homeostasis and water Flashcards
what are the 4 types of cell groups in the body
Nerve
Muscle (smooth and skeletal)
Epithelial
Connective
define homeostasis
the dynamic equilibrium of which reacts to external pressure to maintain a constant internal environment. This is achieved through negative feedback loops of which have three major components, the sensor (nerves), the hypothalamus of which initiates the counteractive change and finally the change/ action.
define resting membrane potentail
determined by the separation of opposite charges across a plasma membrane, this is due to the distribution of key ions (K+ and Na+) when the two sides of the membrane are equal there is no potential.
define passive transport
Does not require energy as substances move down the gradient. (simple diffusion or facilitated diffusion through chanells and permease)
define active transport
Require energy (ATP) as substance is transported up the gradient
define osmosis
The diffusion of water through a selectively permeable membrane is a passive transport.
The water molecule moves from the high concentration of water to the lower concentration of water. The water moves to where there is the most solute as there is less water there.
define Net diffusion
the difference of molecules moving from side to side
Fisk’s first law of diffusion
States that molecules, if possible, will move from the higher gradient into the lower gradient. The rate of diffusion is dependent on the magnitude of the concentration gradient, permeability of the membrane. Other factors include temperature, distance travelled and molecular weight of the substance.
define tonisity
qualitative way of determining the solutions effect on cells, (neutral - isotonic , swelling - hypotonic or shrinking - hypertonic)
define osmolarity
Osmolarity is the concentration of all solutes in a solution by volume. It is quantified with an osmometer (solvent/volume).
Isosmotic = cell = volume.
Hyposmotic = solution < cell and
Hyperosmotic = solution > cell
what is the diffrence between osmolarity and tonicity
osmolairy is a quantative observation and toncicity is a qualatative value. however they both relate to the same thing (concentration of solute).
describe the body fluid distribution of water
33% of water is extracellular
- within that group 25% of that is plasma
67% of water contributes to intracellular fluid.
How much of body weight is water?
60 %
what are the 4 basic principle of fluid regulation
Homeostatic mechanisms respond to changes in ECF, not ICF
Receptors monitor plasma volume and osmotic concentration
All H2O movement is passive
Body’s H2O or electrolyte content will rise if dietary gains exceed losses to environment
3 inter-related processes of fluid regulation
Fluid balance (volume) affects circulatory pressure (Mean Arterial Pressure, MAP)
Electrolyte balance (or osmotic balance)
Acid-base balance H+ ions (H3O+), due to water being in the equilibrium: 2H2O = H3O+ + OH-
