cancerous nodes usually appear swollen, firm, painless, and tend to spread to the next node downstream.

What are some treatments for breast cancer involving lymph nodes?

lumpectomy, mastectomy, along with the removal of nearby axillary nodes.

What are the three main sets of tonsils?

Pharyngeal/adenoids, Palatine, Lingual

Where are the pharyngeal/adenoids tonsils located?

Wall of pharynx

Where are the palatine tonsils located?

Posterior margin of oral cavity