2153 IC3

what is blood pressure

The arterial pressure in the systemic circulation between the aortic valve and the arterioles

• reference to the ARTERIAL system

why is blood presssure important

ensures efficient and fast circulation of blood and sufficient exchange of fluids at the capillaries to meet metabolic requirements of tissues

what are the 2 forces required at the capillaries

for good perfusion (rate of flow of blood through tissue):

1. hydrostatic pressure

   1. needs high enough presssure for blood to exit from capillaries to nearby tissues so pressure in capillaires » tissues

   2. pressure comes from arterial pressure of BP

2. osmotic pressure

   1. dependent on the proteins present; more proteins present in blood due to albumin than the tissues

• Arteriole end: hydrostatic pressure > osmotic pressure : encourages filtration out of the capillary

• Venous end: osmotic pressure > hydrostatic pressure : encourages reabsorption back, pull fluid back from interstitial to capillary

• net filtration pressure is higher at arteriolar end than venous end = more fluid filtered out than reabsorbed back in

what are some causes of edema

1. insuficient albumin in the blood : need albumin for osmotic pressure so that fluid returns back. if insufficient e.g. not eating enough, leaking kidneys, fluid cant return back to circulation

how is high pressure generated

1. heart pumps at great force

2. valves in the heart for directional flow and allows generation of pressure to stay intact

   1. arterial valve for pressure maintenance in arterial system by closing off the aorta and arteries from the ventricle. mitral valve prevents backflow from ventricle to aorta which allows pressure to be generated within the ventricle

3. circulatory system maintains high pressure in the arteries

   1. thick walls, low resistance in the arteries —> allows pressure to be maintained and rapid blood flow

   2. arterioles at the end of arteries have high resistance - like a stopper!

can you explain systolic and diastolic pressure

systolic

• heart contracts

• AV open

what is mean arterial pressure (blood pressure)

cardiac output x total peripheral resistance

7 phases of the cardiac cycle

1. Atrial Contraction: Atria contract, pushing blood into the ventricles.

2. Isovolumetric Contraction: Ventricles contract, increasing pressure but no blood is ejected yet.

3. Ventricular Ejection: Ventricles contract further, forcing blood into the arteries.

4. Isovolumetric Relaxation: Ventricles relax, but no blood enters yet.

5. Rapid Ventricular Filling: Blood rapidly fills the ventricles.

6. Reduced Ventricular Filling: Remaining blood enters the ventricles.

7. Atrial Relaxation: Atria relax, preparing for the next cycle.