Immunity & the Lymphatic system Flashcards
What are white blood cells?
True cells (contain a nucleus and multiply) that act as defense against injury and infection.
Explain the difference between primary and secondary defenses.
Primary defenses = initial barriers which protect us from pathogenic organisms entering and harming our body. e.g Skin, Mucus membranes
Secondary defenses = reaction of the immune system from a pathogenic organism entering the body. e.g phagocytes
Identify the 2 categories of WBC.
Granulocyte
Agranulocyte
Describe Granulocytes (aka. leukocytes)
Contain cytoplasmic granules
Can retain certain stains
3 sub-types - neutrophils, eosinophils and basophils
‘non-specific’ defenses
Few days life span
Produce from stem cells found in bone marrow
Describe Agranulocytes
Clear cytoplasm
2 main sub-types - lymphocytes and monocytes
Describe monocytes
Phagocytotic cells (undergo phagocytosis) May escape into tissues
Describe lymphocytes.
Found in lymphatic system
Offer specific defenses against antigens
Explain phagocytosis
The ingestion of bacteria or other material by phagocytes
Steps:
WBC engulfs bacterium
Bacterium is digested leaving waste products
Waste is expelled from cell
List the origins of WBC
Common ancestors Myeloid tissue (red bone marrow)
May mature elsewhere
What are the 2 types of lymphocyte?
T-lymphocytes
B-lymphocytes
Describe T-lymphocytes
Originate in bone marrow, Mature in thymus
Attack invader cells directly - non specific
Describe B-lymphocytes
Produce antibodies
Programmed to produce one kind of antibody - specific
Identify the 2 types of immune response.
Humoral
Cell Mediated
Explain the humoral immune response
“antibody mediated”
Phagocyte present digested antigen
B-cells divide and produce plasma cells and memory cells
Plasma cells contain antibodies which are secreted and circulate the body
Memory cells remain, prepared for future immune responses
Explain the cell mediated response
Foreign antigens attached to T-cells
T-cells differentiate into several sub-types
These cells attack microbial perimeter directly
Identify the 2 types of immunity
Innate/Inherited (born with)
Acquired (gain after birth)
Describe the 4 types of acquired immunity.
Natural Passive e.g breastfeeding, antibodies transferred through placenta = immunity acquired by the fetus or newborn from the mother
Natural Active e.g had disease previously = experiencing and having recovered from a disease. Active immunity involves the production of antibodies (by B lymphocytes) and cell-mediated response (with T lymphocytes)
Artificial Passive e.g ready-made anitbodies
Artificial Active
List examples of immune problems.
Hypersensitivity - allergies
Transplant rejections
Immuno-deficiency - caused by disease, age, chemotherapy
Auto-immune disorder - body’s immune system attacks own body cells
Describe the 4 blood groups.
A, has anti B antibodies, donors are A and O
B, has anti A anitbodies, donors are B and O
AB, no antibodies, universal receiver
O, anti A and anti B antibodies, donor is O, universal donor
Explain the Rhesus System
Rhesus antigen is found on the surface of RBC
80-100% have Rhesus antigen (= Rh+)
Those who don’t are known as Rh-
List Rhesus incompatibility triggers
Blood transfusion
Childbirth/Placental leak
2nd Rh+ foetus’ RBCs are ‘haemolysed’ (rupture of RBC)
Prophylaxis (action taken to prevent disease)
Describe hydrostatic pressure.
Produced by blood pressure in capillaries
It forces plasma out into tissue fluid
Describe oncotic pressure
Generated by large molecules in solution
It draws tissue fluid into capillary
What happens when the venous end is blocked/ congested?
hydrostastic pressure INCREASES, fluid stays in interstitial space
What happens when blood proteins are low?
oncotic pressure is not high enough to draw fluid back in
What happens when there is a leaky blood vessel?
Fluid and large proteins leak out
What is Oedema?
A condition characterized by an excess of watery fluid in cavities/tissues
causes swollen extremities and dysphoea (difficulty breathing)
Describe the lymphatic system.
Secondary drainage system for tissues
Parallel to blood circulation
Consists of lymphatic capillaries
Permeable - caused by low internal pressure and pores
What is lymph?
Fluid in which WBC are suspended in
Travels around lymphatic system through capillaries/vessels/nodes/ducts
What are lymph nodes and what are their functions?
Small swellings on lymph capillaries
Filter Lymph
Site of lymphocyte maturation
Remove debris, germs and other waste
What are lacteals? State their function
Lymph capillaries found inside small intestine villi
Absorb dietary fat and turn them into chyle
What is chyle?
a milky fluid containing fat droplets which drains from the lacteals of the small intestine into the lymphatic system during digestion
What are Peyer’s Patches? State their function.
Small masses of lymphatic tissue found throughout small intestine
Monitor intestinal bacteria populations
Prevent growth of pathogenic bacteria
What is a thoracic duct?
Vessel that collects and channels lymph
What are cisterna chyli?
Dilated sac found at end of thoracic duct that receives fatty chyle
List lymphoid tissues
Bone marrow Liver Bowels Appendix Thymus Spleen Tonsils
