foundations of human physiology

Hypotonic

Cell swells water entered cell

Isotonic

No change in cell no movement of water

Isotonic

No change in cell no movement of water

Intracellular fluid (ICF)

Liquid inside cells, 2/3 of total water high K+, Mg2+, phosphate and proteins

Intracellular fluid (ICF)

Liquid inside cells, 2/3 of total water high K+, Mg2+, phosphate and proteins

Plasma

Fluid portion of blood type of ECF

Interstitial fluid

Fluid surrounding cells type of ECF

Transcellular fluid

Specialised fluids such as cerebrospinal and synovial fluid type of ECF

Osmosis

Water moves from low to high concentration of solutes across cell membrane

Tonicity

Describes how a solution effects cell volume (isotonic, hypotonic and hypertonic)

Sodium and cell volume

Changes in extracellular sodium levels cause water to move in and out of cells

Buffers

Help prevent rapid change in pH by binding or releasing hydrogen ions. Major physiological buffers include bicarbonate, proteins and phosphate

Lungs and kidneys regulation

These organs provide longer term control of acid based balance. The lungs regulate CO2 kidneys regulate hydrogen and bicarbonate

Homeostasis

The body maintains physiological variables such as temperature pH and fluid balance to allow cells to function normally

Negative feedback

Main mechanism of homeostasis it opposes a change and brings variable back to normal range.

E.g. temp rises → sweating increases→ temp falling

Positive feedback

Amplifies a change until a specific end point is reached.

e.g. during child birth uterine contractions stimulate oxytocin release → increase in contractions until delivery