Ch 22 - Lymphatic System Flashcards
Resistance
The ability to ward off the pathogens that produce disease
Susceptibility
Lack of resistance
Innate Immunity
(aka Nonspecific Resistance)
present at birth and includes defense mechanisms that provide general protection against invasion by a wide range of pathogens
Immunity
(aka Adaptive Immunity)
involves activation of specific lymphocytes that combat a particular pathogen or other foreign substance
Lymphatic System
- lymph
- lymphatic vessels
- several structures and organs that contain lymphatic tissue
- bone marrow
Functions of the Lymphatic System
- Drain excess interstitial fluid and return plasma proteins to the blood
- Transport dietary fats
- Carry out immune responses
Lymphatic Vessels
- begin as lymph capillaries, which are closed on one end
- carry excess tissue fluid and plasma proteins
- if fluids are not picked up by lymph vessels, edema occurs as fluid accumulates in tissues
- form a one-way system towards the heart
Lymphatic Capillaries
- located between cells of many tissues
- found throughout the body except in avascular tissue, the central nervous system, portions of the spleen, and red bone marrow
- merge to form lymphatic vessels
- have greater permeability than blood capillaries
- have a slightly larger diameter than blood capillaries
- have overlapping endothelial cells which work as one-way valves
- Anchoring filaments extend from the capillary and attach into endothelial cells
Lacteal
specialized lymphatic capillaries, in the villus of the small intestine, that carry dietary lipids into lymphatic vessels and ultimately into the blood
Chyle
lymph draining from the small intestine that contains dietary lipids and gives a creamy white appearance
(elsewhere in the body, lymph is a clear, pale-yellow fluid)
Lymph Trunks and Ducts
From the lymphatic vessels, lymph passes through lymph nodes and then into lymph trunks
- Lumbar trunk
- Intestinal trunk
- Bronchomediastinal trunk
- Subclavian trunk
- Jugular trunk
Lymph trunks then merge to form either the thoracic duct or the right lymphatic duct
Lumbar Trunk
drains lymph from lower limbs, wall and viscera of the pelvis, kidneys, adrenals, and abdominal wall
Intestinal Trunk
drains lymph from the stomach, intestines, pancreas, spleen and part of the liver
Bronchomediastinal Trunk
drains lymph from the thoracic wall, lung, and heart
Subclavian Trunk
drains the upper limbs
Jugular Trunk
drains the head and neck
Thoracic Duct
- begins as a dilation called cisterna chyli
- receives blood from abdomen and lower extremities, left side of head, neck, and chest
Right Lymphatic Duct
receives blood from upper right side of the body (right jugular, right subclavian, right bronchomediastinal trunks)
Formation and Flow of Lymph
- Interstitial fluid
- Lymph capillaries
- Lymph vessels
- Lymph trunks
- Lymph ducts
- Junction of subclavian and jugular veins
Aids of Lymph Flow
- skeletal muscle pump/contractions
- respiratory pump/inhalation
- smooth muscle in lymphatic walls contracting
Primary Lymphatic Organs
Organs where immune cells become immunocompetent (capable of mounting an immune response) and where stem cells divide
- Red bone marrow (B cells)
- Thymus (T cells)
Thymus Gland
- lies between the sternum and the heart
- bi-lobed organ consisting of an outer cortex and an inner medulla
- functions at peak levels only during childhood
- produces hormones (such as thymosin) to program lymphocytes
- site of T-cell maturation
- immature T-cells migrate to the cortex and begin to mature
- about 2% survive and then enter the medulla
Secondary Lymphatic Organs
- Lymph nodes
- 600 bean shaped nodes along lymphatic vessels, usually appear in groups
- Spleen
- largest single mass of lymphatic tissue in the body
- Lymphatic nodules
- egg shaped masses of lymphatic tissue not surrounded by a capsule
