The Communication System in The Nervous System

• The nervous system is a rapid and effective communication system and regulator of homeostasis
• It controls every thought, psychological reaction, emotion, and behavior
• Every physiological function reflects the activity of the nervous system
• The nervous system performs macro and micro communication

Macro Communication System

• Sensory functions sense changes within the body and the external environment
• Integration interprets changes in the brain by drawing on intelligence, memory, learning, and emotion
• Motor functions respond by initiating action involving skeletal muscles or internal physiological functions

Sensory Communication into the Brain

• Communication occurs along neurons and between neurons via neurotransmitters
• Neurons are nerve cells that send messages and allow breathing, talking, eating, walking, and thinking
• Neurons in the human nervous system are divided into sensory neurons, motor neurons, and interneurons
• Interneurons (association neurons in the CNS) distribute sensory information and coordinate motor activity
• They play a role in higher functions such as memory, planning, learning, and execution of actions

Receptors

• Receptors are sensors in the body that send sensory information to the brain
• They detect or assess situations or changes (e.g., weather) and respond to stimuli
• Internal monitoring of specialized cells occurs via baroreceptors and chemoreceptors
• Baroreceptors located in the aortic arch monitor blood volume and pressure
• Chemoreceptors in the medulla oblongata control oxygen levels

Types of Nerve Endings

• Free nerve endings monitor pain and temperature
• Encapsulated nerve endings monitor pressure and touch
• Complex sensory organs (e.g., eyes, ears) exist
• Brain integration is the analysis of input data
• Action-motor nerves facilitate internal action-homeostasis, interpretation leading to execution, and external action movement
• The order of nervous system communication is sensory, integration, motor

Nervous System Organization

• The CNS (central nervous system) contains the brain and spinal cord
• The PNS (peripheral nervous system) is everything outside the CNS
• The PNS afferent division carries sensory information from receptors in the body into the CNS
• The PNS efferent division carries motor commands from the CNS to muscles and glands

Somatic Nervous System

• It controls skeletal muscle contractions and voluntary muscle contractions
• It facilitates walking, running, and movement

Autonomic Nervous System

• It controls subconscious actions, contractions of smooth and cardiac muscle, and glandular secretions
• The autonomic nervous system is divided into sympathetic and parasympathetic branches

Nerve Physiology

• A neuron is the basic unit of the nervous system
• It detects information from the outside and internal environment
• It formulates behavioral, autonomic, and voluntary responses to control the body
• Cell Body (Soma) contains a nucleus
• Dendrites receive signals
• The axon creates an action potential and transmits messages along the axon
• Myelin covers the axon for faster signal transmission
• CNS myelin is formed by oligodendrocytes
• PNS myelin is formed by Schwann cells
• Axon terminals transmit action potential to connecting neurons or muscle using neurotransmitters

Neuron Classification

• Unipolar: single projection, no dendrites
• Pseudounipolar: single axon split into two branches
• Bipolar: one axon, one dendrite
• Multipolar: one axon, multiple dendrites

Molecular Mechanism of Neurone Communication:

• The first principal: Understanding the ion environment of the neuron
• When a neuron is inactive waiting for a nerve impulse to come along, the neuron is polarized (resting membrane potential)
  • Inside the cell is negative electrical charge (-65/70mv)
  • Fluids outside the cell have a positive charge
  • Electrochemical gradient exists
• Highly polarized cells are known as highly excitable cells including neurons, and cardiac cells

Electrical Signals

• Electrical signal (nerve impulse) occurs when the nerve impulse occurs when ions rapidly shift across the neuron membrane
• For cells to change permeability, ion channels in the membrane must open/close
• Two types of cells:
  • Leakage channels
  • always open
  • Gated channels - can be stimulated chemically, mechanically, by voltage, or light

Gated Channels

• Are only found on excitable cells and cardiac muscle cells
• Chemically gated: most abundance on dendrites and cells body
• Voltage-gated: mostly at axon hillock and axons
• Mechanically Gated: Mostly on sensory receptors and senory dendrites

Stimulus

• Is need for neurons for electrical potentials
• Two basic signals:
  • Graded potentials: travel over short distances
  • Action potentials: travel rapidly over long distances
• Needs a strong stimulating to reach threshold levels

Graded Potentials

• Are temporary changes in the in-memberane potential
• They vary in size and are detemrined and strength of stimulus
• If its strong enough cause depolarization, and the neuron transmits an action potential
• Graded potentitals travel short distance
• Any signlaim that opens a gated channel produces a grade (local) potencial
• The greater the stimulus the great the number of channels to open
• Can summation and reach axon hillcok

Action Potentials

• Are produced by graded potentials
• Action potentials becomes a self - propagting
• Decribes about one-thousandth of reversal electricity of reversing of a membrance of nerve or mucles cells
• Action potenial is electricity down axon terminal
• Causes release of neurons
• In the neurons the impulses is needed

Sequence of events of action potentials

Phase 1: A stimulus generales graited potential that depolarization the axon hill to the threshold Sodium gates Na+ open quickly and Na+ ions diffuse into the neuron Durig depolarization phase the membrance potential reaches values to +30mv

Phase 2: The potassium channel open to cell becomes more positive but delys one seconds in the openings Potassium leaves and makes inside very negative Na+/K+ pumps restabilzes ions to resting leves

Rates

• Consiousness conuduction, slow conduction
• Saltatory conduction Fast System
• Influence nerve rate condition depends on:
  • Myelination -Axon - The larger diameter the faster propagation -Temperature

Anatomy of the Central

• Brain
• Spinal cord
• Peripheral Nerve
• Cranial Nerve - Spinal Ganglia

Central

• Supreme command center of the body
• Two organs- brain and brain cord
• 3 Membrances and vertebrae
• Bain composed of: Cerebrum, Brainstem, Cerebellum

Peripheral Nervous System

• Sensory- tempature/ light to back brain
• Motor- commands from brain to controll skeletol muscles
• Connects with brain

Blood Supply to the brain

• CNS nurioushed by blood from the carotid and veterbal artiers
• The blood is the dural sunises that carries oxygen and returns it internal juagular veisn

Arteries of Brain

Two main arteries supplying the brain 1.internal corotid artery -supplies artier 2/3 of cereral hemisphere and parts of diecephalon 2. verterbral art - provides 1/3 posteriory and dienchephalon, branstem, cerbelum

Anetrior cerebral artery

• Smolest of cerebal brahcnes
• Vaculary frontol and parts the contain of logical thought, prnsaltiy, and volunatry ovemnents
• Interruption to the blood: Motoir impairmetn and cognitive

Middle Cerebral

• Artier circuit
• Supplies oxygentaed the frontol lobe

Posteriro cerebral artery

• The postier cerebal provide art supplies of temopral and occtiol

Vertebroballislar system

• Left arties rise from the clian and bran

Dural Vinous Sunseses

• Chaness with the period
• Tenngular section and funcsion as the viasn draining of the brain
• Fenous flau tesn to be artier and posteriroir frou otusards

Manifestation of stroke

• The cincal effects of a stokne
• Many srokes resule from the occlusion of the middle artier

Cerebral hemorrhage

• Brain anyerusm (ballooon from a wesken)
• Tropgraphies (oriention)

Division of Brain

• Forebrain> Telencephalon - Cerebral Hemispheres diecephalon
• Midbrain> mESencephalon Connects from breain and hindrbian
• Hindbian> brainstem (Pons and medilla alongnata) and the cerbelm
• Gray matter: cell bodes cluster togehter form nuclei/groups
• White matter: (witing) inside cerebrum and extend through nervous system

Cerebral

• Sepreattes 2 cerbal hemi
• The Bain is divivided into 4 loves sepetarate by sulci and fishtues
• Functional anatomy Premotry area, prinary sulcus Area Bricais and wermickeas

White matter fibres

• white mater interal cerbum connsist of: assotiation fier intterconect single hemsipre Commisural fivers intraconnet cerebal hemisphrers
• **

Parts of White matter

• Commicaitons fibeers
• Basal Ganglia: Grey matt structures Umbrella term of structure of nuclei
• Diencephalon
• Talamus
• Involves processing memory, desiciosn and makings

Whatis brain stem

• Superior
• Midbraain
• The brianstem 3 parts lines postiter cranial foda, coantins emblen neucule

Braintem

• Most superion and smolest aprats of the tranisrem and conud

Parksion disease

• Degeratnion of dopamme Neurons Hallark sing ides the comdito

Sinapsce

• Meets single two neirons
• Pns system

Types of sinap

• Neuro-Neuiru junciton - synpase between neition
• Neuromyscular junstion
• Newtoglndailr junciton a synapse between neur

sequence at chemical synapse

1. actop potential
2. Ca2+ difuseds causes synpatic resuciels release newitranmier
3. neruotion difese from prespatic to reule 4 and 5 the cell and acasese e
4. Remosal or recyln transitter from synoptic class 7 acletochloni, gounds cns and pns
5. are vorurtes and are storred in veisles

Brain specilisist and circults

• Projectiton Fibs
• contain and sensoy from the brain
• faciltata condin to left hemesiphere
• Intteranl cospule
• Assotion filber

The cerebal cortex

• resosiable from high order
• Motor cortesx

Thelmamus and baisis

• Baisia gulia
• the cerebolun