Lecture 6 Flashcards
Describe the Left Ventricle (as a chamber)?
The function is as a muscular pump. The valves prevent back flow. The mean pressure is 95mmHg. There are thick muscular walls, inlet and outlet valves.
Describe the large arteries?
Conducting (lots of volume of blood pushed into the smaller arteries). There are a lot of elastic fibres to help dampen the flow (need the flow to be smoothened). The mean pressure is 95-85mmHg. There are muscular walls which re used to control the diameter, plus there is connective tissue used for strength.
Describe medium-sized arteries?
Distributing arteries (control and push blood into different areas depending on demand). The mean pressure is around 95-85mmHg.
Describe arterioles, met arterioles, pre capillary sphincters?
Small muscular, and can control the pressure and flow into certain areas. There is a massive drop of pressure to 85-35mmHg. Speed has to be the right amount, so that exchange can occur. There is smooth muscle to control the diameter and little CT.
Describe capillaries?
Thin walled and no muscle (as there is no need to control flow - need the exchange of gases and nutrients). The flow has slowed down, and the function is mainly for exchange. The mean pressure is around 35-15mmHg.
Describe venules?
Thin walled, and collecting vessels.
Describe veins?
Thin walled, and return back to the heart from he systemic system.
Describe Elastic Arteries?
Thick denied walls - aorta (and branches) and pulmonary. Often termed conducting arteries. Big ejection of blood from the ventricle. Big bolus comes through the arteries, the arteries have mass layers of elastic fibres, which help to restrain the blood (via the collagen fibres) and helps move the blood forward.
Describe the tunics?
All the vessels have these layers: 1. Tunica Intima. 2. Tunica Media. 3. Tunica Adventitia. the inner and middle layers are usually well defined. The outer layer is a bit muddy.
Describe the Tunica Intima (in elastic arteries)?
There is an endothelium. There is a relatively thick sub endothelial CT (contains elastic fibres which are running circumferentially and longitudinally). To define the end of the TI is the Internal Elastic Lamina. The IEL in elastic arteries is hard to spot due to the TM containing elastin.
Describe the Tunica Media (in elastic arteries)?
Starts after the IEL. Comprises of 50 lamellar units (each unit is made up of elastic lamina, smooth muscle and collagen fibres). Contains External Elastic Lamina. the smooth muscle cells in the TM are essential for the production of collagen and elastin. To get nutrients through to the TM there will be fenestrations (spaces) between the elastin.
Describe the Tunica Adventitia (in elastic arteries)?
There are small vessels in the TA called vasa vasorum (these supply the TA with nutrients and O2).
Describe muscular arteries?
There is an endothelium layer and small subendothelilal CT layer. There is an IEL layer as well. Smooth muscle fibres control the diameter of the vessel. The EEL defines the TM, and less prominent than IEL. The main function is the muscle (controlled by vasodilation/contriction.
Describe the TA (in muscular arteries)?
Small vasa vasorum compared to the elastic arteries.
Describe Atherosclerosis?
Narrowing of the arteries by fatty plaque building up. 1/3 of people have this disease.
Describe aneurysms?
Commonly found in the arteries - it is a problem/weakness in the TI layer.
Describe a berry aneurysm?
This aneurysm is often found in the brain, it can lead to a stroke. There is bleeding into the media wall. Won’t have too much effect but risk of rupture - where you have the stroke.
Describe a dissecting aneurysm?
Weakness in the wall (congenital and potentially hereditary), there can be bleeding in there and it could rupture. High risk of death if it ruptures. Influenced by life choices.
Describe Hypertension?
Huge thickening of the wall and increase of hypertension. Where BP is 140/90mmHg. There are risk factors but causes are unknown. There is a much narrower lumen, duplication of the IEL, thickening of the smooth muscle cells (in TM) the TA may thicken as well. There is a very thick wall:lumen ratio.
Describe arterioles?
Still have three clear layers, but much smaller. Still have IEL, but there is no EEL. In the TM there is three layers of SM or less.
