Flashcards
F214.1 Communication and Homeostasis Biology Revision Cards
Cards in this deck (39)
- 1How are action potentials transmitted?An action potential causes sodium ion channels to open causing sodium ions to diffuse into the neurone. The concentration of sodium ions increases causing them to diffuse sideways down the concentration gradient (local current). This increases voltage causing voltage gated sodium ion channels to open causing the action potential to move down the neurone.
- 2What is saltatory conduction and what are the advantages of it?It means jumping conduction. When action potentials appear to jump from one node of Ranvier to the next. This causes the speed of transmission of action potentials to increase, as the action potentials only appear in the gaps between Schwann cells.
- 3Target TissueA group of cells that have receptors embedded in the plasma membrane that are complementary in shape to specific hormone molecules.
- 4What is the structure of a sensory neurone?
- 5What are the two parts of the adrenal glands? How are the arranged?The adrenal medulla is in the center of the adrenal gland whilst the adrenal cortex is found around the outside of the adrenal medulla.
- 6What is a pre-synaptic knob (or membrane)?A swelling at the end of the pre-synaptic neurone that contains a large number of mitochondria, SER, neurotransmitters and voltage gated calcium ion channels.
- 7How does frequency affect impulse of transmission?The more intense a stimulus, the more frequent the action potentials will be.
- 8What are the roles of synapses in the nervous system?-To connect two synapses together.
-To ensure action potentials only travel in the correct direction.
-Summation
-Acclimatisation - 9How is the transmission of action potentials different in a myelinated neurone?The myelin sheath prevents sodium and potassium ions diffusing into the neuron, except where there are gaps in the myelin such as between Schwann cells (nodes of Ranvier). Ionic exchange only occurs here, elongating the local currents.
- 10What is the definition of negative feedback?A process in which any change in a parameter brings about the reversal of that change, so conditions are kept constant.
- 11Exocrine GlandA gland that secretes hormones into a duct that carries molecules to where they are used.
- 12What happens when blood glucose levels drop too low?The change is detected by alpha cells, which secrete the hormone glucagon. This converts glycogen into glucose (glycogenolysis) and amino acids into glucose (gluconeogenesis).
- 13How is an action potential transmitted across the synaptic cleft?The action potential arrives at the synaptic knob causing voltage gated calcium ion channels to open. Calcium ions diffuse in. This causes the vesicles containing the neurotransmitter to move to and fuse with the membrane (exocytosis). The neurotransmitter diffuses across the cleft and binds to sodium receptors. Sodium ion channels open and sodium ions move into the neurone. If enough ions move in creating generator potentials, then the threshold potential will be reached and the action potential will continue.
- 14Second MessengerA molecule that transmits a signal inside the cell, such as cyclic AMP. It causes an effect in cells by activating enzyme action.
- 15What happens when blood glucose levels rise too high?The change is detected by beta cells which secrete insulin. Adrenaline activates adenyl cyclase in the cell. converting it to ATP and the cAMP. Glucose then enters the cell causing glucose to turn into glycogen (glycogenesis), reducing blood glucose concentration.
- 16What is the function of a sensory neurone?To carry the action potential from a sensory receptor to the cell body.
- 17How is an action potential generated?Sodium ion channels open, allowing some sodium ions to diffuse into the cell. This depolarises the membrane until it reaches the threshold potential (-50mV). The voltage gated sodium ion channels open, allowing more sodium ions into the cell until it reaches +40mV. This causes the sodium ion channels to close and the potassium ion channels to open. The membrane is repolarised until the is a slight over soot (hyperpolarisation). The cell then returns to resting state.
- 18What is the structure of a motor neurone?
- 19First MessengerThe hormone that transmits a signal around the body, such as adrenaline.
- 20What are the exocrine and endocrine functions of the pancreas?Exocrine- digestive enzymes are secreted into the pancreatic duct/
Endocrine- islet of langerhans. Alpha cells secrete glucagon and beta cells secrete insulin. These hormones are secreted directly into the blood capillaries. - 21What is the role of acetylcholinesterase?It is an enzyme found in the synaptic cleft which hydrolyses acetylcholine into ethanoic acid and choline which the re-enter the synaptic knob by diffusion. It stops the transmission of signals.
- 22What is the definition of positive feedback?A process in which any change in a parameter brings about an increase in that change.
- 23HormoneA molecule released into the blood which acts as a chemical messnger.
- 24How is transmission effected in a non-myelinated neurone?The sodium ions can diffuse into the neurone at any point so the local currents are generally much shorter and the speed of transmission is slower.
- 25What are the roles of sensory receptors?Specialised cells that detect changes in the surroundings.The are energy transducers, so change one type of energy into another.
- 26What are the functions of the adrenal medulla?Manufactures and releases adrenaline in response to shock or stress. This increases heart rate and stroke volume. It also causes vasoconstriction and increased mental awareness as well as dilating pupils.
- 27How is insulin secretion controlled?Glucose levels rise and enter the cell. The glucose is then metabolised into ATP which causes the potassium channels to close, increasing the voltage inside the cell to become more positive. Calcium ions then enter the cell causing insulin to be secreted, lowering blood glucose levels.
- 28What is an ectotherm?An organism that relies on external sources of heat to regulate its body temperature.
- 29What is an endotherm?An organism that can use internal sources of heat (e.g. metabolism) to maintain body temperature.
- 30What are the advantages of genetically engineered insulin?Less chance of having an intolerance to it. More effective.
Cheaper to manufacture and to fit demand.
There are less ethical issues. - 31How can stem cells be used to treat diabetes?New stem cells in the pancreas could be used to produce new beta cells.
- 32What causes type two diabetes?The body can still make insulin, but it no longer responds to it. It is controlled through diet and insulin injections.
- 33What causes type one diabetes?The body destroys its beta cells so insulin cannot be made (auto immune). Insulin levels are controlled through injections and blood level monitoring.
- 34What is the mechanism of homeostasis?A change is detected by the receptors, the communication system transmits a message from the receptors to the effectors, causing the change to be reversed.
- 35Cell signallingCommunication between cells. It involves a ligand being secreted and transported from the signalling cell to the target cell where it binds to the receptor sites. This creates a response.
- 36How is resting potential established and maintained?Three sodium ions are pumped out of the cell by diffusion for every two potassium ions pumped in. The membrane is also slightly permeable to potassium ions. The large negative anions maintain the -70mV charge.
- 37Endocrine GlandA gland that secretes hormones directly into the blood- there are no ducts.
- 38What is the function of a motor neurone?To carry the action potential to the effector.
- 39HomeostasisThe maintenance of the internal environment despite changes to the outside environment.
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- Description
- Each card has a question on the front and the answer on the back. The questions cover all of F214 Module 1, Communication and Homeostasis.
- Created by
- Laura Perry · Feb 2016
- Updated
- Jan 8, 2017
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