L11 Circulation 2 Flashcards
What is vasoconstriction and what is the result
The contraction of smooth muscle in the arterial walls
It increases blood pressure
What is vasodilation and what is the result
The relaxation of smooth muscles in arterial walls
It causes blood pressure to fall
What is systolic pressure
The pressure in the arteries during ventricular systole.
It is the highest pressure in the arteries
What is Diastolic pressure
The pressure in the arteries during diastole. It is lower than systolic pressure
What is a blood pressure for a healthy 20 yr old human at rest
120/70mmHg
What is a pulse
The rhythmic bulging of artery walls with each heartbeat
What is the function of veins
Transport blood from capillaries back to the heart
Act as storage reservoir for blood
How is blood returned to heart even though the blood pressure is low in the veins
One way valves in veins prevent backflow of blood
Return of blood is also enhanced by skeletal muscle contraction
Functions of arteries
Transport blood from heart to capillaries
Act as pressure reservoir
Dampen oscillations in pressure and flow
What is the function of arterioles
They control flow to the capillary beds
Features of capillaries
Smallest diameter blood vessels
Allows for diffusion of nutrients, waste etc
What are the 4 steps of the heart conduction system
1 Signsls from SA node spread through atria
2 Signals are delayed at AV node
3 Bundle branches pass signals to heart apex
4 Signals spread throughout ventricles
3 steps of the cardiac cycle
1 Atrial and ventricular diastole 0.4 sec
2 Atrial systole and ventriccular diastole 0.1 sec
3 Ventricular systole and atrial diastole 0.3 sec
What is systole
The contraction or pumping phase
What is diastole
The relaxation or filling phase
