Control systems and homeostasis Flashcards
(16 cards)
Name some of the things that need to regulated for optimal function?
O2 and CO2 tensions, so the partial pressures of these Blood pressure Concentrations of glucose Osmotic pressure Concentrations of important ions Temperature
What is homeostasis, define?
Maintenance of steady states in the body by coordinated physiologic mechanisms.
These mechanisms may decline over time or may not be fully developed at birth
What is a negative feedback loop and a positive feeback
A negative feedback loop works to eradicate the stimulus whilst a positive feedback loops works to continue the stimulus
In a closed system look what are the 3 main components?
A sensor, monitors/detects the current value of the variable
A control centre- stores the desired value of the variable and compares that with the sensory value
An effector - this changes the value of the variable to the value determined by the control centre
What type of control anticipates change?
Feedforward
Anticipatory motor impulses sent before movement to prepare the musculoskeletal system for postural adjustments in an open look system
Eg preparing the breathing rate, heart rate and strength of contraction before exercise has even occured.
An example of a positive feedback loop?
Sodium channels opening in an action potential
Smooth muscle activity increasing in parturition, during child birth
What is osmosis?
Movement of water from an area of high water (low solute) concentration to an area of low water (high solute) concentration. Osmosis tends to equalise the total solute concentrations of the solutions of both sides of the membrane,
What is osmotic pressure and osmolality of a solution dependent on?
Total number of particles dissolved in it. Osmolality is described as Osm/kg H20.
Water crosses plasma membranes rapidly via what? Why?
Aquaporins.
Partition coefficient of water into lipids is low and hence the permeability of the lipid bilayer is also low therefore specific proteins are needed.
What is tonicity?
Tonicity of a solution is determined by the volume response behaviour of living cells placed in that solution.
Which particles determine the solutions tonicity?
Do not pass across the membrane, the non penetrating proportion of the total solute concentration determines a solutions tonicity
What happens when the solution is hypotonic?
If the solution is hypotonic, the cell will swell.
The cell osmalility is higher than the solution meaning fewer water particles, so water particles from the solution will travel into the cell.
What is isotonic?
When the solution produces no permanent change in cell volume
what is facilitated diffusion?
Small ions diffuses across specific pores and ion channel proteins.
Water soluble solutesand ions through a hydrophillic pathway created by a membrane spanning integral protein
what does active transport involve?
Uses a metabolic energy source to move solutes against gradients
Simple diffusion is what?
Passage of lipid solutes across the plasma membrane by diffusion through the lipid bilayer
