Identify and describe the anatomy of lungs
- Left lung has two lobes (upper lobe and lower lobe), right lung has 3 lobes (superior, middle, inferior lobe)
- Left lung: superior lobe takes up more space on the anterior side while the anterior lobe takes up more space in the posterior side
Identify and describe the function of the lungs
What are the lymphatic “tubes”
- capillaries
- vessels
- trunks
- ducts
Primary lymphatic structures
- red bone marrow
- thymus
Secondary lymphatic structures
- lymph nodes
- spleen
- tonsils
- nodules (MALT etc)
Functions of the lymphatic system
- Helps the immune system by housing and transporting immune cells
- Helps the cardiovascular system by returning extra-cellular fluid
Primary vs. Secondary lymphatic structures
Primary: involved in formation and maturation of lymphocytes
Secondary: - house lymphocytes and other immune cells
- site of initiation of immune response
Lymphatic Capillaries
- similar to blood capillaries
- very permeable
- one-way minivalves formed from endothelial cells and anchored by collagen filaments (PREVENTS COLLAPSE OF CAPILLARIES)
What are lacteals and what is their function?
- specialised lymph capillaries present in intestinal mucosa
- absorb digested fat and deliver fatty lymph (chyle) to the blood
What are lymphatic vessels and the 3 types?
- one-way system where lymph flows towards the heart
- lymphatic capillaries (smallest)
- lymphatic collecting vessels (medium sized)
- lymphatic trunks and ducts (largest)
Lymphatic collecting vessels
- similar to veins but have thinner walls and more internal valves
- trunks are formed but he largest collecting ducts
Lymphatic ducts
- lymph is delivered into one of the two large ducts (Right Lymphatic duct and Thoracic duct)
- each duct empties lymph into venous circulation at the junction of the internal jugular and subclavian veins on its own side of the body
- lymph propelled by pulsations of nearby arteries and contractions of smooth muscle in the walls of lymphatics
Right lymphatic duct
Drains right upper arm and the right side of the head and thorax
Thoracic duct
- arises from cisterna chyli and drains the rest of the body
Primary: red bone marrow
- site of hematopoiesis
- B-lymphocytes are a type of white blood cell made in bone
Primary: thymus
- bi-lobed primary lymphoid organ
- anterior superior mediastinum
- function: antigen-independent maturation of T-lymphocytes
- max size at puberty (30 - 40g)
- atrophies and replaced by fat in adulthood
Lymph nodes
- embedded in connective tissue, in clusters along lymphatic vessels
- near body surface in cervical, axillary, and inguinal regions of the body
- functions:
- Filter lymph - macrophages destroy microorganisms and debris
- Immune system - lymphocytes are activated and mount an attack against antigens
Structure of Lymph Node
- bean shaped with external fibrous capsule
- two histologically distinct regions; cortex and medulla
- cortex: contains follicles with germinal centres
- medulla: lymph sinuses contain macrophages
- T cells circulate continuously among blood, lymph nodes, and lymphatic stream
Circulation in the lymph nodes
- lymph enters via Afferent lymphatic vessels
- lymph travels through large subcapsular sinus and smaller sinuses
- lymph exits the node at hilus via efferent vessels
Secondary: spleen
- left hypochondrium
- filters blood
- white pulp = lymphoid tissue
- where immune response is initiated against substance in blood
Secondary: tonsils
- lingual tonsil (tongue)
- palatine tonsil (roof of mouth)
- pharyngeal tonsil (pharynx)
Secondary: lymphatic nodules
- ileum
- appendix
Secondary: MALT (mucosa associated lymphoid tissue)
- bronchial associated lymphoid tissue (BALT)
- gastrointestinal associated lymphoid tissue (GALT)
- example: colon GALT
