The Circulatory System Flashcards
Overall, what does the circulatory system mediate?
The continuous movement of all body fluids
What are the four main functions of the circulatory system?
- To transport oxygen and nutrients to tissues
- To transport co2 and metabolic waste away from tis
- Temperature regulation
- Distribution of molecules and cells, e.g. hormones & immunocytes
What are the two functional components of the circulatory system?
- The blood vascular system
2. The lymph vascular system
What is the blood flow initiated by?
The heart obviously
What is microcirculation?
Microcirculation refers to the smallest vessels in the body. The main sites of interchange between the tissues and the blood
Who was the first known to describe the systemic system and properties of blood in detail?
William Harvey
What are the three layers that the whole system has in common?
The tunica intima - the inner lining
The tunica media - intermediate
The tunica adventitia - outer supporting layer
What is the tunica intima?
The inner lining composed of flattened epithelial cells, endothelium, supported by a basement membrane and delicate collagenous tissue
What is the tunica media?
Intermediate mainly muscular layer. Shows the most variation out of all the layers
What is the tunica adventitia?
The outer supporting tissue layer
The tissues of thick walls of large vessels cannot sustain themselves by diffusion of nutrients from the lumina alone so what are they supplied by?
By the vasa vasorum - small arteries running in the tunica adventitia
The vasa vasorum are small arteries running in the tunica adventitia, where do they go from here?
They send arterioles and capillaries into the tunica media
The heart is made of the same three cell layers as the tissues in the
blood vessels
What are the three layers in the heart - both names?
- tunica intima - endocardium
- tunica media - myocardium
- tunica adventitia - epicardium or visceral pericardium
What are papillary muscles?
A small muscle within the heart that anchors the heart valves
Where are the purkinje fibres found, in which layer?
In the subendocardial layer - run immediately below the endocardium
What is the function of the purkinje fibres?
To transmit electrical impulses in a co-ordinated manner
Describe the structure of the cells making up the endocardium
A surface layer of flattened endothelial cells
What is one of the functions of the endocardium?
Controls myocardial function
Describe the structure of the epicardium
A dense sheet of fibro-collagenous and elastic tissue
What is one of the functions of the mesothelial cells that make up the epicardium?
On the outer surface a single layer of flat mesothelial cells (simple squamous epithelium) are responsible for secreting lubricating fluid
What fibres make up the mycocardium?
Cardiac muscle fibres
What joins together different cardiac muscle cells?
Intercalated discs
Cardiac muscles have ____ nuclei and regular cytoplasmic _______
central and striations
What are purkinje fibres?
Modified cardiac muscle fibres involved in the regulation of co-ordinated contraction of the heart
Where do the purkinje fibres first begin?
About halfway down the interventricular septum
The heart valves consist of leaflets of…
fibroelastic tissue covered by endothelium on both sides
What is the function of the arterial system?
To distribute blood from the heart to capillary beds throughout the body
The cyclical pumping action of the heart ventricles produces a…
Pulsatile flow in the arterial system
