NA. 5.1 Communication & Homeostasis Flashcards
Which condition need to be limited for cells to function
- temperature
- PH
- an aqueous enviroment
- Freedom from toxins & excess inhibitors
What is a stimulus?
an environmental change
What is a response?
a change in an organisms behaviour or physiology in reaction to the stimulus
What is cell signalling?
The way in which cells communicate with each other
What are 2 major communication systems?
- Neuronal(consisting of brain CNS and nerves)
* Hormonal (consisting of blood and glands)
Why do multicellular organisms need communication systems?
- To respond when their internal & external environment changes.
- To coordinate organ function.
What are the features of a Good communication system?
- cover the whole body
- enables Rapid communication
- enables Specific communication
- Brings about both short & long term responses
what is the Homeostasis mechanism
Stimulus →Receptor → Communication Pathway →Effector →Response
Define negative and positive feedback
Negative feedback: self-regulatory mechanisms return internal environment to optimum when there is a fluctuation.
Positive feedback: a fluctuation triggers changes that results in an even greater deviation from the normal level.
What is an ectotherm?
Relies on external sources to regulate its body temperature. Responds to temperature changes behaviourally
e.g; snakes, lizards, most insects
How might ectotherms control their body temp
• Moving in or out of a sunny area
thus increasing or decreasing surface area exposed to sun
• Lie on a warm surface (if cold)
• Burrowing underground (if hot)
what are some advantages of ectothermy?
• More energy used on growth
• Less food used in respiration
∴they need less food
∴ can survive longer without food
What are some disadvantages of ectothermy?
• they are less active in cool temperatures
∴ more vulnerable to predators
∴ cant take advantage of available food if they’re too cold
Outline behavioural methods endotherms use to regulate their body temperature.
• panting (heat lost as water evaporates from mouth)
• Being more or less active (movement generates
heat in muscles, limbs lose heat )
• Hibernation
• Moving in or out of a sunny area thus increasing or decreasing surface area exposed to sun
Outline Behavioural methods endotherms use to regulate their body temperature.
- panting (heat lost as water evaporates from mouth)
- Being more or less active (movement generates heat in muscles, limbs lose heat )
- Hibernation
- Moving in or out of a sunny area thus increasing or decreasing surface area exposed to sun
