Wk 4: Cardiovascular System Flashcards
5 functions of cardiovascular system
- Maintains continuous movement of all body fluids
- Transports O2 & nutrients into tissues
- Transports CO2 & metabolic waste out of tissues
- Temp regulation
- Distribution of molecules: hormones & cells of immune system - e.g: secretions of pituitary gland into bloodstream
What are the 3 tunics (3 coats) of the blood vessels
- Tunica Adventitia (externa) - outer
- Tunica Media - middle
- Tunica Intima - inner
What are the tiny vessels supplying the tunica externa & tunica media
Vaso vasora
Describe the Tunica Externa
Outer supporting tissue layer
Describe the Tunica Media
Intermediate muscular layer
Describe the Tunica Intima
Inner lining of epithelial cells, basement membrane & collagenous tissue
Where is the pericardial membrane positioned
It surrounds the heart
What are the 3 layers of the pericardium & which of these 3 is shared with the heart wall
3 layers:
1. Fibrous pericardium
2. Parietal layer of serous pericardium
3. Visceral layer of serous pericardium (epicardium)
* The visceral layer of the serous pericardium (epicardium) is the layer shared with the heart wall
What is the fibrous pericardium composed of & what does this mean for the function
- Composed of collagen bundles
- Due to lack of elastin in composition, this layer doesn’t change shape/size which prevents overfilling w blood
Function of fibrous pericardium (2)
- Tough
- Anchors heart to diaphragm & vessels
What does the serous pericardium produce
Serous fluid
What is the positioning of the parietal pericardium
It is fused to the fibrous pericardium. It encases the heart like a sac
What is the innermost layer of the pericardium
The visceral pericardium/epicardium
Where is the pericardial cavity positioned
Between the parietal & visceral layers of the serous pericardium
Function of pericardial cavity
Contains a layer of serous/pericardial fluid which acts as a lubricant, decreasing friction as heart moves
What is cardiac tamponade
- Excess fluid build up in the pericardial space
- More fluid accumulates w each contraction
- Puts pressure on heart, prevents full relaxation, heart contains less blood at beginning of each heart cycle, death
What are the 3 layers of the wall of the heart
- Epicardium (tunica adventitia) - outer, shared w pericardium
- Myocardium (tunica media)
- Endocardium (tunica intima) - inner
Which layer of the heart wall contains the cardiac muscle tissue
The myocardium
What is endocardium composed of
- Special squamous epithelium called endothelium
- Elastic fibres
- Collagen fibres
What is myocardium responsible for (1)
Beating of the heart
Describe the blood flow through the pulmonary circuit
- Blood flows from the right side of the heart (deoxygenated)
- Blood flows to the lungs to become oxygenated
- Blood flows to the heart
Describe the blood flow through the systemic circuit
- Blood flows from the left side of the heart (oxygenated)
- Blood flows to the head & rest of body
- Blood flows back to the right side of the heart (deoxygenated)
Why do arteries have smaller lumens than veins
To maintain the pressure of blood flow
What are the 3 layers of both arteries & veins
- Tunica externa - outer
- Tunica media - middle
- Tunica intima - inner
Main characteristic of elastic arteries
40-70 fenestrated elastic membranes in tunica media (need for artery wall to be able to stretch)
Main characteristic of muscular arteries
- Thick tunica media composed mostly of smooth muscle (up to 40 layers)
- Mostly smooth muscle = highly contractile
What are capillaries composed of
Endothelial cells
What are continuous capillaries
Capillaries that have no pores or fenestrae in their walls
What are fenestrated capillaries
Capillaries with pores in their walls that are covered by pore diaphragms
Where are fenestrated capillaries found (3)
- GI muscosa
- Endocrine glands
- Renal glomeruli
Why do veins have valves
Veins part of low pressure circulation so need valves to prevent backflow of blood
What are the walls & lumens of veins like compared to the walls & lumens of arteries
Veins have thinner walls and larger lumens than arteries
Main difference in structure between arteries & veins
The tunica media!!
* Tunica media of arteries are thick, mainly smooth muscle cells & elastic fibres
* Tunica media of veins are thin, mainly smooth muscle cells & collagen fibres (dont need to stretch much as in low pressure circulation)
