Chapter 2 Lecture PDF

Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior Cells of the Nervous System Basic Features of the Nervous System The Central Nervous System - Functional Neuroanatomy of the CNS The Peripheral Nervous System - Somatic Nervous System - Autonomic Nervo...

Chapter 2: Functional Neuroanatomy: The Nervous System and Behavior Cells of the Nervous System Basic Features of the Nervous System The Central Nervous System - Functional Neuroanatomy of the CNS The Peripheral Nervous System - Somatic Nervous System - Autonomic Nervous System 1 Cells of the Nervous System - two major kinds of cells in your nervous system: neurons and glia 2 2 Cells of the Nervous System - neurons are highly organized cells that are specialized to communicate information - estimate: 86 billion neurons in adult human brain - each part of the neuron plays a specific role in this communication dendrites axon cell body Golgi-stained Purkinje cell, basket cell, 2 pyramidal cells 3 3  Cells of the Nervous System - cell body (soma): variable shape and size, contains nucleus - function: synthesis, metabolism, energy - dendrites: thin branching fibers, spiny or aspiny, decreasing diameter - function: input - axon: single thin extension, usually collateralized (branched), constant diameter - function: transmission - axon hillock: site where axon exits soma Cell body (soma) - function: establishing the action potential - myelin: fatty coating around axon - function: insulation and conduction of AP - nodes of Ranvier: gaps in myelin - function: facilitate conduction of AP - axon terminals: swelling at tip of axon branch - function: release neurotransmitters into synapse - synapse: structure consisting of presynaptic membrane, cleft, and postsynaptic membrane - function: transmission of information 4 4 Cells of the Nervous System soma dendrite axon synapse axon hillock myelin and Node of Ranvier axon terminal 5 5 Cells of the Nervous System - neurons come in a variety of shapes and sizes multipolar neuron bipolar neuron unipolar neuron interneuron 6 6  Cells of the Nervous System unipolar cells bipolar cells - neurons come in a variety of shapes and sizes - parvocellular, magnocellular, granule - pyramidal, basket, chandelier, Purkinje - sensory, motor DRG neuron retinal neuron multipolar cells spinal motor pyramidal Purkinje neuron neuron cell 7 7 Cells of the Nervous System - the membrane is composed of 2 lipid (fat) layers, with protein channels - all communication happens across the membrane - selective permeability: some molecules freely cross the membrane (e.g. O2, CO2, urea, H2O); most larger molecules (e.g. proteins) and ions (e.g. Na+, Cl-) cannot freely cross extracellular hydrophillic hydrophobic hydrophillic intracellular 8 8 Cells of the Nervous System - specific “organelles” in the cell body play specialized roles in physiology of neuron - cytoplasm: fluid compartment of cell - function: medium for chemical reactions - nucleus: contains genetic material - function: encoding and transcribing mRNA - ribosomes: ribonucleoprotein molecule - function: translation of mRNA to protein - endoplasmic reticulum: smooth or rough membranous structure - function: rough = protein synthesis and transport - smooth = fat synthesis and transport Endoplasmic Nucleus Mitochondria Reticulum - golgi complex: membranous structure - function: packages proteins for transport Cytoplasm - vesicles: membranous structures Ribosomes - function: package for transport, storage, and Golgi release of substances Complex - mitochondria: membranous, DNA-containing structures - function: energy storage and release - microtubules and filaments: tubulin/actin/protein polymers - function: transport of substances Microtubules 9 9  Cells of the Nervous System nucleus mitochondria endoplasmic reticulum golgi apparatus microtubules 10 10 Cells of the Nervous System kinesins - fast anterograde transport dyneins - retrograde transport 11 11 Cells of the Nervous System - specific “organelles” in the axon terminal play specialized roles in neurotransmission - mitochondria: membranous, DNA-containing structures - function: energy storage and release - golgi complex: membranous structure - function: packages proteins for transport - vesicles: membranous structures - function: package for transport, storage, and release of substances - microtubules and filaments: tubulin/actin/protein polymers - function: transport of substances Microtubules Synaptic vesicles Mitochondria Neurotransmitters Golgi Complex 12 12  Cells of the Nervous System micro RNA 13 13 Cells of the Nervous System 14 14 Cells of the Nervous System - Glia: variety of functions, including insulation, structural support, transport of nutrition, and removal of waste, also implicated in information exchange 15 15  Cells of the Nervous System - Ependymal cells: line the ventricles and central canal and help with the synthesis and circulation of cerebrospinal fluid (CSF) 16 16 Cells of the Nervous System - Oligodendrocyte (aka oligodendroglia): myelin sheath in CNS neurons 17 17 Cells of the Nervous System - astrocytes: formation of the blood-CNS barrier, trophic support for neurons, insulation for synapses and Nodes of Ranvier 18 18  Cells of the Nervous System - the blood-CNS barrier - O2, CO2, fat-soluble molecules pass freely - amino acids and glucose are actively transported - most large molecules and charged molecules cannot pass - advantages - exclusion of toxins, bacteria, viruses… - selective entry of nutrients, ions… - disadvantages - energy expensive - exclusion of most immune defenses 19 19 Cells of the Nervous System - Microglia: sample the extracellular environment of the brain and respond to challenges by mobilizing to engulf and remove waste and invaders, immune defense 20 20 Cells of the Nervous System - Radial Glia: form a scaffold to guide migration of neurons in embryonic development, later mature and differentiate into astrocytes 21 21  Cells of the Nervous System - Satellite Cells: similar to astrocytes, but in PNS, trophic support and insulation for peripheral neurons 22 22 Cells of the Nervous System - Schwann Cells: myelin in the PNS 23 23 Cells of the Nervous System When a peripheral axon is cut, the portion that is not attached to the cell body dies. Schwann cells first shrink and then divide, forming new glial cells along the axon’s former path. The neuron sends out axon sprouts, one of which finds the Schwann-cell path and becomes a new neuron. Schwann cells envelope it, forming new myelin. 24 24  Cells of the Nervous System - myelination of axons central peripheral Schwann cell oligodendrocyte 25 25 Basic Features of the Nervous System - terms used to denote basic anatomical directions: 26 26 Basic Features of the Nervous System - terms used to denote basic anatomical directions: contralateral ipsilateral right left proximal distal proximal distal 27 27  Basic Features of the Nervous System - terms used to denote basic anatomical directions: Coronal or Transverse plane (coronal or frontal section) 28 28 Basic Features of the Nervous System - major divisions of the nervous system { somatosensory branch { somatic ns motor branch { peripheral ns { { autonomic ns sympathetic ns nervous enteric ns system parasympathetic ns { spinal cord { central ns cortex, basal ganglia, hippocampus, forebrain amygdala, thalamus, hypothalamus brain midbrain tectum, tegmentum hindbrain cerebellum, pons, medulla 29 29 Basic Features of the Nervous System - meninges: 3 layers of tough connective tissue surrounding brain and spinal cord - dura mater - arachnoid mater - cerebrospinal fluid in subarachnoid space - pia mater - 2 layers of meninges (dura and pia) in PNS 30 30  The Central Nervous System - ventricular system: 2 major functions of cerebrospinal fluid (CSF) - support and cushioning - transport/removal of waste (half-life = about 3 hours) 31 31 The Central Nervous System - ventricular system: - CSF synthesized in choroid plexus, absorbed by arachnoid granulations 32 32 The Central Nervous System - hydrocephalus: - inability of CSF to drain into the bloodstream; if in childhood, head will expand, if in adulthood, the head will not expand - treated by implantation of shunt - congenital hydrocephalus - present at birth, not necessarily hereditary - other forms - association with premature birth, and with spina bifida - association with brain hemorrhage, meningitis, tumours - rarely genetic in origin, or may be combination of hereditary and environmental factors 33 33  The Central Nervous System - major divisions of the brain: forebrain, midbrain, hindbrain 34 34 The Central Nervous System - major divisions of the brain: midsagittal section thalamus fornix pineal gland hypothalamus superior cingulate colliculus gyrus inferior colliculus corpus callosum pituitary cerebellum midbrain pons medulla spinal cord hindbrain 35 35 The Central Nervous System - major divisions of the brain: forebrain - gyri, sulci, fissures - 2 hemispheres - 4 lobes 36 36  The Central Nervous System - functional anatomy of the brain: frontal section dorsal right hemisphere left hemisphere longitudinal fissure corpus callosum white matter cortex (grey matter) gyrus sulcus caudate nucleus internal capsule putamen lateral globus ventricles pallidus lateral fissure optic nerves ventral amygdala 37 37 The Central Nervous System - functional anatomy of the cortex - 6 layers of grey matter (cell bodies) on top of a layer of white matter (axons) - limbic cortex has 3 or 4 layers of grey matter over layer of white matter - cortical layers have differing cell types and densities 38 38 The Central Nervous System - functional anatomy of the cortex - primary sensory and motor cortices - unimodal association cortices - multimodal association cortices 39 39  The Central Nervous System - functional anatomy of the cortex: primary somatosensory (S1) and motor (M1) cortices primary primary motor cortex somatosensory cortex primary visual cortex primary auditory cortex 40 40 The Central Nervous System - functional anatomy of the cortex: primary somatosensory (S1) and motor (M1) cortices primary primary motor cortex somatosensory cortex primary visual cortex primary auditory cortex 41 41 The Central Nervous System - functional anatomy of the cortex: primary visual cortex primary primary motor cortex somatosensory cortex primary visual cortex primary auditory cortex 42 42  The Central Nervous System - functional anatomy of the cortex: Primary Auditory Cortex, Wernicke’s and Broca’s areas primary primary motor cortex somatosensory cortex primary visual cortex primary auditory cortex 43 43 The Central Nervous System - forebrain systems: thalamus - about 20 subnuclei - implicated in sensory and motor function, and overall excitability of cortex - sensory signaling to cortex and reciprocal inputs from cortex - motor signaling between cerebellum and motor cortex 44 44 The Central Nervous System - forebrain systems: basal ganglia - caudate and putamen (neostriatum), subthalamic nucleus, globus pallidus, substantia nigra - regulation (not initiation) of movement, suppressing excess movement - hyperdirect, direct, and indirect pathways - also implicated in cognitive and limbic function, and procedural learning 45 45  The Central Nervous System - forebrain systems: limbic system - thalamus, amygdala, hippocampus, limbic cortex, parts of hypothalamus, fornix, and mammillary bodies - motivation and emotion 46 46 The Central Nervous System - forebrain systems: hypothalamus - about 22 subnuclei, regulates autonomic ns, endocrine function - stress responses, 4 F’s, drinking, emotion, biological rhythms - close association with pituitary gland 47 47 The Central Nervous System - forebrain systems: pituitary gland - Master gland, regulates glands all over the body - anterior pituitary = endocrine cells, respond to hypothalamic releasing and inhibiting hormones - posterior pituitary = neural projections from hypothalamus 48 48  The Central Nervous System - the midbrain: tectum (dorsal) - superior (optic) and inferior (auditory) colliculi - the midbrain: tegmentum (ventral) - rostral aspect of reticular formation (arousal, motor function) - periaqueductal grey (species-specific behaviors) - red nucleus and substantia nigra (motor function) - ventral tegmental area (motivation) tectum superior colliculus PAG cerebral aqueduct reticular formation red nucleus substantia nigra VTA cerebral peduncle tegmentum 49 49 The Central Nervous System - the hindbrain: - pons: contains most of reticular formation (arousal, motor function) - medulla oblongata: contains caudal aspect of reticular formation, nuclei that control cardiovascular system, respiration, muscle tone 50 50 The Central Nervous System - the hindbrain: cerebellum - cortex projects to 3 deep cerebellar nuclei - coordinated movements, ballistic movements, balance - integrates ascending somatosensory information w/descending motor commands - cognition and language spinocerebellum cerebrocerebellum vestibulocerebellum regulation of muscle tone, coordination of skilled voluntary movement unfolded planning and modulation of voluntary activity, storage of procedural memories maintenance of balance, control of eye movements 51 51  The Central Nervous System - the hindbrain: cerebellum - cortex projects to 3 deep cerebellar nuclei - coordinated movements, ballistic movements, balance - integrates ascending somatosensory information w/descending motor commands - cognition and language Purkinje cell parallel fiber Purkinje molecular layer Purkinje cell cell layer granular layer granule cell mossy fiber stellate cell Golgi cell basket cell climbing fiber Purkinje cell axon 52 52 The Central Nervous System - spinal cord - 33 vertebrae: C1-7, T1-12, L1-5, S1-5, coccyx1-4 - 31 spinal nerves: C1-8, T1-12, L1-5, S1-5, coccyx1 53 53 The Central Nervous System - spinal cord - white matter: ascending sensory tracts and descending motor tracts - sensory input through dorsal root ganglia to dorsal horns, cell bodies in DRGs - motor output through ventral horns, cell bodies in central grey - grey matter: interneurons and cell bodies of motor neurons 54 54  Basic Features of the Nervous System - major divisions of the nervous system { somatosensory branch { somatic ns motor branch { peripheral ns { { autonomic ns sympathetic ns nervous enteric ns system parasympathetic ns { spinal cord { central ns cortex, basal ganglia, hippocampus, forebrain amygdala, thalamus, hypothalamus brain midbrain tectum, tegmentum hindbrain cerebellum, pons, medulla 55 55 The Peripheral Nervous System - somatic nervous system: cranial and spinal nerves - spinal nerves start at junction of unipolar sensory and multipolar motor neurons - dermamyotome is area innervated by single spinal nerve 56 56 The Peripheral Nervous System - somatic nervous system: cranial and spinal nerves - 12 pairs of cranial nerves, most to head/neck - On Old Olympus Towering Tops, A Finn And German Viewed Some Hops blue = sensory red = motor 57 57  The Peripheral Nervous System - autonomic nervous system 58 58 The Peripheral Nervous System - autonomic nervous system: sympathetic = thoracolumbar “fight-or-flight” - increased pulse rate and cardiac output - increased blood pressure - bronchodilation - dilated muscle vasculature - constricted gut and skin vasculature - inhibited digestion - release of glucose from liver - dilated pupils - increased perspiration - etc. SNS 59 59 The Peripheral Nervous System - autonomic nervous system: parasympathetic = craniosacral “rest-and-digest” - decreased pulse rate and cardiac output - decreased blood pressure - bronchoconstriction - constricted muscle vasculature - dilated gut and skin vasculature - increased digestion - decreased glucose release - constricted pupils PSNS - decreased perspiration - etc. blue = sensory red = motor green = PSNS 60 60  The Peripheral Nervous System - autonomic nervous system - SNS preganglionic release ACh - direct projections to control adrenal medulla to release E and NE - SNS postganglionic release NE - PSNS preganglionic and postganglionic release ACh 61 61 The Peripheral Nervous System - autonomic nervous system - the enteric nervous system 62 62 The Peripheral Nervous System - Christopher Reeve - implications for our understanding of his injury, and hope for advances in medical science 63 63