Lymnaea Stagnalis

If the frequency of action potentials in the excitatory presynaptic cell increases than the number of action potentials in the postsynaptic cell will increase as well. This is due to temporal summation of EPSP at very frequent times. This causes the postsynaptic cell to produce many action potential in succession.

A member of Roman political elite born in Gallia, Gnaeus Julius Agricola pursued several positions and a political career in Rome and other provinces of the country. He held a high office and had a lengthy public service, but he is mostly known because of his son-in-law, Tacitus writings, who wrote about his great leadership on every front.

Pinnington, N., Elliott, A., Sciences, F. of L., Manchester and Kingdom, U. (2007) Proceedings of the physiological society. Available at: http://www.physoc.org/proceedings/abstract/Proc%20Physiol%20Soc%208PC39 (Accessed: 3 March 2016).

3) Increasing frequency of stimulation of the trigger zone does not increases the production of the action potentials. This goes back to the threshold All or nothing theory.

The resting heart rate fluctuates over time because it is under control of the autonomic nervous system and the fluctuations are a result of the sympathetic and parasympathetic systems trying to balance each other out.

To send a message, a neuron will send a ripple of electrical energy down its axon. This ripple is called "action potential." The way it works is by changing the chemical makeup of the axon's negatively charged interior. Positively charged sodium ions move into the cell and negatively charged potassium ions move out, then the ions move to their original positions. This produces a wave of positively charged

Once a presynaptic neuron is passive, an electrical current is spread along the length of the axon (Schiff, 2012). This is known as action potential (Pinel, 2011). Action potential happens once an abundant amount of depolarisation reaches the limit through the entry of sodium, by means of voltage gated sodium channels

In Joyas Voladoras, by Brian Doyle, Doyle compares the different types of hearts in various living organisms. He begins with the hummingbird, moving on to the blue whale, mammals and birds, reptiles and turtles, fish, insects and mollusks, worms, and unicellular bacteria. Although Doyle spends a great deal of the essay talking about the physical characteristics of the each organism’s heart, he actually conveys a deeper message. Doyle shows how all living things are related, both internally and externally.

The heart serves an important purpose within the body, pumping blood throughout the circulatory system to supply all parts of the body with vital nutrients and molecules. It pumps oxygen and nutrient rich blood to be exchanged for carbon dioxide, which is then pumped to the lungs and eliminated from the body. The movement of blood throughout the body is due to the heart’s ability to push blood along the circulatory system at a steady, unfaltering rate. This rate, known as heart rate, is regulated and can be altered at a moment’s notice by signaling within the body and heart itself. In vertebrates, the autonomic nervous system controls and regulates heart rate. The autonomic nervous system is divided into two subunits, the sympathetic nervous system and parasympathetic nervous system. The parasympathetic nerve that innervates the heart is the vagus nerve. In this laboratory experiment, the regulation of heart rate was observed by studying a certain breed of turtle, the Red-eared Slider (Trachemys scripta elegans). Both chemical and electric signaling can influence the components of the nervous

The cardiac cycle describes the coordinated and rhythmic series of muscular contractions associated with the normal heart beat.

Depolarization in membrane potential triggers an action potential because nearby axonal membranes will be depolarized to values near or above threshold voltage.

• autorhymicity- The heart is autorhythmic. This means it generates its own rhythmic action potential independent of the nervous system.

Subclass Stichotrichia (Small & Lynn, 1985) Size, small to large; shape, often elongate, sometimes very drawn out posteriorly, in cross section round to dorsoventrally compressed; freeswimming with a few loricate forms; perilemma in some groups; pellicular alveoli weakly developed; somatic ventral ciliature as ventral cirri ranging from small and quite inconspicuous, occasionally as few as 2–3 cilia per cirrus, arranged in longitudinal, sometimes spiraled, files to a few, larger cirri in scattered groups, with in the latter case marginal files of cirri differentiated ; transverse cirri, may or may not be present; caudal cirri, may or may not be present; dorsal somatic ciliature as one to many kineties – typically three – of dikinetids without

Nerve cells generate electrical signals to transmit information. Neurons are not necessarily intrinsically great electrical conductors, however, they have evolved specialized mechanisms for propagating signals based on the flow of ions across their membranes.

The compound action potential adds up all the action potentials that each individual neuron experiences in the sciatic nerve. Different stimulus amplitudes cause different neurons to fire an action potential; this is due to the fact that each neuron has a different threshold potential, or the minimum voltage the neuron needs to fire an action potential. The individual neuron action potential is an ‘all-or-nothing’ event, but the CAP, as a summation of different individual neurons, is not. The CAP amplitude will increase with larger stimulus potentials because more neurons with higher individual thresholds will be recruited. For this frog sciatic nerve, there are three fiber types, A, B, and C. A fibers are further divided, in the order of decreasing diameter, into α, β, γ, and δ fibers. There is an inverse relationship between the diameter of the nerve fiber and the threshold potential: the larger the diameter, the lower the threshold. Thus, as the largest fibers, the Aα neurons will be the first to be stimulated at a low stimulus potential, and the Aδ neuron fibers will be the last to be recruited. Because the sciatic nerve is mostly composed of A fibers, the recruitment of A-subtype nerve fibers are more readily distinguishable from the data. The minimum potential required to stimulate the Aα fibers was between 75 mV and 80 mV. Once the stimulus potential reached 90 mV, Aβ neurons were recruited and contributed to the increase in amplitude of the CAP. At a stimulus