1 Biology 232 – Physiology & Anatomy 1 Additional Slides for Lecture Exam #3(With guided notes… be sure to look in the notes sections for PowerPoint in this document… these will be very helpful!)These notes will guide you through a few basic ideas that will help further shape your understanding of the nervous system. They are important for you to understand for exam #3.
2 Know this individual’s name and his work. Wilder Penfield 1891 – 1976Physician and Neuroscientist who mapped the brain in what became the “homunculus”
3 Figure 12.9: Motor and sensory areas of the cerebral cortex, p. 438. ShoulderTrunkKneeTrunkNeckHipLegHipHeadArmArmElbowElbowWristForearmHandFingersHandFingersThumbThumbEyeNeckNoseBrowFaceEyeLipsGenitalsFaceToesTeethGumsLipsThis is the homuncular map Penfield created. What is interesting to note are the following:The regions of the body are mapped across these motor and sensory areas of the cortex showing the relative amount of cortex devoted to each region. So, interestingly, some areas are disproportionally larger or smaller than there respective size in the body. For example:Notice how SMALL the cortex representation for the TORSO is compared to how big the torso is in our body. This shows that there are relatively fewer nerve connections to the torso.Notice how LARGE the cortex representation for the LIPS, FACE, FINGERTIPS, and FOOT are relative to how big these structures are in our body. This shows that there are a lot more nerve connections between these structures and our brain.The above associations are LOGICAL. Think about how much more precise SENSORY and MOTOR function you have for your LIPS, FACE, FINGERTIPS, and FOOT compared to how less precise your SENSORY and MOTOR control is for your torso.JawJawTongueTonguePharynxSwallowingMotor cortex(precentral gyrus)Intra-abdominal
4 Figure 12.5: Ventricles of the brain, p. 434. LateralventricleLateralventricleAnteriorhornThirdventricleSeptumpellucidumPosteriorhornThirdventricleInter-ventricularforamenCerebralaqueductCerebralaqueductFourthventricleInferiorhornFourthventricleMedianapertureLateralapertureCentralcanalFrom lab, you know that the blue spaces are the ventricles. They are fluid filled spaces in the brain. They are filled with cerebrospinal fluid (CSF). Also note that CSF flows AROUND the brain and spinal cord as well and is held in position by the meninges. There are three meningial layers…. The DURA mater, the ARACHNOID mater, and the PIA mater.The DURA mater is the OUTERMOST meningial layer and is DURAble.The ARACHNOID mater is the MIDDLE meningial layer and looks spider-web like.The PIA mater is the inner most layer and articulates directly with the brain.You should already know these three layers from lab.Centralcanal(a)Anterior view(b)Left lateral view
5 Figure 12.26: Formation, location, and circulation of CSF, p. 466. Superiorsagittal sinusSuperiorcerebral veinArachnoidvillusChoroid plexusCerebrum coveredwith pia materSubarachnoid spaceArachnoid materSeptumpellucidumMeningeal dura materPeriosteal dura materGreat cerebral veinCorpuscallosumTentorium cerebelliInterventricularforamenStraight sinusConfluence of sinusesThird ventriclePituitary glandCerebellumCerebral aqueductChoroid plexusLateral apertureCerebral vesselsthat supplychoroid plexusFourth ventricleMedian apertureI am repeating information from the previous slide above here, but please note that CSF flows AROUND the brain and spinal cord as well and is held in position by the meninges. There are three meningial layers…. The DURA mater, the ARACHNOID mater, and the PIA mater.The DURA mater is the OUTERMOST meningial layer and is DURAble.The ARACHNOID mater is the MIDDLE meningial layer and looks spider-web like.The PIA mater is the inner most layer and articulates directly with the brain.You should already know these three layers from lab.Central canalof spinal cordSpinal dura materInferior end ofspinal cordFilum terminale(inferior endof pia mater)(b)
6 Figure 12.31b: Anatomy of the spinal cord, p. 473. Posterior median sulcusGray commissurePosterior funiculusDorsal (posterior) hornGraymatterWhitecolumnsAnterior funiculusVentral (anterior) hornLateral hornLateral funiculusDorsal rootganglionSpinal nerveCentral canalDorsal rootAnterior medianfissureVentral rootPia materHere again you can see the three meningial layers.ArachnoidSpinal mater(b)
7 Three terms to know in regards to these injuries: Figure 13.12a: Dermatomes, p. 518.C2C3C4C5T1T2T3T2T4T2T5T6T7T8C5T9C5T10C6C6T11T12C6L1L1C6C7S2C7C8S3C8L2L2L3L3Please note that these dermatomes represent the regions of the body that are innervated by the respective spinal nerve identified in each. This mapping system helps to illustrate how various spinal cord and spinal nerve injuries may impact the body. The individual with such an injury will lose nervous system control over the somatic skelletal muscular actions below the point of injury (in cases of spinal cord) or radiating away from the point of injury (such as peripheral nerve).A SPECIAL NOTE: Notice how spinal nerve innervation of the arms is mostly through CERVICAL spinal nerves but there is some input as well from THORASCIC spinal nerves.Three terms to know in regards to these injuries:Paraplegia – the disorder resulting typically from a severing of the lower spinal column (such as T 10 – Lumbar). Paraplegia results in the loss of control of the legs.Quadraplegia – the disorder resulting typically from a severing of the upper spinal column (such as from C1 – T1). Paraplegia results in the loss of control of both arms and legs.Hemiplegia – Severing of a peripherial spinal nerve or peripherial cranial nerve. In these instances, the lost of control is outward in the peripherial body away from the injury site.Please note that paraplegia and quadraplegia occur in a variety of forms. There are more mild and more severe forms of each depending upon the location of the injury.L4L4L5L5S1S1(a)
8 Figure 13.12b: Dermatomes, p. 518.C2C3C4C5C6C7C8T1T2C5T3T4T5T6T7T8T9T10C6C6T11C7T12C7L1C8L2S1L3C8L4S2L5S3S4S5S1S2S2S1L1L5L2L5Here is the dorsal side of the dermatome map. When the (now deceased) actor, Christopher Reeves had his tragic injury in the early 1990s, he severed and/or compressed his spinal column in the region of the C1 and C2 vertebrae. His injuries from the severing were so severe, he only could sense touch on the surface of his face.L3L4L4L4L5L5S1(b)
9 Figure 14. 2: Comparison of somatic and autonomic nervous systems, p Centralnervous systemPeripheral nervous systemEffector organsAcetylcholineSomatic nervous systemSkeletal muscleAcetylcholineNorepinephrineSmoothmuscle(e.g., ingut)GanglionSympatheticdivisionAcetylcholineEpinephrine andnorepinephrineAutonomicnervoussystemBloodvesselGlandsAdrenal medullaAcetylcholineWhen we compare the somatic and autonomic nervous systems together, it is truly striking how COMPLEX the autonomic system is in comparison with the somatic. Most of the neurotransmitters (NTs) used in the somatic system are in effect acetylcholine or a very close correlate to it. However, in the autonomic nervous system, we see literally, thousands of different NTs used within the function of the autonomic nervous system. In the example above, you can see examples of both the (relatively) simple somatic, and the (much more) complex autonomic nervous system.CardiacmusclePara-sympatheticdivisionGanglionKey:= Preganglionic axons(sympathetic)= Postganglionic axons(sympathetic)= Myelination= Preganglionic axons(parasympathetic)= Postganglionic axons(parasympathetic)
10 Figure 14.3: Overview of the subdivisions of the ANS, p. 536. ParasympatheticSympatheticEyeEyeBrain stemSalivaryglandsSkin*CranialSalivaryglandsSympatheticgangliaHeartCervicalLungsLungsT1HeartStomachThoracicStomachPancreasLiverand gall-bladderPancreasL1I think this diagram is crucial to know and understand how patients with spinal cord injuries can survive and maintain (at least some) function of body parts below the site of injury.For example, a person who is quadriplegic with a C4 spinal severing…. Have you ever thought about… how does his/her stomach still function in being able to digest food? How does he/she maintain heart rate and heart compression strength?Well, the basic idea is that the point of entry for many PARASYMPATHETIC innervations of body regions with the CNS is MUCH, MUCH higher up the length of the spinal column than are the corresponding sympathetic innervations. By being higher in location, they can still maintain a level of functional control over these organs.Liver andgall-bladderAdrenalglandLumbarBladderBladderGenitalsGenitalsSacral
11 English physiologist who first advanced the theory of how the Important historical figure related to the reflex arcs you have studied in lab and we mentioned in lecture. Remember that the reflex arcs are important for us in maintaining balance and body posture/position.Marshall Hall – 1857English physiologist who first advanced the theory of how thereflex arc worked.
12 Figure 13.14: The basic components of all human reflex arcs, p. 521. Spinal cord (in cross section)Stimulus2Sensory neuron3Integration center1ReceptorMotor neuronInterneuronSkin45EffectorYou have studied reflex arcs in lab. The basic notion is that you need to keep in mind that these are ABBREVIATED pathways for neural message movement. In most scenerios they are used to elicit a quicker response time. There actions are autonomically controlled. Examples for balance and body position include the Patellar Reflex, the Achillies Reflex, and the Babinski (Plantar) Reflex.In the above, the pain response is also a reflex arc. The pain signal routes quickly to the spinal cord, and while some of the signal may go to the brain, a large part of the signal passes through the spinal cord via the interneuron and moves immediately back out to the periphery to effect change in the muscle group(s) controlling the area of the body where the pain is being experienced to have us reflexively “jerk” the body part away from the pain.
13 Sigmund Freud is the founding father of an important area of psychology called Psychoanalysis. His work that revolutionized the field of psychology really was due to his training and effort as a physiologist. He studied the nervous system, and was focused on studying parts associated with the autonomic nervous system. While studying the autnomic nervous system, he theorized about the governance of this region and coined the terms “id”, “ego”, and “superego” to demarcate his theories.Sigmund Freud
14 CNS PNS Sensory division Motor division Sympathetic division Autonomic Figure 14.1: Place of the ANS in the structural organization of the nervous system, p. 533.CNSPNSSensory divisionMotor divisionSo, here we are looking at the sympathetic and parasympathetic nervous systems. As stated in class, these are responsible for the facets of our stress responses. Remember that the sympathetic is activated in the “fight or flight” responses and the parasympathetic in the “resting and digesting” responses.SympatheticdivisionAutonomicnervoussystemSomaticnervoussystemParasympatheticdivision
15 Figure 14.8: Referred pain, p. 543. HeartLungs anddiaphragmLiverGallbladderGallbladderHeartAppendixLiverStomachPancreasSmallintestineOvariesThis diagram displays what are known as referred pain sites in the body. Referred pain occurs in regions of the body to signify pain/damage that is occurring in some other region of the body that lacks its own direct pain receptors.The classic example of this is seen in a patient who is experiencing or is very close to experiencing a heart attack. Prior to the catastrophic heart attack itself, a patient will often report the sensation of a radiating pain down the inner left arm. This is because this is a classic referred pain site for heart pain in human males, and most every male with some sort of heart attack damage will display this referred pain site.Unfortunately, until recently, it was not recognized that women’s physiology may differ in regard to referred pain signals. A much lower percentage of women near or experiencing a heart attack will display the referred pain symptoms of pain radiating down the inside left arm (estimates are that only ~35% show this sign). In the other cases, the referred pain site may be in the lower back region or (more commonly) as pain in the jawline.Please keep in mind that medical science is still rather inexact at this time. There are many things we do not yet know about countless subjects. But the recent identification of sexually dimorphic differences in referred pain sites is an important, relatively recent, discovery.ColonKidneysUrinarybladderUreters