L2: Homeostasis-maintaining physiological variables Flashcards
- Explain the underlying principles of physiological homeostasis, including the importance of negative feedback - Describe the role of the autonomic nervous system in physiological control - Describe the role of hormonal systems in physiological control - Describe the role of paracrine homeostatic signalling in physiological control - Describe feed-forward and positive feedback control mechanisms
What is physiological variable?
A measure of a bodily condition or bodily function
What is homeostasis?
The changing maintenance of physiological variables within a predictable range
What is negative feedback?
Change is sensed, response is initiated to reverse that change
Why is negative feedback important?
Control the body’s homeostasis
Why do we need homeostasis? Short term/long term effect?
Short term- Immediate survival
Long time- health & well-being
2 examples of physiological variables
Blood glucose concentration & blood pressure
What does positive feedback mean?
Change in a variable triggers a response to cause further change- amplified
What does a inter-dependent variable mean?
Variable that is closely connected & influenced by other variables within a system
What does feed-forward mean?
Anticipation of a change brings response to that change before it can be detected by negative feedback sensors
What does osmolality mean?
Concentration of particles dissolved in a fluid
Where are the neuronal integrating centres?
Midbrain or brain stem
Which nervous systems are there communication with effectors?
Sympathetic & parasympathetic nervous systems
What is fine-tuning?
Makes very small changes to something in order for it to work as well as possible
What are the 3 classes of hormones?
- Tyrosine derivatives
- Peptides, polypeptides, glycopeptides
- Steroids
Features of steroid hormones
Insoluble in water
What is the receptor location of steroids?
Intracellular: cytoplasm or nucleus
What is the receptor location of thyroid hormones?
Intracellular: cytoplasm or nucleus
What is the receptor location of peptides, glycoprotein?
Cell surface: plasma membrane
What is the mechanism of action of steroids & thyroid hormones?
Alter gene transcription slowly
What is the mechanism of action of peptides, glycoproteins?
Second messengers to change enzyme activity rapidly
What happens in the efferent pathway in the paracrine homeostatic control?
Involves secretion of diffusible substances from 1 group of cells to act on another group of cells nearby
What type of cells detect INCREASE in blood glucose concentration?
Beta cells
What type of cells detect a DECREASE in blood glucose concentration?
Alpha cells
