Haematopoieic and Lymphatic systems Flashcards
Define HAEMATOPOIESIS
Haematopoiesis is the continual production of all blood cells.
In the fetus, production occurs in the spleen and the liver.
In newborn to adults, production occurs in red bone marrow.
Define THROMBOPOIESIS
Thrombopoiesis is the production of platelets. They are produced from pluripotent stem cells and clot if there is a cut.
Define LEUKOPOIESIS
Leukopoiesis is the formation of white blood cells produced from pluripotent stem cells. They are an important part of the immune system.
Define ERYTHROPOIESIS
Erythropoiesis is the process of red blood cell production. These start as pluripotent stem cells in red bone marrow.
Define ERYTHROPOIETIN
Erythropoietin is the hormone produced in the kidney that can be released to stimulate red blood cell production. It helps to ensure sufficient oxygenisation around the body.
Define PLURIPOTENT STEM CELLS
Pluripotent stem cells are stem cells that can become RBCs, WBCs or platekets depending on which activation message is sent out. They are found in red blood marrow.
Define HYPOXIA
Hypoxia is a deficiency in the amount of oxygen reaching the tissues in the body. The heart is forced to work harder.
What are the three types of cells?
Red blood cells (carry oxygen), platelets (help prevent leaks from damaged blood cells through clotting), white blood cells (important for immune responses).
What is blood comprised of?
Cells and cell fragments suspended in fluid. The liquid portion of blood is plasma, which makes of 50% of the total. Blood carries oxygen, electrolytes, hormones, nutrients and drugs all around the body.
The cellular portion of blood contains RBC, WBC and platelets.
What are the characteristics of RBCs?
- round with no nucleus
- reddish/orange in colour
- no central pallor
- 5-7 micrometres in diameter
- lifespan of about 140-150 days
Define EXTRA CELLULAR FLUID
Extra cellular fluid is the fluid that always surrounds the outside of cells.
How is red blood cell production controlled?
Through the release of the hormone erythropoietin from the kidneys.
What is the effect of EPO on RBCs?
- increased number of stem cells differentiate to become red blood cells.
- stages of red blood cell development are sped up
- transit time out of red blood marrow is reduced
What are the two types of white blood cells?
Granulocytes and agranulocytes
Define GRANULOCYTES
Granulocytes are WBCs present in the cytoplasm that appear in the form of granules. They make up 65% of total WBCs. An example is basophil.
Define AGRANULOCYTES
Agranulocytes are WBCs found in the cytoplasm without granules, They make up 35% of total WBCs. An example is a monocyte.
What is the pH of blood?
Between 7.35 and 7.45 meaning it is slightly alkaline.
Define the LYMPHATIC SYSTEM
The lymphatic system is the network of vessels through which lymph drains from tissues into the blood.
Define LYMPH
Lymph is the fluid that circulates through the lymphatic system. It is extra cellular fluid without the nutrients and oxygen. It is a specialised component of the circulatory system and lymph vessels return lymph to the blood system in parallel to venous return.
What are the functions of the lymphatic system?
- maintains homeostasis
- drains excess fluid from tissues back to the blood
- filters out bacteria from lymph nodes
Define CHYLE
Chyle is a milky fluid containing fat droplets which drains from lacteals of the small intestine into the lymphatic system during digestion.
How does lymphatic circulation work?
The lymph is moved through the body in its own vessels making a one-way journey from the interstitial spaces to the subclavian veins at the base of the neck. Since the lymphatic system does not have a heart to pump it, its upward movement depends on the motions of the muscle and joint pumps.
Define DIFFUSION
Diffusion is the movement down from an area of high concentration to an area of low concentration
Define BULK FLOW
Bulk flow is the movement of water and solutes together due to a pressure gradient.
What is the structure of a lymphatic vessel?
They resemble veins except their walls are thinner and they have nodes located at intervals.
Define a LYMPH NODE
Lymph nodes are small swellings in the lymphatic system where lymph is filtered and lymphocytes are formed. Located in lymph vessels throughout the body.
In particular they are in the groin, arm, and abdominal cavity.
What is the function of a lymph node?
To trap and engulf foreign particles when they are there. It acts as the line of defence for things moving around the body.
What are the two lymph ducts?
The thoracic duct and the right lymphatic duct
Define the THORACIC DUCT
The thoracic duct is the main vessel of the lymphatic system passing upwards in front of the spine and draining into a vein near the base of the neck (subclavian vein).
Define the RIGHT LYMPHATIC DUCT
Drains lymph from the right upper limb, right side of the thorax and the right halves of the head and neck. Opens in veins close to the heart - subclavian leading to the vena cava.
What is the lymphatic pump?
Influenced by high/low pressure, the muscles and their contraction, the lungs and blood flow. The most rapid flow occurs at the peak of inspiration.
Define the THYMUS
The thymus is a gland located behind the sternum and between the lungs. It is only active until puberty after which time it starts to shrink and become replaced with fat. Produces the hormone thymosin, which is a disease fighting hormone.
Define the SPLEEN
The spleen is an abdominal organ involved in the production and removal of blood cells. Part of the immune system, and made of red/white pulp. The white pulp is lymph nodes and red pulp is connective tissue.
What are the functions of the spleen?
- defence
- haematopoiesis - the final development and activation stages of monocytes and lymphocytes
- RBC/platelet destruction if they are damaged.
- acts as a blood reservoir
Define the TONSILS
The tonsils are collections of lymphoid tissue including the tongue, larynx, pharynx, intestine, prepuce and vagina. They have invaginations on the surface called crypts, but may exist without them.
