9. Homeostasis and Control Systems Flashcards
Define homeostasis
A situation in which active control minimise intra or extracellular change in the face of a changing external environment
What are the different types of control?
Control of extracellular environment and control of intracellular environment
What is negative feedback?
Any deviation of the controlled variable away from the normal value results in repsonses which reduce that deviation
Why would negative feedback be deliberately introduced?
To inr
Why would negative feedback be deliberately introduced?
To inrease the stability and accuracy of a system by correcting or reducing the influence of unwanted changes
What are the three components of a homeostatic control system?
Detectors
Comparator
Effectors
What does a negative feedback loop do?
One that tends to slow down a process
What does a positive feedback loop do?
Tends to accelerate a process
What are examples of feedback in biology?
Thermoregulation Insulin oscillations Operations of genes Repressor and activator proteins Hormones Enzymes
What is the controlled variable for contractions and what happens?
Controlled variable- Oxytocine
Control at organ level (uterus)
Positive feedback loop continues until the baby is born
What is the controlled variable for thermoregulation and what happens?
Core temperature
Control at whole body level
Stable overa large external temperature range
What is the controlled variable for thermoregulation and what happens?
Core temperature
Control at whole body level
Stable over a large external temperature range
What are the detectors for the thermoregulation?
Thermreceptors
Central and peripheral
What is the afferent path for thermoregulation?
Sensory nerves
What is the comparator for thermoregulation?
Hypothalmus
What is the efferent path for thermoregulation?
efferent nerves
How do effectors increase heat production ?
Increased skeletal muscle tone and shivering
Behavioural responses- relies on cognitive function and conscious activation of somatic nerves
Metabolic activity in brown fat
How do effectors reduced heat loss?
Peripheral vasoconstriction
Piloerection in sympathetic nerves
Behavioural responses
How is heat loss increased ?
Sweating through the sympathetic nerves
Peripheral vasodilation
Behavioural responses
What is pyrexia?
Elevation of core temperature
Typically associated with infection
Results from abnormal “set point” in the hypothalmus
