5.1 Flashcards
what are the 4 conditions that animals nee to maintain inside their cells
-a suitable temperature
-a suitable pH
-an aqueous environment that keeps the substrates and products in solution
- freedom from toxins and excess inhibitors
the environmental change is a _____ and the way in which the organisms changes its behavior and physiology is its _____
stimulus
response
what is environmental change
stimulus
one waste product is carbon dioxide, what happens if it builds up in the tissue fluid and what does this act as
it will alter the pH (lower pH) of the tissue fluid and could disrupt the action of enzymes and other proteins. The accumulation of this acts as a stimulus which leads to the removal of CO2 so that the cell can survive.
the build-up of waste products in the tissue fluid can also act directly on cells, how do cells respond and what could be a consequence of this
they respond by reducing their activities so less waste is produced however this may not be good for the whole of the organism
the composition of tissue fluid is maintained by the…
…blood
how are toxins in the tissue fluid removed
they are likely to enter the blood and removed from the blood by excretion.
why is important that the concentrations of waste products and other substances in the blood are monitored closely
to ensure that the body does not excrete too much of any useful substances but also removes enough of the waste products to maintain good health, it also ensures that the cells in the body are supplied with the substrates they need
why is a multicellular organism more efficient than a single celled organism
because its cells are differentiated
why is a good communication system required
to ensure that different parts of the body work together effectively.
5 features of a good communication system:
-cover the whole body
-enable cells to communicate with each other
-enable specific communication
-enable rapid communication
-enable both short-term and long term responses
what is cell signaling
the way in which cells communicate with each other (one cell will release a chemical that is detected by another cell, the second cell will respond to the signal released by the first cell).
what are the two major systems that work by cell signaling:
the neuronal system and the hormonal system
what is the neuronal system?
an interconnected network of neurons that signal to each other across synapse junctions. The neurons can conduct a signal very quickly and enable rapid responses to stimuli that may be changing quickly.
what is the hormonal system? (Detailed)
a system that uses blood to transport its signals. Cells in an endocrine organ release the signal (a hormone) directly into the blood. The hormone is transported throughout the body, but is only recognized by specific target cells. the hormonal system enables longer term responses to be coordinated.
what is essential to enable signals to be specific
molecules that have a specific SHAPE which is complimentary to that of a surface cell receptor.
whats an effector
a cell, tissue or organ that brings about a response
whats homeostasis
maintaining a constant internal environment despite changes in external and internal factors
whats negative feedback
the mechanism that reverses a change, bringing the system back to optimum
whats positive feedback
the mechanism that increases a change, taking the system further away from the optimum
what are sensory receptors
cells/ sensory nerve endings that respond to a stimulus in the internal or external environment of an organism and can create action potentials.
what are 6 aspects maintained by homeostasis
- body temperature
-blood glucose conc
-blood salt conc
-water potential of the blood
-blood pressure
-co2 conc
what is the standard response/pathway to a change in the environment
stimulus-> receptor-> communication pathway(cell signaling)-> effector-> response
(a number of specialized structures are required for this pathway to work:
talk about temperature receptors which is a type of sensory receptor
they are found on the body found in the skin, they monitor changes in the external environment. other receptors may be internal such as temperature receptors in the brain
what happens when a receptor detects a change
it will be stimulated to send a message to an effector.
what things allow for the standard response to a change in the environment to work
- sensory receptors such as temperature receptors.
-a communication system such as the neuronal system ( this acts by signaling between cells- it is sued to transmit a message from the receptor cells to the effector cells via a coordination center which is usually in the brain)
-effector cells such as livre cells or muscle cells. these cells will being about a response
the messages from the receptor to the coordination center is known as the…
input
the messages sent to the effectors is known as the…
output
give an overview of feedback
when the effectors respond to the output from the coordination center, they bring abt a response that will change the conditions inside the body, such changes will be detected by the receptors . This will have an effect upon the response pathway. In effect, the input will change, this is known as feedback
body parts involved in the neuronal system
-brain
-spinal chord
-nerves (a bundle of neurons)
how is info transmitted in the neuronal system
sends electrical signals/ impulse
are responses rapid or gradual for the neuronal system
rapid
but there are some exceptions where its gradual:
e.g. pain felt after response
-nerve damage= slower
example of responses for neuronal system
- reflexes
-voluntary movement
body parts involved in the hormonal system
cells in an endocrine organ
-the circulatory system (the blood)
-hormones made in and released from glands
how is info transmitted in the hormonal system
hormones released in the blood and they bind to receptors on target cells
are responses rapid or gradual for the hormonal system- are there any exceptions?
gradual
however there are rapid exceptions e.g.
-insulin
-adrenaline
-cortisol
give examples of negative feedback
-temp control (bringing it back to optimum)
-sweat to bring temp down
-nerves sensing stomach is expanding (feeling full)
give examples of positive feedback
-dilation of the cervix via the release of oxytocin. as the cervix begins to stretch this causes the posterior pituitary gland to secrete the hormone oxytocin, this increases uterine contractions which stretches the cervix more causing the secretion of more oxytocin
-the uterus contracting during dilation
- breast swelling once baby is born to produce milk via oxytocin
describe negative feedback
-at first there is an optimum condition
-there is then a change away from the optimum
-the receptor detects a change
-an input is sent to the communication system and this informs the effector
-the coordination center then sends an output to the effectors
-the effectors react to reverse the change
-there is a return to the optimum condition
-this is a loop cycle
describe positive feedback
- the response is here to increase the og change
1. at first there is an optimum condition
2. there is then a change away from the optimum
3. the receptor detects a change
4. am input is sent to the communication system/coordination center and this informs the effector
5. the coordination center then sends an output to the effectors.
6. the effectors react by increasing the og change
7. this leads to further change away from the optimum and this repeats from step 3
communication system=
=coordination center
where is the thermoregulatory center located
in the hypothalamus
for neg feedback to work, a number of processes must occur, what are the 3 processes:
- a change in the internal environment must be detected
- the change must be signaled to other cells
- there must be an effective response that reverses the change in conditions
talk abt temp control via negative feedback when the temp falls
- a fall in core temp
-thermoregulatory center in hypothalamus detects change
-nervous and hormonal systems carry signals to skin, liver and muscles
-more heat is generated and less heat is lost
-temperature rises
NOTE: this would be the opposite for if the temp rises
are conditions always exactly constant
no there are slight fluctuations, this is where conditions are acceptable
give an example of positive feedback to do with enzymes
below core body temp, enzymes become less active and the exergonic ( biochemical reaction that releases energy) that releases heat are slower and release less heat. this allows the body to cool further and slows the enzyme controlled reactions even more, this causes the body temperature to spiral downwards
what type of feedback does the activity of neurons rely on
-positive feedback
why is controlling body temp important
- it can have a dramatic effect on the activity of cell processes, can change the rate of chemical reactions
-the structure of proteins can also be affected by changes. (enzyme function may be lost)
-enzymes can be affected, if temperature drops, reactions slow down and less heat is released causing the body to cool further leading to positive feedback
-core temp is vital for organs
what are ectotherms
(cold blooded)
an organism that relies on external sources of heat to maintain body temperature, their body temp fluctuates with the external temperature.
using behavioral mechanisms, some ectotherms are able to control their body temperature in all but the most extreme conditions. they are not able to control their body temp as effectively as endotherms
what are endotherms
(warm blooded) an organism that uses heat from metabolic reactions to maintain body temperature. They control their temp in very strict limits , they use a variety of mechanisms to control body temp and are largely independent of external temperatures. they use physiological and behavioural adaptations to control their body temp
how do ectotherms control their temp
- they do not use internal energy sources to maintain body temperature when cold however once they are active their muscle contractions will generate some heat from increased respiration. temperature regulation relies on behavioral responses that can alter the amount of heat exchanged with the environment
if ectotherms are not warm enough, they try to absorb more heat from the environment, they may:
-move into a sunny area
-lie on a warm surface
-expose a larger surface area to the sun
if ectotherms are too hot they try to avoid gaining more heat to try and increase heat loss to the environment, they may:
-move out of the sun
-move underground
-reduce body surface exposed to the sun
an example of an ecotherm is a snake, state its behavioral adaptation and benefit
behavioral adaptation:
basks in the sun
benefit:
absorbs heat directly from the sun
an example of an ecotherm is a locust, state its behavioral adaptation and benefit
behavioral adaptation:
in early morning they sit side on exposing a large sa to the sun but at midday, they face the sun head on exposing a smaller sa, they may also climb to the top at midday to get away from the soil surface
benefit:
in the cool morning, they can absorb more heat, but at midday when the sun is hotter they absorb less heat. the soil surface gets hot and radiates heat; if the locus moves away from the soil it gains less heat from the soil
behavioral adaptation:
increases the rate of breathing and the depth of breathing movements when its hot.
benefit:
more water evaporates from the tracheal system, cooling the body
an example of an ecotherm is a lizard, state its behavioral adaptation and benefit
behavioral adaptation:
many lizards use burrows or crevices between rocks. they will hide in the burrow during the hottest part of the day and the coolest part of the night
benefit:
an underground burrow tends to have a more stable temperature than air. in the hottest part of the day it will be cooler in the burrow, but at night the burrow may be warmer than the air outside
an example of an ectotherm is a horned lizard, state its behavioral adaptation and benefit
behavioral adaptation:
can change its shape by expanding or contracting its ribcage
benefit:
expanding the ribcage increases the surface area exposed to the sun, so more heat can be absorbed
advantages of ectothermy
ectotherms rely on external sources of heat to keep warm. they do not use energy to keep warm thus:
- less of their food is used in respiration
-more energy and nutrients gained from food can be converted to growth
-they need to find less food
-they can survive for long periods without food
what are disadvantages of ectothermy
they are less active in cooler temperatures. this means that they are at risk from predators while they are cold and unable to escape and they cannot take advantage of food while they are cold.*
endotherms do not rely on external sources of heat, what can they do
they can use physiological adaptations and behavioral means to control their body temperature
whats the hypothalamus
the part of the brain that coordinates homeostatic responses
many of the physiological adaptations to control body temperature involve the…
…skin as its in contact with the external surface. (the changes that take place in the skin alter the amount of heat being lost to the environment)
what does temperature regulation rely on:
relies on the effectors in the skin and muscles
many chemical reactions in the body are ______, what does this mean
many chemical reactions in the body are EXERGONIC, this means they release energy in the form of heat
how can endotherms release heat
by increasing respiration (an exergonic reaction) in the muscles and liver to release heat.
whats an useful physiological adaptation of endotherms to alter the amount of heat lost to the environment:
directing blood towards or away from the skin
what are 3 things that the organ of the skin does if its too hot: (physiological mechanisms)
skin:
1. sweat glands secrete fluid onto the skin surface; as this evaporates it uses heat from the blood as latent heat of vaporisation
2. hairs and feathers lie flat to reduce insulation and allow greater heat loss
3. vasodilation of arterioles and precapillary sphincters directs blood to the skin surface so more heat can be radiated away from the body
what are 3 things that the organ of the skin does if its too cold:(physiological mechanisms)
skin:
1. less sweat is secreted, so less evaporation means less heat is lost
2. hairs and feathers stand erect to trap air, which insulates the body.
3. vasoconstriction of arterioles and precapillary sphincters leading to skin surface. Blood is diverted away from the surface of the skin and heat is lost.
what does the gaseous exchange system do if the body gets too hot (physiological mechanisms)
some animals pant, increasing evaporation of water from the surface of the lungs and airways. Evaporation uses heat from the blood as the latent heat of vaporisation
what does the gaseous exchange system do if the body gets too cold (physiological mechanisms)
less panting so less heat is lost
what does the liver do if the body gets too hot (physiological mechanisms)
less respiration takes place so less energy is converted to heat**
what does the liver do if the body gets too cold (physiological mechanisms)
increased respiration with the liver cells means that more energy from food is converted to heat
what does the skeletal muscles do if the body gets too hot (physiological mechanisms)
fewer contractions mean less heat is released
what does the skeletal muscles do if the body gets too cold (physiological mechanisms)
spontaneous muscle contractions (shivering) release heat
what does the blood vessels do if the body gets too hot (physiological mechanisms)
dilation to direct blood to the extremities so that more heat can be lost
what does the blood vessels do if the body gets too cold (physiological mechanisms)
constriction to limit blood flow to the extremities, so that blood is not cooled as much - this can lead to frostbite in extreme conditions
what are the behavioural adaptations used by endotherms if they are too hot (physiological mechanisms)
- hide away from sun in the shade or in a burrow
- orientate body to reduce SA exposed to sun
-remain inactive and spread limbs out to enable greater heat loss
-wet skin to use evaporation to help cool the body. cats lick themselves and elephants spray water over their bodies.
what are the behavioural adaptations used by endotherms if they are too cold (physiological mechanisms)
-lie in the sun
-orientate body towards sun to increase SA exposed
-move about to generate heat in the muscles or, in extreme conditions roll into a ball shape to reduce SA and heat loss.
what’s advantages of endothermy:
-maintain a fairly constant body temperature whatever the temperature externally
-remain active even when external temperatures are low, which means they can take advantage of prey that may be available or escape from potential predators
-inhibit colder parts of the planet
what’s disadvantages of endothermy:
- use a significant part of their energy intake to maintain body temperature in the cold
-need more food - -use for growth a lower proportion of energy and nutrients gained from food
-may overheat in hot weather
what detects temp change in the blood and what happens due to this
temperature receptors in the hypothalamus of the brain detect this. The hypothalamus then sends out impulses to cause different responses that will reverse the change.
and why do some responses need to be quick in regards to change in temp in the blood and how is this carried out
some responses need to be quick in order to prevent further change in body temp.
the neuronal system transmits the output from the hypothalamus in order to make the responses rapid. Howeverr, other responses may need to be longer term; the hormonal system transmits the output to cause these responses.
if the core temperature is too low, the hypothalamus will bring about:
-changes in the skin to reduce heat loss
-release of heat through extra muscular contraction
-increased metabolism in order to release more heat from exergonic reactions.
(if core rises above optimum opposite changes will occur- this is neg feedback
what does the thermoregulatory centre in the hypothalamus monitor
blood temp and detects changes in the core body temp
if the extremities start to cool down or warm up, what can this affect
the core body temperature
what monitors the temperature in the extremities
peripheral temperature receptors
name the type of sensory cell in the skin that detects changes in environmental temperature
peripheral temperature receptors
give 3 examples of responses that conserve heat
-vasoconstriction of arterioles near to skin surface
-contraction (standing up) of erector pili muscles
-curling up (behavioural response)
give an example of a physiological response that generates heat
-shivering
-( can be secretion of adrenaline)
two responses that cool the body
sweating
finding shade
how does the adaptation of having shunt blood vessels ( link arterioles carrying blood towards feet with small veins that carry blood away from their feet) help control penguins body temp
-less blood flows to feet so core body temp is maintained, blood thus loses less heat as less flows to feet
