PSIO Exam 3 Flashcards
Lymphatic System Functions
- drain excess interstitial fluid
- transport dietary lipids
- carry out immune responses
Primary Lymphatic Organs
- red bone marrow
- thymus
Secondary Lymphatic Organs and Tissues
- lymph nodes
- spleen
- lymphatic nodules/follicles
Lymphatic Vessels
- drain excess ISF and return it to the blood stream
- originate in “close ended” lymph capillaries, which lie adjacent to blood capillaries in the tissue space
Lymphatic Capillaries
- slightly larger than blood capillaries
- have one way valves
Lymph Nodes
found at irregular intervals along the lymph vessels
Non-Specific Resistance
the body’s lines of defense against invasion by pathogen (ie. bacteria, viruses, fungi, and environmental hazards)
Non-Specific defenses include:
- physical barriers (first line of defense)
- fever
- inflammation
- cells and chemicals
Physical Barriers to pathogenic invasion
- skin
- mucus membranes
- hairs and cilia
- acid
- tears
Skin as a Physical Barrier
sebaceous glands, sudoriferous glands (sweat glands), and lysosome
Mucus Membranes as a Physical Barrier
mucus is secreted by specialized epithelial cells called goblet cells
Hairs and Cilia as a Physical Barrier
mucus-coated hairs, cilia on specialized epithelial cells that line trachea
Acid as a Physical Barrier
the pH of the stomach is about 2.0
Tears as a Physical Barrier
also contain lysosome
Fever
- abnormally high body temperature in response to invading microorganisms
- the body’s thermostat is reset upwards in response to PYROGENS (chemicals secreted by leukocytes and macrophages exposed to bacteria and other foreign substances)
- high fever is dangerous because it can denature enzymes
How can moderate fever be beneficial
- the liver and spleen sequester iron and zinc (needed by microorganisms). The combination of raised fever and lowered iron inhibits bacterial growth.
- an increase in the metabolic rate, which speeds up the repair of tissues
- triggers production of interferons