The Vascular System Flashcards
Describe arteries:
Wide lumen
elastic wall
maintains pressure
Describe arterioles:
- Narrow lumen
- Contractile wall
- Controls resistance and pressure of blood by altering lumen size
Describe capillaries:
- Narrow lumen
- Thin walls
- Site of exchange of nutrient, oxygen and metabolic waste
Describe venues and veins:
- Wide lumen
- Compliant wall
- Low resistances
- Blood reservoir
- Valves to prevent back flow
There are 3 major types of capillaries; continuous,
fenestrated and sinusoidal. Which of the following best
describes fenestrated capillaries?
Select one: A. Located in the bone, liver and endocrine glands, very permeable allowing larger molecules such as plasma proteins between blood and interstitial space B. Located in specialist areas of the body, highly permeable, contains ‘windows’ allowing small peptides C. Located in most regions of the body, semi-permeable allowing H2O and small solutes
B
What are continues capillaries?
Supplies most of the body - allows small solutes and H2O to cross
What adaptions do continuous capillaries have?
Blood-brain barrier, whereby gap junctions between endothelial cells
prevent movement between the blood and interstitial space
What are fenestrated capillaries?
Contain pores – allows much greater movement between blood and
interstitial space; including that of small peptides
Where are fenestrated capillaries located?
Specialised areas
-Endocrine, intestines and glomerulus
What are sinusoidal capillaries?
Resemble fenestrated capillaries but more ‘pores’ allowing larger molecules such as plasm proteins to cross
Where are sinusoidal capillaries located?
Bone, liver and other endocrine organs
What are three different types of capillaries?
- Continuos capillaries
- Fenestrated capillaries
- Sinusoidal capillaries
What three factors determine how blood travels through blood vessels?
- Pressure
- Flow
- Resistance
What is pressure in relation to blood flow?
The driving force behind blood flow, generated by the heart. Blood flows
from high to low pressure regions
What is flow in relation it blood flow?
Volume per unit time (L/min; Q). Blood flow is determined by ΔP (starting point vs endpoint) and
resistance to flow
What is resistance in relation to blood flow?
An impediment to flow; high
resistance means a higher ΔP is needed to achieve the same flow
What is the equation for blood flow?
Change in pressure / resistance
What factors does resistance to blood flow depend on?
- Blood viscosity
- Vessel length
- Vessel radius
How does blood viscosity affect resistance to blood flow?
The thicker the blood, the higher the resistance to flow
How does vessel length affect resistance to blood flow?
The longer the vessel, the higher the resistance to flow
How does vessel radius affect resistance to blood flow?
The narrower a vessel is, the higher the resistance to flow
What is the equation for resistance?
(8 x blood viscosity x blood length) / ( π x vessel radius^4)
What is the function of the cardiovascular system?
Delivery of oxygen and nutrients to tissue and removal of waste products
What does the cardiovascular system consist of?
Pump (heart), pipes (blood vessels) and a carrier (blood)
Do we have a singular or double circulation is the cardiovascular system?
Double circulation
What is the double circulation in the cardiovascular system?
- Pulmonary circulation
- Systematic circulation
What is the pulmonary circulation?
Specialised circulation that is relatively short, simple and operates at a lower pressure than systematic circulation
Is there a difference in cardiac output in two circulations of the cardiovascular system?
No - equal
Is there a difference in resistance to flow in two circulations of the cardiovascular system?
Pulmonary - short
Systematic - high
Is there a difference in pressure in two circulations of the cardiovascular system?
Pulmonary - short
Systematic - high
What is the normal pressure in the pulmonary circulation?
25/10 mmHg
What is the normal pressure in the systematic circulation?
120/80 mmHg
What is the major determination of blood pressure and flow?
Resistance determined by radius of blood vessels
What does mmHg stand for?
millimeters mercury