Presentation on theme: "Chapter 34 Organization and Control of Neural Function"— Presentation transcript:
1 Chapter 34 Organization and Control of Neural Function Essentials of PathophysiologyChapter 34 Organization and Control of Neural Function
2 Pre lecture quizTFThe dorsal horn cell columns contain the afferent (sensory) neurons and the ventral horn cell columns contain the efferent neurons.The brain is divided into three regions: the hindbrain, the midbrain, and the forebrain.The parasympathetic nervous system functions in maintaining vital functions and responding when there is a critical threat to the integrity of the individual—the “fight-or-flight” response.The blood-brain barrier and the cerebrospinal fluid–brain barrier protect the brain from substances in the blood that would disrupt brain function.Cerebrospinal fluid helps maintain a constant ionic environment that serves as a medium for diffusion of nutrients, electrolytes, and metabolic end products into the extracellular fluid surrounding central nervous system neurons and glia.
3 Pre lecture quiz______________ are the functioning cells of the nervous system.The _________________ nervous system contains two divisions: sympathetic and parasympathetic.Inside the skull and vertebral column, the brain and spinal cord are loosely suspended and protected by several connective tissue sheaths called the _________________.Neurons communicate with each other through structures known as ________________, of which there are two types: electrical and chemical.The main ___________________ for the autonomic nervous system are acetylcholine and the catecholamines, epinephrine and norepinephrine, which control neural function by selectively causing excitation or inhibition of action potentials.AutonomicmeningesNeuronsneurotransmitterssynapses
4 Neurons Dendrites receive stimuli Stimuli pass down axons Schwann cells contain myelin (“white matter”)Help increase speed of impulse transmission
5 Peripheral nervous tissue Supporting CellsPeripheral nervous tissueSchwann cells: wrap a layer of myelin around axonsSatellite cells: separate nervous cells from supporting tissueCentral nervous tissueOligodendroglia: myelinating cellsAstroglia: regulate ion content in intercellular fluidMicroglia: phagocytesEpendymal cells: line the neural tube cavity
6 What is the function of each? IdentifyMicroglial cellNeuronOligodendritic cellEpendymal cellAstrocyteECBDWhat is the function of each?A
7 QuestionTell whether the following statement is true or false. All neurons are myelinated.
8 AnswerFalse Rationale: The myelin sheath increases the speed of impulse transmission (the impulse can skip over the myelinated/insulated parts of the neuron), but speed is not important everywhere (like the digestive tract). If every neuron was myelinated, neurons would take up a lot more space, too.
9 The Basics of Cell Firing Stimulus opens Na+ gatesAt threshold, more Na+ gates openNa+ enters cell: depolarizationK+ gates openK+ diffuses out: repolarizationAction potentialThreshold potentialResting membrane potentialStimulus
10 Synaptic Transmission What is happening at stages 1–4?What will result if you block stage 2?Stage 3?Stage 4?
11 Neuron Secretions Neurotransmitters Neuromodulators Amino acidsPeptidesMonoaminesNeuromodulatorsAttach to receptors and change their response to neurotransmittersNeurotrophic factorsNeuron survival and to develop connections between neurons
12 General Organization of the Nervous System Begins as a hollow tubeFirst segments of the tube become the brainForebrainMidbrainHindbrain
13 Organization of the Spinal Cord DorsalAfferentSensoryVentralEfferentMotor
14 Scenario A woman developed polyneuropathy. Her spinal nerves were damagedShe lost the ability to tell where her body was positionedShe has to look every time she takes a step, to tell where she is moving her feet toQuestion:What parts of her spinal nerves were damaged?
15 Cell Columns of the Spinal Cord What problems would you expect in someone who suffered ischemia to:Area AArea BArea CABC
16 QuestionIf you place your hand on a hot surface, which ganglion carries the impulse to the spinal cord?VentralDorsalInterneuronAssociation neuron
17 AnswerDorsalRationale: Afferent neurons carry sensory impulses to the spinal cord through the dorsal root ganglion; efferent neurons carry motor responses through the ventral root ganglion to effector cells in the tissue.
18 Layers of the White Matter Archi layerConnects neighboring segmentsContains neurons reticular activating systemPaleo layerFibers reach to the brain stemNeo layerPathways for bladder control and fine motor skillsDevelop by fifth year of life
20 Functions of the Hindbrain Medulla oblongata, cerebellum, and ponsReflex centers for heart and respiration rates, coughing, swallowing, vomiting, etc.Gives rise to cranial nerves V–XII controlling viscera, hearing, facial, and mouth/throat functionsCerebellum allows fine motor coordination
21 Functions of the Midbrain Cerebral peduncles carry nerve fibers from the cerebrum to the hindbrainCerebral aqueduct lets cerebrospinal fluid drain from the fourth ventricle inside the cerebrumSuperior colliculi control reflex eye movementsInferior colliculi control reflex reactions to soundGives rise to cranial nerves III and IV, controlling eye movement
22 Functions of the Forebrain Thalamus: “switchboard” or relay station for impulses going to and coming from the cerebrumHypothalamus: homeostatic controlCerebrumGives rise to cranial nerves I and II, for smell and sight
24 QuestionWhich part of the brain maintains vital functions like breathing, heart rate, and digestion?ForebrainMidbrainHindbrainCerebellum
25 AnswerHindbrainRationale: Also known as the brain stem, this is the vasomotor center that controls cardiopulmonary function and digestion.
26 Dura Mater Has two layers Inner layer bends over to form a fold (falx cerebri) that separates the cerebral hemispheresIt forms a second fold (tentorium) that holds the cerebrum up off the cerebellum
27 Dura Mater (cont.)Between the layers of the dura, at the base of each fold, venous blood drains out of the brain in a sinusBridging veins carry blood from the brain across the inner layer of the dura mater to the sinusThe sinus also collects cerebrospinal fluid
28 Arachnoid Lies just beneath the dura mater Waterproof Cerebrospinal fluid (CSF) lies under the arachnoid to cushion the brainExtensions of the arachnoid (villi) poke through the inner layer of the dura mater into the sinuses, to let CSF drain into the sinuses
29 Pia Mater Lies right on the surface of the brain Holds the cerebral arteries in place
30 Meninges and Meningeal Spaces Epidural space: meningeal arteriesDura materSubdural space: bridging veinsArachnoidSubarachnoid space: cerebral arteries, cerebrospinal fluidPia mater
31 Cerebrospinal FluidLeaks out of capillaries inside the brain’s hollow ventriclesComposition controlled by the blood-brain barrierPasses out an opening below the cerebellumCirculates around the brain and spinal cord in the subarachnoid spacePasses through arachnoid villi into blood in the dural sinuses and is returned to the heart
32 Autonomic Nervous System SympatheticCatecholaminesEpinephrine, norepinephrine, dopamineAttach to adrenergic receptorsParasympatheticAcetylcholineAttaches to cholinergic receptors
33 Adrenergic Neurotransmitters Synthesized in the sympathetic systemAttach to adrenergic receptorsAlpha-1 receptors: constrict blood vesselsAlpha-2 receptors: negative feedback to stop neurotransmitter releaseBeta-1 receptors: speed and strengthen heartBeta-2 receptors: bronchodilationNeurotransmitter is removed from synapse by reuptake or degraded by enzymes
34 Cholinergic Neurotransmitter— Acetylcholine Released from parasympathetic system and from motor neuronsAttaches to cholinergic receptorsNicotinic receptors: excite skeletal muscle cellsMuscarinic receptors: slow heart, stimulate GI tract, vasodilateNeurotransmitter is removed from synapse by acetylcholinesterase
35 QuestionTell whether the following statement is true or false. The sympathetic division of the ANS is also known as fight-or-flight.
36 AnswerTrue Rationale: The SNS is characterized by the release of adrenaline, which results in pupil dilation, bronchodilation, and increased HR, BP, and glucose production—all the things that come in handy when you are running from something!