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10c; control systems
 

10c; control systems

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10c; control systems 10c; control systems Presentation Transcript

  • Lecture 10c: Control Systems
  • Nervous SystemSignal moves from brain along nerve totarget muscle, which contracts in responseCentral nervous system (CNS)- brain andspinal cordPeripheral nervous system(PNS)- nervesoutside of CNSThey are connected to each other and worktogether
  • NeuronsRememberneuronanatomy
  • NeuronsMyelin sheaths- cover axons, they increase the speed atwhich nerve impulses travel3 types of neurons Sensory: take nerve impulses from sensory organs to the CNS, may be a simple nerve ending or part of an organ like the eye Interneurons: only in the CNS, carry impulses around the CNS only, what thinks Motor: take nerve impulses from the CNS to muscles or glands
  • Nerve ImpulseNerve impulses are electrical in natureNerve impulses are dependent on concentrationgradientsA neuron maintains: High conc. of K+ inside the cell and a high conc. of Na+ outside the cell, via membrane pumps Inside of cell is negative compared to outside
  • Nerve ImpulseThe difference in charge is called an action potential-the Na+ ions want to go inside the cell, the K+ ionswant to go outWhen the neuron is signaled, gated channels open thatallow the Na+ to rush into the cell, making it positiveinsideThen the Na+ channels close and K+ channels open,and the original gradient is restoredThis movement of the charged area is the movement ofthe nerve impulse
  • Nerve ImpulseThe action potentials are self-propagating along thelength of an axon- as each area changes its charge itstimulates the next area to do the sameUnmyelinated nerves conduct at about 1m/ sec,myelinated nerves conduct at about 1oom/ sec The myelin causes the action potential to jump along the length of the nerveRefractory period- a short time in which the gates cannot open- prevents nerve impulse from goingbackwards
  • Nerve Impulse
  • SynapseHow does a signal get from one nerve to the next?The gap between two nerves, or a nerve and a muscle,is called the synapseNeurotransmitters- chemicals which carry theimpulse from the first cell to the next across thesynapse When the impulse gets to the end of the axon, synaptic vesicles release neurotransmitters into the synapse, and they are received by the next cell
  • SynapseThere are at least 25 known neurotransmitters, caneither excite or inhibit the receptor cell Acetylcholine and norepinephrine are two best knownAfter release, they are very rapidly either resorbed orbroken down, so as to not constantly stimulate the cellEach neuron has many dendrites and synapses withmany other cells (1000- 10,000) If it gets more excited than inhibited, it will send an impulse
  • DrugsCocaine: prevents resorption of dopamine, which then staysin synapse and continues to stimulate receptor- causes therush Prolonged use- cells become resistant to dopamineHeroin: binds to endorphin receptors, results in no pain andgood feelings Prolonged use- body stops making its own endorphinsMarijuana: binds to a receptor for anandamide, whichcreates a peaceful and contented feeling Prolonged use- psychotic symptoms, hallucinations, etc.
  • CNSBrain- very complex organ, we are learningmore about it all the timeWe will discuss: Cerebrum Diencephalon Cerebellum Brain Stem
  • Cerebrum!!Communicates with and coordinates thedifferent parts of the brain Mostly white matter- made up of long axons going between brain areasHas 4 lobes: frontal, parietal, occipital, temporalCerebral cortex is outer layer of grey matter,where higher level thought, voluntary motion,and interpretation of sensation occur
  • Cerebrum- lobes andCerebellum
  • CerebrumEach area (lobe) has specific functions Parietal lobe has primary sensory area, receives info from skin, muscles, joints Frontal lobe has primary motor area, makes decisions about voluntary movement and initiates this mvmt. Frontal lobe as prefrontal area, which integrates information received from other areas and is where critical thinking and decision making occurs
  • DiencephalonLocated under the cerebrumContains the thalamus receives all sensory info except smell integrates this info and sends it to the cerebrum also involved with memory and emotionsAnd the hypothalamus helps maintain homeostasis regulates hunger, thirst, sleep, body temp link between nervous and endocrine systems
  • CerebellumLocated in the back of the headAlso receives sensory input Uses info from joints and skeletal muscles to know where body is Uses info from cerebral cortex to know what body parts should be doing Sends motor info to the body Maintains balance and posture Assists in learning new mechanical skills
  • Brain StemConnects the brain to the spinal cordContains midbrain Visual and auditory reflex centers/ startleMedulla oblongata reflex centers regulate heartbeat, breathing, blood pressure Reflex centers for vomiting, sneezing, swallowing, hiccuping Internal organ control as wellPons- links medulla with midbrain, vital for breathing
  • How does the brain combinedifferent stimuli?Limbic system- blends higher mentalfunctions with more primitive emotions Includes the diencephalon parts of the cerebrum Binds memory to reasoning Binds memory, emotion, and reasoning Why we don’t always act on strong emotions
  • MemoryShort term memory stored in the prefrontalarea, but long term memory is different Mixture of semantic and episodic memory Semantic- the words or numbers Episodic- association with people, places, etc. In order to learn, both types must be activated
  • Peripheral Nervous SystemOutside of the CNS- contains nerves, whichare bundles of axonsCell bodies are either within the CNS (spinalcord, mostly) or are stored in ganglia-collections of cell bodies within the PNS Sensory neurons have their cell bodies in what is called the dorsal root ganglion- a ganglia that is next to the spinal cord
  • Somatic SystemThe part of the PNS that takes sensoryinfo from receptors/ sense organs to theCNS, and takes motor commands fromthe CNS to the skeletal musclesIn a reflex, the command to move comesfrom the spinal cord, not the brain However, the brain is told about the stimulus that caused the reflex as well
  • Autonomic SystemAutomatically and involuntarilycontrols cardiac and smooth muscle,and gland activityParasympathetic- promotes the relaxed ornormal stateSympathetic- promotes ‘fight or flight’,used in emergency situations
  • Endocrine SystemsNow, we will talk about the other controlsystem in the bodyThis system consists of glands andtissues that secrete hormones Hormones are secreted directly into the blood, where they have effects on many different bodily functions
  • HormonesHormones bind to receptors on cells that canrespond to them, and then the cell undergoes ametabolic change Steroid hormones cause the cell to make a protein Peptide hormones bind to membrane receptor, then start a cascade of events inside the cell- just one binding can have a huge impact
  • Hypothalamus and PituitaryGlandHypothalamus- helps regulate theinternal environment Communicates with medulla oblongata Controls secretions of pituitary gland, which is connected to the brain
  • Anterior PituitaryHypothalamus causes the AP to releasehormones that stimulate other glandsInvolved in stimulating gonads to producegametes and sex hormones, and in productionof milkInvolved in growth via growth hormoneInvolved in carbohydrate and fat metabolismMore, too, involving thyroid, etc.
  • Posterior PituitaryAntidiuretic hormone- released when bldis too concentrated, causes water to bereabsorbed in the kidneyOxytocin- causes uterine contractionsand also milk release during nursing
  • Thyroid and ParathyroidGlandsThyroid- gland in the neck, hormones itproduces increase the metabolic rate Stimulate all cells to work at a faster rateThyroid and the parathyroid also involve inCa+ regulation in the body Ca+ important to muscle and nerve function, blood clotting
  • Adrenal GlandsSit on top of the kidneysHave inner and outer portion Adrenal cortex (outer) and adrenal medulla (inner)Stimulated by the hypothalamus toproduce its hormones
  • Adrenal MedullaProduce epinephrine and norepinephrine Helps the sympathetic nervous system in response to an emergency Short-acting
  • Adrenal CortexProduce mineralocorticoids Ex. aldosterone, regulates salt and water volumeand glucocorticoids Ex. cortisol, regulates carb, protein, and fat metabolism
  • PancreasTwo types of tissue, exocrine discussed indigestionOther type is endocrine, discusses hereProduces insulin and glucagon Glucagon- secreted between meals, when bld glucose is low- stimulates liver to break down glycogen to glucose- it raises bld glucose levels
  • PancreasInsulin secreted when blood glucose is high, stimulatesuptake of glucose by cells-- so insulin lowers bld glucose levelDiabetes Mellitus- Body cells do not take up or metabolizeglucose- cells need glucose even though there is plenty in theblood Type I- the pancreas does not produce insulin- must take insulin injections Type II- liver and other cells become resistant to insulin due to poor health and eating habits End results of both types can be the same: blindness, kidney disease, circulatory disorders, death