Exchange in and control of the peripheral circulation Flashcards
What is a junction?
where one endothetlial cell meets another.
What is a cleft?
Gap between the cells, seen in majority of cells
What is transocytosis?
Macromolecules, including protein can be trasnported across individual epithelial cells via this process called transcotyosis. The structure that transports them across are known as pores.
What are three classes of capillaries?
- Continous: Have no clefts and no pores e.g brain. May have just clefts with no pores e.g muscle and most capillaries
- Fenstrated: Have both clefts and pores e.g intestine, kidney, specialised for fluid exchange
- Discontinuous: Clefts and massive pores e.g liver. Allows large proteins to move across
How does exchange in capillaries occur via bulk flow?
- It is determine by starlings flow
Go over this confused
How does exchange in capillaries occur via diffusion?
- It is self regulating and non saturable
- Non polar substance such as oxygen and carbon dioxide can diffuse across thephospolipid membrane. Barrier to polar substances however they go through the clefts and pores.
Some cases you need carrier mediated trasnport e.g glucose transporter in the brain
What happens if lymphatic system is overloaded with fluid?
There will be accumulation of fluid which is known as oedema.
What can oedema be caused by?
- Raised central venous pressure
- Lymphatic obstruction
- Hypoproteinaemia
- Increased capillary permeability
How does raised central venous pressure cause oedema?
Raised central venous pressure may due to left ventricular failure. If the left side of the heart is not pumping blood effectively whilst the right side of the heart is still okay, there will be blood accumulation in the lungs. This will result in an increased hydrostatic pressure in the capillaries which leads to pulmonary oedema.
How does lymphatic obstruction cause oedema?
Lymphatic obstruction may be due to
- filaria: This lives in lymph nodes and blocks lymphatic drainage.
- surgery: damaged lymph nodes causing accumulation of fluid
How does hypoproteinaemia cause oedema?
Hypoproteinaemia may be due to:
- malnurtion: individual may not have enough proteins in the diet causing them to not having enough proteins in the capillary to build up oncotic pressure and losing more fluid in the lymph nodes
- kidney failure
- neuphrotic syndrome: kidneys are damaged in this and too much protein is leaked out via urine
How does increased capillary permeability cause oedema?
Increased capillary permeability may be caused by:
- rheumatoid arthiritis: autoimmune disease where body attacks the joints, again don’t have enough protein in the capillaries to build up oncotic pressure
How is total peripheral resistance controlled ?
The radius of resistance vessels is also used to control Total peripheral resistance and therefore reglate mean arterial pressure.
What is mean arterial pressure?
Mean arterial pressure is the driving force pushing blood through your systemic circulation
What are the two levels of control over the smooth muscle surrounding the arterioles?
- Local (intrinsic) mechanism: concerned with meeting the needs of each individual tissue
- Central (extrensic) mechanism: Concerned with ensuring that the total peripheral resistance and therefore mean arterial pressure of the whole body stays in the right ball park.
Explain local intrinsic control
idk look at this
need to look at coronary circulation, pulmonary circulation, cerebral circulation and renal circulation
