5.1.1 Communication And Homeostasis Flashcards
Why do multicellular organisms need communication systems
Animals and plants need to respond to changes in their internal and external environment
Also need to coordinate the activities of different organs
Why do we need to keep our water potential constant
If our blood has lower WP than tissue fluid water moves into blood by osmosis- the tissues dehydrate
Why do we need to keep our pH constant
pH affects amount of H+ ions- causes 3D structure of enzyme to change, active site changes, fewer ESC
Define stimulus
A change in internal or external environment that causes a response
What is a response
A change in behaviour or physiology due to a stimulus
Define cell signaling
Communication between cells that allows cells to work together to trigger a response or a reaction inside the cell
What is hormone cell signaling
Involves hormone released into the blood that binds only to specific target cells with matching receptors
What is homeostasis
Maintenance of a a stable internal environment within a narrow range despite external environment changes so that enzymes can function optimally
What is negative feedback
Corrective homeostatic mechanism that works to restore any detected change in the internal environment to optimum state
Give an example of negative feedback
Vasodilation
Sweating
= cool body
What is positive feedback
A process that increase any change detected by receptor
Taking it further away from a set point
Give a positive example of positive feedback
Oxytocin- as cervix stretches during labour
Ethylene gas in fruit
Explain how hypothermia is an example of positive feedback
1) person is cold
2) enzyme slow down (less kinetic energy)
3) less metabolic reaction
4) less energy produced
5) less heat
6) person gets colder
7) enzymes slow further
…
What is an endotherm
An animal that can regulate and maintain core body temperature
They generate heat from respiration and metabolism
Evaluate the pros and cons of being an endotherm
Advantages:
- constant body temp independent of external temp
- organism can be active despite external conditions
- can live in colder environments
Disadvantages:
- large energy intake
- less food used in growth
How do we as humans loose heat
Radiation to the environment
Evaporation of water to vapour
Convection of heat into air currents
Conduction of heat through skin
What part of the brain is responsible for monitoring blood temp
Thermoregulatory centre
In the area of the hypothalamus
What are the two centres that are activated in response to a change in temp
Heat gain centre- activated by a fall in blood temp
Heat loss centre- activated by a rise in blood temp
Describe the two sets of receptors involved in detecting heat
Thermoreceptors in the hypothalamus measure blood temp
Peripheral thermorecpetors in the skin monitor external temp - send impulses to the hypothalamus
What happens if your body temperature decreases
Heat gain centre activated by a fall in blood temp
This is detected by receptors in the hypothalamus and peripheral thermoreceptors in the skin
Name three methods of conserving heat
Physiological:
- vasoconstriction
- raising of hair
Behavioural:
- shelter from wind
- animals huddle together
How does the raising of hair cause the body to conserve heat
Erector muscles in the skin contract raising hair to trap a layer of insulating air to trap heat and reduce the cooling of skin
How does vasoconstriction conserve heat
Decrease of arterioles lumen to reduce blood flow to the capillaries in the skin of the organisms- reducing heat loss by radiation
3 ways heat is lost from the skin
Conduction
Convection
Radiation
What happens when external body temp decreases
Peripheral thermoreceptors in the skin are stimulated, thermoregulatory centre in hypothalamus detects change in blood
Vasoconstriction
Erector pilli muscled contract raising hair to trap a layer of insulating air to trap heat
How are penguins adapted to withstand heat
Arteries in penguins legs that are able to adjust blood flow to feet based off of temperature
Penguin feathers are highly specialised to keep water away from the skin and insulate
4 ways to generate heat
Physiological:
Shivering
Release of adrenaline and thyroid hormones
Increased metabolic rate
Behavioural:
Basking in the sun
What happens if your body temperature increases
Heat loss centre activated by a rise in blood temperature
Receives input from peripheral thermoreceptors and receptors in hypothalamus
Explain the process of vasodilation
Increase in the diameter of the arterioles lumen beaut the surface of the skin, increasing blood flow to the skin surface
What do hairs do in order to loose heat
Erector pilli muscles relax in the skin reduces the layer of insulation provided
Behavioural mechanisms of losing heat
Avoid the heat of the day, sheltering in burrows or shade to prevent body heat from rising
How is heat lost from the skin surface
Conduction convection and radiation
What happens if we get too hot
External temperature increases
Peripheral thermoreceptors stimulates
Impulse sent to hypothalamus
Vasodilation
More blood at surface of capillaries
Describe the process of sweat
Sweat produced from glands
Kinetic heat energy passes to sweat
Which evaporates removing heat from the body
And cools the body down
List 2 behavioural adaptations
Digging burrows
Basking in sun
List 2 anatomical adaptations
Blubber
Thin large ears
What is an ectotherm
Organisms that mainly rely on external/ environmental sources of heat to regulate their body temperature
Give an example of ectotherm
Reptiles, fish, and amphibians are all ectotherms
Why do ectotherms living in water not need to thermoregulate
Water has a high specific heat capacity- water temp is constant
3 advantages of being an ectotherm
Use less food in respiration
Survive long periods without eating
Greater proportion of energy used for growth
3 disadvantages of ectotherms
Less active In cooler temps
May need to warm up in the morning- basking- predators?
Not capable of activity in winter
3 ways ectotherms gain heat
Basking in sun
Change body shape to maximise exposure
Alter colour to increase absorption
3 ways to lose heat
Bathe in water or find shade in a burrow
Reduce contact with ground
Increase breathing movements
