Module 5.1 Flashcards
what is cell signaling
the way in which cells communicate with each other
what does cell metabolism rely on
relies on enzymes and that enzymes need a specific set of conditions in which to work efficently . All living thins need to m inain a certain limited set of conditions inisde their cells .
-suitable temperature
-suitable pH
-an aqueous enviornment that keeps the substrates and products in solution .
-freedom from toxins and excess inhibitors
what happens wihtout these seet conditions in a cell
the cell will become inactive and die . In a multicellular organism , cells are specialised and rely upon one another ,therefore they must be able to communicate in order to coordinte their activities .
how does an organism react to a changing environment
all living orgnisms have an external environemnt that consists of the air water or soil aroundthem . This external environmen changes which may place stress on the living organisms . For instance , a cooler environemnt will cause greater heat loss if the organisms is to remian active and survive , the changes i the enivornemnt m ust be monitoired and the organisms must change its behaviour or PHYSIOLOGY to reduce the sres .
stimulus resposne need tobe chaned .
example of changing response to a certain stimulus
the environment may chnage slowly as the season passes . These changes elict a gradual resposne , for example , the artic fox , has a much thicker white coat in water and a thinner grey/ brown coat in summer . The change in the coat provides a greyer insualtion and camoulage in winter , ensuring the naimal can surivive , yet in the summer the animal does not overheat
how are cells and tisseus protected from the external enviornemnt
they are protected by epithelial tissues and organs such s skin or bark . In many animals the internal cells and tissues are bathed in tissue fluid
affect of a build up of a waste product - carbon dioxide
if this is alloed to build up in the tissue fluid outside the cells , it will alter the pHh of the tissue fluid and could disprupt the actions of enzymes and ohter protiens .
–the accumulagtion of excess waste or toxins in this internal enviorment acts as a stimulus to cuse removl of thse products so that the cells can surivvie .
what may the build up of waste products do to the cell
it may act directl on the cells , which respond by reducing thier activities so that less waste is produced However , this response ma not be good for the whole organism .
how is the composition of the tissue fluid maintained
it is maintained by the blood . As the blood flows throughout the bodya nd transports usbstnced to and from the clels . an waste or toxins accumulitng in the ittisue fluid is liekly to enter the blood and be carried away we will lern about this later
why is it impotant that concentrations of waste product and other substances in the blood are monitored closely
this ensures that the body does nt excrete too much of any useful substance but removes enough of the waste prducts to maintian good health . It enusres all the cells in the body are supplied with the substrates they need .
what is a good communcition system
good as all clels re diferentaited and specilised to form a particular function .
-cover the whole body .
-enbale cells to communicate with each other .
-enable specific communication .
-enable rapid communiction .
-enable both short term and long term resposnes .
what are the two major systems of communiction that work b y cell signalling
neuronal ssytem and hormonal system
what is the neuronal system
an interconnected network of neurones that signal to each other across synapse junctions . The neurones can conduct a signal very quickl and enable rapid responses to stimuli that may be changing quickly .
what is the hormonal system
a system tht uses the blood to transport its signalls . Cells in an endocrine organ release he signals directly into the blood . The hormone is transported throughout the body but is only recognised by speficifc target cells . The hormonal ssytem enables longer term resposnes to be coordiianted . cells gilling receptos shi .
what is an effector
a cell , tissue or organ that brings about a response
what is homeostasis
maintaining a constant internal enviornment despite change in external and internal factors
what is negative feedback
the mechanisms that reverses a change bringing the system back to the optiumum
what is positive feedback
the mechanisms that increases a change taking the sstem 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 .
aspects maintained by homeostasis
-body temperature
-blood glucose concentraiton
-blood salt concentration
-water potential of the blood
-blood presure
-carbon dioxide concentration
any resposne to change in the environemnt requries a complex mechanism coordinated by cell signalling ; what is this
stimulus , receptor , communication pathway , (cell signalling ) , effector , resposne
sensory receptors help the pthway above how does communiction systems help the pathway above .
a communicaiton system such as the neuronal system or the hormonal sytem . This acts by signalling between cells . it is used to transmit messgae from the receptor cells to the effector cells via a coordinationc entre which is usall int he brian ,.
THe messages from the receptor ot th oordinaiton centre are known as input . The emssage sent to he effecors such are knwon as the ouptut .
sensory receptors help the pthway above how dooes effectord help the pathway above .
effector cells such as the liver cels or muscle cells . These cells bring about a resposne
what is feedback
when the effectors respond to the output form the coordination centre , they bring about a reposnse that will chnge the conditions inside the body . Such changes will be detected by the receptors , this iwll also then have an effect upon the response pathway .
how does negtive feedbck work
when the conditions change , the receptors detect this stimulus and send an inpuot to the coordination centre .
-The coordiantion centre sends an ouput to the effectors and the effectors respond to this output . When the effectors brign about a chnage that reverses the initial change in conditions , the strem moves closer the optimum and the stimulus is reduced
how does negtive feedbck work (2)
the receptors detect the reduction in stimulus and reduce the inpt to the coordintion cener . The otuput , from the coordination centre to the effecors is also reduces so the effectors reduce thier citity . As the sytem gets clsoer to the optimum the response is reduced .
fir a negaive feedback to worka numeber of processes must occur , what does this including
1.a change to the internal environemt must be detected .
2.the change m ust be signalled to other cells .
3there must be an effective resposne tht reverses the change in conditon .
ernign tip on levels on codntiosn
there is a narrow ange of flcutuation at a set point does not stay perfect .
What happens during positive feedback
It is less com,on than negative feedback . When positive give feedback occurs , the response is to increase the original change . This destabilises the system and is usually harmful .
Example of positive feedback
For example below a certain body temperature , enzymes become less active and the exergonic reactions that release heat are slower and release less heat . This allows the body to cool further snd slows the enzyme controlled reaction even more causing the bicycle to,rorsgjtr to dojfs, dosnsadds .
Example of positive feedback being beneficial - used to stimulate an increase in a change
An edamame of this is seen at the end of pregnancy to bring about dilation of cervix . As the cervix begins to stretch this causes the dilation of the cervix as the cervix begins to stretch this causes the posterior pituitary gland to secrete the hormone oxytocin . Oxytocin increases uterine contractions which can stretch the cervix more , which causes secretion of more oxytocin . Once the cervix is fully dilated the baby can be bring , ending the production of oxytocin .
What is an ectotherm
An organism that relies on external sources of heat to maintain body temperature .
What is an endotherm
An organism that uses heat from metabolic reactions to maintain body temperature
How does body temperature have an affect on the activity of cell processes
As temperature rises , molecules have more kinetic energy . They move about more quickly and collide more frequently . This means thst essential chemical reactions occur more quickly . In opposite conditions. Chemical reactions would slow down .
how can the strucutre of proteins be affected by chaning body temperatrue
the sttrucure of proteins can also be affected b changes - especially increases in body temperature Many proteins have a metabolic ufnction for example , enzymes increase the rate of biological reactions .
-Enzymes re gloular proteins and hve a very speciifc tertiary strucutre , giving them a specific 3d shape . In the case of enzymes the hsape of he activity site is complementary tot he shpe of the substrate and any change in dhpe will ffect their aility fo fucntion normally . if temperature is allowed to increse too much , enzymes change shape nd function is lost .
