CVS: Introduction to Lymphatics Flashcards
What is lymph and what does it contain?
- Formed from interstitial (tissue) fluid
- Fluid originates as a plasma filtrate
- Contains:
- Salts
- Proteins
- Fat
- Cells (mainly lymphocytes, but also dendritic cells + macrophages)
What are lymph nodes?
Filter stations on drainage pathway for lymph fluid
Describe the function of the components of the lymphatic system
Consists of lymphatic vessels which absorb and direct fluid and immune cells, as lymph, from tissues to lymph nodes (+ other lymphoid organs) which act as filter stations to cleanse and initiate acquired immunity
Lymph glands are connected to lymph vessels. Lymph vessels absorb the microbes responsible for an infection and transport them to lymph glands.
In lymph glands, immune cells become sufficiently developed to produce resources to fight specific infections
What are secondary lymphoid organs?
Organs that acts a filters where foreign invaders e.g. microbes, are capture and lymphocytes, activated
What are 2 examples of mucosa-associated lymphoid tissues?
- Tonsils
- Peyer’s patches (small intestine, jejenum, ileum)
What are the primary lymphoid organs?
- Thymus
- Bone marrow
These generate lymphocytes from immature progenitor cells
What organs are the secondary lymphoid organs?
SLOs are defined structures comprising of lymph nodes, the spleen and mucosa-associated lymphoid tissue (MALT) where lymphocytes are activated
What are tertiary lymphoid organs (TLOs)?
Acquired loose lymph node-like immune cell clusters in tissues
What is the lymphatic system?
Countercurrent system (to heart) that drains waste materials from tissues and recycles surplus fluid, salts, proteins, fat and immune cells back to body
The lymphatic system is a network of drainage tubes connected to lymph glands which act as drainage channels for the body’s tissues
What are the functions of the lymphatic system?
- Fluid homeostasis
- Cellular drainage from tissues
- Immune surveillance
- Regulation of inflammation
- Facilitation of fat transport around body
How does the lymphatic system drain?
- Interstitial fluid drains into blind-ended lymphatic capillaries
- Muscles in walls of collecting vessels contract, push lymph proximally
- Contractions in arteries + skeletal muscles, breathing, BP and volume of lymph in lymphatic system can also influence the rate at which lymph is drained via the lymphatic vessels
- Valves along walls collecting vessels prevent lymph from flowing backwards
What are the 2 types of lymphatic vessels?
- Smaller peripheral, non-contractile initial lymphatics (capillaries)
- Main contractile lymphatic collecting vessels
Describe the anatomy of the lymphatic capillaries
- Blind ended
- No smooth muscle
- Incontinuous basement membrane
Describe the anatomy of the collecting vessels
- Smooth muscle coverage
- Luminal valves
- Basement membranes
What does a tender lymph gland indicate?
Immune response to infection