Physiology: Chp 9 Part B - PDF

Physiology: Chp 9 part B Central Nervous System Juan J. Bustamante, Ph.D. Assistant Professor Pharmaceutical Science Phone (361) 221-0643 Email: [email protected] Office: Room 223 © 2016 Pearson Education, Inc.  Emergent Prope...

Physiology: Chp 9 part B Central Nervous System Juan J. Bustamante, Ph.D. Assistant Professor Pharmaceutical Science Phone (361) 221-0643 Email: [email protected] Office: Room 223 © 2016 Pearson Education, Inc.  Emergent Properties of Neural Networks Plasticity is the restructure of the brain networks in response to sensory input and experience. Affective behaviors are related to feeling and emotion Cognitive behaviors link to thinking © 2016 Pearson Education, Inc. Figure 9.12 Simple and complex pathways in the brain learn & make decisions © 2016 Pearson Education, Inc. Figure 9.3a The Central Nervous System Posterior View of the CNS Cranium Cerebral hemispheres Cerebellum Cervical spinal nerves Thoracic spinal nerves Sectioned vertebrae Lumbar spinal nerves Sacral spinal nerves Coccygeal nerve © 2016 Pearson Education, Inc. Figure 9.4b Cerebrospinal Fluid Cerebrospinal Fluid Secretion Cerebrospinal fluid is Cerebrospinal fluid is secreted into the ventricles and reabsorbed into the flows throughout the subarachnoid space, where it cushions the central nervous system. Arachnoid villi blood at fingerlike projections of the Choroid plexus arachnoid membrane of third ventricle called villi. Pia mater Arachnoid membrane Brain is encased in bony Sinus skull, or cranium Choroid plexus of fourth ventricle Spinal cord The brain floats in Central canal cerebrospinal fluid (CSF) Subarachnoid space Arachnoid secreted by the choroid membrane Dura mater plexus in the ventricles. © 2016 Pearson Education, Inc. Figure 9.4a Cerebrospinal Fluid Ventricles of the Brain Lateral ventricles The lateral ventricles consist of the first and second ventricles. The third and fourth ventricles Third ventricle extend through the brain stem and connect to the central canal that runs through the spinal cord. Compare the frontal view to the Fourth ventricle cross section in Fig. 9.10a. Cerebellum Central canal Spinal cord Lateral view Frontal view CSF us a salty solution that is continuously secreted CSF serves 2 purposes: 1) Physical protection 2) Chemical protection Regulate extracellular environment Waste remove © 2016 Pearson Education, Inc.  CSF serves 2 purposes: 1. Physical protection The brain and spinal cord float in the thin layer of fluid between the membranes. The buoyancy of CSF reduces the weight of the brain nearly 30-fold. Lighter weight translates into less pressure on the blood vessels and nerves attached to the CNS. The CSF also provide protective padding. When there is a blow to the head, CSF must be compressed before the brain can hit the inside of the cranium. However, water is minimally compressible, which helps CSF cushion the brain. © 2016 Pearson Education, Inc.  CSF serves 2 purposes: 2. Chemical protection CSF creates a closely regulated extracellular environment for the neurons. The choroid plexus is selective about which substances it transported into the ventricles, and, and as a result the CSF is different from the plasma. The concentration of K+ is lower in the CSF, the concentration of H+ is higher in the CSF, and the concentration of Na+ is similar to plasma. CSF contain very little proteins and no blood cells. The sampling procedure, know as spinal tap or lumber puncture, is generally done by the withdrawing fluid for the subarachnoid space between vertebrae at the lower end of the spinal cord. The presence of proteins or blood cells in the CSF suggest an infection. CSF fluid exchange solutes with the interstitial fluid of the CNS and provide a route by which wastes can be removed. © 2016 Pearson Education, Inc. Concept Check 5. If the concentration of H+ in CSF is higher than that of the blood, what can you say about the pH of the CSF? 7. Is the CSF fluid more like plasma or more like interstitial fluid? © 2016 Pearson Education, Inc. Figure 9.3b The Central Nervous System Sectional View of the Meninges The meninges and extracellular fluid cushion the delicate brain tissue. Venous sinus Cranium Is associate with veins that drain blood from the brain through the Dura mater vessels or cavities call sinuses Subdural space Arachnoid membrane Is associate arteries that Pia mater supply blood to the brain Brain Pia mater, arachnoid membrane, dura mater Subarachnoid Space collectively called the meninges – help contains cerebrospinal fluid stabilize the neural tissue and protect it from secreted by choroid plexus bruising against the bones and the skeleton © 2016 Pearson Education, Inc. Figure 9.4d Cerebrospinal Fluid Cerebrospinal Fluid Reabsorption Cerebrospinal fluid is reabsorbed into the blood at fingerlike projections of the arachnoid membrane called villi. Cerebrospinal fluid Bone of skull Dura mater Endothelial lining Blood in venous sinus Fluid movement Arachnoid Cerebral cortex villus Dura mater (inner layer) Pia Subarachnoid Arachnoid Subdural mater space membrane space © 2016 Pearson Education, Inc.  CNS: Gray and White Matter The CNS consists of the brain and the spinal cord. Gray matter – Unmyelinated nerve cell bodies – Clusters of cell bodies in the CNS (brain and spinal cord) are nuclei – Dendrites – Axon terminals White matter – Myelinated axons – Axon bundles connecting CNS regions are know as tracts Contain very few cell bodies © 2016 Pearson Education, Inc. Figure 9.3c The Central Nervous System Posterior View of Spinal Cord and Vertebra Central canal Gray matter White matter Meninges lie between bone and tissues to stabilize neural tissue Spinal and protect from bruising nerve Pia mater Spinal Arachnoid Meninges cord membrane note: Subarachnoid space contains Dura mater cerebrospinal fluid secreted by choroid plexus Body of Autonomic A ganglion is a cluster vertebra ganglion of nerve cell bodies outside the CNS (CNS equivalent to a nucleus) Spinal nerve Spinal cord runs through vertebral column © 2016 Pearson Education, Inc. Concept Check 6. Why is a rupturing a blood vessel running between the meninges potentially a surgical emergency? © 2016 Pearson Education, Inc.  The Blood-Brain Barrier Highly selective permeability of brain capillaries Astrocytes foot processes promote tight junctions between endothelial cells Protects brain from toxic water soluble compounds and pathogens/bacteria Small lipid-soluble molecules cross the blood-brain barrier Note: a few areas of the brain lack a functional BBB – Hypothalamic-hypophyseal portal system (brain to anterior pituitary) – Vomiting center of the medulla oblongata © 2016 Pearson Education, Inc. Figure 9.5 The blood-brain barrier Although not a literal barrier, the highly selective permeability of the brain capillaries shelter the brain from toxins and form fluctuations in hormones, ions, and neuroactive substances such as neurotransmitter in the blood. This cerebral angiogram shows the extensive blood supply Neurons are to the brain, which has about 400 miles of capillaries. protected from harmful substances in the blood because brain capillaries are not leaky. Astrocyte Anterior cerebral artery Posterior Astrocyte foot Tight junctions cerebral processes secrete prevent solute artery paracrines that movement between promote tight endothelial cells. Middle junction formation. cerebral artery Circle of Willis Internal Capillary carotid lumen artery Basal lamina © 2016 Pearson Education, Inc. Cells of the NS compose primary of two Cell types Neurons: the functional unit Glial cells (glia, neuroglia) CNS (Ependymal cells, Astrocytes, PNS (Schwan cells & Microglia & Oligodendrocytes) Satellite cells) © 2016 Pearson Education, Inc  CNS: Neural Tissue – Metabolic Needs Oxygen – Passes freely across blood–brain barrier – Brain receives 15% of blood pumped by heart Glucose – Membrane transporters move glucose from plasma into the brain interstitial fluid – Brain responsible for about half of body’s glucose consumption – Progressive hypoglycemia leads to confusion, unconsciousness, and death. © 2016 Pearson Education, Inc.  Parkinson’s Disease Parkinson’s disease is neurological disorder in which the brain levels of neurotransmitter dopamine are too low because the dopaminergic neurons are either damage or dead. Dopamine administered in pill or injection is ineffective. Why? © 2016 Pearson Education, Inc. Figure 9.8b Anatomy Summary Lateral View of Brain Frontal Parietal lobe lobe Cerebrum Temporal lobe Occipital lobe Pons Cerebellum Medulla oblongata © 2016 Pearson Education, Inc. Figure 9.13 Functional areas of the cerebral cortex FRONTAL LOBE PARIETAL LOBE Primary motor cortex Primary somatic sensory cortex Skeletal Motor association Sensory information muscle area (premotor cortex) Sensory association area from skin, movement musculoskeletal system, viscera, and taste buds Coordinates information from other association OCCIPITAL LOBE areas, controls some behaviors Visual Prefrontal association association area Vision area Visual cortex Taste Gustatory cortex Smell Olfactory cortex Auditory Auditory cortex association area Hearing TEMPORAL LOBE © 2016 Pearson Education, Inc.  Brain Function: Cerebral Cortex From a functional viewpoint, it can be divided into three specializations Sensory areas Sensory input translated into perception (awareness) Motor areas Direct skeletal muscle movement Association areas Integrate information from sensory and motor areas Can direct voluntary behaviors Cerebral lateralization © 2016 Pearson Education, Inc. Figure 9.14 Cerebral lateralization Cerebral lateralization “cerebral dominance” “left brain or right brain dominate” LEFT HAND RIGHT HAND Functional specialization is Prefrontal Prefrontal cortex not symmetrical across the cortex cerebral cortex: each lobe has special functions not Speech center C shared by the matching lobe O R on the opposite side P U Writing Analysis S by touch C Auditory A Auditory cortex L cortex (right ear) L (left ear) FIGURE QUESTIONS O S Q: If you are stroke right destroyed brainin 1. What would a person see if a all function General interpretive U M Spatial visualization (hemisphere) dominate the right visual cortex? 2. What is the function of the corpus center (language and and analysis then you are most likely left mathematical callosum? 3. Many famous artists, including calculation) handed? Leonardo da Vinci and Michelangelo, were left-handed. How is this Visual cortex Visual cortex (right visual field) (left visual field) related to cerebral lateralization? LEFT RIGHT HEMISPHERE HEMISPHERE © 2016 Pearson Education, Inc.  Once sensory information reaches the appropriate cortical area, information is processing has just begun. Sensory Neural pathways extend from extend from sensory Information area to appropriate associated areas, which intergrade somatic, visual, auditory and other is stimuli in perception, the brain’s interpretation of sensory stimuli. Processed Often the perceived stimulus is very different from into the actual stimulus. Light waves - photoreceptor – color perception Pressure waves – sound Chemoreceptor – taste and smell What happens if the brain’s interpretation is wrong? One interesting aspect of perception is the way our brain fills in missing information to create a complete picture. © 2016 Pearson Education, Inc. Figure 9.15b Perception © 2016 Pearson Education, Inc. What is this object? Figure 8.1 The Organization of the Nervous System Chp 10 Chp 11 © 2016 Pearson Education, Inc. Figure 13.10 The corticospinal tract © 2016 Pearson Education, Inc.  The Spinal Cord One segment of spinal cord, ventral view, showing its pair of nerves White matter Gray matter Dorsal root: carries sensory (afferent) information Ventral root: carries to CNS motor (efferent) information to muscles The cell bodies of afferent neurons are located in the and glands dorsal root ganglia. Ventral horns contain cell bodies of afferent neurons. © 2016 Pearson Education, Inc.  White matter in the spinal cord consists of tracts of axons carrying information to and from the brain. To the brain KEY Ascending tracts carry sensory information to the brain. From the brain Descending tracts carry commands to motor neurons. © 2016 Pearson Education, Inc.  Gray matter consists of sensory and motor nuclei. Visceral sensory nuclei Somatic sensory nuclei Dorsal root Dorsal ganglion horn Autonomic Lateral Ventral efferent horn nuclei horn Ventral root Somatic motor nuclei © 2016 Pearson Education, Inc. Figure 9.7 Spinal reflexes Afferent neurons connect with interneurons in the dorsal horns © 2016 Pearson Education, Inc.  SYMPATHETIC PARASYMPATHETIC Ganglion Hypothalamus, Hypothalamus, Reticular formation Eye Pupil constricts Reticular formation Pupil dilates Mucus and enzymes Salivary glands secreted Pons Pons Watery secretion Medulla Increases heart rate Slows heart rate Medulla C1 and contractility 2 Heart C1 2 3 Vagus 3 4 Relaxes airways Constricts airways nerve 4 5 5 6 Lungs 6 Spinal 7 Increases bile 7 cord 8 Liver secretion 8 T1 Inhibits digestion T1 2 Ganglion Stomach Increases motility 2 3 Decreases enzymes and secretion 3 4 and insulin 4 5 Intestines Increases motility 5 Inhibits 6 digestion and secretion 6 7 Spinal 7 cord 8 Pancreas 8 9 Inhibits digestion Release enzymes 9 10 and insulin 10 11 Increases Adrenal medulla 11 12 renin secretion secretes catecholamines 12 L1 Kidney L1 2 2 Relaxes bladder Release of urine 3 3 4 Urinary bladder 4 5 5 S1 Induces ejaculation Penis S1 2 2 Induces erection 3 3 4 Stimulates Testes 4 5 Engorgement 5 contraction and secretions Co1 Pelvic Co1 Figure 11.5 Sympathetic chain nerves Uterus © 2016 Pearson Education, Inc.