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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.
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Know this individual’s name and his work.
Wilder Penfield 1891 – 1976 Physician and Neuroscientist who mapped the brain in what became the “homunculus”
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Figure 12.9: Motor and sensory areas of the cerebral cortex, p. 438.
Shoulder Trunk Knee Trunk Neck Hip Leg Hip Head Arm Arm Elbow Elbow Wrist Forearm Hand Fingers Hand Fingers Thumb Thumb Eye Neck Nose Brow Face Eye Lips Genitals Face Toes Teeth Gums Lips This 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. Jaw Jaw Tongue Tongue Pharynx Swallowing Motor cortex (precentral gyrus) Intra- abdominal
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Figure 12.5: Ventricles of the brain, p. 434.
Lateral ventricle Lateral ventricle Anterior horn Third ventricle Septum pellucidum Posterior horn Third ventricle Inter- ventricular foramen Cerebral aqueduct Cerebral aqueduct Fourth ventricle Inferior horn Fourth ventricle Median aperture Lateral aperture Central canal From 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. Central canal (a) Anterior view (b) Left lateral view
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Figure 12.26: Formation, location, and circulation of CSF, p. 466.
Superior sagittal sinus Superior cerebral vein Arachnoid villus Choroid plexus Cerebrum covered with pia mater Subarachnoid space Arachnoid mater Septum pellucidum Meningeal dura mater Periosteal dura mater Great cerebral vein Corpus callosum Tentorium cerebelli Interventricular foramen Straight sinus Confluence of sinuses Third ventricle Pituitary gland Cerebellum Cerebral aqueduct Choroid plexus Lateral aperture Cerebral vessels that supply choroid plexus Fourth ventricle Median aperture I 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 canal of spinal cord Spinal dura mater Inferior end of spinal cord Filum terminale (inferior end of pia mater) (b)
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Figure 12.31b: Anatomy of the spinal cord, p. 473.
Posterior median sulcus Gray commissure Posterior funiculus Dorsal (posterior) horn Gray matter White columns Anterior funiculus Ventral (anterior) horn Lateral horn Lateral funiculus Dorsal root ganglion Spinal nerve Central canal Dorsal root Anterior median fissure Ventral root Pia mater Here again you can see the three meningial layers. Arachnoid Spinal mater (b)
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Three terms to know in regards to these injuries:
Figure 13.12a: Dermatomes, p. 518. C2 C3 C4 C5 T1 T2 T3 T2 T4 T2 T5 T6 T7 T8 C5 T9 C5 T10 C6 C6 T11 T12 C6 L1 L1 C6 C7 S2 C7 C8 S3 C8 L2 L2 L3 L3 Please 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. L4 L4 L5 L5 S1 S1 (a)
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Figure 13.12b: Dermatomes, p. 518. C2 C3 C4 C5 C6 C7 C8 T1 T2 C5 T3 T4 T5 T6 T7 T8 T9 T10 C6 C6 T11 C7 T12 C7 L1 C8 L2 S1 L3 C8 L4 S2 L5 S3 S4 S5 S1 S2 S2 S1 L1 L5 L2 L5 Here 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. L3 L4 L4 L4 L5 L5 S1 (b)
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Figure 14. 2: Comparison of somatic and autonomic nervous systems, p
Central nervous system Peripheral nervous system Effector organs Acetylcholine Somatic nervous system Skeletal muscle Acetylcholine Norepinephrine Smooth muscle (e.g., in gut) Ganglion Sympathetic division Acetylcholine Epinephrine and norepinephrine Autonomic nervous system Blood vessel Glands Adrenal medulla Acetylcholine When 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. Cardiac muscle Para- sympathetic division Ganglion Key: = Preganglionic axons (sympathetic) = Postganglionic axons (sympathetic) = Myelination = Preganglionic axons (parasympathetic) = Postganglionic axons (parasympathetic)
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Figure 14.3: Overview of the subdivisions of the ANS, p. 536.
Parasympathetic Sympathetic Eye Eye Brain stem Salivary glands Skin* Cranial Salivary glands Sympathetic ganglia Heart Cervical Lungs Lungs T1 Heart Stomach Thoracic Stomach Pancreas Liver and gall- bladder Pancreas L1 I 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 and gall- bladder Adrenal gland Lumbar Bladder Bladder Genitals Genitals Sacral
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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 – 1857 English physiologist who first advanced the theory of how the reflex arc worked.
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Figure 13.14: The basic components of all human reflex arcs, p. 521.
Spinal cord (in cross section) Stimulus 2 Sensory neuron 3 Integration center 1 Receptor Motor neuron Interneuron Skin 4 5 Effector You 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.
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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
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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. CNS PNS Sensory division Motor division So, 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. Sympathetic division Autonomic nervous system Somatic nervous system Parasympathetic division
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Figure 14.8: Referred pain, p. 543.
Heart Lungs and diaphragm Liver Gallbladder Gallbladder Heart Appendix Liver Stomach Pancreas Small intestine Ovaries This 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. Colon Kidneys Urinary bladder Ureters
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