Neuronale en hormonale regulatie - samenvatting Martini H12-16
Neuronale en hormonale regulatie (AB_1168)
Vrije Universiteit Amsterdam
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Neuronale en hormonale regulatie Samenvatting Martini 12 Neural tissue Page 413: Figure A functional overview of the nervous system. Page 414: Figure The anatomy of a multipolar neuron Typical CNS neurons cant divide. Neural stem cells in adult nervous system, , but typically inactive except in the nose and hippocampus. The axon terminal reabsorbs breakdown products of neurotransmitters formed at the synapse and reassembles also receives a continuous supply of neurotransmitters synthesized in the cell body, along with enzymes and lysosomes. These materials travel the length of the axon on neurotubules, pulled along protein called kinesin and dynein, that run on ATP. The movement of materials between the cell body and axon terminals is called axoplasmic transport. Slow streams is few mm a day, fast stream mm a hour. Axoplasmic transport in both directions. Cell body to axon terminal anterograde, flow, carried kinesin. At the same time, from axon terminal to cell body in retrograde flow, dynein (alters function of cell). Sensory neurons or afferent neurons deliver information from the sensory receptors to the CBS. The cell bodies of sensory neuros are located in peripheral sensory ganglia (a ganglion is a collection of neuron cell bodies in the PNS.) Somatic sensory neurons: monitor the outside world and our position within it Visceral sensory neurons: monitor internal conditions and the status of other organs. Sensory receptors are either the processes of specializes sensory neurons or cells monitored sensory neurons: Interoceptors: inside, sensation of distension, deep pressure, pain Exteroceptors: info from external environment like touch, temperature of pressure sensations and the more complex systems Proprioceptors: monitor the position and movement of skeletal muscles and joints Motor neurons or efferent carry instructions from the CNS to peripheral effectors in a peripheral tissue, organ or organ system. Somatic nervous system: somatic motor neurons that innervate skeletal muscles (control) Autonomic (visceral) nervous system: visceral motor neurons innervate all peripheral effectors other than skeletal muscles (no conscious due one neuron axon). Another set in peripheral autonomic ganglia (due two neuron axons). Interneurons (association neurons) are located between sensory and motor neurons. They distribute sensory information and coordinate motor activity. More complex more interneurons. Part in higher functions like memory, planning and learning. Page 419: Figure An introduction to neuroglia White matter dominated myelined axons (of the CNS) Gray matter neuron body cells, dendrites and unmyelinated axons (due to short axons and collaterals form synapses with densely packed neuron cell bodies) (of the CNS) Two types of neuroglia in the PNS Satellite cells: surround neuron cell bodies in regulate the environment around the neurons, much as astrocytes do in the CNS Schwann cells (neurilemma): either form a thick, myelin sheath or indented folds of plasma membrane around peripheral axons. Important membrane processes Resting membrane potential. All living cells have a membrane potential that varies from moment to moment depending on the activities of the cell. The resting membrane potential is the membrane potential of an unstimulated, resting cell. All neural activities begin with a change in the resting membrane potential of a neuron. Graded potential. A typical stimulus produces a temporary, localized change in the resting membrane potential. The effect, which decreases with distance from the stimulus, is called a graded potential. Action potential. If the graded potential is large enough, it triggers an axon potential in the membrane of the axon. An action potential is an electrical impulse that is propagated (spread) along the surface of an axon and does not diminish as it moves away from its source. This impulse travels along the axon to one of more synapses. Synaptic activity the produces graded potentials in the plasma membrane of the postsynaptic cell. The presynaptic cell typically releases neurotransmitters, such as ACh. These chemicals bind to receptors on the postsynaptic plasma membrane, changing is permeability and producing graded potentials. The mechanism is comparable to that of the neuromuscular junction. Information processing. The response of the postsynaptic cell ultimately depends on what the stimulated receptors do and what other stimuli are influencing the cell at the same time. The integration of stimuli at the level of the individual cell is the simplest form of information processing in the nervous system. Membrane potential The extracellular fluid (ECF) and intracellular fluid (cytosol) differ greatly in ionic composition. o ECF: high sodium and chloride ions o Cystosol: high postassium ions en negativly charged proteins Cells have selectively permeable membranes. o Ions only through to membrane channels. Rust membrane through Membrane permeability varies ion. Active and passive transport not equeal due membrane permeability varies ion. Easer for out fdue potassium leak channel, than for to enter through sodium leak channel. Neg charged proteins are to large to cross the membrane (In Page 426: Spotlight Resting Membrane Potential Electrochemical gradient is for a specific ion is the sum of the chemical and electrical forces actin on that ion across the plasma membrane. Page 427: Figure Electrical gradients for potassium and sodium ions. Page 428: Table Resting Membrane Potential Depolarization shift from the resting membrane potential toward a more positive potential Sodium ions enter the cell and are attracted to the negative charges along the inner surface of the membrane (toward 0 mV) Repolarization process of restoring the normal resting membrane potential after depolarization (combination of ion movement through membrane channel and activities of ions pumps) Hyperpolarization increase of negativity of the resting membrane potential General properties of synapses Electrical synapses direct physical contact between cells due to locked gap junctions ions changes in the membrane potential of one cell produce local currents that affect the other cell as if the two shared a common membrane electrical synapse propagates action potentials quickly and efficiently from one cell to the next (rare) Chemical involved neurotransmitter (ACH acetylcholine) o Excitatory neurotransmitters cause depolarization and promote the generation of action potentials o Inhibitory neurotransmitters cause hyperpolarization and suppress the generation of action potentials The effect of a neurotransmitter on the postsynaptic membrane depends on the properties of the receptor, not on the nature of the neurotransmitter. Cholinergic synapses synapse that release ACh 1. Released at all neuromuscular junctions involving skeletal muscle fibers 2. At many synapses in the CNS 3. At all synapses in the PNS 4. At all neuromuscular and neuroglandular junctions in the parasympathetic division of the ANS Page 441: Figure Events in the functioning of a cholinergic synapse 1. An action potential arrives depolarizes the axon terminal 2. Extracellular calcium ions enter the axon terminal 3. ACh binds to receptors and depolarizes the postsynaptic membrane 4. ACh is removed AChE to acetate and choline hydrolysis Synaptic delay msec between the arrival of the action potential at the axon terminal and the effect on the postsynaptic membrane (calcium influx and neurotransmitter release) Synaptic fatigue low on ACh with to intensive stimulation, resyntheses and transport mechanism who cant keep up with the demand for the neurotransmitter synapse weakens until ACh has been replenished Activities of the neurotransmitters Norepinephrine in brain and ANS. Excitatory, depolarizing effect on the postsynaptic membrane. Dopamine is CNS nt in brain. Inhibitory effects (precise control of movement) of excitatory effects (inhibits Parkinson. Serotonin CNS nt. Attention and emotional state, chronic depression inhibit reuptake. GABA in CNS, brain to reduce anxiety. Nitric oxide gas) generated axon terminals that innervate smooth muscle in the walls of blood vessels in the PNS and synapses of the brain. Carbon monoxide (CO) component of automobile exhaust, generated axon terminals in the brain. Neuromodulators change the response to neurotransmitters or alter the rate of release opiods) 1. Long term effect that relatively slow to appear 2. Trigger response that involve a number of steps and intermediary compounds 3. May affect the synaptic membrane or both 4. Can be released along or along with a nt Page 446: Figure Mechanisms of Neurotransmitter Function Individual neurons process information integrating excitatory and inhibitory stimuli. The are of the axon hillock determines how the neuron responds. Excitatory postsynaptic potential depolarization) or inhibitory postsynaptic potential hyperpolarization). Temporal summation addition of stimuli occurring in rapid succession at a single synapse that is active repeatedly Spatial summation simultaneous stimuli applied at different locations have a cumulative effect on the membrane potential (multiple synapses that are active simultaneously) The closer the initial segment get to threshold, the easier it will be for the next depolarizing stimulus to trigger an action potential (getting closer to initial segment facilitated). Pagen 450: Figure Presynaptic inhibition and presynaptic facilitation The greater the degree of depolarization, the higher the frequency of action potentials o New one after the absolute refractory period happend Holding above threshold langer than normal stimulus 13 The spinal cord, spinal nerves, and spinal reflexes Page 458: Figure Gross anatomy of the adult spinal cord Every spinal segment is associated with a pair of dorsal root ganglia, located near the spinal cord. These ganglia contain the cell bodies of sensory neurons. The axons of the neurons from the dorsal roots, which bring sensory information into the spinal cord. A pair of ventral roots contains the axons of motor neurons that extend into the periphery to control somatic and visceral effectors. Distal to each dorsal root ganglion, the sensory and motor nerves are classified as mixed that is, they contain both afferent (sensory) and efferent (motor) fibers. Spinal nerve T1 is under vertebra T1 Seven cervical vertebrae, eight cervical nerves (first between C1 and skull) Spinal cord stops between L1 and L2 Page 462: Figure The sectional organization of the spinal cord Gray matter integrates information and initiates command. Around the central canal Horns are the areas of gray matter on each side of the spinal cord Cel bodies of neurons, neuroglia and unmyelinated axons White matter carries information from place to place Myelinated and unmyelinated axons Organization of gray matter Nuclei are masses of gray matter within the CNS Sensory nuclei receive and relay sensory information from peripheral receptors Motor nuclei issue motor commands to peripheral effectors Posterior gray horns contain somatic and visceral sensory nuclei Anterior gray horns contain somatic motor nuclei Lateral gray horns contain visceral motor nuclei (only thoracic and lumbar segments) Gray commissures contains axons from one side of the cord to the other before they reach an area in the gray matter Organization of white matter 3 columns (posterior, lateral, anterior) Each columns contains tracts whose axons share functional and structural characteristics. A tract is a bundle of axon in the CNS that is somewhat uniform in diameter, myelination and Page 478: Figure Classification of reflexes Muscle spindles receptors in stretch reflexes (monosynaptic reflexes). The stimulus (increasing muscle length) activates a sensory neuron, which triggers an immediate motor response (contraction of the stretched muscle) that counteracts the stimulus. 14 The brain and cranial nerves Page 489: Figure Introduction to brain structures and functions Six major brain regions higher mental functions o Consists of paired left and right cerebral hemispheres o Cortex is extensive areas, superficial layer of gray matter o Cerebral cortex is an neural cortex covers cerebral hemispheres Gyri elevated ridges (bolle) Sulci shallow depressions (gaten) Deeper fissures Cerebellum (adjust ongoing movement recall earlier sensations same movements) o Hidden cerebral covered cerebellar cortex Diencephalon o Left and right relay and processing centers for sensory information centers involved with emotions, autonomic function and hormone production Infundibulum, a narrow stalk, connect the hypo tot the pituitary glad (part of the endocrine system) Midbrain o Nuclei that process visual and auditory information controls reflexes triggerd those Pons (brainstem) o Connects cerebellum to brainstem o Somatic and visceral motor control Medulla oblongata (brainstem) o Connects brain to spinal cord o Relays sensory information to the thalamus and to centers in other portions of the brain stem center regulate automatic function o The CNS begins as hallow neural tube. This tube has internal cavity, neurocoel. In the cephalic portion of the neural tube, three areas enlarge rapidly through expansion of the nuerocoel. This enlargement creates three prominent divisions called primary brain vesicles. Page 490: Table Development of the brain The neurocoele within expands to form chambers, ventricles. The ventricles are filled with cerebrospinal fluid (CBF) the CSF continuously circulates from the ventricles and central canal interior the subarachnoid space of the surrounding cranial meninges. The CSF passes between the interior and exterior of the CNS through three foramina in the roof of the fourth ventricle. The brain is protected and supported the cranial meninges (schedelvlakken), cerebrospinal fluid, and the bloodbrain barrier. CBF completely surround and bathes the exposed surfaces of the functions: Cushioning delicate neural structures Supporting the floats in CFS Transporting nutrients, chemical messengers, and waste products Depends of nutrients and oxygen are met an extensive circulatory supply. Arterial blood reaches the brain through the internal carotid arteries and the vertebral arteries. Most of the venous blood from the brain leaves the cranium in the internal jugular veins, which drain the dural sinusus. Bleeding in brain are harmful because they compress the brain. Cerebrovascular diseases are cardiovascular disorders with normal blood supply to the brain area determines symptoms degree of starvation determines their severity The medulla oblongta is continuous with the spinal cord and contains vital centers. Also center for coordination of complex autonomic reflexes and the control of visceral functions. 1. Autonomic nuclei controlling visceral activities 2. Sensory and motor nuclei of cranial nerves 3. Relay stations along sensory and motor pathways (to the thalamus) Autonomic stations: reticular formation, cardiovascular centers, solitary nucleus Relay stations: olivary nucleus, nucleus cuneatus, nucleus gracilis Page 498: Figure Medulla oblongata The pons contains nuclei and tracts that carry or relay sensory and motor information. Links cerebellum with midbrain, diencephalon, cerebrum, spinal cord. Four groups of components 1. Sensory and motor nuclei of cranial nerves 1. 2. 3. 4. 5. 6. 7. 8. The subconscious control of skeletal muscle contractions Control of automatic function Coordination of activities of the nervous and endocrine systems Secretion of two hormones, antidiuretic hormone t restricts water loss the kidneys (ADH) and oxytocin stimulates smooth muscle contractions in uterus and glands (OXT) The production of emitions and behavioral drives Coordination between voluntary and autonomic functions The regulation of body temperature Control of circadian rhythms Page 505: Figure Hypothalamus in sagittal section Cranial nerves 1. Olfactory smell 2. Optic vision 3. Oculomotor eye movements 4. Trochlear eye movements 5. Trigeminal mixed sensory and motor to face 6. Abducens eye movements 7. Facial mixed sensory and motor to face 8. Vestibulocochlear special sensory balance and equilibrium and hearing 9. Glossopharyngeal mixed sensory and motor to head and neck 10. Vagus mixed sensory and motor, widely distributed in the thorax and abdomen 11. Accessory motor to muscles of the neck and upper back 12. Hypoglossal motor tongue movements 15 15 Page 536: Figure Overview of events occurring along the sensory and motor pathways Sensory receptors connect our internal and external environment with the nervous system. General senses pain, touch, pressure, temperature (to primary sensory cortex). The special senses are smell, sight, taste, balance, hearing in sense organs (more complexer receptors to special are in the cerebral cortex). The CNS interprets sensory information on the basis of the frequency of arriving action potentials. Arriving information sensation Conscious awareness of a sensation perception Receptor specificity depends detection of stimuli. Free nerve endings from dentriets, protected the accessory cells and connective tissue layers. Receptive field is small on fingertips and tongue, no matter the stimulus the action potential is an electrical signal. In special senses the receptor potential develops in the receptor cell and the generator potential appear lager in the sensory neuron. Labeled line the link between peripheral receptor and cortical the CNS interpret the type of stimulus entirely on the basis of the labeled line over which it arrives. Cant detect difference between true or false sensation generated along the line. If activity in a labeled line that carries touch sensations stimulates the facial region of your primary sensory cortex, you perceive a touch on the face. All other characteristics of the stimulus (strength, duration, variation) are conveyed the frequency and pattern of action potentials. Translation sensory coding. Tonic receptors always active (background with impulses) Phasic receptors usually unactive (impulse provide information about the intensity and rate of change of stimulus o Combined are extremely complicated sensory information Adaption reduction in sensitivity in the presence of a constant stimulus. adaption when the levenl of receptor activity changes. o Thermoreceptors receptors o Painreceptors Central adaption is when along the sensory pathways inside the CNS. o Mostly involves inhibition of nuclei along a sensory pathway reduces amount of information subconscious level further restrict the amount of detail that arrives at the cerebral cortex o Output form higher centers can increase receptor sensitivity or facilitate transmission along a sensory pathway The somatic nervous system is an efferent divison that controls skeletal muscles. Motor commands issued the CNS are distributed the somatic nervous system (SNS) and the autonomic nervous system (ANS). The somatic nervous system, also called the somatic motor system, controls the contractions of skeletal muscles. The output of the SNS is under voluntary control. Upper motor neuron which cell body lies in a CNS processing center o Synapses lower Lower motor neuron whose cell body lies in a nucleus of the brain stem or spinal cord (only axon extends outside the CNS) o Innervates single motor unit in a skeletal muscle Conscious and subconscious motor commands control skeletal muscles traveling over three integrated motor pathways. The basal nuclei and cerebellum monitor and adjust activity within these motor pathway. Output motor nuclei or primary motor cortex. Motor homunculus: cortical areas that have been mapped out in a diagrammatic form Page 550: Table Principal descending (motor) pathways Page 551: Figure The corticospinal pathway 1. Corticospinal pathway (voluntary control over skeletal muscles). Three pairs of descending tracts (who enter the with matter of the internal capsule, descend into the brain stem, and emerge on either side of the midbrain as the cerebral peduncles): a. Corticobulbar tracts b. Lateral corticospinal tract c. Anterior corticospinal tract 2. Medial pathway helps to control gross movements of the thrunk and proximal limb muscles. Upper motor neurons are located in the a. Vestibular nuclei (border pons and head vestibulospinal tracts b. Superior colliculi (roof of receive visual tectospinal tracts c. Interior colliculi (roof of receive auditory tectospinal tracts Page 572 A structural comparison of the sympathetic and parasympathetic divisions of the ANS. Characteristic Sympathetic Division Parasympathetic Division Location of CNS visceral motor Lateral gray horns of spinal Brain stem and spinal segments neurons segments Location of PNS ganglia Near vertebral column Typically intramural Preganglionic fibers Length Relatively short Relatively long Neurotransmitter Acetylcholine Acetylcholine released Postganglionic fibers Length Relatively long Relatively short Neurotransmitter Normally Acetylcholine released sometimes nitric oxide or ACh Neuromuscular or Varicosities and enlarged axonic Junctions that release neuroglandular junction terminals that release transmitter to special receptor transmitter near target cells surface Degree of divergence from CNS 1:32 1:6 to ganglion cells General function Stimulates Promotes relaxation, nutrient increases prepares uptake, en0ergy storage for emergency or and Anatomical and physiological changes begin 30 and accumulate over time. of years lead relative normal lives, but exhibit noticeable changes in mental performance and in CNS function. Common anatomical changes: A reduction in brain size and narrower gyri wider sulci A reduction in number of except brain stem nuclei A decrease in blood flow to the arteriosclerosis stroke Changes in the synaptic organization of the synaptic connections are lost neurotransmitter production declines Intracellular and extracellular changes in CNS lipofuscin (granular pigment), neurofibrillary tangles (dense mats inside), plaques (extracellular accumulations of fibrillar proteins, surrounded normal dentriets and axons). Amyloid (AB) protein. Senile dementia, most common is The nervous system monitors all other systems and issues commands that adjust their activities. The efficiency of these activities typically decreases with aging.
Neuronale en hormonale regulatie - samenvatting Martini H12-16
Vak: Neuronale en hormonale regulatie (AB_1168)
Universiteit: Vrije Universiteit Amsterdam
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- Neuronale en Hormonale regulatie Hoorcolleges
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- Neuronale en hormonale regulatie
- Overzicht aandoeningen NHR
- Summary Neuronal and hormonal regulation: book " Anatomy and Physiology ", FH Martini, E. F. Bartholomew