lymphatic system Flashcards
What are the components and function of the lymphatic system?
Made up of a network of capillaries, lymph nodes and organs running throughout the body. It’s involved in immunity, fluid balance, digestive absorption and removing waste.
What is Lymph and what does it contain?
It is a clear watery fluid within the lymphatic system. It contains plasma, small proteins and white blood cells.
How do things get into the lymph vessel?
High pressure causes fluid and small molecules to leak out of capillaries. Some of the molecules will filter back in as the pressure within the blood vessel changes. About 21l goes out, only 3-4l doesn’t come back in. What doesn’t return to the blood vessels ends up in the lymph vessels.
How do lymph vessels vary in structure from and sit around blood vessels?
Lymph capillaries are intertwined with other capillaries In the system. They have a blind end- don’t connect to anything else. Sit in the interstitial space. Have the same 3 layers as blood vessels. Walls of lymph capillaries are more permeable than blood vessels so more water is drawn towards them.
They join together to form larger lymph vessels, getting bigger and bigger towards the centre of our body.
What is the structure of lymph vessels?
3-layer structure: Outer fibrous capsule, muscular layer, smooth inner lining.
How do the contents of lymph vessels travel around the body?
Contents pushed along by structures round it, doesn’t have a pump. Muscles contracting squeeze it. Pulsation through nearby arteries can also help. They also have valves to prevent backflow.
What are the two largest lymph vessels?
thoracic duct and the right lymphatic duct.
Where does the cisterna chyli sit?
Cisterna chyli of thoracic duct sits between l1 and l2
How are lymph vessels involved with fatty substances?
Villi in small intestine have lymphatic vessels which draw in fatty acids. through the lymph vessel system, they end up in the blood stream.
Where are lymph nodes found and why?
In groups along lymph nodes as lymph drains back through these nodes on the way back to the venous system. it will go through about 8-10 nodes
Main groups- cervical (head and neck will drain through) axillary (armpit area) mediastinal (thoracic area) groin area (lymph from legs) lymph from pelvis will drain through abdomen nodes.
What is the structure of a lymph node?
Multiple afferent vessels bringing lymph into the node. Only one efferent one draining lymph out.
Middle sections of reticular and lymphatic tissue. Lymphatic tissue is made of lymphocytes and macrophages. Lymph is filled by these tissues. Will filter out micro bacteria, dead cells, foreign particles. Each node filters a bit, and after multiple, it should be very clear.
What is the structure of a lymph node?
Multiple afferent vessels bringing lymph into the node. Only one efferent one draining lymph out.
Middle sections of reticular and lymphatic tissue. Lymphatic tissue is made of lymphocytes and macrophages. Lymph is filled by these tissues. Will filter out micro bacteria, dead cells, foreign particles. Each node filters a bit, and after multiple, it should be very clear.
What is the structure of the spleen?
Largest lymph organ. In hypochondriac region of abdomen. Purplish, 12cm by 7 cm by 2 cm.
Contains reticular and lymphatic tissue. Enclosed in a fibrous capsule.
Made up of white white pulp- lymphatic tissue in immune response.
Red pulp- tissue engorged with blood
Where does haemolysis take place?
What is haemolysis?
Primary site is the spleen
The breakdown of red blood cells.
What does the spleen store and why?
350ml of blood and about a third of the platelets in the body. Stored for emergency use
How do tonsils aid the lymphatic system?
They sit at the back of the mouth and throat and do not have an outer fibrous capsule so they can catch inhaled or swallowed antigens. They have deep grooves to help catch bacteria. Cells within them then fight bacteria.
What is the category that tonsils come under?
MALT: mucosa associated lymphoid tissue which are collections of strategically placed lymphoid tissue. They are exposed to external environments. Also Peyer’s patch in small intestine to catch swallowed pathogens.
What does the thymus gland do?
It matures T cells into t lymphocytes, which then go to the blood stream or lymphatic tissue. They are able to distinguish between body cells and invader cells.
What is bone marrow involved in?
Haematopoiesis which is the production of red blood cells and platelets.
What is a pathogen and what are the 6 types?
An organism causing harm or disease to its host.
Parasites invade and leech off the body.
Protozoa are single cell organisms that are free-living or parasitic.
Fungi
Prokaryote also known as bacteria
Virus
Prion- a protein that attacks the brain
What is innate/non-specific immunity and what are the different aspects?
Generic responses that the body is born with.
Defence at body surface-the skin forms a barrier, cilia and mucus in the respiratory tract, nose hair
phagocytosis
natural anti-microbial surfaces- sebum on the skin, stomach acid, saliva
inflammatory response isolates and inactivates the infection site. promotes damage repair and healing.
Immunological surveillance
What is adaptive/specific immunity?
Develops and improve over a lifetime
Responds to a specific invader
Slower acting system because it is specific
Produces memory t and B cells which speeds up the process if the same pathogen is encountered again.
How does phagocytosis work?
Entrapment- phagocyte engulfs the bacteria or sends out protrusions to draw it in.
Formation of a phagosome – keeps the bacteria contained and holds it all together
Degradation- lysosomes produce enzymes to breakdown whatever has been engulfed. Breaks it down into components, some of which reused by the cell
Exocytosis- release of breakdown products out of the cells.
The cell debris floats into tissue and gets drawn into the lymphatic system.
What effect does the thymus gland have on t cells? what do they then do?
It matures them into t lymphocytes. They then sit in the spleen or the lymph nodes until they are needed.
How are T cells involved in active immunity?
They respond to one type of antigen, but they can’t detect antigens. They need an antigen presenting cells such as a macrophage or dendritic cell. They will engulf the bacteria and break it down, presenting the antigen on its own surface. The T cell will then recognise the antigen. It will replicate and differentiate into 4 types of cell.
What do T cells replicate/differentiate into and what do they do?
Regulatory T cells turn off the immune response once the threat has been dealt with.
Helped T cells produce a protein called cytokines to support t and B cells.
Memory T cells after infection fought, they remain in our system and speed up the process if it comes around again.
Cytotoxic T cells are the ones that go and destroy the bacteria.
Where are b cells produced?
What is their role?
In the bone marrow.
Role is to produce antibodies.
What are the functions of b cells?
B cells are fixed in lymphatic system
Don’t need to be presented with antigen, will just recognise it.
Activated when pathogen comes past.
Cytokines aid the B cells in enlarging and dividing.
Become memory B cells to remember antigen
Or they turn into plasma cells which produce antibodies which then circulate and seek out the antigen to mark it for T cells to and macrophages to destroy.
How does inflammation at an infection site progress?
Mast cells tucked between tissue release mediators eg histamine and serotonin. These act on the blood vessels causing vasodilation at the site. Increases blood flow and nutrients for the healing process. Increased blood flow causes redness and increased temperature. It also increases pressure within the blood vessels, pushing more fluid into surrounding tissues, causing swelling. Mediators also increase permeability of capillaries, adding to the swelling. Loss of fluid thickens the blood, reducing flow rate of blood, allowing white blood cells to adhere to the site of infection. Neutrophils start to undergo phagocytosis process to kill the bacteria off. Temperature raise in the area also helps increase phagocytosis. Neutrophils are short-lived but their presence attracts more macrophages, killing off remaining bacteria. Bacteria break down causes cell debris which becomes pus. Swelling in the area puts pressure on nerve endings, triggering them causing pain. This can prevent usage of the area, helping it to heal. Loss of function comes about if pain is very severe, or if infection is severe enough to cause lots of damage. After this process, wound-healing processes start to repair the skin.
How does the body respond to infection?
Raise in temperature to try and kill off pathogens which don’t like the temperature. If it gets too hot, our enzymes stop working and it becomes a problem for us. Temperature crease also promotes phagocytosis.
Hr increases to help transport the white blood cells around the body and oxygen and nutrients at a quicker rate.
Respiratory rate increases to support increased hr.
Blood sugar increase slightly due to higher demand. As the sources deplete, blood sugars can drop.
Blood pressure increases because increase in hr increases the cardiac output.
