Unit 1 - Homeostasis Flashcards
definition of homeostasis:
the mechanisms used to maintain the parameters of internal environment under conditions of dynamic equilibrium
def of internal changes
are changes that we can control so you need water → trigger you to become more thirsty so you drink water
def of external changes:
you go outside and it is cold → triggers arm hairs to go up to try and keep you warm
ways of measuring homeostasis:
Establish values and use homeostatic ranges
Ex. glucose in blood → normal range is 75-96. This is because a normal value will never been accurate but a range is more accurate
purpose of regulatory mechanisms:
How our body compensates the changes of homeostasis
types of regulatory mechanisms:
Local mechanisms: responses mediated by the cells at the site of the dysregulation
Long distance mechanisms: responses mediated by control centers that involves a general response
Components of a long distance reflex pathway: - 9
- input singal: needs to be received by a receptor. They are changes in a parameter (temperature, pressure, pH) that initiate the mechanism
- Sensor or receptor: is the sensing components and monitors and responds to the changes
- Threshold: the amount of stimulus change necessary to initiate the mechanism. If a stimulus is below the threshold, no response loop is initiated
- Afferent pathway: connects the receptor with the control center
- Nervous system: afferent neurons
- Endocrine system: the endocrine cell acts as both receptor and control center - Integrating center: processes the input signal, compares it with the homeostatic range and provides a response
- Efferent pathway: connects the control center to the effector through a chemical messenger (hormone) or a motor nerve
- Target: cell or tissue responsible for bringing about the normal state
- Response:
- Cell response: specific responses on target cells
- Systemic response: consequences for the body derived from the cell response - Feedback loops: going back to normal
positive feedback loops: - 4
- Not many examples
- Physiological but not homeostatic
- The response magnifies or reinforces the initial stimulus, and an outside factor is required to shut off the cycle
- Example: giving birth
negative feedback loops: - 3
- They are homeostatic, thus they are present most reflex pathways
- The response opposes the initial stimulus, shutting off the response loop
- They stabilize the variable and maintain it within the homeostatic range
Nervous system vs endocrine system:
types of fluid in the body: - 3
- Intracellular (ICF)
* Fluid inside each cell (cytoplasm) - Extracellular ECF
* Fluid surrounding the cells
* Subdivisions:- Internal fluid (IF) non (circulating )
- Plasma and lymph (circulation)
- Transcellular
* Synovial fluid in joints, fluid, pericardial fluid, intraocular fluid and CFS
* Always filled with fluid either intracellular and extracellular
extracellular and intracellular fluid main component
Extracellular fluid main component: Sodium: Na+
Intracellular fluid main component: potassium: K+
Although the molecules are different the final concentracion should be the same so that extracellular and intracellular compartments are isosmotic → having the same or equal osmotic pressure
electrical neutrality:
Neutral net charge within each compartment (same amount of positive and negative charge in outside and inside of cells) but electrical disequilibrium among them
three mechanisms that cooperate to keep a normal pH range of plasma:
Normal pH range of plasma is 7.38-7.42
- Buffers (bicarbonate)
- Ventilation (lungs)
- Kidneys
when does pH changes occur
under physiological circumstances (exercise) or pathological states (alkalosis, acidosis)
