Homeostasis 1&2 Flashcards
(54 cards)
Homeostasis
Property of a system in which a variable is actively regulated to remain very nearly constant
Tissues
Group of cells sharing same characteristics or specialisations
Organs
Collections of tissues, usually several types, synchronised to perform a function
Literal meaning of homeostasis
Homeo = similar stasis = condition
The 2 systems which co-ordinate and control all of the systems
Nervous and endocrine
Physiology
Study of how the body works normally - optimum conditions with body constantly monitoring internal state and responding to disruption
3 Common challenges to internal environment
Diet, exercise and temperature
These 3 factors of challenges to internal environment impact on what 3 things
- Bodily fluid composition
- Energy stores
- Body temperature
At extremes does homeostasis become more or less effective?
Less
Describe the mechanism of negative feedback control
- Magnitude of change in monitored variable
- Sensed by receptor
- Compared to reference level in integrating centre
- Signal to effector to generate response
Is the magnitude of generated signal and response smaller than, proportional to or greater than the magnitude of difference from normal?
Proportional to
Can negative feedback prevent the change
No can only correct after the system has been displaced
Negative feedback: self amplifying or self limiting?
Self limiting
Homeotherm
Maintain constant core temperature over a wide range of external temperatures
Feed forward have what additional feature?
Additional receptors to detect and anticipate change earlier eg temperature receptors in skin
Positive feedback: self amplifying or self limiting?
Self amplifying
Is positive feedback common in normal health or pathology?
Pathology eg diabetes mellitus and cancer
Give 2 examples of positive feedback in normal health
Nerve action potential and ovulation and sexual behaviour
Hyperglycaemia
Associated with diabetes and includes neural dysfunction, blindness, kidney damage and electrolyte disturbances
Homeostatic mechanisms represented by reflexes - name the 2 types these reflexes can be
Neural and/or hormonal
Simple or complex
Give 4 examples that homeostasis can control
- O2 and CO2 levels
- Water and ion balance
- Blood pressure and blood volume
- Nutrient levels
How much in percentage does water make up of the human body?
About 60%
Describe how the output and input mechanism is controlled in humans
Input = thirst mechanism output = urinary losses
Extra cellular fluid includes
Plasma and interstitial fluid
