Chapter 20) Lymphatic System Flashcards
1
Q
Lymphatic System
A
- System that returns fluids that leak from blood vessels back to the blood
- Consists of three parts
- Network of Lymphatic Vessels (lymphatics)
- Lymph (Clear Water) - Fluid in vessels
- Lymph nodes- Clean Lymph
2
Q
Lymphatic Organs/Tissue
A
- Proivides the structural basis of the immune system
- House phagocytic cells and lymphocytes
- Structures
- Spleen, Thymus, Tonisls
- Other lymphoid tissues scatterd in body
3
Q
Lymphatic Vessels
A
- Lymph Vessels (lymphatics)
- Return intersitial fluid and leaked plasma protiens back to the blood
- Around 3L/ Day
- Once intersitial fluid enters the lymphatics it is called lymph
- Distrubition and Structure
- One Way system; Lymph flows toward the heart
- Diffrent types include
- Lymphatic capillaries
- Collecting lymphatic vessels
- Lymphatic Trunks
- Lymphatic Ducts
4
Q
Lymphatic Capillaries
A
- Similiar to Blood Capalaries except there are a few key diffrences
- Very permeable (take up proteins, cell debris, pathogens and cancer cells)
- Endothelial Cells overlap losley to form easially opened, one-way vales (flaplike-minivalves)
- Anchored by collagen filaments, preventing collapse of capillaries. Any increase in insterstitial fluid volume opens minivalves
- Features above ensure than when pressure in instersital fluid is greater than the pressure in lymphatic capillaries, fluid will enter lymphatic capillaries
- when tissues become inflamed lymphatic capallaries will uptake even larger particles
- Absent in Teeth and bones but can be found in central nervous system but are limited to specific loacations in the meniges
- Lacteals) Spcialized Lymph capillaries transports absorbed fat from the small intestine to the blood stream.
- lymph is milky white because of fat
- Lymph is known as C
- Lymph in Lymphatic Capillaries flows through larger and thicker walled channels
- Collecting Vessels > Trunks > Ducts
5
Q
Collecting Lymphatic Vessels
A
- Similar to Veins, Except for:
- Thinner walls with more internal valves
- Anstomose more frequently
- Collecting Vessels in Skin Travel with Superficial Veins
- Deep Vessels Travel With the Arteries
- Exact anatomical distrubution of lymphatic vessels varies greatly between indvudials
6
Q
Lymphatic Trunks
A
- Largest Collecting Vessels untite to form Lymphatic Trunks, Which Drains into farily large areas of the body
- Major Trunks
- Paired Lumber
- Paired broncohmedistinal
- Paired Subclavian
- Paired Jugular
- Single Intestinal Trunk
7
Q
Lymphatic Ducts
A
- Lymph is eventually delivered into one of the two large ducts in the the thoracic region
- Right Lymphatic Ducts
- Drains lymph from the right upper arm and right side of the head and thorax
- Thoracic Duct
- Much larger
- recives lymph from the rest of the body. Collects lymph from the two large Lumbar Trunks from digestive organs
- Begins as an enlargeg sac (cisterna chyli) located between lumbar and thoraic vertabrae
- As thoracic duct runs superiorly it recived drainage from left thorax, upper limb, and the side of the head.
- Each terminal empties lymph into venous system circulation at the area where the Internal Jugular and Subclavian Veins meet.
8
Q
A
9
Q
Lymph Transport
A
- Lymph Flows by
- Milking action of skeletal muscle
- Pressure changes in throax during breathing
- Valves to prevent backflow
- Pulsations of Nearby arteries
- Contractions of smooth muscle in walls of lymphatics (not smallest vessels)
- Lymph transport is sporadic and slow. When physical activity increases lymph flows more rapidly
10
Q
Lymphoid Cells
A
- Lymphocytes) Main warriors of immune system
- Arise in red bone marrow
- Mature into one of two cells
- T cells (T lymphocytes) and B cells (B lymphocytes)
- Protect against antigens (anything precived as foreign)
- T cells) manage immune response, some directily attack and destroy cells
- B cells) Produce plasma cells which secrete antibodies. Mark antigens for destructuion
- Other cells
- Macropgages) Phagotize foreign substances, help activate T cells
- Dendtrtic Cells) Deliver antiges to lymphnodes
- Reticular Cells) produce strome which is network that suports other cells in lymhoid organs and tissues
11
Q
Lymphoid Tissue
A
- Important componant of the immune system
- Houses and provides proliefation site for lymphocytes
- Furnishes an ideal survelliance vantage point for lymphocytes and macrophages
- Lymphoid tissue is largely composed of reticular connective tissue (loose CT) (except for thymus)
- Two main Types of Lymphoid tissue
- Diffuse Lymphoid Tissue) Loose arangment of lymphoid cells and reticular fubers that appears in every organ
- Larger collections appear in lamina propria (Loose CT) of mucous membranes
- Lymphoid Follicles (nodules) Solid, spherical bodies of tightly packed lymphoid cells and reticular fibers
- Germinal Centers) ligher area where B cells proliferate
- Peyer’s patches) lymphoid follices located in intestional walls
12
Q
Lymphoid Organs
A
- Grouped into Two functional categories
- Primary Lymphoid Organs
- Where B and T cells Mature
- Red bone marrow and the thymus
- Secondary Lymphoid Organs
- Where mature lymphocytes first encounter antigens and are activated
- Include the lymph nodes, spleen, and collections of mucosa-associated lymphoid tissue (MALT) that form the tonsils, Peyer’s Patches, and the appendix
- All lymphoid organs help to protect the body, only lymph nodes filter lymph.
13
Q
Lymph Nodes
A
- Most important secondary lymphoid organ
- Cluster along the lymphatic vessels
- Hundreds are embedded in connective tissue around the bodu
- Large clusters in Cervical, Azillary, and Inguinal regions (places where lymph vessels become trunks)
- Functions
- Cleansing the Lymph) macrophages destroy mircoorganisms and debris.
- Immune system activation) Lymphocytes activated and mount attack agaisnst antigens.
- Structure
- External Fibrous Capsule provides protection
- Trabecule extend inward and divide nodes
- Cortex) contains follicles with germinal centers, Heavy B cell concentration
- Dendrrtic cells are abundent in the cortex
- Medulla) consisits of medullary cords, and contain B and T cells.
- Lymph Sinuses) throuought the Node are large lymphatic capillaries spanned by crisscrossing reticular fibers.
14
Q
Circulation in the Lymph Nodes
A
- Lymph enters the cortex side via afferent lyphatic vessels > Travels through Large subcapsular sinus > through smaller sinuses to medullary sinuses
- Fewer vessels draining the node than entering it which ensures there is propper time to carry out protective functions
15
Q
Spleen
A
- Removes bloodborne pathogens and aged red blood cells
- Largest lymphoid organ
- served by splenic artery and vein
- Functions
- Site of lymphocyte prolifeation and immune surveillance and response
- Cleanses blood of ages cells and platelets, Marcophages rmove debris
- Recycles breakdoen products of RBC’s and releases them to blood for processing in liver
- Structure( two distinct areas)
- White Pulp) surrounds central arteries
- where immune functions take place, composed of mostly lymphocytes
- Red Pulp) where agged RBC’s and blood-born pathogens are destroyed. Contains a huge number of erythrocytes and macrophages that engulf them
- White Pulp) surrounds central arteries
