Homeostasis Flashcards
What is homeostasis?
Maintenance of a constant and ‘normal’ internal environment.
How does homeostasis work at steady state exercise?
Balance between demands placed on body and the body’s response to those demands (e.g., HR, body temp, arterial BP)
How does homeostasis work in terms of blood pressure?
Arterial BP may oscillate over time, however mean pressure remains constant due to baroreceptor responses and kidney function.
What is a biological control system?
Series of interconnected components that maintain a physical or chemical parameter at a near constant value.
What are the components of a biological control system?
- sensory/receptor
- control centre
- effector
What is negative feedback?
Response reverses the initial disturbance in homeostasis.
E.g., respiratory system’s control of CO2 conc in extracellular fluid
What is positive feedback?
Biological response increases the original stimulus.
E.g., childbirth
Define ‘Adaptation’
Change in structure and function of cell or organ tissue (=improved ability to maintain homeostasis)
Define ‘Acclimation’
Adaptation to environmental stresses (heat or hypoxic stress)
What is hormesis?
Process in which a low-to-moderate dose of a potentially harmful stress (for
example, chemical agent or environmental stress) results in a beneficial adaptive response on the cell or organ system.
What is cell signalling?
Communication between cells using chemical messengers, coordinating cellular activity. Important for maintenance of homeostasis.
What are the 5 different cell signalling pathways?
- intracrine signalling (CM inside cell triggers response)
- juxtacrine signalling (CM passed between 2 connected cells)
- autocrine signalling (CM acts on that same cell)
- paracrine signalling (CMs act on nearby cells)
- endocrine signalling (CMs (hormones) released into blood)
How is heat distributed in an individual exposed to cold conditions?
Heat is preserved and periphery of the body is relatively cold.
How is heat distributed in an individual exposed to hot conditions?
Heat needs to be lost from the body so heat is distributed to the periphery through blood flow.
What is a feedforward loop?
Physiological response in anticipation of a change in a variable. E.g., increase in HR prior to running a race.
