Unit 5 - Communication and Homeostasis Flashcards
The need for communication systems
Respond to changes in the internal and external environment
Coordinate the activities of different organs
How we respond to changes
Hormonal
Neuronal
Cell communication
Process by which a cell detects and responds to signals in its environment. It is the way in which cells interact w/ their environment and other cells around them
Properties of a good communication system
Covers entire body
Be v. spp in the communication
Rapid
Enable both long and short-term responses
Methods of cell signalling
Chemical or neuronal
Affecting distant or nearby cells
Types of cell signalling
Autocrine Gap Junction Synaptic Paracrine Endocrine Contact - dependent
Ending communication
Reuptake by cells
Broken down by neurotransmitters
Messenger removed from liver e.g. hormone
Response
A change in behaviour or physiology as a result of a change in the environment
Stimulus
Any change in the environment that causes a response
Effector
An organ or cell that acts in response to a stimulus
Receptors
An organ or cell able to detect and respond to environmental stimuli and transmit an impulse to a sensory nerve
Homeostasis
The maintenance of a constant or near constant internal environment within a narrow limit even though the environment’s changing
Homeostatic control and principle
Stimulus Receptor Communication pathway Effector Response
Negative feedback
Varying physiological value is returned to its mean value by the controlling mechanism
Positive feedback
Varying physiological value is pushed above its mean value by the controlling mechanism
Why should body temp be kept constant
To keep enzymes working at their optimum and so that they don’t denature at higher temps
Why should blood glucose conc. be kept constant
To supply sufficient glucose to tissues for respiration without decreasing the water potential of the blood too much
Contributes to oncotic pressure (forming tissue fluid)
Why should blood salt levels be kept constant
To maintain water potential and blood pressure
Why should the water potential of blood be kept constant
To maintain blood pressure and to ensure cells are in the correct conditions
Why should the blood pressure be kept constant
To ensure it is high enough to deliver blood efficiently but without damaging blood vessels
Why should the carbon dioxide levels be kept constant
CO2 reacts w/ water to form an acid - change in pH can alter protein structure and effect enzymes activity
Behavioural adaptations of ectotherms when its too hot
Finding shade
Reduce contact/decrease SA exposed to the sun
Burrow underground
Behavioural adaptations of ectotherms when its too cold
Basking in the sun
Finding a hot surface to lie on
Increase SA exposed to sun
Adaptations of endotherms when its too hot
Sweat Vasodilation Hairs and feathers lie down Panting Decrease respiration rate No shivering
