THE NERVOUS SYSTEM -2 Anatomy Physiology and Pathology.

THE NERVOUS SYSTEM -2

Anatomy Physiology and Pathology

Blood Supply to the BrainCircle of WillisBlood-Brain barrierAllows – water, Glucose, Essential amino acidsFat soluble substances- O2, CO2, fats,No way in – non-essential amino acids, K+ ions, toxins, micro-organisms, proteins, waste products &chemicals (most drugs)Sneaky ones- Alcohol, narcotics, anaesthetics, nicotine

Cerebrospinal Fluid

Clear watery fluid in sub-arachnoid space

Forms buffer/ cushion

Produced by the ventricles and choroid plexus

Maintains a constant pressure and volume of about 150 ml.

Too much – HYDROCEPHALUS

Tested with lumbar puncture

CommunicationLines of PNS

Sensory

Somatic-Skin, muscles

joints

Visceral-Internal organs

Motor

Somatic orVoluntary NS

Autonomic NS

Sympathetic

Parasympathetic

Cranial nerves

Olfactory – smell

Optic – sight

Occulomotor –eye movement

Trochlear – eye motion- down and in

Trigeminal- Motor – mastication, lateral jaw movement. Sensory- maxillary mandibular and ophthalmic.

Cranial nerves

Abducens – eye motion – lateralFacial – Motor – facial expressions, closing of eye and mouth. Sensory- taste on anterior 2/3 of tongueAuditory or Vestibulochoclear – hearing and balanceGlossopharyngeal – Motor- swallowing. Sensory – posterior 1/3 of tongue taste and eardrum, Eustachian tube and pharynx

Cranial nervesVagus – Motor- thoracic and abdominal organs (promote digestion and regulate heart activity). Sensory – pharynx, larynx, heart, lungs, bronchi, GI tract, external ear.

Spinal accessory – Sternocleidomastoid and upper trapezius muscles

Hypoglossal – tongue movement and sensory impulses from tongue.

Spinal plexuses

Cervical

Brachial

Lumbar

Sacral

Contain both sensory and motor fibres

Autonomic nervous system

Regulates homeostatic control mechanisms

Outside conscious awareness

Some e.g.. – digestion, constriction of blood vessels, stress responses

Sympathetic and Parasympathetic (Cranio-sacral)

STRESS RESPONSEInjuryInfectionTemperatureEmotionsOverworkPainShock Any one of these will produce cortisol and Adrenalin

Effects of cortisol

Stimulation of protein and fat catabolism

Uptake of amino acids and conversion to glucose

Inhibition of glucose uptake

Vasoconstriction

Inhibition of inflammation and specific immune responses

Action of Adrenalin & Sns

Increased blood coagulation

Faster breathing rate and heart beat

Moving blood from centre to muscles

Less fatigue

More energy/ glucose available for use

Over stimulation is detrimental

Diseases of the Nerves

Injury

Functional disorders

Infections

Degeneration

Structural defects

Tumours

Major nervous symptoms

HeadachesNumbnessTinglingWeaknessSudden loss of sightMemory lossCo-ordination difficultiesMuscle rigidity/ spasms/ tics

What to ask ?

Try to think of relevant questions to confirm or rule out nervous system affection.

Try to think of various examinations / tests possible to confirm/rule out neural involvement.