14 - Lymphatic System and Immunity Flashcards
Define a pathogen.
Any substance or microorganism that causes disease or damage to the tissues of the body is considered a pathogen.
What are the three functions of the lymphatic system?
- Fluid balance
- Lipid absorption
- Defence.
How is fluid balance a part of the lymphatic system functions?
About 30 liters of fluid pass from the blood capillaries into the interstitial spaces each day, whereas only 27L pass from the interstitial spaces back into the blood capillaries. The remaining fluid enters the lymphatic capillaries, and it passes through the lymphatic vessels to return to the blood.
How is lipid absorption a part of the lymphatic system functions?
The lymphatic system absorbs lipids and other substances from the digestive tract through lymphatic vessels called lacteals located in the lining of the small intestine. Lipids enter the lacteals and pass through the lymphatic vessels to the venous circulation. The lymph passing through these lymphatic vessels appears white because of its lipid content and is called chyle.
How is defence a part of the lymphatic system functions?
Pathogens, such as microorganisms and other foreign substances, are filtered from lymph by lymph nodes and from blood by the spleen. In addition, lymphocytes and other cells are capable of destroying pathogens. Because the lymphatic system is involved with fighting infections, as well as filtering blood and lymph to remove pathogens, many infectious diseases produce symptoms associated with the lymphatic system.
What is the structure of lymphatic capillaries?
The lymphatic capillaries are tiny, close-ended vessels consisting of simple squamous epithelium. They are more permeable than blood capillaries because they lack a basement membrane.
How is backflow of fluid in the lymph prevented?
By overlapping squamous cells in the capillary walls. They act as valves.
Lymphatic capillaries are present in most tissues of the body. Exceptions are …
The CNS, bone marrow, and tissues lacking blood vessels, such as the epidermis and cartilage.
The lymphatic vessels converge and eventually empty into the what
The blood.
The lymphatic vessels converge and eventually empty into the blood at two locations in the body. Where?
Lymphatic vessels from the right upper limb and the right half of the head, neck and chest form the right lymphatic duct, which empties into the right subclavian vein. Lymphatic vessels from the rest of the body enter the thoracic duct, which empties into the left subclavian vein.
What are the lymphatic organs?
The lymphatic organs include:
- The tonsils
- The spleen
- The thymus
What is spleen in norwegian?
Milt
What is thymus in norwegian?
Brissel
The tonsils are plural. Why?
There are three groups of tonsils!
What are the three groups of tonsils?
- The palatine tonsils
- The pharyngeal tonsil
- The lingual tonsil
What is the adenoid, or the adenoids?
This is a common name for the pharyngeal tonsil when it is enlarged.
Where are the palatine tonsils?
The palatine tonsils are located on each side of the posterior opening of the oral cavity.
Which tonsils are normally referred to as “the tonsils”?
The palatine tonsils.
Where is the pharyngeal tonsil?
The pharyngeal tonsil is located near the internal opening of the nasal cavity. When the pharyngeal tonsil is enlarged, it is commonly called the adenoid, or adenoids.
Where is the lingual tonsil?
The lingual tonsil is on the posterior surface of the tongue.
What is lymphatic tissue?
Lymphatic tissue is a tissue type that consists of many lymphocytes and other cells, such as macrophages, and is found within lymphatic organs.
What are lymph nodes?
Lymph nodes are rounded structures, varying from the size of a small seed to that of a shelled almond. Lymph nodes are distributed along the lymphatic vessels, and most lymph passes through at least one lymph node before entering the blood.
Although lymph nodes are found throughout the body, there are three superficial aggregations of lymph nodes on each side of the body. Where are these three? (six)
- The groin
- The armpit
- The neck
As lymph moves through the lymph nodes, two functions are performed. Which?
- Activate the immune system
2. Remove pathogens from the lymph.
How can the lymph nodes “activate the immune system?”
Pathogens in the lymph can stimulate lymphocytes in the lymphatic tissue to divide. The lymphatic nodules containing the rapidly dividing lymphocytes are called germinal centres. These newly produced lymphocytes are released into the lymph and eventually reach the blood.
How large, and where is the spleen located?
The spleen is roughly the size of a clenched fist and is located in the left superior corner of the abdominal cavity.
How is the spleen structured?
The spleen has an outer capsule of dense connective tissue and a small amount of smooth muscle. Trabeculae from the capsule divide the spleen into small, interconnected compartments containing two specialised types of lymphatic tissue. White and red pulp.
What is the difference between the two types of lymphatic tissue in the spleen?
White pulp is lymphatic tissue surrounding the arteries within the spleen. Red pulp is associated with the veins.
What is the function of the spleen?
The spleen filters blood. Cells within the spleen detect and respond to foreign substances in the blood and destroy worn-out red blood cells. The spleen also functions as a blood reservoir, holding a small volume of blood.
What is the function of the white pulp?
The lymphocytes in the white pulp can be stimulated in the same manner as in lymph nodes.
What is the function of the red pulp?
Macrophages in the red pulp remove foreign substances and worn-out red blood through phagocytosis.
What is the size and location of the thymus?
The thymus is a bilobed gland roughly triangular in shape. It is located in the superior mediastinum, the partition dividing the thoracic cavity into left and right parts.
What is the function of the thymus?
The thymus is the site for the maturation of a class of lymphocytes called T cells. Large numbers of T cells are produced in the thymus, but most degenerate. The T cells that survive the maturation process are capable of reacting to foreign substances.
Where do the pre-B cells mature?
In the red bone marrow.