Vascular Biology Flashcards
Describe how differences in blood pressure and osmotic pressure determine where fluid flows
Explain the differences between primary and secondary lymphedema and provide examples of how this leads to lymphedema
Define endothelial cells and describe key functions of the cells
Explain how VE-cadherin connects cells
Describe how VE-cadherin is organised in distinct vessel types and explain how this organisation allow function
Define the two processes that occur to form the vascular tree during development
Explain how adhesion decline occurs and provide a disease example where defective endothelial adhesion is a symptom
What is the blood vasculature system
it is a closed circulatory system that transports and exchanges gases and nutrients
what is the lymphatic vasculature system
It returns extravasated fluid and macromolecules back to the blood. I
What are the 3 distinct layers of the tunica
- Inner = Tunica Intima: single layer of endothelial cells and underlying connective tissue (basement membrane)
- Middle = Tunica Media: smooth muscle cells, elastic fibres and connective tissue
- Outer = Tunica Adventitia; perivascular soft tissue, connective tissue, nutrient vessels, and autonomic nerves
What is the structure and function of arteries
- Arteries are thick and have elastic Tunica Media
- Arteries have a high abundance of smooth muscle cells, which can constrict or dilate by contracting
- Arteries have a pulsatile flow with high blood pressure
- Arteries are affected by aging, such as stiffing of the walls and other structures deteriorating
What is the relevance of elasticity in the AORTA
The elastic fibres allow the wall to be extended and recoil in response to cardiac contraction and relaxation.
Loss of the elasticity can lead to thoracic aortic aneurysms and aortic dissection
What is Marfan syndrome and its symptoms
Marfan syndrome has a mutation in the fibrillin1 gene, it causes there to be less Fibrillin which reduces the elastic properties of tissue, which affects all connective tissues, the heart, blood vessels, eyes and the skeleton
What are the structure and functions of veins
- Low pressure
- elastic lamina are absent
- thinner wall than artery
- larger luman than artery
- they have venous valves to prevent backflow
What is the function of venous valves
- Venous valves help the lower extremity veins that need to work against gravity
- valves only open in one direction
- Surrounding muscles assist in the operation of the venous valves by contracting when open and relax when closed
What are varicose veins and their causes
- Varicose veins are caused by genetic factors, lifestyle factors and aging.
- ECM degradation causes thinning of the venous wall and valve dysfunction, this then disturbs the flow patterns causing blood pooling, local dilations and folding also known as varicose veins
What is the structure and functions of the capillaries
- Capillaries have a small lumen, the size of one red blood cell
- Capillaries only have a Tunica intima (a single layer of endothelial cells attached to the basement membrane)
- Capillaries function is to exchange oxygen and nutrient
How does capillary gas and nutrient exchange work
There is a balance between blood pressure and osmotic pressure that determines the movement of water and small molecules. This occurs via diffusion of both O2 and CO2. The O2 is bound to hemoglobin or erythrocytes
What is the function of the lymphatic system
- Transport excess fluid that is not taken up by the blood
- They uptake tissue-derived immune cells (T and B lymphocytes) antigens
- The filtering of lymph fluid occurs in the lymph nodes before fluid enters back into circulation
- It works as an adaptive immune response
Explain the structure of the Lymphatic capillaries
- Lymphatic capillaries are blind-ended and have a partial basement membrane
- Lymphatic capillaries are connected to the ECM with anchoring filaments which are elastic fibers made with fibrillin
- Lymphatic capillaries have a single layer of overlapping endothelial cells which allows the entry of cells
Explain the structure of the Collecting Lymphatic Vessels
- Collecting lymphatic vessels have a continuous basement membrane
- Lymphatic valves prevent backflow by opening and closing, which is assisted by smooth muscle cells, skeletal muscle and respiratory movements
- Lymphatic vessels conduct fluid and immune cell transport
What is Lymphedema
- Lymphedema is the accumulation of fluid caused by drainage failure
- Primary Lymphedema is congenital and due to the reduced lymphatic vasculature/function
- Secondary Lymphedema can be caused by, cancer, infections of the skin and soft tissue, trauma such as burns and large wounds, and Latrogenic due to surgery, radiation, or drugs.
What is Hennekam Syndrome
- Lymphatic vessels are abnormally expanded which leads to reduced function
- Hennekam syndrome is autosomal recessive, meaning both parents carry the LOF mutations
What is the endothelium
- Endothelium is made up of specialised simple squamous epithelium
- Endothelium is the inner lay of the Tunica intima
- High permeability = reduced connectivity
