What two systems does the circulatory system involve?
The cardiovascular system The lymphatic vaacular system
What is the cardiovascular system made up of?
Closed system consisting of heart, arteries, capillaries and veins
Roles of the circulatory system?
-Transport of nutrients and oxygen to the tissues -Transport of CO2 and other metabolic waste from the tissues - Temperature regulation - Distribution of hormones and immune cells - Reproductive function in males- penile erection
Basic 3 layer structure to a blood vessel?
Tunica Intima - most inner Tunica Media Tunica adventitia
Description of tunica intima?
Single layer of squamous epithelial cells termed endothelial cells, supported by a basal lamina and a thin layer of connective tissue- It is the inner most layer
Description of tunica media?
Made up predominantly of smooth muscle Thickness of this layer varies tremendously
Description of tunica adventitia?
Made up of supporting connective tissue- outer most layer
What is the tunica intima separated from the tunica media by?
Layer of elastic tissue called the internal elastic membrane
What is the tunica adventitia separated from the tunica media by?
Layer of elastic tissue called th eexternal elastic membrane
What colour do elastic fibres stain?
What are the very largest arteries called? And why are they termed this?
Elastic arteries. Because they have many sheets of elastic fibres in their tunica media to provide elastic recoil
Describe the make up of arterioles?
Have only one or 2 layers of smooth msucle in the tunica media and almost no adventitia. They are particularly important in controlling blood flow in tissue.
What are capillaries essentially composed of?
Endothelial cells and a basal lamina
What do capillaries have at intervals just outsude of the basal lamina?
Pericytes - connective tissue cells that have contractile properties
Wher are continuous capillaries found?
In muscle, connective tissue, lung, skin & nerves
Where are fenestrated capillaries found?
Mucosa of the gut, endocrine glands and glomeruli of the kidney
Where are discontinuous capillaries found?
Liver spleen and bone marrow
Description of discontinuous capillaries?
Large gaps through which macromolecules can fit , in some cases even cells can fit through aswell
Basal lamina is discontinuous or not present
What is microvasculature?
Small arterioles connecting to postcapillary venule through this network of metarterioles, thoroughfare channels and capillaries.
What helps control flood flow through microvasculature?
Pre-capillary sphinctors - composed of smooth muscle at the beginning of the capillary
What do capillary networks drain into?
Post capillary venules
Describe post capillary venules?
Endothelial lined and contain a thiin layer of connective tissue and occasional pericytes - important sites for exchange
When is a post capillary venule described as a venule?
When smooth muscle cells start to be acquired in the tunica media layer.
Thin tunica media- few layers of smooth muscle - markedly thinner than in an artery
Large veins have- thick tunica adventitia - with bundles of longitudnally orientated smooth muscle
Veins are flexible- can accommodate expansion
Have a tunica intima
Difference between large veins and small/medium veins?
Large veins (HPC/VC) have bundles of longitudnally orientated smooth muscle cells
Small/medium veins have Valves- inwards extensions of the tunica intima
What of these is a small artery and which is a small vein?
A= small artery
B = Small vein
3 Layers of the heart?
Endocardium - inner layer
Myocardium - Middle layer
Epicardium- Outer layer
Layers of e heart from the outside in?
Parietal layer of serous pericardium
Visceral layer of serous pericardium
What does the endocardium do?
Lines the entire inner surface of the heart including the valves