Homeostasis - Foundations 1.2 08/10/17 Flashcards
What are 5 examples of homeostasis in the body?
- Body temperature
- Blood volume
- Body weight
- Blood O2 levels
- pH
Definition of homeostasis
The body’s ability to maintain a relatively stable, constant condition in its internal environment
Definition of equilibrium
No net change over time. Competing influences produce no net change.
Definition of steady state
Supplied energy that keeps an individual system in its own balance (equilibrium) despite possibly being is non-equilibrium conditions w/ its environment
Equation that relates steady state, equilibrium, and body temperature
Heat Production + Heat Gain = Heat Loss
Definition of physiological gradients
A change w/ respect to distance of something that can be measured (think graph and axes)
What 3 things do physiological gradients, in part, determine?
- Thermal energy
- Rate of movement of fluid
- Ions and molecules
Define pressure gradient
Pressure difference along a specified distance
Body temp equation
Gradient = Ts - Ta /X
Body temp equation in regards to thermal flux (Jt)
Jt = K(Ts - Ta)/X
Blood pressure equation
Gradient = (P1 - P2)/X
Gas gradient equation
Gradient = (PaO2 - PcO2)/X
Are intracellular, interstitial, and blood osmotic pressures normally the same?
Yes; at 300 mOsm (milliosmoles)
Hypertonic
Higher osmotic pressure
Hypotonic
Lower osmotic pressure
What does dehydration cause?
An increase in blood osmolarity, which causes the interstitial to shrink and become hypertonic relative to cells
What is blood osmolality?
Ions, carbs, sugars, etc
Define negative feedback
A response the body produces to allow the body to get back to its normal, set point
Is negative feedback bidirectional?
Yes; meaning anything that goes below or above a set point for that process can activate negative feedback
What are the negative feedback system components?
- Controlled variable (BP, temp)
- Feedback sensor (monitors controlled variable level)
- Controller/comparator (controlled variable and set point compared, error signal determined)
- Activator (physiological response to reduce deviation from set point)
What are 5 examples of negative feedback control?
- Body temperature
- Blood pressure
- Blood gases
- Muscle movement
- Thyroxin hormone
Is arterial pressure under autonomic control?
Yes
What increases arterial pressure?
Constriction of blood vessels
Which nervous system stimulates the heart to constrict blood vessels?
Sympathetic
Baroreceptor
Receptor that is sensitive to pressure (carotid)
Chemoreceptors
Measure gas in the blood (arterial and medullary)
Hypercapnea
High PCO2
Muscle spindles
Muscle stretch receptors
Positive feedback
A process by which deviation from the set point tends to promote even further deviation
Cardiac Ischemia
Damage or disease in heart’s major blood vessels
Feedforward Mechanism
Controlled regulation for anticipation of a predicted outcome
