Neural System

Nervous System Functions

Controls muscles, glands, and organs; regulates heart rate, breathing, digestion, urination; maintains homeostasis; responds to stimuli

Nervous System Definition

Network of specialized cells that control physical and cognitive functions

How the Nervous System Communicates

Uses electrical impulses to send signals between brain and body

Main Components of Nervous System

Brain, spinal cord, nerves

Central Nervous System (CNS)

brain and spinal cord

Peripheral Nervous System (PNS

All nerves outside the CNS

CSF

Clear fluid that surrounds brain and spinal cord

Cushions and supports CNS

circulates through ventricles and drains into blood stream

What is CSF made from?

choroid plexus in ventricles (600-700 mL/day)

composition of csf

proteins, glucose and white blood cells

neurons

Transmit electrical signals

neuroglia (glial cells)

Support, protect, and nourish neurons

functions of neuroglia

Support tissue, protect neurons, regulate fluid, defend against pathogens, assist repair

Resting Potential

Neuron’s charge at rest (Na⁺ outside cell)

Signal Transmission

Electrical impulse triggers neurotransmitter release across synapse

synapse

gap between neurons where signals pass

Neurotransmitter Types

Excitatory (stimulate) vs inhibitory (reduce activity) (i.e: Acetylcholine, dopamine, norepinephrine, serotonin, GABA, glutamate)

Neuron Metabolic Needs

Require constant oxygen and glucose

Effects of Hypoxia/Hypoglycemia on Neurons

Neurons die within minutes

Repair Ability

PNS can regenerate; CNS cannot

Acetylcholine Effects/Diseases

learning and memory; alzheimer’s diseases; muscle movement in pns

dopamine effects/diseases

reward circuits, motor circuits involved in parkinson’s disease; schizophrenia

Norepinephrine effects/diseases

arousal; depression

serotonin effects/diseases

depression, aggression, schizophrenia

glutamate effects/diseases

learning, major excitatory neurotransmitter

GABA effects/diseases

anxiety disorders, epilepsy, major inhibitory neurotransmitter in brain

Endogenous opioids effects/diseases

pain, analgesia, reward

Function of frontal lobe

controls voluntary movement,

involved in personality

function of parietal lobe

processes sensory input (minus smell, hearing and vision)

function of occipital lobe

processes visual info

function of temporal lobe

responsible for hearing and memory

Spinal Cord Location

Extends from medulla through vertebral canal → L2 vertebra (continues as cauda equina)

31 pairsn( spinal nerves)

Reflex Arc

Automatic, unconscious response

Patellar Reflex

Knee tap causes leg extension

Withdrawal Reflex

Pull away from painful stimulus without conscious action

PNS Function

Connects body to CNS; controls movement and sensation

Nerve Structure

Bundles of axons

Ganglia→ Clusters of neuron cell bodies outside CNS

Dorsal Roots→ Sensory

Ventral Roots→ Motor

ANS Function

Controls involuntary functions (HR, BP, digestion)

Sympathetic Nervous System (SNS)

“Fight or flight” → ↑ HR, ↑ BP, bronchodilation, ↓ digestion

Parasympathetic Nervous System

“Rest and digest” → Normal HR/BP, ↑ digestion, bronchoconstriction

ANS Neurotransmitters

Acetylcholine (cholinergic = parasympathetic), norepinephrine (adrenergic = sympathetic)

Hydrocephalus

Excess CSF in brain → Enlarged ventricles, brain compression, increased pressure thins cerebral cortex → brain damage

Congenital: linked to genes( LICAM1, AP1S2)

Normal Pressure (NPH) = enlarged ventricles in older adults

Communicating vs. Noncommunicating hydrocephalus

Communicating = Too much CSF produced or poor absorption into bloodstream

Noncommunicating = Blockage in CSF flow

Hydrocephalus symptoms

Infant = Large head, bulging fontanelle, vomiting, high-pitched cry

Adult = Headache, confusion, memory loss, gait problems

treatment of hydrocephalus

Shunt (VP = drains into peritoneal cavity or VA = drains into right atrium of heart)

Risk Factors of Hydrocephalus

prematurity, birth complications, spina bifida, brain tumors, CNS infections, hemorrhage, head injury

Spina Bifida

Neural tube defect (failure of spine to close)

development - neural tubes form early in pregnancy and normally close by 4 weeks

Risk factor of SB

folic acid deficiency

Spina Bifida Occulta

Mild; no neurologic symptoms

small gap in one or more vertebrae

may only dimple, birthmark, tuft of hair over site

Meningocele

Meninges protrude; usually no nerve damage

cystica on surface of infants back

Myelomeningocele

Severe; spinal cord protrudes; paralysis common

most cases sac is covered by skin, most cases tissues and nerves exposed → infection

bowel & bladder incontinence

seizures

Multiple Sclerosis

Autoimmune destruction of myelin in CNS → Slowed or blocked nerve impulses

• diagnosed w/ MRI

Relapsing remitting MS

• most common

• clearly defined relapse of new or worsening symptoms

• followed by remission, symptoms improve or disappear

No apparent diseases progression bw attacks

Secondary Progressive MS

• begins as RRMS

  • later shifts to steady neurological decline with increasing disability

Primary Progressive MS

• continuous worsening of neurologic function from onset

  • No early relapses or remission

MS Clinical Manifestations

Fatigue, weakness, vision problems, numbness, poor coordination

After a nerve impulse crosses the synapse, what occurs next?

Neurotransmitters are reabsorbed or broken down

A patient with multiple sclerosis is experiencing worsening symptoms followed by periods of recovery. Which type of MS does this describe?

Relapsing-remitting

Which structure carries sensory information into the spinal cord?

Dorsal root

Which condition is the most severe form of spina bifida?

Myelomeningocele

A nurse is caring for an infant with hydrocephalus. Which finding should the nurse expect?

High-pitched cry

A nurse is reviewing cerebrospinal fluid (CSF) function. Which statement is correct?

CSF cushions the brain and spinal cord

Which finding indicates activation of the sympathetic nervous system?

Increased heart rate

Which neurotransmitter is classified as inhibitory?

GABA

A nurse is caring for a client with a suspected spinal cord injury. Which finding is most concerning regarding neuron survival?

Decreased oxygen supply to the brain