Flashcards in Communication and Homeostasis Deck (47):
Any change in the environment that causes a response.
Change in behaviour or physiology as a result of a change in the environment.
Maintenance of the internal environment in a constant state despite external changes.
Process that brings about the reversal of any change in conditions. It ensures that an optimum steady state can be maintained, as the internal environment is returned to its original set of conditions after any change. Essential for homeostasis.
Process that increases any change detected by receptors. Tends to be harmful (except in pregnancy and dilation of cervix) and does not lead to homeostasis.
Organism that relies on external sources of heat to regulate its body temperature.
Organism that can use internal sources of heat, such as heat generated from metabolism in the liver, to maintain its body temperature.
One that has a potential difference across it.
Loss of polarisation across the membrane. Refers to the period when sodium ions are entering the cell, making the inside less negative with respect to the outside.
Small depolarisation caused by sodium ions entering the cell.
Achieved when the membrane is depolarised to a value of around +40mv. It is an all or nothing response.
Potential difference or voltage across the neurone cell membrane while the neurone is at rest. At -60mv inside the cell compared with the outside.
Channels in the cell membrane that allow the passage of charged particles and ions. They respond to changes in the potential difference across the membrane.
Potential difference across the membrane is -50mv. If depolarisation reaches threshold potential, an action potential is created.
Depolarisation of cell membrane so that inside is more positive than outside. Potential difference is +40mv. Action potential can be transmitted along the axon or dendron plasma membrane.
Movements of ions along the neurone. Flow of ions is caused by an increase in concentration at one point, which causes diffusion away from the region of higher concentration.
Way that the action potential appears to jump from one node of Ranvier to the next.
Chemical that diffuses across the cleft of the synapse to transmit a signal to the postsynaptic neurone.
Those that use acetylcholine as their transmitter substance.
Swelling at the end of the presynaptic neurone.
Enzyme in the synaptic cleft that breaks down acetylcholine.
All or nothing
Refers to the fact that a neurone either conducts an action potential or it does not. All action potentials are of the same magnitude of +40mv.
Several small potential changes can combine to produce one larger change in potential difference across the membrane.
Molecules that are released by endocrine glands directly into the blood. They act as messengers, carrying a signal from the endocrine gland to a specific target organ/tissue.
Gland that secretes hormones directly into the blood. Have no ducts.
Gland that secretes molecules into a duct that carries the molecules to where they are used.
Those that possess a specific receptor on their plasma membrane. Shape of receptor is complementary to shape of hormone molecule.
Enzyme associated with the receptor for many molecules, including adrenaline. It is found on the inside of the cell surface membrane.
The first messenger
Hormone that transmits a signal around the body.
The second messenger
Cyclic AMP, which transmits a signal inside the cell.
Tube that collects all the secretions from the exocrine cells in the pancreas and carries the fluid to the small intestine.
Islets of Langerhans
Small patches of tissue in the pancreas that have an endocrine function.
What do alpha cells secrete?
What do beta cells secrete?
Hormone that causes blood glucose levels to go down.
Hormone that causes blood glucose levels to rise.
Liver cells. They are specialised to perform a range of metabolic functions.
Disease in which blood glucose concentrations cannot be controlled effectively.
State in which the blood glucose concentration is too high.
State in which the blood glucose concentration is too low.
Genetically engineered bacteria
Bacteria whose DNA have been altered. E.g. A gene coding for human insulin has been inserted into DNA of bacteria.
Unspecialised cells that have the potential to develop into any type of cell.
Result of all the chemical reactions taking place in the cytoplasm.
Muscle tissue that can initiate its own contractions.
Region of tissue in the wall of right atrium that can generate an impulse and initiates the contraction of the chambers.
Found in base of brain. Region of the brain that coordinates the unconscious functions of the body such as breathing rate and heart rate.