Lymphatic System Flashcards
carries excess interstitial fluid
from tissues back to cardiovascular
circulation and provides locations
for immune cells to monitor
the body.
lymphatic system
take in fluids from the
extracellular space and carry them
through lymph nodes, where
immune cells scan the fluids for
foreign particles.
Porous lymphatic vessels
Fluid must be returned to circulation to maintain cardiovascular function via
lymphatics
are necessary to monitor the body for infection.
lymph nodes
The lymphatic system consists of two semi-independent parts:
(1) a meandering network of lymphatic vessels
(2) various lymphoid tissues and organs scattered throughout the body
house phagocytic cells and lymphocytes, which play essential roles in body defense and resistance to disease.
lymphoid tissues and organs
if excess fluids did not go back to the blood, fluid accumulates in the tissues, producing
edema or swelling
impairs the ability of cells to make exchanges with the interstitial fluid and ultimately the blood.
Excessive edema
The function of the lymphatic vessels is to form an elaborate drainage system that picks up this excess interstitial fluid, now called
Lymph
The lymphatic vessels, also called
lymphatics
vessels that form a one-way system, and lymph flows only toward the heart.
lymphatics
weave between the tissue cells and blood capillaries in the loose connective tissues of the body and absorb the leaked fluid
microscopic lymph capillaries
the edges of the endothelial cells forming their walls loosely overlap one another, act as one-way swinging doors
flaplike minivalves
when the fluid pressure is higher in the interstitial space, allowing fluid to enter the lymphatic capillary, the gape is
open
when the pressure is higher inside the lymphatic vessels, preventing the lymph from leaking back out and forcing it along the vessel.
the endothelial cell flaps are forced together, it is closed
Lymph is transported from the lymph capillaries through successively larger lymphatic vessels, referred to as
lymphatic collecting vessels
drains lymph from the right arm and the right side of the head and thorax
right lymphatic duct
receives lymph from the rest of the body
thoracic duct
Both ducts empty the lymph into the subclavian vein on their own side of the body
right lymphatic duct and thoracic duct
Like veins of the cardiovascular system, lymphatic vessels are
thin walled, and the larger ones have valves
The lymphatic system is a what type of pressure, pumpless system
low-pressure
muscle in the walls of the larger lymphatics contracts rhythmically, helping to “pump” the lymph along.
smooth muscle
action of the skeletal muscles and pressure changes in the thorax during breathing
milking action
Cells in lymph nodes in particular help protect the body by
removing foreign material and producing lymphocytes
Particularly large clusters are found in what parts of the body?
- inguinal
- axillary
- cervical regions
Within the lymph nodes, which engulf and destroy bacteria, viruses, and other foreign substances in the lymph before it is returned to the blood
macrophages
type of WBC, are also strategically located in the lymph nodes and respond to foreign substances in the lymphatic stream
Collections of lymphocytes
during an active infection
had “swollen glands”
the term swollen glands is a
misnomer
Lymph nodes vary in shape and size, but most are
kidney-shaped
Each node is surrounded by,
fibrous capsule
connective tissue strands called, extend inward to divide the node into a number of compartments
trabeculae
Lymphocytes arise from the
red bone marrow
The outer part of the node
cortex
cortex, contains collections of lymphocytes called
follicles
follicles have dark-staining centers called
germinal centers.
enlarge when specific B lymphocytes (the B cells) are generating daughter cells called
germinal centers.
specific B lymphocytes (the B cells) are generating daughter cells, which release antibodies, called
plasma cells
plasma cells releases
antibodies
The rest of the cortical cells are lymphocytes “in transit,” the so-called
T cells
circulate continuously between the blood, lymph nodes, and lymphatic stream, performing their surveillance role
T cells
are inward extensions of cortical tissue that contain both B and T cells.
medullary cords
Lymph enters the convex side of a lymph node through
afferent lymphatic vessels
meander through the lymph node and finally exits from the node at its indented region
hilum
exits from the node at its indented region, the hilum, via
efferent lymphatic vessels
is a soft organ located in the left side of the abdominal cavity, just beneath the diaphragm, that curls around the anterolateral aspect of the stomach
spleen
what organ where spleen return some of their breakdown products
liver
the rest of the hemoglobin molecule is secreted in
bile
Other functions of the spleen include
storing platelets and acting as a blood reservoir
both the spleen and liver contract and empty their blood into circulation to help bring the blood volume back to its normal level during?
hemorrhage
In the fetus, the spleen is an important site
hematopoietic site (blood cell–forming)
the adult spleen produces only
lymphocytes.
which functions at peak level only during youth, is a lymphoid mass found in the anterior mediastinum overlying the heart.
thymus
are small masses of lymphoid tissue deep to the mucosa surrounding the pharynx (throat)
tonsils
Their job is to trap and remove bacteria or other foreign pathogens entering the throat.
tonsils
Tonsils carry out this function so efficiently that sometimes they become congested with bacteria and become red, swollen, and sore, a condition called
tonsillitis
which resemble tonsils, are found in the wall of the distal small intestine.
Peyer’s patches
Lymphoid follicles are also located in the wall of the
appendix
a tubelike offshoot of the proximal large intestine
appendix
always present in tremendous numbers in the intestine
macrophages of Peyer’s patches and the appendix
Peyer’s patches, the appendix, and the tonsils are part of the collection of small lymphoid tissues referred to as
mucosa-associated lymphoid tissue (MALT)
to protect the upper respiratory and digestive tracts MALT acts as a
sentinel
