Homeostasis Flashcards
Homeostasis
- Same/steady state achieved by a give and take process that uses the systems of the body to maintain a constant env’t for the cells
- The internal milieu of the cells is the ECF
- So homeostasis means Keeping the ECF fairly constant
Does homeostasis mean keeping the body at a steady/same HR or RR?
No. Cells have parameters that need to be met to live/be healthy. As demands on the body change (illness, stress, exercise, sleep, etc), HR and RR will change in order to maintain the correct gas exchange, blood flow that is necessary for the ECF steady state.
Fluid compartments of the body
1) . ICF - 28L, 40% of BW
2) . Interstitium - 20L, 20% of BW
3) . Plasma - 3L, 4% of BW
Which fluid compartment is directly regulated by homeostasis?
Plasma and Intersitium make up ECF
Molecules/Ions higher in ECF
Na+ Ca+ HCO3- Cl- Glucose Fatty acids
Molecules/Ions higher in ICF
K+ Mg+ Phosphate Proteins High Energy compounds - ATP
Where is osmotic pressure higher - ECF or ICF?
ECF - due to Donnan effect
Donnan effect
Albumin is a large protein that exerts pressure - holds fluid in the capillaries. It is impermeable by the cellular membrane. Albumin is charged. Therefore the neutrality must be maintained by also pulling in Na+. For every albumin, there are 18 Na+. This intensifies oncotic pressure.
What are the parts of the homeostatic mechanism or feedback loop?
There are five parts to the homeostatic feedback loop:
- Receptor
- Afferent pathway
- Control center
- Efferent
- Effector
A change in the stimulus is sent to the receptor, this will use an afferent pathway to send to control center. Then an efferent pathway is sent to an effector, and the effector carries out the response.
How would a feedback loop would regulate a physiological process by negative feedback and positive feedback.
A feedback loop is way to control some physiologic parameter. A change in that parameter exerts a stimulus on the system. That stimulus must sense the stimulus and communicate the intensity of the stimulus to a control center or integrating center. The control center evaluates the incoming stimulus information and determines if the physiologic parameter has departed from normal or from the setpoint. If an action is needed, the control center communicates this to an effector, a muscle or a gland. The effector produces a response to the stimulus. If the response opposes the stimulus and returns the system to setpoint, the system is a negative feedback loop. If the response reinforces the stimulus and adds an additional increase to the stimulus, the system is a positive feedback system.
Examples of negative feedback
Examples of parameters regulated by negative feedback include: BP, temp., H2O, oxyhemoglobin curve, baroreceptors, body fluids
Examples of positive feedback
labor, orgasm, action potential, lactation, blood clotting, hormonal changes leading to ovulation
Example of negative feedback becoming positive feedback
unmanaged congestive heart failure.
How does health and disease relate to homeostasis?
the ability to maintain homeostasis depends on the integrity of the physiologic system (age, gender, and genetics) the nature of the stress and situational factors (time and place). If homeostatic mechanisms cannot be maintained, disease results
what kind of conditions decrease the likelihood that homeostasis will be maintained?
pathogens and parasites, genetic disease, cancer, autoimmune disease, degenerative changes, trauma, toxins, environmental factors, nutritional deficiencies or excesses.
