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Chapter 17The Lymphatic System and Immunity
Lymphatic System
- Pathogen: a disease producing microbe/bacteria or virus
- Immunity Resistance: ability to fight off disease
- Two Types:1) Innate 2) Adaptive - Present at birth - Developed over time - Non-specific - Specific recognition - Non-memory - Has memory - Fast response - Slower response
Lymphatic System
Lymphatic vessel
- Made up of Lymph, Lymphatic Vessels, Lymphatic Tissue, and Red Bone Marrow
- Lymph = interstitial fluid that is in lymphatic vessels
- Three main functions:1) Drains excess interstitial fluid2) Transports dietary lipids3) Carries out high specific immune responses
Lymphatic Circulation
1) 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
2) Joins with larger lymphatic vessels- Lymph nodes located along the vessels- Masses of B cells and T cells
Interstitial fluid
Blood capillary
Lymphatic capillary
Lymph
Interstitial fluid
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
Lymphatic Organs and Tissues
Two main groups (based on function):1) Primary lymphatic organs
- Where stem cells divide and develop into mature B and T Cells- Red bone marrow and Thymus
2) Secondary lymphatic organs- Where most immune responses occur- Lymph nodes, spleen, lymphatic nodules
Secondary Lymphatic Organs
- Lymph Nodes- About 600
- Filter lymph to trap foreign particles
- Macrophages and lymphocytes destroy invaders
Efferent lymphaticvessels
Valve
Afferentlymphatic vessel
Valve
Afferent lymphaticvessels
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
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