1. Chapter 17 The Lymphatic System and Immunity

2. Lymphatic System
Pathogen: a disease producing microbe/bacteria or virus
Immunity Resistance: ability to fight off disease
Two Types:
Innate 2) Adaptive
- Present at birth Developed over time
- Non-specific Specific recognition
- Non-memory Has memory
- Fast response Slower response

3. Lymphatic vessel
Lymphatic System
Made up of Lymph, Lymphatic Vessels, Lymphatic Tissue, and Red Bone Marrow
Lymph = interstitial fluid that is in lymphatic vessels
Three main functions:
Drains excess interstitial fluid
Transports dietary lipids
Carries out high specific immune responses

4. Lymphatic Circulation
Interstitial fluid
Blood capillary
Lymphatic capillary
Lymphatic Circulation
Starts with lymphatic capillaries
Smallest lymph vessels
Found in spaces between cells
Lets interstitial fluid in but not out
↑ pressure inside capillary forces cell membrane to close
Joins with larger lymphatic vessels
- Lymph nodes located along the vessels
- Masses of B cells and T cells
Lymph
Interstitial fluid

6. Lymphatic Circulation
3) Lymph travels to one of two main channels: - Thoracic Duct: from left side of neck, head, chest; lower body - Right Lymphatic Duct: from upper right side of body 4) Travels back into blood Overall flow of lymph: Blood -> interstitial fluid -> lymph capillaries -> lymph vessels (through lymph nodes) -> thoracic duct or R. lymphatic duct -> Blood

7. Lymphatic Organs and Tissues
Two main groups (based on function):
Primary lymphatic organs
Where stem cells divide and develop into mature B and T Cells
Red bone marrow and Thymus
Secondary lymphatic organs
- Where most immune responses occur
- Lymph nodes, spleen, lymphatic nodules

8. Secondary Lymphatic Organs
Efferent lymphatic
vessels
Valve
Afferent
lymphatic vessel
Afferent lymphatic
Lymph Nodes
About 600
Filter lymph to trap foreign particles
Macrophages and lymphocytes destroy invaders

9. Secondary Lymphatic Organs
Spleen
Largest mass of lymphatic tissue
White pulp:
- B cells/T cells (kills invaders)
- Macrophages (engulfs pathogens)
Red pulp:
(1) removes worn-out or defective blood
cells/platelets
(2) stores platelet
(3) Produces blood cells during fetal life

10. Secondary Lymphatic Organs
Lymphatic Nodules
Line the gastrointestinal, urinary, reproductive tracts, and respiratory airway (includes tonsils)
Small and solitary or occur as large aggregations
Provide immune responses against inhaled or ingested foreign substances