Blood And The Lymphoid System Flashcards
What are leukocytes ?
General white blood cells
What are the 2 types of leukocytes ?
- granular leukocytes (can be seen)
- agranular leukocytes (can’t be seen)
What are the different granular leukocytes ?
- neutrophils (55-65%)
- eosinophils (1-4%)
- basophils (0.5%)
What are the different agranular leukocytes ?
- lymphocytes (20-35%)
- monocytes (2-8%)
What do monocytes specialise into in cells ?
Macrophages
What are the 2 cell types created by small lymphocytes ?
- T cells involved in cell mediated immunity
- B cells involved in humoral immunity
What are plasma cells ?
Activated versions of B cells
Briefly describe the structure and function of neutrophils
- contain a bilobed nucleus
- contain lysosomes
- have phagocytic roles
Briefly describe the structure and function of eosinophils
- contain secretory vesicles
- involved in the formation of antibody antigen complexes
- produced by inflammatory mediators
Briefly describe the structure and function of basophils
They are mast cell precursors
Briefly describe the structure and function of lymphocytes
- contains very little cytoplasm
- involved in immunity
Briefly describe the structure and function of monocytes
- contains a kidney shaped nucleus
- macrophage precursors
- have phagocytic roles
What is the lifespan of erythrocytes ?
120 days
Where are erythrocytes made and removed ?
- made in bone marrow
- removed in the spleen, liver and bone marrow
Where do blood cells come from ?
Most come from the bone marrow
What are the 2 types of bone marrow ?
1) yellow marrow which is basically fat
2) red marrow which is involved in blood formation (haemopoesis)
- red marrow is found at the ends of long bones e.g. ends of the femur and humerus, sternum, ribs and vertebrae
Describe the structure of sinusoids
- contain discontinuous endothelium
- allows for easy entrance and exit of cells
How are platelets made ?
Platelets are made by megakaryocytes
What does polyploid mean ?
- contains several copies of the genome
What is a lymphoid tissue and organ ?
A tissue (usually loose connective tissue) or organ which is very rich in lymphocytes
What are the 2 types of lymphoid tissues and organs ?
- primary lymphoid tissue/organ : where lymphocytes are made
- secondary lymphoid tissue/organ : where the lymphocytes act
What are the primary lymphoid organs ?
- bone marrow : B cells differentiate into plasma cells in secondary lymphoid tissues and secrete antibodies
- thymus : T cells in secondary lymphoid tissues make antibodies and incorporate them into their plasma membranes
What is the function of the thymus gland ?
- has an endocrine function
- produces hormones controlling lymphocyte development
- mostly generates T cells
Where are secondary lymphoid tissues and organs found ?
- can be contained within loose connective tissues or other structures (unencapsulated lymphoid tissue)
- can be contained within specific organs e.g. lymph nodes and spleen
Describe the distribution of unencapsulated lymphoid tissue
- found in the respiratory system, alimentary system and urinary system
- there are dense aggregations of lymphocytes in the lamina propria (beneath the epithelia)
What is the role of lymphatic vessels ?
They drain tissue fluid and return it to the blood
- the lymph fluid will pass through a series of lymph nodes which are rich in lymphoid tissue
What are the main components of the lymphoid nodules ?
- B cells
- plasma cells
What is the main component of diffuse lymphoid tissue ?
T cells
What is white pulp ?
Lymphoid nodules - B cells and plasma cells
Diffuse lymphoid tissue - T cells
What is red pulp ?
- Rich in blood
- tests erythrocytes and removes old damaged ones
Why are there different types of secondary tissue ?
They act as 3 lines of defence against infection :
1) unencapsulated - filters the tissue fluid if infection crosses the epithelium
2) lymph nodes - filters the lymph fluid
3) spleen - filters blood
