Communication And Homeostasis Flashcards
What is homeostasis?
The maintenance of a constant internal environment, regardless of fluctuations in the external environment.
What is a receptor?
A cell/protein on a cell surface that detects a specific stimulus.
What is a stimulus?
Change in internal/external environment.
What is an effector?
Cell that brings about change/response to a stimulus.
What is a response?
Any behaviour/ psychological change in an organism due to a stimulus.
What happens when plants and animals detect changes in internal/external environment?
- Increases chance of survival and reproduction to pass on alleles.
- Animals can keep internal conditions optimum for metabolic reactions.
When do enzyme controlled reactions occur and what is maintained?
- Can only occur if the conditions are at a steady state/right.
- Cells need to communicate to monitor and respond to changes that are away from the steady state.
- “dynamic equilibrium” is maintained (conditions close to optimum) e.g. temp, blood glucose conc, pH.
How do nerves carry out cell signalling?
- When changes in stumuli are detected, nerve impulses pass along sensory neurones to brain, the along motor neurones to effector which respond.
- Nerve cells communicate using NT’s across synapses.
How do hormones carry out cell signalling?
- Chemical messengers released from cells in one part of the body -> travel to target cells in another part VIA THE BLOODSTREAM.
- Cell surface receptors (proteins) have complimentary shapes to hormone -> so specific hormones affect specific cells.
What is negative feedback?
When a change in something brings about a series of events which act to reverse the change, maintaining a normal set point.
Process of negative feedback.
- Stimulus produces change in variable.
- Change detected by sensory receptor.
- Info sent to control centre (brain and hypothalamus).
- Info sent to effector.
- Effector brings about the response, returning/maintaining normal set point.
What is positive feedback?
Amplifies a change away from the normal set point, e.g. blood clotting.
What is thermoregulation?
- Regulation of constant internal core body temp (e.g. head, thorax, vital organs).
- Determined by heating and cooling balance.
Direct and reflected radiation from sun.
- causes water to evaporate off skin.
- Metabolic heat is generated from internal reactions (e.g. cell respiration) - ATP for muscle contraction = inc heat
