Communication and Homeostasis 5.1 Flashcards
What is the need for communication systems in
multicellular organisms?
To coordinate the different organs in the body and maintain homeostasis by responding to changes in the internal and external environment
Why do we maintain a constant internal environment?
- to give enzymes optimum conditions
(temp, PH, aqueous environment and freedom from toxins)
What are the features of a good communication system?
- to cover the whole body
- enable specific communication
- enable rapid communication
- enable cells to communicate with eachother
- enable short and long term responses
What is cell signalling?
The way in which cells communicate with each other
What are the two ways that cells can communicate with eachother?
- homronal communication
- neuronal communication
What are the characteristics of nuronal communication?
- uses neurones to carry messages
- short lasting
- uses electrical impulses
- quick response
- synapses
What are characteristics of hormonal communication?
- uses blood to carry messages
- long lasting
- uses chemicals
- slow response
- target cells
What is homeostasis?
The act of maintaining a constant internal environment around an optimum despite external change
What are things that have to be maintained at a constant level?
- body temp
- blood glucose conc.
- water potential in blood
- blood salt conc.
- CO2 conc.
- blood PH
How does homeostasis work?
- receptors detect a change
- stimulates effectors to cause a response
- response counteracts the change
(negative feedback)
What is an effector?
Organ tissue or cell that produces a response to a stimulus
What is a sensory receptor?
Sensory nerve endings that respond to a stimulus in the internal or external environment and can create an action potential
What is a positive feedback?
A process which causes an increase in change to take the system further away from the optimum
What is negative feedback?
A process that counteracts change to bring the system back to the optimum
What is an ectotherm?
A type of organism which depends on its ebvironment to maintain body temperature
What are behavioural ways to regulate body temperature for ectotherms?
- seek the sun
- seek the shade
- seek cooler water
- brumination
- estivation
- spread limbs out
- open mouth and pant
- turn body sideways towards sun
What are physiological ways to regulate body temperature for ectotherms?
- change colour (pale grey or black)
- increase or decrease heart rate
What is an endotherm?
A type of organism that uses metabolic processes to warm up and maintain a constant core temperature without using external sources
What are behavioural ways to regulate body temperature for endotherms?
- drink water
- move into shade
- find cool water
- remain inactive
- move into sunlight
- move around more
- increase SA exposed to sun
What are physiological ways to regulate body temperature for endotherms?
- sweating
- vasodilation, vasoconstriction
- decrease or increase metabolic rate
- panting
- hairs lie flat
- no spontaneous contraction
- shivering
- piloerection
- release of adrenaline and thyroxine
- less sweating
How can temperature change be detected in endotherms?
- peripheral temp receptors in the skin detect changes in the extremities and send the information to the thermoregulatory centre in the hypothalamus
- temp receptors in the hypothalamus detect the change
What happens when the hypothalamus is informed about a temperature change?
It sends out impulses to cause different responses to reverse the change
