Glands and Lymphatics Flashcards
what are the three major roles of lymph nodes
returns fluid from the tissues back to the heart
helps hormones and lipids enter the blood
immune surveillance
what can diffuse through pores on vascular capillaries
albumin and fluid
how many litres of fluid seep out from the capillaries every day
20 litres
how many litres of fluid remain in the interstitial space
three litres
what do lymphatic vessels do
collect excess fluid and return it to the blood
why can the course of lymphatic vessels be described at closed
the fluids get into the lymphatic capillaries to be dumped into the veins, it does not circulate throughout the lymph
describe the structure of lymphatic vessels
walls made of endothelial cells that only loosely overlap. anchored to structures in the interstitial space by collagen filaments to allow for flexibility.
describe how lymph travels if there is no pump like with the blood
smooth muscle reacts to arterial pressure, and there is squeezing of skeletal muscle throughout the day that exerts external pressure to keep the lymph going along.
there are valves to prevent the lymph going backward
what are the lymphatic trunks
lumbar
bronchio-mediastinal
subclavian
jugular
intestinal
what are the main lymphatic ducts
right lymphatic and thoracic
what do the lymphatic trunks drain into
the lymphatic ducts
what does the lymphatic duct collect from
right arm
right head
right chest
what does the thoracic duct collect
everywhere apart from what the right lymphatic duct collects
where does lymph enter the veins
the junction of the jugular and subclavian vein
what is the advantage of the porosity of the lymphatic capillaries
they can pick up molecules that are normally too large like nutrients and fatty acids that can be delivered to tissues
describe how fatty acids enter circulation
absorbed from the small intestine, packaged into chylomicrons to go into the lacteals of the villi to enter the lymphatic vessels
describe the immune function of lymphoid organs
remove foreign material from the lymph to prevent it from entering the blood
act as lookout points for the body’s immune system
what makes up the lymphatic system
lymphoid organs and diffuse lymphoid tissue
describe diffuse lymphoid tissue
loose arrangement of lymphoid cells in protein in the gastrointestinal tract and respiratory tract
what are lymph nodes
tightly packed balls of lymphoid tissue
what are peyers patches
lymph nodes in the lining of the ileum of the small intestine
describe the function of lymph nodes
unfiltered lymph drains into them, any pathogens are detected by dendritic cells to be destroyed.
the dendritic cells sample the lymph and present antigens to b cells to produce antibodies
how are antibodies produced
antigens are presented to b cells which turn into plasma cells to produce antibodies
where is the spleen located
below the diaphragm above the stomach, under the ribs on the left hand side of the body.
describe the structure of the spleen
contains white and red pulp
describe the white pulp of the spleen
giant lymph node, receives blood to filter it.
antibody coated bacteria are filtered out of circulation to generate antibodies from b cells
describe red pulp of the spleen
old or damaged red blood cells are destroyed, and their parts are broken down or recycled.
when is the thymus most active in a persons life
neonatal
preadolescence
what happens to the thymus once puberty has been reached
atrophies and begins to be replaced by fat
what is the main function of the thymus
involved in development of t cells to ensure any that react to self antigens are destroyed by apoptosis
what are the two primary lymphoid organs
the bone marrow
the thymus
what happens at the primary lymphoid organs
all immune cells are generated and developed
what are the secondary lymphoid organs
spleen
lymphatic vessels
lymph nodes
tonsils
adenoids
mucosa associated lymphoid tissue
what happens in the seconary lymphoid organs
immune cells go here to finish their development and interact with other immune. they also generate adaptive immune responses
where does maturation of myeloid and lymphoid cells begin
the bone marrow
describe the structure and location of bone marrow
spongy structure, found in the centre of many bones in the body
which form of marrow has the most active generation of blood cells
red marrow
what happens to red marrow as we age
it becomes infiltrated with fat to become yellow marrow
where is immune tolerance initiated in the body
the thymus
describe the location of the thymus
superior to the heart, behind the sternum, upper chest
when is the thymus most functionally active
childhood
what are the three main components of lymph fluid
interstitial fluid
white blood cells
chyle
what is interstitial fllulid
fluid that leaves the vascular space and bathes the tissues
similar in composition to plasma but lower in protein count
what is chyle
this is the chylomicrons that are absorbed into the lymph from digested foods in the gut
what are chylomicrons
lipoprotein complexes
what does lymph look like
watery milk
where in the body is the primary site of b cell maturation
spleen
what is the function of the spleen
immune surveillance
proliferation and maturation of lymphocytes
degradation of damaged or old erythrocytes
how is lymph returned to circulation
via the subclavian veins
what do lymph nodes contain
lymphoid follicles with b cell zones and t cell zones
what is MALT
mucosa associated lymphoid tissue
what is the mucosa associated lymphoid tissue
aggregates of lymphocytes that make up lymphoid follicles, located in various points in the gut, pharynx and bronchi. allows the immune cells to access the antigens we breathe in or consume
where in the body is MALT
gut
pharynx
bronchi
where are immune cells frequently met with pathogens, or aggregated to be educated activated and matured
the seconary lymphoid organs
where are immune cells generated and developed
the primary lymphoid organs
describe the overall structure of the thymus
composed of thymic lobules that are separated by connective tissue septa
what are the two main components of each thymic lobule
the peripheral cortex and the inner medulla
explain the staining behaviour of the thymus gland
the cortex stains more deeply than the medulla due to having a higher concentration and density of thymocytes
what are the three layers of the thymic cortex
superficial
middle
inner
describe the superficial layer of the thymic cortex
superficial subscapular cells forming a squamous sheath and a blood thymus layer
describe the middle layer of the thymic cortex
stellate thymic epithelium and cytoreticular cells
describe the inner layer of the thymic cortex
squamous cortical thymic epithelial cells to form the corticomedullary barrier
describe the composition of the thymic medulla
squamous thymic epithelial cells and cytoreticulum
what are hassalls corpuscles
congregations of thymic epithelial cells
what do thymic nurse cells do
educate the thymocytes.
there are 50 thymocytes to one nurse cell
which area of the thymus has more thymocytes
the thymic cortex
what are the two major categories of cells in the thymus
thymic epithelial cells
thymocytes
summaries thymic epithelial cells
derivatives of the third pharyngeal pouch, eosinophilic cytoplasm, pale nuclei. have intermediate filament bundles
describe the composition of the blood thymus barrier
composed of squamous thymic epithelial cells, pericytes and vascular epithelium
what is the function of the thymus blood barrier
reduce the likelihood of exposing thymocytes to improper antigens
what are cytoreticular cells
antigen presenting cells that participate in the thymic education program
they release cytokines to help create the microenvironment necessary for thymic education
what do hassall corpuscles do
they release cytokines to regulate dendritic activit
how many thymocytes are associated with each thymic nurse cell
50
where are monocytes found in the thymus
the corticomedullary junction
where are macrophages most abundant in the thymus
the peripheral cortex
what are the three subtypes of epithelial cells found in the peripheral cortex of the thymus
squamous thymic
stellate thymic
other squamous thymic
what are the squamous thymic epithelial cells important for
thymus blood cells
what are the stellate thymic epithelial cells important for
forming the cytoreticulum
what are the three subtypes of epithelial cells in the thymic medulla
- squamous thymic
- stellate thymic
- hassall corpuscles
what are some non thymic cells found in the thymus
myeloid
fibroblasts
myoid
what are the myoid cells in the thymus for
facilitation of the migration of lymphoid tissues across the thymus
how are the t cells matured
MHC proteins are presented in the cortex of the thymus to the maturing thymocytes
if they survive, they advance to the medulla
if they bind to the self antigen, they die
if they don’t, they can either retain CD4 or CD8.
what are the t cells that retain CD4 called
helper t cells
what are the t cells that retain CD8 called
cytotoxic t cells
which lobe of the thymus is thicker
the left
describe the arterial supply of the thymus
inferior thyroid
internal thoracic vessels
what does the thymus blood supply drain into
the superior vena cava directly
describe the vascular supply of the spleen
splenic artery and splenic vein
what provides lymph to the spleen
the celiac node
what innervates the spleen
the celiac plexus
what supplies the tongue with blood
the lingual artery, a branch of the external carotid artery
describe the thoracic duct
the largest lymphatic vessel, that takes up 75% of lymph
describe the route of the thoracic duct
it is paravertebral and passes from T12 to the root of the neck
what are the tributaries of the thoracic duct
left and right lymphatic trunks
left and right intestinal lymphatic trunks
what is the cysterna chyli
the confluence of the intestinal lymph trunks
what does the thoracic duct drain into
pirgoff’s angle
where is pirgoff’s angle
the angle at the junction between the left subclavian and the left internal jugular veins
