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Immune System - Coggle Diagram
Immune System
Lymphatic System
carry away excess tissue fluid
from interstitial spaces, eventually returning it to the blood
Lymph nodes, which are situated along lymphatic vessels,
contain lymphocytes, which help defend body against disease
lymphatic vessels are thinner than those of veins, but are
constructed with the same 3 [layers]
Major areas of concentrations of lymph nodes: cervical, thoracic,
axillary, supratrochlear, abdominal, pelvic, and inguinal regions
Lymph Nodes
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Lymphocytes attack viruses, bacteria and parasitic cells that
enter a lymph node
Macrophages engulf and destroy foreign particles, debris, and
damaged cells
Pathogens
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Innate (nonspecific) defenses:
• Guard against many types of pathogens; respond quickly Include species resistance, mechanical barriers, chemical barriers, natural killer
cells, inflammation, phagocytosis, and fever
Mechanical barriers: Prevent the entry of certain pathogens by providing a physical
separation of pathogens and internal tissues
- represent the body’s first line of defense
- Examples: unbroken skin and mucous membranes of the body
Inflammation: Function of inflammation is to stop the spread of pathogens and infection
- Characterized by redness, swelling, heat, and pain
Chemical barriers: Chemicals that kill many pathogens
- Acidic environment provided by HCl in gastric juice is lethal to
some pathogens
- Enzymes, such as pepsin in the stomach and lysozyme in tears,
destroy many pathogens
- Interferons, hormone-like peptides secreted by lymphocytes
and fibroblasts when viruses or tumor cells are present, block
viral replication and slow tumor growth
Natural killer (NK) cells:
- Small group of lymphocytes, other than T cells and B cells
- Defend the body against viruses and cancer cells by secreting
cytolytic substances called perforins which lyse (break apart)
cell membranes of pathogens
Phagocytosis:
- Engulfment and digestion of pathogens, foreign particles, and
debris
- Most active phagocytes are neutrophils and monocytes, which
leave bloodstream in areas of injury
- Neutrophils engulf smaller particles; monocytes attack larger ones
- Monocytes give rise to macrophages outside the blood, which are
either free or become fixed in various tissues
Adaptive (specific) defenses or immunity: Respond against only a specific type of pathogen; respond more slowly
- Accomplished by specialized lymphocytes, which secrete cytokines or antibodies
Thymus
Shrinks in size during the lifetime; large in children, small in
adults, replaced by adipose & connective tissue in the elderly
Lobules contain lymphocytes, some of which mature into T cells
or T lymphocytes, that leave the thymus to provide immunity