Deemah Dabbagh Nervous system Composed of Brain CNS Spinal cord CNS Nerves to body parts PNS Function Maintain homeostatis by detecting stimuli in the environment Structure ID: 920964
Download Presentation The PPT/PDF document "The Nervous System CLS 224" is the property of its rightful owner. Permission is granted to download and print the materials on this web site for personal, non-commercial use only, and to display it on your personal computer provided you do not modify the materials and that you retain all copyright notices contained in the materials. By downloading content from our website, you accept the terms of this agreement.
Slide1
The Nervous System
CLS 224
Deemah
Dabbagh
Slide2Nervous system
Composed of:
Brain (CNS)
Spinal cord (CNS)Nerves to body parts (PNS)Function:Maintain homeostatis by detecting stimuli in the environment
Slide3Structure
The nervous system is composed of two general types of cells:
Neurons (nerve cells): building blocks of the
NSNeuroglia cells (supporting cells)
Slide4The Neuron
Also known as the nerve cell
Basic unit of the nervous system
Composed of:A cell bodyDendritesAn axonResponsible for receiving and transmitting nerve impulses and forming long fibers by linking together
Slide5Slide6Important physiological properties of a Neuron
Excitability:
respond to a stimuli (e.g. change in environment)
Conductivity: Ability to transmit a signal (pass it on to other cells)
Slide7Neuron Cell body
Also called soma or
perikaryon
Contains:Nucleus , nucleoluscytoplasmorganelles responsible for cell maintenance
Slide8Neuron Cell Body
Nissl
Bodies
A unique structure to neuronsLarge granular bodies , clusters of rough ERGives the cell body its gray color (gray matter)Synthesize and release proteins
Slide9Slide10Dendrites
Extensions of the cell body
Multi-branched portions which receive impulses and bring them towards cell body
Increase the surface area for connection with other neurons
Slide11Axon
“The tail of the neuron”
A long cell process arises from a slight elevation of the cell body (Axonal Hillock)
Propagates the signal down the neuron and then to other cellsMay have branches called collaterals
Slide12Axonal Transport
Occurs through microtubules
Materials can move
up the axon towards the cell body (retrograde transport)Materials can move down the axon away from the cell body (anterograde transport)Transport can:Fast (mitochondria, pathogens, synaptic vesicles)Slow (enzymes and other substances)
Slide13Classification of Neurons
Based on their anatomy
Based on what they do
Slide14Anatomical Classification
Unipolar
Bipolar
Multipolar
Slide15Unipolar Neuron
A single process
called “
pseudounipolar” in humansOne process protruding from cell body At a short distance from the cell body the process divides into two branches (central and peripheral)It is a sensory (touch, pain) neuron in the peripheral nervous system
Slide16Bipolar Neuron
T
wo processes protruding from cell body; axon and dendrite
Dendrites receive information and axon gives informationSensory neuron e.g. retinal neuron, olfactory neuron
Slide17Multipolar Neuron
Neuron with a cell body and 3 or more processes
One process is the axon, the others are dendrites
Most abundant in the brain and spinal cord
Slide18Functional Classification of Neurons
Sensory
Motor
Slide19Sensory Neurons
A
fferent: carry impulses from peripheral body toward the CNS
Most sensory neurons are unipolar. Some are bipolar.
Slide20Motor Neurons
E
fferent: carry information from the CNS to the periphery
MultipolarSend CNS signals down to body parts, like glands and muscles
Slide21Neurotransmission
Neurotransmission depends on action potential:
S
hort lasting electrical event on the plasma membrane of neurons.
Slide22Action Potential (AP)
All cells, including neurons, have a maintained polarity on both sides of their membrane
the polarity is maintained by stable concentrations of Na+ outside the cell and K+ inside the cell
Stimulus causes the polarity to changeThis creates an electrical potentialElectrical potential propagates along the axon until it reaches the axonal terminal branchesSignal is the transmitted to the next neuron
Slide23Slide24Transmission of signal from presynaptic neuron to post-synaptic neuron
Slide25Some important notes:
Clusters of cell bodies are named differently when they are in the CNS and PNS
In the CNS,
Clusters of cell bodies are called nucleiIn the PNS, Collections of cell bodies are called gangliaWhite matter: myelinated regions of CNS containing mostly nerve fibersGray matter: unmyelinated regions of CNS containing mostly cell bodies
Slide26Neuroglial
Cell
Also known as
glia cellGliaGeneral Functions:SupportNutritionHelp maintain homeostasisForm myelinHelp in signal transmission within the nervous system
Slide27Types of Neuroglial
Cells
Astrocytes
OligodendrocytesMicroglial cellsEpendyma
Slide28Astrocytes
Structural support
Most abundant of all the glial cells
Found between blood vessels and neuron cell bodiesPlay an important role in the blood brain barrier
Slide29Oligodendrocytes
Found in the CNS
Produce myelin
Myelin sheath is a fatty insulator protecting nerve fibers (axons)They can myelinate multiple neurons In the PNS myelination of neurons is done by Schwann cells. (one cell per schwann)
Slide30Microglia cells
Fewer in number than all other glia cells
Have a phagocytic function (engulf pathogens, damaged neurons
ect…)They increase in number during infections
Slide31Epyndema Cellscuboidal epithelial cells
Line the cavities of the brain and spinal cord
Ciliated, helps in circulating CSF that fills those cavities
Slide32Divisions of the Nervous system
Slide33Divisions of the Nervous System
Central nervous system (CNS)
Brain (coordinates all bodily activities)
Spinal cord (connects brain to body)Peripheral nervous system (PNS)Made up of nerves outside of the CNS:SomaticAutonomic
Slide34Central Nervous System
Slide35Central Nervous System CNS
The Brain:
Cerebrum
Diencephalon CerebellumBrain stem
Slide36The Central Nervous System
Cerebrum:
The largest part of the brain
Two lateral hemispheres (left and right)Left side is logical, right side is creativeConnecting the 2 hemispheres is a layer of neurons called the corpus collosum.Cerebrum is divided into 4 lobes
Slide37The Central Nervous System
Cerebrum:
Functions:
Provides higher brain functions (deep thinking, intelligence,learning)memorySensory information (touch, smell, taste, visual, hear)Coordinates skeletal musclesLanguage, comprehension, speechPersonality development (sense of humor, competitiveness
Slide38The Central Nervous System
Cerebrum:
Frontal lobe
Primary motor area: conscious movement of all skeletal musclesHigher intellectual reasoningParietal lobe:Somatic sensory cortex area: Touch, pain, temperature..etc)Temporal lobe:Auditory area, olfactory areaOccipital lobe:Visual area
Slide39The Central Nervous System
Diencephalon:
Composed of:
ThalamusHypothalamusEpithalamus
Slide40Diencephalon cont:
Thalamus:
Relay station for sensory impulses
Cerebrum Sensory signals thalamus brain stem spinal cord PNSHypothalamus:Regulates body temp, water balance, metabolism (TSH)Stress management: by adrenocorticotropic hormone (ACTH) adrenal glandsControls pituitary gland: GH, prolactin, oxytocin…etc.Important part of the “limbic system” or emotional visceral brain (thirst, appetite, pleasure, pain..etc)Influences controls of the medulla oblongataEpithalamus:Contains pineal gland
melatonin (sleep hormone)
Choroid
plexux
forms CSF
Slide41The Central Nervous System
Brain Stem:
Midbrain
Bulges in front called cerebral peduncles: coordinate fine motor movements (e.g. grasping an object between a thumb and a finger)Dorsally: protrusions called corpora-quadrigemina: involved in vision and hearingPonsInvolved in the control of breathingMedulla oblongataCardioregulatory centers (heartbeat, blood pressure, vasoconstriction…)
Breathing, swallowing, vomiting
Slide42The Central Nervous System
Cerebellum:
Located under the cerebrum
Functions:Controls balance and movement coordination By receiving information from the body and sending information to the body
Slide43The Central Nervous System
Spinal Cord:
Receives signals from the brain
Passes signals to the PNS (which take them to the rest of the body)
Slide44Peripheral Nervous System is Subdivided into:
Somatic nervous system
Autonomic nervous system
Slide45Somatic Nervous System
Connects CNS to skeletal muscles and
skin
Conscious controlvoluntary
Slide46Autonomic Nervous System
Connects CNS to viscera and
glands
Unconscious, involuntary control (breathing, heartbeat, digestive system..etc)Further subdivided to:Sympatheticparasympathetic
Slide47Sympathetic VS Parasympathetic
Sympathetic:
Also called thoracolumbar division
Fight or flight (scared, excited, thriving for survival..etc)Dialation of pupilsInhibit salivationRelax bronchi (to get more air in)Accelerate heartbeatInhibit peristalsis and secretion (can survive longer without food)Stimulate glucose production and release
Slide48Sympathetic VS Parasympathetic
Parasympathetic:
The “
craniosacral division”Relaxed modeConstrict pupilsStimulate flow of salivaConstrict bronchiSlow heartbeatStimulate peristalsis and secrestionStimulate bile release
Slide49Autonomic Nervous system
Two primary neurotransmitters:
Acetylcholine
Major neurotransmitterUsed by parasympathetic and sympathetic nervous systemNorepinephrineUsed by sympathetic nervous system
Slide50Protection of CNS
Meninges
Blood Brain barrier
Slide51MeningesThree C.T. membranes covering structures of the brain:
Dura matter (outer most)
Arachnoid matter (middle)
Pia matter (inner most)
Slide52Blood Brain BarrierProtects brain from blood borne substances
Composed of the least permeable capillaries in the body (brain capillaries).
Only water, glucose and essential
a.a can pass through its capillaries walls.Metabolic wastes; urea, toxins..etc are prevented