24.3: Blood pressure and exchange in capillaries

Systolic Blood Pressure

The highest pressure during ventricular contraction.

Diastolic Blood Pressure

The lowest pressure during ventricular relaxation.

Alveoli

Small air sacs in the lungs where gas exchange occurs.

Blood Osmotic Pressure

The osmotic pressure generated by large proteins in the blood plasma that draws fluid back into capillaries

Blood Hydrostatic Pressure

the pressure exerted by blood within blood vessels which drives fluid out of the capillaries into the surrounding tissues.

Filtration

The movement of water and solutes from capillaries into the interstitial fluid when blood hydrostatic pressure is greater than osmotic pressure.

Reabsorption

The movement of water back into capillaries from the interstitial fluid by osmosis when osmotic pressure is greater than blood hydrostatic pressure.

Starling's Forces

Two opposing forces (solute/blood osmotic potential and pressure/blood hydrostatic pressure) that control water movement across capillaries.

partial pressure of respiratory gases

incoming blood to lung has lower partial pressure of O2 than alveoli = O2 diffuses into blood. Whereas incoming blood has higher partial pressure of CO2 = CO2 diffuses from blood to alveoli