Week 4 Flashcards
what are the two primary functions of the lymphatic system and how do these processes work together to keep the body healthy?
- reabsorbs plasma/interstitial fluid/lymph leaked by capillaries
- scans for invaders, activates immune system
- as lymph passes through lymph nodes, it scans for pathogens and activates immune system responses if necessary
explain the organisation of the lymphatic system
interstitial fluid passes through endothelial cells in lymphatic capillaries, then travels through lymphatic vessels to lymphatic trunks, then merge to form larger lymphatic ducts
how is lymph pushed through the system?
muscular contractions and organ movements push lymph, one way lymphatic valves assist directional flow
what are the two major lymphatic ducts and what part of the body do they drain?
right lymphatic duct
- drains right arm and right upper body
- drains into the right subclavian vein
left lymphatic duct
- drains rest of the body
- drains into left subclavian vein
name the lymphatic cells and their functions
T-cell and B-cells (lymphocytes)
- produced in bone marrow
- t-cells mature in thymus
- t-cells recognise and destroy abnormal cells
- b-cells produce antibodies to neutralise pathogens
Macrophages
- evolve from monocytes
- engulfs and destroys foreign cells
- activates t-lymphocytes
what are lymphatic tissues, where are they found, and name 2 examples
loose connective tissue containing lymphocytes, lines entry points for pathogens (mucosa-associated lymphatic tissue- MALT)
- tonsils (pharyngeal, palatine, lingual)
- Peter’s patches (clusters in small intestine, protects appendix where two intestines meet)
what is the structure and purpose of lymph nodes?
structure- fibrous capsule, spongy interior with lymphocytes and macrophages, afferent vessels: into node, efferent vessel: out of node
purpose- destroys pathogens in lymph with WBC, stores/produces T and B cells
lymph moves slowly, swollen nodes indicate active immune response
what is the structure and functions of the spleen?
structure- internal tissue red and white pulp
functions
white pulp: many lymphocytes, activates response and monitors blood
red pulp: macrophages destroy old RBC, platelets, pathogens
(enlarges during infection)
what is the thymus and its function?
both a lymphatic organ and endocrine gland, shrinks after puberty
function- nursery for T-cells
what are the formed elements of blood?
red blood cells- carry oxygen
white blood cells- protect against infection
platelets- vital in blood clotting
(haematocrit: %RBC in blood, ~40%, fluctuates due to dehydration)
explain the production of blood cells (haematopoesis)
blood cells have limited lifespans
production occurs in red bone marrow, yellow doesn’t produce (also nodes, spleen)
matures from haematopoetic stem cells, mature form influenced by hormones/growth factor
cells enter bloodstream through bone marrow
explain how RBC (erythrocytes) function
gas exchange
- contains haemoglobin: carries oxygen to cells, removes CO2
- haemoglobin: globin (protein) and haem (iron molecule), 4 O2 binding sites
- O2 binds to haemoglobin in lung capillaries (oxyhaemoglobin), released in tissues, replaced by CO2
- production (erythropoiesis): in kidneys via hormone erythropoietin, triggered by low O2
- iron, folic acid, vitamin B12, protein required for RBC production
- anaemia linked to iron deficiency (haem is iron)
explain the purpose of WBC (leukocytes) and platelets (thrombocytes)
leukocytes
- immune response, production doubled when infection is detected
thrombocytes
- small, irregularly shaped, no nucleus
- crucial in homeostasis: blood clotting and bleeding control
