Vascular Strcuture Flashcards
What is a capillary bed
A network of capillaries surrounding tissue
How are capillaries suited for exchanging materials between blood and body tissue
The tunica external and media are absent and the endothelial cells have small spaces between them. This allows exchange of material to and from the tissue
Function of a vein
Collect deoxygenated low pressure blood and return it to the heart
What is the size of a veins lumen
Large
Why do veins have large lumens
To offer the least resistance to prevent back flow of blood
How is blood flow increased to tissue
Vasodilation increases blood tissues
What effect does a drop of blood pressure have on the body
It stimulates baroreceptors in the aorta and carotid arteries
What is diastolic blood pressure
Lowest pressure exerted against the blood vessel walls which occurs in ventricular diastole
What is systolic blood pressure
Highest pressure exerted against the blood vessel walls which occurs during ventricular systole
3 ways that blood pressure can be altered
Vessel length
Diameter
Blood viscosity
What happens if the vessel is long in length
The longer = greater frictional resistance
How does vessel diameter affect blood pressure
Smaller the tube = greater frictional resistance
How does blood viscosity affect blood pressure
Higher the viscosity = greater resistance
3 layers of blood vessels
Tunica intima
Tunica media
Tunica externa
What happens to elastic arteries when ventricles contract
Semi lunar valves open and the force of blood stretches the elastic arteries
What happens to elastic arteries when ventricles relax
Blood moves down pressure gradient towards their heart and closes semilunar valves, the elastic forces recoiled into the periphery and the flow is constant
What determines the leakiness of capillaries
Amount of tight junctions
What is vascular tone
Refers to blood vessels being vasodilated or vasoconstricted
What is a muscle pump
When muscles contract, the veins also contract so blood is squeezed and the valves makes sure that blood only moves towards the heart
Blood flow is directly proportional to…
Pressure gradient - high to a low
Blood flow is inversely proportional to…
Resistance
What are baroreceptors
Primary sensory receptor found in the aortic arch
What effect does a stretched baroreceptors have
Increases impulse to cardiovascular centre of medulla oblongata
What two factors help control cardiac output
Heart rates and stroke volume
What factors effect how we control blood vessel diameter
Hormones - Adrenalin
Vasodilation/constriction (arteriolar)
What does blood pressure represent
The force added from the heart and the peripheral resistance provided by blood vessels
3ways to measure blood pressure
Mean arterial pressure
Systolic pressure
Diastolic pressure
What is hypotension
Low blood pressure, poor nutrition, pooling of blood in elderly
What is hypertension
High blood pressure due to increased peripheral resistance, obesity and smoking is the cause
