Intro to Medical sciences and Homeostasis 1 Flashcards
Homeostasis 1
How is the body organised?
Body = a complex society of cells structurally and functionally organised into tissues, organs and systems.
Define tissues
Groups of cells that share the same characteristics or specialisations.
Define organs
Collections of tissues, usually of serval different types, that synchronise to perform a particular function.
What is the equation of life?
Nutrients + O2 = Energy (ATP) + waste (incl. CO2)
Define homeostasis
Similar conditions - body trying to monitor internal state and respond to any disruptions in a constant effort to maintain optimum “similar condition” - a relatively constant internal environment in which all processes work optimally - this is physiology!
How is optimal internal environment maintained by organ systems?
Fundamental life processes of all cells require maintenance of a constant internal environment - involves cooperative action of organ systems, coordinated by nervous system and endocrine system (hormones).
What are common everyday challenges to our internal environment?
- External temp
- Diet
- Exercise
(all impact on body fluid composition, energy stores and body temp etc and physiological mechanisms must act to counteract these potential threats to homeostasis )
What are the mechanisms to maintain homeostasis?
- Negative Feedback (most important)
- Feedforward
- Positive Feedback
Describe negative feedback
Homeostatically regulated condition (eg body temp) shifts from normal range - signal (usually nervous or endocrine) generated - produces a response (eg shivering or sweating) that corrects the original disturbance & brings the regulated condition back within normal range.
‘negative’ feedback - condition that triggered homeostatic response becomes switched off/ removed by that response.
Size of response = (proportional) size of disturbance
What are the characteristics of negative feedback systems?
- There’s oscillation around the set point
2. Restores the regulated condition after its initial disturbance, but cant prevent it from happening.
Explain feed forward systems
Additional receptors permit system to anticipate change and therefore activate response earlier.
eg. temp receptors in our skin detect external temp and activate response (drive to go find a coat) before any significant change in core temp can occur.
Explain positive feedback mechanisms
Opposite effect to -ve!
-ve = aims to restore disturbed conditions to optimum.
+ve = sets off a train of events that leads to an even greater disturbance.
= leads to instability and are more common in pathophysiology, rare in normal physiology., but they do occur eg, in the neve action potential, in ovulation and sexual behaviour.
