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Communication and Homeostasis
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1. Accelerator nerve and vagus nerve: From the medulla 26. Homeostasis: Maintenance of internal environment in
oblongata to the heart. constant state despite external changes.
2. Acetylcholinesterase: Enzyme in the synaptic cleft that breaks 27. Hormonal System: Transported in the blood. Cells in
down acetylcholine into ethanoic acid and choline. endocrine organ release signal only recognized by specific
3. Action potential : Depolarisation of the cell membrane so that target cells. Long-term response.
this inside is more positive than the outside, with a potential 28. Hormone: Molecule released in blood that acts as chemical
difference across the membrane of +40mV. This can be messenger.
transmitted along the axon or dendron plasma membrane. 29. Hormones: Molecules released by endocrine glands directly
4. Adenyl cyclase: Enzyme associated with receptor for many into blood. Messengers carrying signal from endocrine gland to
hormones i.e. adrenaline. Inside of CSM. a specific target organ or tissue.
5. All or nothing: Neurone either conducts an action potential or it 30. Hydrolysis: Splitting of large molecules into smaller molecules
does not. All action potentials are of same magnitude +40mV. with addition of water.
6. Cardiovascular centre: Specific region of medulla oblongata 31. Hyperglacemia: Blood glucose levels too high.
that receives sensory inputs about levels of physical activity, 32. Hyperpolarisation: Potential difference overshoots slightly,
blood CO2 concentration and blood pressure. Sends nerve more negative than -60mV.
impulses to SAN in heart to alter frequency of excitation waves. 33. Hypoglacemia: Blood glucose levels too low.
7. Cell metabolism: Result of all chemical reactions taking place in 34. Insulin: Causes blood glucose level to decrease
35. Islets of Langerhans: Small patches of tissue in pancreas that
8. Cell signalling: Communication between cells - one cell releases have endocrine function.
chemical that is detected by another cell - second cell responds
36. Local current: Movement of ions along the neurone. Flow of
to signal by first cell.
ions caused by an increase in concentration at one point, which
9. Cholinergic synapses: Use acetylcholine as their transmitter causes diffusion away from the region of higher concentration.
37. Medulla oblongata: Base of brain and it is the region that
10. Communication system: Stimulus - receptor - cell signaling - coordinates the unconscious function of body i.e. breathing and
effector - response heart rate.
11. Depolarisation: Loss of polarisation across the membrane. It 38. Myelin Sheath: Insulating layer of fatty material.
refers to the period when sodium ions are entering the cell
39. Myogenic : Muscle tissue can initiate its own contractions.
making the inside less negative with respect to the outside.
40. Negative feedback : Reversal of change in conditions. Ensures
12. Diabetes mellitus: Disease in which blood glucose
optimum steady state is maintained.
concentrations cannot be controlled effectively.
41. Neuronal System: Interconnected network of neurons that
13. Ectotherm: Organism that relies on external sources of heat to
signal to each other across synapse junctions. Rapid response.
regulate its body temperature.
42. Neurone: Specialised cell transmitting electrical energy (nerve
14. Effector: Bring about response that reverses change detected
43. Neurotransmitter: Chemical that diffuses across the synaptic
15. Endocrine gland : Secretes hormones directly into the blood.
cleft to transmit a signal to the postsynaptic neurone.
16. Endotherm: Organism that can use internal sources of heat to
44. Oxytocin: Increases uterine contractions which stretch the
maintain body temperature.
cervix - just before child birth.
17. Exocrine gland : Secretes molecules into duct that carries
45. Pacemaker: Tissue in the right atrium wall that can generate an
molecules to where that are used.
impulse and initiates contraction of the chambers.
18. Exocytosis: The transport of material out of a cell by means of a
46. Pancreatic duct: Tube that collects all secretions from exocrine
sac or vesicle.
cells in pancreas and carries fluid to small intestine.
19. First messenger: Hormone that transmits a signal around the
47. Physiology: Way in which living organism or bodily part
20. Generator potential : Small depolarisation caused by sodium
48. Polarisation: Potential difference across membrane. This is the
entering the cell.
21. Glucagon: Causes blood glucose level to increase
49. Positive feedback : Increases any change detected by
22. Gluconeogenesis: Amino acids and fats converted to glucose. receptors. Harmful and doesn't lead to homeostasis.
23. Glycogenesis: Glucose converted to glycogen for storage. 50. Receptors: Detect stimulus/ change in conditions.
24. Glycogenolysis: Glycogen converted to glucose. 51. Refractory period : Short time after each action potential where
25. Hepatocytes: Liver cells - specialized to carry out metabolic it is impossible to stimulate the cell membrane to reach another
functions. action potential. Also ensures action potentials are only
transmitted in one direction.
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Repolarisation: Potential difference becomes negative again.
53. Response: Change in behaviour/physiology as a result of a change in the environment.
54. Resting potential : Potential difference or voltage across the neurone cell membrane whole the neurone is at rest. It is about -60mV
inside the cell compared with the outside. Other cells may also maintain a resting potential that might change under certain
55. Saltatory conduction: Action potential appears to jump from one node of Ranvier to the next.