Biology Unit 4.1.1- Communication

Ectotherms- organisms that rely on external sources of heat to regulate its own body temperature
1. need to maintain body temperature- structures of protein need certain temperatures. if not kept close to optimum, it affects the ability of functioning in a cell
2. Advantages...
  1. less food needed for respiration
  2. survive long periods without eating
  3. energy obtained used fro growth
3. Disadvantages...
  1. less active in cooler climates- risk of predatation
  2. not active through winter, therefore need sufficient food supplies to survive winter
4. Temperature regulations
  1. when cold- change in behaviour or physiology to increase heat absorption from environment
  2. when hot- change in behaviour or physiology to decrease heat absorption from environment
5. examples
  1. expose body sun, increased heat absorption
    1. snake
  2. orientate body to sun- increased SA, therefore, more heat absorption
    1. locusts
  3. orientate body away from sun- decreased SA, therefore less heat absorption
    1. locusts
  4. burrow- decreased heat absorption
    1. lizards
  5. alter body shape- increase or decrease SA towards sun
    1. Horned Lizards
  6. increase breathing movements- increases water evaporation
    1. locusts
The need for communication
1. Keeping cells active
  1. Enzymes have a specific set of conditions to work effectively
    1. Temperature
    2. pH
    3. aqueous conditions
    4. toxin free
2. Stimulus and Response
  1. stimulus- any change in the environment that causes a response
  2. Response- a change in behaviour/physiology as a result of change in the environment
  3. 1. External environments- consists of air, water, soil. stimuli is the change in the evironment, response is change in the species behaviour or physiology
  4. 2. Internal environments- activities of cell metabolism alters own environment because toxins may be produced and this affects the pH
  5. 3. maintenance of internal environments- toxins enter blood from TF and are carried away. toxins and wasted are then excreted
3. coordination/ good and bad communication systems
  1. cover whole body
  2. enable cell communication
  3. short and long term responses
  4. enable specific and rapid communication
4. cell signaling- neuronal and hormonal
  1. neuronal- rapid response, short term, nerves and synapses.
  2. hormonal- slower, long term, endocrine release signals and carried in blood
Homeostasis, negative feedback and positive feedback
1. Homeostasis- maintenance of internal environments at a constant state despite external changes
  1. Temperature
  2. blood glucose
  3. blood salts
  4. water potential
  5. blood pressure
  6. co2 concentration
2. Negative feedback- process that brings about a reversal of any change in conditions. ensures that an optimum is at a steady state.
  1. stimulus->receptors->communication pathway->effector->response
  2. structures required fro pathway
    1. sensory receptors- temperature and glucose receptors
    2. communication system- hormonal and neuronal
    3. effector cells- liver, muscles
3. Positive feedback- the process that increases any change detected by receptors. could be harmful and doesnt lead to homeostasis
  1. temperature could get too low or high, denaturing or stunning enzymes
  2. BUT, there are positives- release of oxytocin during labour to dilate cervix so baby can be born,
  3. constant- there is always some variation around the optimum but its acceptable as long as its not a significant value
Endotherm- organisms that can use internal sources of heat- chemical reactions are exergonic
1. Advantages...
  1. constant body temperature
  2. active even when cooler (night)
  3. inhabit in colder parts
2. disadvantages...
  1. food/energy needed for maintenance of temp
  2. less food used for growth
3. Physiological temp regulations (for hot, opposite for cold)
  1. Sweat glands (skin)- increased sweat, increased evaporation, using heat from blood to supply latent heat of vaporisation
  2. lungs, mouth, nose- increased panting, therefore evaporation (latent heat)
  3. Hairs on skin- lay flat, less insulation, heat lost.
  4. arterioles (skin)- vasodilation- more blood near surfaces
  5. liver clells- less metabolism, therefore less exergonic heat
  6. skeletal muscles- no random contractions
4. behavioural temp regulations
  1. move into shade
  2. decrease SA exposed to sun
  3. remain inactive, spread limbs out

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Biology Unit 4.1.1- Communication

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	Created by Sarah Pirbhai almost 11 years ago