Histology (1) Flashcards
Where is blood flow at its fastest?
- Where cross-sectional area’s at its least
Outline the route through vessels from the heart and back.
- Heart -> Large (elastic/conducting) arteries -> Medium (muscular/distributing) arteries -> Arterioles -> Metarterioles -> Capillaries -> Post capillary venules -> Venules -> Medium veins -> Large veins -> Heart
Name the branches of the aortic arch.
- Brachiocephalic
- Left common carotid
- Left subclavian
What is the major vessel that arises from the right ventricle and what does it split into?
- Pulmonary trunk
- Right and left pulmonary arteries
Outline the initial route of the aorta and where it terminates.
- Posteriorly oblique arch descends into thoracic cavity
- Terminates by bifurcating into left and right common iliac arteries in the pelvis.
What happens to the arteries during systole?
- Increase in blood pressure, so elastic arteries stretch.
What happens to arteries during diastole?
- Aortic pressure decreases
- Walls of aorta recoils maintaining pressure on blood and moving it towards smaller vessels.
What are the walls of arteries and veins from inner to outer?
- Tunica intima
- Tunica media
- Tunica adventitia
What is the role of elastic arteries?
- Maintain blood pressure during diastole
- Stretch during systole
What is the function of end arteries?
- Terminal artery supply all/most of the blood to a body part without collateral circulation
- So if occluded causes an insufficient blood supply to tissue
What is the function of arterioles?
- Muscular arteries branch off to form arterioles
- Regulates the amount of blood reaching specific tissues/organs
What is the function of metarterioles?
- Arteries supplying blood to capillaries (capillary beds)
- Contains precapillary sphincters to control blood flow into capillary bed.
What is the role of capillaries?
- Blood supply to tissues
- Only 1 cell thick to allow shortest possible diffusion pathway
What are the different types of capillaries?
- Continuous
- Fenestrated
- Sinusoids
What are continuous capillaries and where are they found?
- Located in nervous, muscle and connective tissues
- Exocrine glands and lungs
- Continuous endothelial layer
What are fenestrated capillaries and where are they found?
- Parts of gut, exocrine and renal glomerulus
- Interruptions exist across endothelium - bridged by diaphragm
What are sinusoids and where are they found?
- Liver, spleen and bone marrow
- Gaps present in walls allowing whole cell exchange between blood and tissue
What are post capillary venules?
- A more permeable version of capillaries
- Pressure is lower than in capillaries
- Fluid tends to drain into them.
- Unless inflammation - leukocytes and fluids emigrate
What are venules?
- Merge of capillaries into venules
What do veins arise from and what is their role?
- Venules
- Contains valves to prevent retrograde of blood
- Reservoir of blood, to be used when needed.
What is the venae comitantes?
- Deep paired veins accompanying one side of the smaller arteries on each side of the artery
- 3 vessels wrapped together into one sheath.
