Lymphatic System Flashcards
What are the main lymphocyte cells?
- T cells: cellular adaptive immunity
~75% circulating lymphocytes - B cells: humoral adaptive immunity
- Natural Killer cells: innate (nonspecific) immunity
Induce apoptosis of virus- or cancer-infected cells
Name the auxiliary immune cells
MACROPHAGES
DENDRITIC CELLS =
antigen presenting cells
What are the functions of macrophages?
Widely distributed throughout lymphoid organs
Functions include:
Phagocytosis
Enhancement of inflammatory response
Presentation of antigens to T cells
What are the functions of dendritic cells?
Mobile, antigen-presenting cells
Possess wispy cellular extensions for antigen capture & phagocytosis
Migrate to lymph nodes and present antigens to naïve lymphocytes
What are the subtypes of T cells
- Subtypes:
- cytotoxic,
- helper,
- regulatory T cells
What are the subtypes of B cells
- plasma: Antibodies
- memory cells:
What are supporting cells?
- Reticular cells: fibroblast-like cells that produce a connective tissue stroma (L. ‘bed covering’) for lymphoid tissues and organs
What is the normal ratio of cells?
500 RBCs:
30 platelets:
1 WBC
Whats the function of Lymphoid tissue?
Proliferation site for lymphocytes
Surveillance point for lymphocytes & macrophages
What are the types of Lymphoid tissue?
Diffuse lymphoid tissue: Loose arrangement of lymphoid cells & reticular fibres
Lymphoid follicles:Solid, spherical bodies consisting of tightly packed lymphoid cells & reticular fibres.
What are the primary Lymphoid organs?
Sites of B & T cell maturation
Red bone marrow, thymus
“preschool”
What happens at the secondary Lymphoid organs?
Where mature lymphocytes first encounter their antigens and become activated
What are the secondary Lymphoid organs?
Lymph nodes*> filtering, spleen, tonsils, appendix, intestinal follicles
What is the gross structure of lymph nodes?
Dense fibrous capsule
Compartmentalised by trabeculae
Stroma of reticular (internal network - like skeleton)
connective tissue
Whats the functions lymph nodes?
House lymphocytes AND macrophages
Site of immune system activation
Filtering of lymph (microorganisms, debris)
What is the histology of the lymph node?
Cortex: germ cells (B cells) & T cells transit
Medulla: medullary cords
Lymph sinuses: lymphatic channels
What is the Nodal circulation process?
Lymph flows into the node through numerous afferent lymph vessels (convex side)
Lymph moves through the subcapsular sinus towards the medulla
Flow occurs through medullary sinuses
Exits via efferent lymph vessels
What is the structure of the spleen
Largest lymphoid organ, size of a clenched fist
Dark red,
highly vascular,
ovoid organ
encapsulated by fibroelastic connective tissue + smooth m. cells
What are the surfaces of the spleen?
Diaphragmatic surface:
- outer,
- convex
Visceral surface:
- inner, concave
- Impressions from stomach, kidney, colon, pancreas
What are the peritoneal ligaments of the spleen ?
gastrosplenic
splenorenal ligaments
What is the location and function of the spleen?
LOCATION:
Lt Hypochrondriac region, LUQ behind stomach
Roughly deep to Ribs 9 - 11 ribs (separated by diaphragm)
Rests on the Lt colic flexure
Function:
- immunity
- blood filter
- reservoir
- recycle iron from RBC
- erythropoiesis in foetus
What is the histology of the spleen?
White pulp: site of immune functions
Mostly lymphocytes suspended on reticular fibres
Red pulp: where senescent RBC and bloodborne pathogens are destroyed
What is the vascular supply to the spleen ?
Arterial:
Splenic a.: largest branch of the celiac trunk
Splenic a. runs a tortuous course along the superior border of the pancreas
Venous:
Splenic V.
What is the lymph and neural supply to the spleen?
Lymph nodes in the splenic hilum
Sympathetic: abdominopelvic splanchnic nerves via the celiac ganglion (T6-T10)
Parasympathetic – CNX Vagus
visceral afferent supply to spleen
What are microbiome?
Make 90% of microbes in human body and are external.
Microbiome: a collection of microbial genomes
Microbiota: a collection of microbes
What is Dysbiosis?
A shift on healthy microbiome to a disease-associated state
