Chapter 16: The Brain and Cranial Nerves

Anatomy 201 Exam III OBJECTIVES GUIDE____________ Chapter 16: The Brain and Cranial Nerves Sections :16.1 through 16-19. I highlighted anatomy and selected topics of some areas (see lectures). Identify the major regions of the brain and explain their functions. Have a general idea of the functions of various regions of the brain, the limbic system, the basal ganglia, the cerebral cortex, the cerebellum, brain stem and mid 6 MAJOR REGIONS OF THE BRAIN 1) 2) 3) 4) 5) 6) Cerebrum Diencephalon (thalamus, hypothalamus, epithalamus) Mesencephalon (Midbrain) Pons Medulla Oblongata Cerebellum LIMBIC SYSTEM Includes nuclei and tracts along the border between the cerebrum and diencephalon FUNCTIONS 1) Establishing emotional states and related behavioral drives 2) Linking the conscious, intellectual functions of the cerebral cortex with the unconscious and autonomic functions of other portions of the brain 3) Facilitating memory storage and retrieval Includes the Hippocampus- lies deep within the temporal lobe; plays an essential role in learning and storage of long-term memories. MEMORY CONSOLIDATION. Also includes the Amygdala- emotion processing BASAL GANGLIA Masses of gray matter that lie within each hemisphere deep to the floor of the LATERAL VENTRICLE. They are embedded in the white matter of the cerebrum FUNCTIONS 1) subconsciously control and integrate skeletal muscle tone 2) coordinate learned movement patterns 3) process, integrate, and relay information from the cerebral cortex to the thalamus BASAL GANGLIA DOES NOT INITIATE PARTICULAR MOVEMENTS ONCE A MOVEMENT IS UNDER WAY, BASAL GANGLIA COORDINATES THE MOVEMENT BY PROVIDING THE GENERAL PATTER & RHYTHM. CEREBRAL CORTEX The cerebral cortex performs higher-order functions that involve complex communication within the cerebral cortex and between the cerebral cortex and other areas of the brain. CEREBELLUM The second largest part of the brain Has 2 hemispheres that lie posterior to the pons and inferior to the cerebral hemispheres. CEREBELLUM ADJUSTS MOTOR ACTIVITIES based on sensory info and memories of learned movement. BALANCE BRAINSTEM Contains important processing centers that relay information to and from the cerebrum or cerebellum. Made up of medulla oblongata, the pons, and the mesencephalon(midbrain). MIDBRAIN Processes visual and auditory information and coordinates reflexive somatic motor responses to visual and auditory stimuli. Contains centers that maintain LOC’S- (maintains consciousness and levels of alertness) How does the brain develop in the early embryo? The brain starts as a small, hollow tube that forms 3 primary vesicles: the prosencephalon, mesencephalon, and rhombencephalon. The prosencephalon and rhombencephalon subdivide to form secondary brain vesicles. Hollow tube is a fluid filled internal cavity called the Neurocel. Passageway expands to form enlarged chambers called ventricles Expansion = the 3 primary vesicles By the 4th week of development- three areas in the cephalic portion of the tube have extended rapidly Prosencephalon (FOREBRAIN)- Subdivides to form the telencephalon (CEREBRUM) & the diencephalon (EPITHALAMUS, THALAMUS, HYPOTHALAMUS) Mesencephalon (MIDBRAIN) (does not further divide) Rhombencephalon (HINDBRAIN)- Subdivides to form the metencephalon (PONS, CEREBELLUM) & the myelencephalon (MEDULLA OBLONGATA) What is a fissure? What is a sulcus? What is the central sulcus and longitudinal fissure? FISSURE- deep groove SULCUS- folds LONGITUDINAL FISSURE- separates the cerebrum into L and R cerebral hemispheres Cerebrum: cerebral hemispheres, longitudinal fissure, gyri, sulci, lobes (basic function of each one), superficial gray layer-cortex, ventricles, (how are they organized), pre-central and post-central gyrus (What are these two strips of cortex all about? how are they organized? CEREBRUM Largest region of the brain. Consists of paired cerebral hemispheres, which rest of the diencephalon and brainstem. Conscious thought processes and all intellectual functions originate in the cerebral hemispheres. The cerebrum is divided into L and R hemispheres, covered by thick blanket of superficial gray matter (cerebral cortex) Cerebral cortex: performs the most complicated neural functions and these analytical and integrative activities require large numbers of neurons. Cortical surface is marked by gyri and sulci Gyri-increase surface area of cerebral hemispheres and provide space for additional cortical neurons Longitudinal fissure- separates the two cerebral hemispheres Central sulcus- extends laterally from the longitudinal fissure Lateral sulcus- marks the frontal lobes inferior border Precentral gyrus- forms the anterior margin of the central sulcus Surface of this gyrus is primary motor cortex. Neurons of the primary cortex direct voluntary movements by controlling somatic motor neurons in the brainstem and spinal cord. Postcentral gyrus- forms the posterior margin of the central sulcus and its surface contains the primary somatosensory cortex. The posterior columns of the spinothalamic tracts provide the neurons in this region with sensory information from touch, pressure, pain, and temperature receptors. Name and be able to recognize the lobes of the cerebral cortex. 4 MAJOR LOBES OF CEREBRAL CORTEX Frontal lobe Parietal lobe Temporal lobe Occipital lobe Cranial Meninges: Organization: pia, arachnoid, dura (give specifics of each layer). Give the basic anatomy of each layer. How does the Tentorium cerebelli, falx cerebelli, falx cerebri-come into play here? Arachnoid sinus? CRANIAL MENINGES Within the cranial cavity, the cranial meninges protect the brain. The meninges surround the brain and act as a shock absorber, preventing contact with the skull bones. They are continuous with the spine meninges and have the same three layers: DURA MATTER (OUTERMOST LAYER) ARACHNOID MATTER (MIDDLE) PIA MATTER (INNERMOST) DURA MATTER (OUTERMOST LAYER) “Tough mother” Is made up of dense connective tissue Has 2 fibrous layers 1) Outermost layer: PERIOSTEAL CRANIAL DURA Is fused to the periosteum lining the cranial bones 2) Innermost layer: MENINGEAL CRANIAL DURA Periosteal and meningeal dura are separated by a space containing interstitial fluid and blood vessels, including large collecting veins called Dural sinuses. Dura matter has 4 major folds FALX CEREBRI TENTORIUM CEREBELLI FALX CEREBELLI DIAPHRAGMA SELLAE ARACHNOID MATTER (MIDDLE) “Spidery mother” Contains villi for return of CSF to general circulation Network of connective tissue A delicate membrane covering the brain between the superficial dura matter and the deeper pia matter Subdural space: separates the dura matter and the cranial arachnoid matter. Deep to the arachnoid mater is the subarachnoid space. Subarachnoid space: contains a delicate, weblike meshwork of collagen and elastic fibers linking the arachnoid mater to the underlying pia matter. Has projections called arachnoid granulations: CSF flows through, crosses arachnoid matter, and enters venous circulation * PIA MATTER (INNERMOST) “Delicate mother” Loose connective tissue Tightly attached to the surface contours of the brain, sticking to its contours, and lining the sulci HIGHLY VASCULAR MEMBRANE Acts as a floor to support and anchor the large cerebral vessels as the branch and follow the convolutions of the brain, supplying superficial areas of the cerebral cortex w blood. Where does CFS enter the venous system for recycling? At the ARACHNOID GRANULATIONS Cerebrospinal fluid flows past the bundles of connective tissue fibers (termed the arachnoid trabeculae), crosses the arachnoid mater, and enters the venous circulation. What is an Epidural hematoma? EPIDURAL HEMATOMA is an accumulation of blood between the inner table of the skull and the dura mater. Most result from: SKULL FRACTURES Most are located: in the TEMPOROPARIETAL REGION where a skull fracture crosses the path of the middle cerebral artery TX: often requires emergency surgery to relieve pressure to the brain that involves drilling a hole in the skull and allowing the blood to drain. What ventricles of the brain? How are they situated? 4 VENTRICLES OF THE BRAIN 1 in the L hemisphere 1 in the R hemisphere 3rd ventricle within the diencephalon 4th ventricle between the pons and cerebellum Each ventricle is filled w CSF and lined by ependymal cells (type of glial cell) LATERAL VENTRICLES: ventricles in the cerebral hemispheres are separated by the septum pellucidum Each lateral ventricle has a body, anterior horn, posterior horn, and inferior horn. There is NO DIRECT CONNECTION* between the 2 lateral horns Each individual lateral horn communicates w the 3rd ventricle through the interventricular foramen THIRD VENTRICLE Communicates with the fourth ventricle through the aqueduct of the midbrain FOURTH VENTRICLE Communicates w the central canal of the spinal cord Choroid Plexuses: Where are they found? Histology? Function? CHOROID PLEXUS All ventricles contain a CHOROID PLEXUS Choroid plexus: a combination of specialized ependymal cells and highly permeable capillaries. -Choroid plexus produces CSF Ependymal cells within the choroid plexus use both active and passive transport mechanisms to secrete CSF into the ventricles. -Choroid plexus also actively removes wastes from CSF Medulla Oblongata: Location, basic function(s). MEDULLA OBLONGATA The medulla oblongata is continuous with the spinal cord and brainstem All communication between the brain and spinal cord passes through the medulla oblongata through ascending or descending tracts Medulla includes 3 groups of nuclei with various functions 1) Relay stations and processing centers: Ascending tracts synapse sensory or motor nuclei within the medulla. Sensory and motor nuclei act as RELAY STATIONS & PROCESSING CENTERS. 2) Nuclei of cranial nerves: Medulla oblongata contains sensory and motor nuclei for 5 cranial nerves. (VIII IX X XI & XIII) 3) Autonomic nuclei: The reticular formation in the medulla oblongata contain nuclei and centers responsible for regulating vital autonomic functions. These reflex centers receive input from cranial nerves, the cerebral cortex, diencephalon, and brainstem and their output adjusts the activities of one or more peripheral systems. Cardiovascular centers: Adjust HR, strength of cardiac contractions, and flow of blood trough peripheral tissues. Respiratory rhythmicity centers: set the basic pace for breathing Pons: Locations function, PONS Pons is a prominent bulge superior to the medulla oblongata Pons contain sensory and motor nuclei for four cranial nerves, nuclei involved with involuntary control of respiration, and nuclei that process and relay cerebellar signs. The pons also contains ascending, descending, and transverse tracts Pons contains: 1)sensory and motor nuclei for four cranial nerves: CN V, VI, VII, VIII innervate jaw muscles, the anterior surface of the face, one of the extra-ocular muscles, and organs of hearing and equilibrium in the internal ear. 2) nuclei regulating the involuntary control of respiration: centers regulate the activity of the respiratory rhythmicity center in the medulla oblongata 3) nuclei that process and relay cerebellar commands: info entering the cerebellum by the middle cerebellar peduncles passes through the pons 4) ascending, descending, and transverse tracts: the longitudinal tracts of the pons connect the pons to other portions of the CNS. . Mesencephalon- Structures found here, Corpora Quadrigemina MESENCEPHALON (MIDBRAIN) The mesencephalon (midbrain) contains nuclei that process visual and auditory stimuli. The mesencephalon also contains major nuclei of the reticular formation. Its surface posterior to the cerebral aqueduct is called the roof, or tectum, of the mesencephalon. This region contains two pairs of sensory nuclei (superior colliculi and inferior colliculi) known as the corpora quadrigemina Superior and inferior colliculi nuclei are relay stations concerned w processing visual and auditory sensations SUPERIOR COLLUCULI- Receive visual input from the lateral geniculate of the thalamus on the ipsilateral (same) side INFERIOR COLLUCULI- receive auditory input from nuclei in medulla oblongata **(REMEMBER: BIG CHEEKS , LITTLE CHEEKS) ** Fornix, Corpus Collosum, optic chiasm, FORNIX- A tract of white matter connecting the hippocampus w the hypothalamus. Once it's exiting the hippocampus, the fornix curves medially and superiorly, passing the corpus collosum inferiorly. Forms an arch and curves, ending in the hypothalamus. Fibers of the fornix end in the mammillary bodies. CORPUS CALLOSUM – Bundle of axons linking centers in the left and right cerebral hemispheres. OPTIC CHIASM – Where the optic nerves from the eyes arrive at the brain. “Crossing point of the optic nerves. . What is the pineal gland? Secretion? PINEAL GLAND The small, red, pinecone-shaped pineal gland, or pineal body, is part of the epithalamus that contains neurons and interstitial cells that resemble the neuroglia of the CNS. Also contains special secretory cells called pinealocytes Pineal gland secretes MELATONIN What is meant by “lateralization” of the cerebral cortex. What is contralateral? (cerebrum) What is ipsilateral? (Cerebellum) LATERALIZATION Each of the two cerebral hemispheres is responsible for specific functions that are not ordinarily performed by the opposite hemisphere, a type of specialization L hemisphere controls: Language Language-based skills Reading Writing Speaking Performing analytical tasks Mathematical calculations Logical decision making R hemisphere controls: Analyze sensory info Recognition Emotions Art Imagination Each cerebral hemisphere receives sensory information from and generates motor commands to the contralateral (opposite) side of the body. Therefore, the left hemisphere controls the right side, and the right hemisphere controls the left side. This crossing over has no known functional significance. Each cerebellar hemisphere regulates and coordinates muscular activity only on its ipsilateral side (SAME SIDE) Diencephalon: Thalamus: Location, structure, and function (be familiar with figure 16.11 in text) and in presentation (the families of nuclei- note the sensory) THALAMUS The thalamus is the largest mass of nuclei within the entire CNS, and the connections within the thalamus are more diverse than any other part of the CNS. Nuclei in the thalamus integrate and relay sensory and motor information. REMEMBER THIS IS YOUR SENSORY RELAY SYSTEM FOR EVERY SENSE EXCEPT SMELL!! All ascending sensory information from the spinal cord synapses in the thalamic nuclei before the information is relayed to the cerebrum or brainstem. The thalamic nuclei process sensory and motor information and then relay it to the basal nuclei and cerebral cortex. The five major groups of thalamic nuclei, are the following: 1) Anterior nuclei- play a role in emotions , memory, and learning. Relay info from the hypothalamus and hippocampus to the cingulate gyrus 2) Medial nuclei- provide an awareness of emotional states. Connect emotion centers in the hypothalamus w the prefrontal cortex of the cerebrum 3) Ventral nuclei- relay info from basal nuclei of cerebrum and cerebellum to somatic motor areas of the cerebral cortex Relay sensory info about touch, pressure, pain, temp, and proprioception (position) to sensory areas of the cerebral cortex. 4) Posterior nuclei- include pulvinar and geniculate nuclei Pulvinar: integrates sensory info and then projects it to the association areas of the cerebral cortex Lateral geniculate: receives visual information from the eyes. Efferent fibers project to the visual cortex and to the mesencephalon Medial geniculate: relay auditory information to the auditory cortex from receptors of the inner ear. 5) Lateral nuclei- relay stations in feedback loops that adjust activity in the cingulate gyrus and parietal lobe, have an impact on emotional states and the integration of sensory info Diencephalon: Hypothalamus: Location, structure, and functions: (figure on page 419) HYPOTHALAMUS The hypothalamus contains centers involved with emotions and visceral processes affecting the cerebrum and parts of the brainstem. & Controls a wide variety of autonomic functions and functionally links the nervous and endocrine systems. Form the floor of the third ventricle Extends from the area superior to the optic chiasm to the posterior margins of the mamillary bodies Hypothalamic centers continually receive sensory information from the cerebrum, brainstem, and spinal cord Hypothalamic neurons also detect and respond to changes in the CSF and interstitial fluid composition Centers also respond to stimuli in the circulating blood FUNCTIONS INCLUDE: -Subconscious control of skeletal muscle contractions: They stimulate other parts of the brain and direct somatic motor patters r/t emotions of rage, pleasure, pain and sexual arousal -Control of autonomic functions: hypothalamus adjusts and coordinates autonomic functions such as HR, BP, RR, & digestive functions -Coordiantion of activities of the nervous & endocrine systems: inhibits or stimulates endocrine cells within the pituitary gland -Secretion of hormones: Supraoptic nucleus secretes ADH to regulate water loss by kidneys Paraventricular nucleus secretes oxytocin to stimulate smooth muscle in uterus and prostate gland -Production of emotions and behavioral drives: produce sensations that lead to changes in voluntary or involuntary behavior. EX: stimulation of thirst center produces desire to drink -Coordination between voluntary and autonomic functions: sympathetic and parasympathetic functions -Regulation of body temp: pre-optic area controls physiological responses to changes in body temp -Control of circadian rhythms: Suprachiasmatic nucleus coordinates daily cycles of activity linked to day-night cycle. Nucleus receives input from retina of the eye MAINTAIN HOMEOSTASIS* Cerebellum: Location and structurally organization (Folia, arbor vitae, lobes, peduncles) functions. CEREBELLUM THE SECOND LARGEST SINGLE STRUCTURE OF THE BRAIN The cerebellum has connections with the cerebral cortex, internal ear, and spinal cord. Each cerebellar hemisphere regulates and coordinates muscular activity only on its ipsilateral side (same side) It has 2 cerebellar hemispheres w a folded surface composed of cerebellar cortex. Folia- are the folds on the surface of the cerebellar hemispheres Lobes- each hemisphere has 2 lobes, anterior and posterior lobe which are separated by primary fissure. Anterior and posterior lobes assist in the planning, execution and coordination of limb and trunk movement Flocculonodular lobes- lie anterior and inferior to the cerebellar hemisphere. Flocculonodular lobe is important for balance and eye movements. Vermis-Separates L and R cerebellum hemispheres Arbor vitae-” tree of life”. Internal white matter of the cerebellum forms a branching array that resembles a tree. PEDUNCLES: are tracts that link the cerebellum w the brainstem, cerebrum and spinal cord Superior peduncles- link the cerebellum with nuclei in the mesencephalon, diencephalon and cerebrum Middle peduncles- connect the cerebellar hemispheres with sensory and motor nuclei in the pons Inferior peduncles- connect the cerebellum and nuclei in the medulla oblongata and carry ascending and descending cerebellar tracts from the spinal cord. FUNCTIONS OF THE CEREBELLUM: (according to the book) Cerebellum has TWO MAJOR FUNCTIONS 1) Adjusting the postural muscles of the body coordinates rapid, automatic adjustments to maintain balance and equilibrium. 2) Programming and fine-tuning voluntary and involuntary movements: stores memories of learned movement patters. FUNCTIONS OF THE CEREBELLUM (according to her powerpoint) -posture -balance -coordination -eye movements -speech White matter brain: Types of fibers: commissural, association, and projection. How are they the same? How are they different? (Compare) WHITE MATTER Association fibers: connect regions of cortex within the same hemisphere Commissural fibers: bridges between the 2 cerebral hemispheres. EX) corpus callosum Projection fibers: tracts that link the cerebrum w other regions of brain and spinal cord What are the basal nuclei? Be familiar with their names. We focused on the Substantia Nigra. BASAL NUCLEI (SUBSTANTIA NIGRA) The basal nuclei are paired masses of gray matter within the cerebral hemispheres. Substantia nigra: Nerve cells in the substantia nigra produce the neurotransmitter dopamine and are responsible for relaying messages that plan and control body movement. Parkinson disease* is characterized by dopaminergic cell loss in the substantia nigra What is the Limbic system? Be familiar with included structures. Location? Basic function. LIMBIC SYSTEM The limbic system includes nuclei and tracts along the border between the cerebrum and diencephalon Limbic system includes: Hippocampus, amygdala, cingulate gyrus, fornix, hypothalamus, thalamus FUNCTIONS OF THE LIMBIC SYSTEM -Establishing emotional states and related behavioral drives -Linking the conscious, intellectual functions of the cerebral cortex w the unconscious and autonomic functions of other portions of the brain -Facilitating memory storage and retrieval Cranial Nerves: Know each by name and number. What is the Reticular Formation? How is it situated in the brain? General Functions? RETICULAR FORMATION Loose network of neurons that project from the brain stem (found in all areas) to the cerebral cortex FUNCTION to arouse the cortex to incoming sensory stimuli Important for your SLEEP/AWAKE cycles! **Be familiar with the Homunculus or “little man”. Why the differences in size of body structure that is represented on the sensory or motor cortex? They are located on pre and post CENTRAL SULCUS. This is the only question that I don't know where to find the answer to!! I remember her showing us a picture of the little man, but I looked through all the PowerPoints and it's not there. I remember her saying that the differences were r/t how sensitive those areas are? IDKKK 🙁 ** Epithalamus, structure, and function EPITHALAMUS The epithalamus, the roof of the third ventricle, contains the pineal gland. Anterior portion of the epithalamus contains a choroid plexus that extends through the interventricular foramina into the lateral ventricles Posterior portion of the epithalamus contains the pineal gland, an endocrine structure that secretes the hormone melatonin Chapter 17: The Autonomic Nervous System We covered sections 17.1 -17.4 (some sections modified)- pay close attention to modified PowerPoint I posted and presented in class!! 1. Compare and contrast the roles of somatic and autonomic nervous systems. SOMATIC NERVOUS SYSTEM (SNS) Lower motor neurons innervate skeletal muscles Has efferent and afferent neurons Afferent pathways originate in the skeletal muscles Associated with voluntary movements of skeletal muscle SOMATIC- ALWAYS THINK MUSCLE AUTONOMIC NERVOUS SYSTEM (ANS) Innervates visceral effectors Has efferent and afferent neurons Afferent pathways originate in the visceral receptors Associated with involuntary activities of smooth muscles, glands, and visceral structures 2. How is the autonomic nervous system subdivided? The autonomic nervous system is subdivided into SYMPATHETIC “FIGHT OR FLIGHT”; primarily concerned w the elevation of metabolic rate and increased alertness ALSO CALLED THORACOLUMBAR DIVISION* Most active during stress, exertion, emergencies PARASYMPATHETIC “REST AND DIGEST”; generally responsible for activities that conserve enegy and lower metabolic rate ALSO CALLED CRANIOSACRAL DIVISION * Most active during resting conditions 3. The somatic nervous system innervates skeletal muscle. What does the autonomic NS innervate? (Know all effectors) The ANS innervates the following effectors (target tissues): -Smooth muscle -Cardiac muscle -Glands 4. Differences between the somatic NS and autonomic NS are not only the EFFECTORs but also the number of EFFERENT NEURONS. How do they differ?? (Notice the first and second neuron of the efferent neurons. The preganglionic: is it myelinated? The post-ganglionic: Is it myelinated? SOMATIC NS SOMATIC NERVOUS SYSTEM IS A 1 NERON SYSTEM (PREGANGLIONIC FIBER ONLY) Only have 1 preganglionic fiber, there is no second fiber. Preganglionic fiber- myelinated AUTONOMIC NS AUTONOMIC NERVOUS SYSTEM IS A 2 NEURON SYSTEM (PREGANGLIONIC AND POSTGANGLIONIC FIBER) In the autonomic nervous system, the axon of a visceral motor neuron innervates a second neuron located in a peripheral effector. Preganglionic fibers- myelinated Postganglionic fibers- unmyelinated (you can see myelination in this picture below) 5. Distinguish between the sympathetic and parasympathetic divisions of the nervous systems. Explain this in terms of thoracolumbar and craniosacral. Also, what is the third division of the ANS, the enteric nervous system? Sympathetic NS (thoracolumbar division) Preganglonic neurons are only located between T1-L2 of the spinal cord hence its name THORACOLUMBAR. Ganglionic neurons are in 3 locations 1) Sympathetic chain ganglia (or PARAVERTEBRAL GANGLIA) - a chain that is on both sides of the vertebral column. Preganglionic fibers go into this chain and postganglionic fibers leave this chain. Postganglionic fibers leaving this chair innervate effector organs in body wall, head/neck, limbs and thoracic cavity 2) Collateral ganglia (or PREVERTEBRAL GANGLIA)- These are ANTERIR to the vertebral column Postganglionic fibers exiting these ganglia innervate effector organs in the abdominopelvic cavity 3) Specialized sympathetic neurons are located in the interior of the adrenal gland, known as the adrenal medulla which acts as a modified sympathetic ganglion and relases neurotransmitters directly into the bloodstream for distribution throughout the body as hormones. Sympathetic NS has a SHORT PREGANGLONIC FIBER (extends from spinal cord to sympathetic chain) & a LONG POSTGANGLONIC FIBER (extends from spinal cord to body organs) **Preganglionic fiber releases ACH. Postganglionic fiber releases Norepinephrine** Sympathetic division has extensive divergence; a single preganglionic fiber may innervate as many as 32 ganglionic neurons in several different ganglia. As a result a single sympathetic moter neuron produces a complex and coordinated response PARASYMPATHETIC NS (craniosacral division) Preganglonic neurons are located in the brainstem and in sacral segments of the spinal cord, hence its name CRANIOSACRAL DIVISION. Postganglionic neurons are NEAR (terminal) the target organ or WITHIN (intramural) the target organ Parasympathetic NS has LONG PREGANGLIONIC fiber and SHORT POSTGANGLIONIC FIBER Parasympathetic division does not diverge as extensively as do those of the sympathetic division. A typical preganglionic fiber synapses on 6-8 ganglionic neurons. As a result, the effects of parasympathetic stimulation are more specific and localized. **ALL preganglionic ang postganglionic fibers release ACH at their synapses and neuroeffector junctions** Release of ACh stimulates nicotinic receptors on ganglionic neurons Release of ACh on neuroeffector junctions stimulates muscarinic receptors ENTERIC NERVOUS SYSTEM Autonomic NS includes a third division- the enteric nervous system. Enteric nervous system is an extensive nerve network in the walls of the digestive tract that initiates and coordinates digestive motility and secretions. ENS is affected mostly by sympathetic and parasympathetic divisions, but many complex visceral reflexes are initiated and coordinated locally. 6. Describe the preganglionic fibers and neurons and postganglionic fibers and neurons These questions are very repetitive. All concepts have already been covered ^^ ( size of pre/postganglionic, myelination, and region from where they emerge) 7. Name the neurotransmitter released by most postganglionic sympathetic fibers. Neurotransmitter released by most postganglionic sympathetic fibers is: NOREPINEPHRINE. 8. Be familiar with neurotransmitter releases at each preganglionic and postganglionic synapse for both sympathetic and parasympathetic. Parasympathetic Preganglionic synapse: ACh is released Postganglionic synapse: ACh is released Sympathetic Preganglionic synapse: ACh is released Postganglionic synapse: NE is released 9. Know terms “Cholinergic” and Adrenergic Cholinergic- r/t ACh Adrenergic- r/t Norepinephrine and epinephrine 10.What does the communicating rami have to do with the connection between the spinal cord and the autonomic pathway of innervation? 11.Where on the spinal cord (gray matter) do we find nuclei for autonomic tissue? 12.What is meant by “fight or flight” and “rest or digest” with respect to the autonomic nervous system? FIGHT OR FLIGHT- An increase in sympathetic activity that generally stimulates tissue metabolism, increases alertness and prepares the body to deal with emergencies. REST AND DIGEST- increase in parasympathetic activity that conserves energy and promotes sedentary activities, such as digestion. 13.Which cranial nerves carry parasympathetic fibers? (There are four) CN III (3)- OCCULOMOTOR CN VII (7)-FACIAL CN IX (9)- GLOSSOPHARYNGEAL CN X (10)-VAGUS 14.Explain what happens when a preganglionic fiber synapses on modified neurons of the Adrenal Medulla. Which neurotransmitter is released? Some preganglionic fibers originating between T5 and T8 pass through the sympathetic chain and the celiac ganglion without synapsing and proceed to the adrenal medulla. There they synapse on modified neurons to perform an endocrine function (release neurotransmitter directly into the blood as if they were hormones) Modified neurons release the neurotransmitters: NE (norepinephrine) & E (epinephrine) into an extensive network of capillaries. Neurotransmitters work as hormones, exerting their effects in other regions of the body. Circulating blood delivers the hormones throughout the body, changing metabolic activities of many different cells 15.What do we mean by “dual innervation” with respect to the sympathetic and parasympathetic nervous systems? 17.4. DUAL INNERVATION Most organs innervated by the autonomic nervous system are innervated by both the sympathetic and parasympathetic branches. Typically, one division will increase activity of the organ, and the other will decrease the organ’s activity. Where dual innervation exists, the two divisions often have opposite, or antagonistic, effects. Dual innervation is most common in the digestive tract, the heart, and the lungs ** EX: sympathetic stimulation decreases digestive tract motility, while parasympathetic stimulation increases its motility. The parasympathetic and sympathetic fibers mingle together forming plexuses: Cardiac, pulmonary, esophageal, celiac, inferior mesenteric, and hypogastric plexus 16.Compare the Sympathetic and Parasympathetic Division of the ANS (Table 17.1) 17.What is the organization of the Sympathetic NS with respect to sympathetic chain ganglionic neurons and target organs? 18.What is the organization of the Parasympathetic division of the ANS? 19.What is a visceral reflex? Know general. VISCERAL REFLEX Autonomic reflexes are initiated in the viscera They provide autonomic motor responses that can be modified, facilitated, or inhibited by higher centers, especially those of the hypothalamus. Visceral reflexes play an important role in regulating and coordinating the activities of various organs in the digestive system All visceral reflexes are polysynaptic (have more than 1 synapse) Visceral reflex arc- made up on a receptor, sensory nerve, processing center, and 2 visceral motor neurons. Visceral reflexes can be SHORT OR LONG Long reflexes: Visceral sensory neurons deliver info to the CNS by dorsal roots. Processing steps involve interneurons in CNS. ANS carries the motor commands to appropiate visceral effectors after a synapse within a peripheral autonomic ganglion Coordinate activities of the entire organ ** Short reflexes- bypass the CNS entirely Control very simple motor responses w localized effects Control patters of activity in one part of a target organ ** Circulatory System Chapters ( 20, 21, and 22) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. Know the structure of the heart. Be able to identify all of the chambers and the distinguishing anatomical characteristics of each region. Include the septa, papillary muscle, valves, chordae tendineae, trabeculae carinae, and pectinate muscle. Be able to describe in detail the endocardium, myocardium, epicardium, and pericardium. Know the pathway of the blood through the heart. Be able to identify all of the major vessels of the coronary circulation. What is the electrical conduction system of the heart? Be able to identify all of the associated structures. Compare and contrast the structure of the fetal heart with the heart of an adult. Distinguish between systemic and pulmonary circulation. Compare and contrast the anatomical structure of arteries, arterioles, veins, capillaries, venules, . Know Tunics. Be able to identify the major blood vessels of the body. What is so important about the tunica media? How does it vary? How in which vessels? In which vessels do we have vasodilation and vasoconstriction? Explain which tissue and nervous system accounts for this. what is an anastomosis? Be familiar with some of the examples. What is a metarteriole and sphincter system? How does it regulate blood flow? Purpose? Be able to identify the major vessels of the hepatic portal system. Describe fetal circulation in detail. Know the shunts, blood pathway and vessels. What is the composition of blood? What are the types formed element including specifics about leucocytes( If stated, know its special characteristic). Which are granulocytes? Stem cell pathway for all blood cells. What is the basic structure and function of hemoglobin. Compare and contrast with myoglobin. What is hematocrit? How much blood do we have? 15. Relative Difference in blood pressure found in arteries and veins? How do veins facilitate transfer blood back to the heart? 16. How do capillaries differ? 17. What is endothelium? Where do we find it? Which vessels are made of only endothelium? 18. What is a Vasa Vasorum? 19. Know major arteries and veins of the body. Respiratory System ( Chapter 24) Sections: 24.1 though 24.8 STOP (not covered 24.9) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. Which structures are in the Respiratory System? Divide the RS into the Upper RS. What are the basic functions of the Respiratory System? What is the most common respiratory epithelium? Know the common one and the 3 others and where each is found) What are the nasal conchae? How do they function? Respiratory Defense System? Vibrissae? Mucous? Going from the NASAL CAVITY TO THE PHARYNX- What is another name for pharynx??( a common passageway) Where does it start? What are the subdivisions of the pharynx? (Naso, Oro and Laryngo) The nasopharynx is connected to middle ears by eustachian tube. Consequence? What epithelial tissues are found in nasopharynx? Oropharynx? Laryngopharynx? Hint: PCCE only is nasopharynx. What is the larynx? Describe the cartilages of the larynx. What is the function of the epiglottis? Be familiar with the different types of cartilage found in these regions and structures? What is the mucocillary escalator? Where do we find this? What are the parasinal cavities? From which bones? (Text talks about meatuses- Go with sinuses as we discussed the actual bones) What does the acronym MALT stand for? 14. What is another name for the larynx? What happens here? What can be found here? 15. Which types of cartilages do we find covering larynx and trachea? Names? Functions? 16. The basics of how vocal cords work what is involved. See slide. 17. Laryngeal Muscles: Intrinsic muscles/ Extrinsic 18. Trachea: mucosal epithelium 19. Bronchial Tree-Primary/Secondary/Tertiary- (At T-3 The Trachea branches into Bronchial tree) How do terminal bronchioles differ from primary bronchioles? (these lack cartilage-no PCCE) See slide and/or page 635 21. The lungs: Know about the right and left lobe organization and fissures. What is the hilum? Basically, know the how the right and left lungs differ. What is the pleural cavity? The mediastinum? (The two pleural cavities are separated by the mediastinum. 22. What are mast cells? How do they affect bronchial tubes? Histamine? 20. 23. 24. Describe what happens at the alveoli? How many cell types are there? What does each one do? What type of epithelial tissue? What is a surfactant? Why here? See presentation for details. Inspiration/Expiration: Which muscles are the primary muscles using in inspiration? expiration? The accessory muscles? We covered the origin/insertion/action of primary muscle and nerve of the diaphragm. (phrenic).