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