BMS 300 1nd EditionExam #3 Study Guide Lectures: 29- 37Lecture 29 (October 17th, 2014)What are some basic facts about the heart and the way it moves blood? - what we see on the right side we also see on the left - the resistance of flow from the left is lower than the right - we have a continuous layer of endothelium everywhere in the chambers What are mesothelial cells? Mesothelial cells are a kind of epithelium in the cavity that provide a kind of sack which are attached by a basal lamina. What is OHM’s law? OHM’s law ΔV=R x current ΔP= resistance x flow What kind of vessels supply oxygenated blood to the myocardium?They pair at coronary arteries and they are called capillaries (exchange vessels). There is a cardiac sinus  venous return in the right atrium. Lecture 30 (October 20th, 2014)What are contractile and conductile cardiomyocytes and what is their function alone and together? Contractile cardiomyocytes: comprise the myocardium of the atria and ventricles by doing two things:>generate force by sarcomere shortening >99% of cardiomyocytesConductile cardiomyocytes: to carry/propagate electrical signals from sites of signal initiation to the contractile cells. Without these you can’t generate a heartbeat or a contraction and your heart can’t function without both of them the two have to work in concert with each other. One downside of conductile cardiomyocytes is that they largely lack contractile machinery and have specialized ion channels. They both contain a single nucleus, they are fairly small, and fairly similar. The two are interdigitated with each other at the site known as the intercalated disk.-the plasma membranes of the two never fuse, they are always separate but in the disks there are gap junctions. These gap junctions (as communicating junctions) provide electrical continuity and there are also desmosomes (anchoring junctions) not as important in the conductile cell. Describe the conductile system and its functions. There’s a wall that separates the left and right ventricles from each other called the septum. The other piece is that the only connection between the atria and ventricles is throughthe atria ventricular valves and there’s a connective tissue layer that isolates the atrial myocardium from the ventricular myocardium. All of them will be connected together but there are separate electrical pathways that are only connected by the conductile system.On the outside wall of the right atrium is a structure known as the sinoatrial node (SA node) >cluster of conductile cardiomyosins If you look at the surface of the right atrium you will see clusters of the SA nodes and there’s a linkage that goes over to the left atrium. Once we get down on the wall of the ventricular myocardium there is a structure known as the atrial ventricular node and there are also bundle of HIS which is a common bundle that comes out of the AV node which splits into two branches the left and the right bundle branch, these bundle branches then branchesfurther and they are called purkinje fibers which play the role of delivering action potentials to contractile cardiomyocytes.Lecture 31 (October 22nd, 2014) What kind of channels do we see in the contractile cells? **the distribution of channels is extremely important In the contractile cells we see many channels >v-gated Na+ channels >v-gated Ca2+ channels dihydropurine receptors >v-gated K+ channels -all of these channels are working in concert to generate the cardiac contractile action potential -they all work at the T-SR junction to release Ca2+ from the sarcoplasmic reticulum Describe the contraction of contractile cells. In the contractile cells there are Z-lines >have the attachment of actin thin filaments >these are characterized by having filamentous actin, trophin complexs (trophin C), and tropomyosin -all of the rules of muscle contraction apply here as well -there is an extension of the sarcolemma called the transverse tubule -there are regions with sarcoplasmic reticulum and just about touches the t-tubule membrane What happens at the interface of the conductile cells? >sarcoplasmic reticulum: ca2+ storage > along the sarcolemma there are v-gated sodium channels -when the gate on the sodium channel swings open there is now an influx of sodium ions which causes us to reach threshold and we get the influx of sodium to produce depolarization (not much over 0mm). The v-gated sodium channels inactivate. -there’s a very long plateau that is produced from the influx of Ca2+ through v-gated Ca2+ channels (dihydropyrine receptors) and their function is to allow calcium into the cell fromthe extracellular environment and in the sarcoplasmic reticulum is the rhymaine receptor which is opened by the Ca2+ influx. This process is calcium induced calcium release. This all then causes classic muscle contraction.-after all this occurs there is the opening of the v-gated potassium channels which then closes the ca2+ channels and stops the release of calcium which makes contraction stop. Then there’s a period of diastolic filling when the blood is flowing into the ventricles and here we arethen resetting the sarcomeres, waiting for the action potential from the conductile system to arrive. **this pattern happens throughout life, when it stops so do we Describe the function of the autonomic nervous system.The autonomic nervous system affects cardiac muscle, smooth muscle, and glands and ithas different role on cardiac muscle is the conductile and contractile cardiomyocytes. -sympathetic branch: fight or flight-parasympathetic branch: rest and digest What happens in the central nervous system? In the central nervous system there will always be a neuronal cell body which then sendsa process out into the periphery called the autonomic ganglion in the PNS which then also sends a process out and innervates a targe. -one issue we will always see is the neuron with a cell body in the CNS (preganglionic autonomic neuron) because in the periphery it synapses onto the postganglionic autonomic neuron. -in all cases the neurotransmitter released from the 1st cell releases astrochyline -the input region contains nicoytinc acetylcholine -the “target” is the heart -postganglionic synapse onto the target releases acetylcholine for the parasympathic branch but for the sympathetic branch it releases norepipherine -in both cases the neurotransmitter released binds to a G-protein coupled receptor **G-protein