Communication & Homeostasis Flashcards
Advantages of ectothermy
- do not use energy to keep warm
—> therefore less food used in respiration - more energy & nutrients from food can be used for growth
- can survive long without food
Advantages of endotherms
-Body temperature doesn’t fluctuate with external temperature, therefore can maintain constant temp
-Remain active even when external temperatures are low
-> can take advantage of available prey & escape
-> can live in colder parts of the world
behavioural endotherm responses if too cold
- move into the sun
- hot drink
- put more clothes on
Behavioural endotherm responses if too hot
- move out of sun
- drink cold water
- panting / gasps
- remove clothing
- lying on ground
Behavioural responses of ectotherms that are too cold
- move into the sun
- lie on surfaces
- increase body surface area exposed to sun
Behavioural responses of ectotherms that are too warm
- move out of the sun/ go underground
- reduce body surface area exposed to the sun
Body reactions if body / blood temperature too cold
- Hypothalamus heat centre stimulated
- Shivering
- Vasoconstriction
- Increased metabolic rate
- Piloerection of hairs
body responses if the body / blood temperature is too hot
heat loss centre in hypothalamus stimulated
- vasodilation
- decreased metabolic rate
- sweating
- flattening of hairs
Disadvantages of ectothermy
- less active in cooler temperatures
–> more at a risk of predators (as a result), as unable to escape - cannot take advantage of food available when cold
Do smaller or larger organisms have faster rates of respiration
Smaller organisms -> bigger SA:V -> faster heat loss -> faster rate of respiration
Excretory organs
Liver
Lungs
Kidneys
Skin
Feature of endotherm (ms)
Scales / hairs / fur to trap layer of heat
How could positive feedback increase hypothermia’s effects? (4)
- Lower temp = reduces molecule Ke
- Enzyme activity slows
- Respiration rate slows
- Loss of metabolic heat generated, so more heat lost
How does a negative feedback loop work
- Stimulus (change away from optimum conditions)
- Receptors (detect the change)
- Communication system (informs effector & change is signalled to other cells)
- Effector (brings about response which…
- reverses change of conditions
- causes a return to optimum conditions)
How does a positive feedback loop work
- Stimulus: Change away from optimum conditions
- Receptors: detect change
- Communication system: informs effector & change is signalled to other cells
- Effector: brings response to increase the change of conditions
How does cell signalling work (steps)
A cell releases a signal which is detected & responded to by other cells
(This is done as…)
- signal has specific shape which is complementary to the shape of that of the cell surface receptor
- binds to receptor
causes specific changes in the receptor
How does flattening of hairs occur
- Hair erector muscles react
- Hairs lie flat
- Prevents the hair forming an insulating layer of warm air between skin & hair, increasing heat loss
How does sweating occur
- Sweat glands secrete sweat to cool skin
- Heat energy from the body is lost as sweat evaporates from the skin: this heat energy is used to converted H2O (l) to (g)
How is metabolic rate decreased
- Less thyroxine released from the thyroid gland
- Decreased basal metabolic rate as a result
- So less heat released from metabolic reactions
How is metabolic rate increased
More thyroxine is released from the thyroid gland
Increased basal metabolic rate
So more heat released from exothermic metabolic reactions
Thermoregulation process (due to the hypothalamus)
- hypothalamus = thermoregulatory centre of the brain
- regulates body temperature by monitoring blood temperature & initiating responses if too long
- there are cold / warm receptors in the skin: stimulated as are those in the hypothalamus
-> response!
Toxic waste products excreted
Urea (by kidneys)
CO2 (by lungs)
Bile pigments (found in faeces)
Weaknesses of endothermy
- lots of energy used to maintain body temperature (especially in cold)
- needs more food
- may overheat in hot weather
- lower proportion of energy & nutrients from food used in growth
What are ectotherms
They rely on external heat sources to maintain their body temperature therefore, body temp fluctuates with external temp
What are endotherms
They can use heat from their own metabolic reactions to maintain their internal body temperatures within strict limits
-> these detect external temperatures by hot and cold peripheral receptors
What are features of a good communication
Enables cell to be in communication with each other
Cover the whole body
Enable short and long term responses
Enable specific & rapid communication
What are the two communication systems that work by cell signalling
Nervous System
(Neuronal communication: CNS & PNS. The nerve impulses passed along neurons to send info through the nervous system.)
Endocrine system
(Hormonal communication produces hormone)
They both co-ordinate and regulate body functions
What do communication systems do
Allow animals & plants to respond to changes in internal & external environments
What do effectors (/cell/tissues/organs) do
Bring about a response
What do endotherms do (not temp wise, HEAT wise:
Sometimes needed for ms
They GENERATE HEAT (energy) from metabolic processes / respiration
What do receptors do
Monitor and detect stimuli (changes to the environment)
What do to about aquatic ectotherms (e.g think of waters high SHC)
- water temp is way less variable that land due to waters high SHC
Therefore, it’s easier for these ectotherms to maintain a stable internal body temperature within strict limits
What does a negative feedback loop do
Reverses the effects of stimulus & brings the system back to optimum
What internal conditions are maintained by homeostasis
pH
Body temp
Blood pressure
Metabolic waste
Blood glucose / salt / O2 / CO2 conc
Water potential of the blood
What is a positive feedback loop
It increases the effect of the stimulus and brings the system further away from optimum
What is a response
How an organism changes its behaviour / physiology
What is cell signalling
How cells communicate with each other
What is homeostasis
Maintaining stable internal environment & conditions within narrow limits, despite changes in either/and internal & external environments
Therefore, it maintains optimal conditions for enzyme activity & cell function
What is shivering / effects
The regular & rapid relaxation & contraction of muscles
Increases respiration rate
More heat released
What is vasodilation
- Muscles in the arteriole walls relax
- Arterioles near the skin dilate
- More blood flows through the skin capillaries
- More heat is lost to the environment
What’s vasoconstriction
- muscles in arteriole wall contract
- arterioles near the skin contract
- less blood can flow through capillaries in skin
- less heat lost to environment by radiation
What’s an example of homeostatic control
Excretion - the removal of toxic waste products of metabolism from the body (via excretory organs)
What’s are stimuli
External environmental changes
What’s piloerection
- Hair erector muscles contract
- Hairs stand on end
- Forms the insulating layer of warm air between the skins surface and hairs
- So reduces heat loss
What’s the standard homeostasis response pathway
A negative feedback loop
What’s thermoregulation
- an example of a neg feedback loop
The regulation of constant body temperature (for endotherms)
Why is excretion important
Prevents build up of toxic waste products of metabolism
If left to accumulate
1. They can interfere with cell processes by altering pH
2. May prevent normal metabolism
3. May act as an enzyme inhibitor & reduce activity
