Nervous System Anatomy and Physiology

• The text will now be summarized into a set of study notes
• Keep in mind the above instructions

Care of Clients with Problems

• This study note covers Perception and Coordination (Neuro).

Lesson 1: Review of Anatomy and Physiology of the Nervous System

Nervous System

• It is the body's primary control and communication network.

Main Function

• Sensory receptors detect internal or external stimuli as part of the sensory function.
• Sensory information is analyzed and decisions are made for appropriate responses during integration.
• Motor function involves eliciting appropriate motor responses by activating effectors via cranial and spinal nerves.

Divisions of the Nervous System

• The brain, containing about 85 billion neurons, resides in the skull as part of the central nervous system (CNS).
• The spinal cord connects to the brain through the foramen magnum and is surrounded by vertebral bones.
• The peripheral nervous system consists of nervous tissues outside the CNS.
• A nerve is a bundle comprising of axons as well as associated connective tissue and blood vessels.
• There are 12 pairs of cranial nerves that arise directly from the brain.

Sensory (Afferent) Division

• Transmits information to the nervous system.

Motor (Efferent) Division

• Transports impulses away from the body's central nervous system (reaction).

Subdivisions

• The somatic nervous system (voluntary) controls skeletal muscles.
• Cardiac and smooth muscles, as well as glands, are under the control of the autonomic nervous system (involuntary).
• The parasympathetic nervous system promotes rest, digestion, and cessation while also supporting rest, digestion.
• The sympathetic nervous system drives the fight or flight response.

Protection of the Central Nervous System

• Scalp
• Periosteum
• Bone/Skull
• Epidural Space
• Meninges (connective tissue membranes)

Meninges

• Connective tissue membranes that enclose and safeguard the CNS

Layers of the Meninges (DAP)

• The Dura Mater is the outermost membrane known for being tough and fibrous, typically grey in shade.
• The Arachnoid Mater is the middle membrane, thin, and closely spider web-like
• The arachnoid mater contains choroid plexus which produces cerebrospinal fluid.
• The Pia Mater is the thin, transparent innermost membrane closely adheres to the brain and extends into every fold of the brain's surface.

Cerebrospinal Fluid (CSF)

• The cerebrospinal fluid is produced in the choroid plexuses and acts as a protective watery cushion for the brain.
• The normal volume is 150 mL.
• Arachnoid villi serve as the location for CSF absorption.
• It is generally transparent and without color.

Blood Brain Barrier

• Only water, glucose and essential amino acids can pass through the walls of these capillaries efficiently.
• Substances such as metabolic wastes, toxins, proteins, and the majority of drugs cannot enter the brain tissue.
• Alcohol, nicotine, heroin, bilirubin (in infants), fat, and fat-soluble molecules, respiratory gases, and anesthesia are allowed.
• Formed by endothelial cells of brain capillaries

Neuroglia (Glial Cells)

• Astrocytes use foot processes to surround blood capillaries. They perform a variety of tasks, from axon guidance and synaptic support, to the control of the blood-brain barrier and blood flow.
• Microglia/Microglial Cell spider-like phagocytes that clear the brain of debris.
• Ependymal cells are cillia-like and forms a lining in the brain
• The cerebrospinal fluid that circulates has cilia extending from the surfaces.
• Oligodendrocytes create a myelin sheath around portions of three axons located within the central nervous system.
• Schwann cells form part of the myelin sheath of an axon in the peripheral nervous system.
• Satellite cells provide neuron protection.

Neuron (Nerve Cell)

• The basic unit of the brain
• Capable of receiving stimuli, conducting action potentials, and transmitting signals/impulses to other neurons or effector organs.

Structure of a Neuron

• The cell body (soma) is the origin of information for gene expression and the neuron's metabolic hub.
• The neuron's core carries genetic information and supports the structure and energy needs of the neuron.
• Nissl substance and neurofibrils are parts of the soma.

Processes

• Dendrites transmit impulses toward the cell body.

Axon

• Transmits impulses towards the cell body
• Separated by synaptic cleft gaps, axonal terminals house neurotransmitter-containing vesicles.
• Separates axon terminals from another neuron, the synapse is the location where nerve impulses are transmitted between two neurons.
• Myelin Sheath: Specialized layers that encircle the axons of certain neurons.
• Increases the rate and effectiveness with which axons produce action potentials
• Oligodendrocytes create the central nervous system (CNS).
• PNS - schwann cells

Nodes of Ranvier

• Gaps can be found in the myelin sheath that contain sodium-potassium pumps.

Glial Cells

• CNS and PNS auxiliary cells
• No action-potential conductivity.

Functional Classification of Neurons

• Responsible for helping activate senses the sensory afferent neuron
• This is often triggered or activated by chemical and physical inputs.
• Pacinian Corpuscle - deep pressure
• Meissner's Corpuscle - touch receptor
• Muscle Spindle (proprioceptors) - respond to a degree of stretch or tension
• Impulses originate from the sense organs.

Motor Efferent Neurons

• Movement is an impluse and involves impulses from the brain.
• Interneurons/Association Neurons send signals in the pain center of the brain.

Structural Classification of Neurons

• Multipolar structure neuron Contains multiple dendrites along with a single axon.
• Bipolar Contains a dendrite plus an axon.
• Unipolar neuron that contains only one nerve process is what extends from the cell body, which forms the axon that extends into dendrites
• Pseudo-unipolar appears to have a single axon, devoid of any dendrites

Functional Properties

• Irritability is the capacity to respond to a stimulus and transform it into a nerve impulse.

Polarization

• The neuron's inside carries a negative charge, while the neuron's outside carries a positive one
• Potassium is predominant within a cell, whereas sodium predominates outside of it.

Depolarization (Action Potential)

• Neurons get excited by stimuli, allowing sodium to diffuse inside the cell and potassium to exit outside.

Propagation of Action Potential

• Neuron exhibiting increased permeability to Sodium a.k.a "saltatory conduction"

Repolarization (Hyperpolarization)

• Commences with the sodium-potassium pump, expelling sodium from the cell and drawing potassium back inside.

Conductivity

• Capacity to transmit impulses is "to travel".

Terminologies

• Tracts: group of nerve fibers within the CNS
• Nerves: PNS (peripheral nervous system); transfers electrical impulses to the rest of the body
• • White matter: consists of myelinated fibers
• Gray matter: mostly unmyelinated fibers and cell bodies

Brain

• Resides in the cerebral cortex, which is responsible for memory, speech, logical and emotional responses, interpretation of sensation, consciousness and voluntary movements.
• Composed of 4 lobes

Left Hemisphere

• Muscles on the right side of the body are controlled.
• Spoken and written language numerical and scientific skills reasoning systemic analysis.

Right Hemisphere

• Controls muscles on the LEFT side of the body
• Musical and Artistic Awareness
• Space and Pattern Perception
• Insight
• Imagination
• Creates comparative spatial realtionships.

Regions of Human Brain

• Frontal lobe: Controls voluntary motor activity
• Reasoning, concentration, abstraction
• Contains the BROCA's AREA
• Voluntary eye movement
• Accesses prior knowledge and current experiences
• Judgment
• Parietal Lobes Contains somatic sensory areas (sensation, texture, size, shape, and spatial relationship)
• Taste impulses for interpretation, pain, coldness, light touch
• Perception of body parts and body position awareness, singing, playing musical instruments, and processing nonverbal experiences
• Temportal Lobe contains the Auditory Area, Deep inside (olfactory area), Wernicke's area
• Damage results in: Dyslexia
• Occipital lobe: contains visual area
• Damage Visual agnosia-impairment in recognizing visually presented objects

Diencephalon

• The Thalamus acts as a relay station for sensory impulses ascending to the sensory cortex. Transfers impulses to the cortex for localization and interpretation.
• The Hypothalamus is responsible for regulating body temperature, water balance, metabolism, controlling emotions, Regulates the pituitary gland
• The Epithalamus is where the pineal gland (melatonin production), probable role in growth and development, Regulate the food getting reflex. includes choroid plexus - forms CSF

Brainstem

• Midbrain: Responsible for motor coordination, Visual reflex and auditory relay centers.
• Pons: regulates respiratory center
• Medulla Oblongata: Centers that control; heart rate, blood pressure, breathing, swallowing, vomiting
• Reticular Formation: Involved in motor control of visceral organs
• Reticular activating system- playrole in aware/ sleep cycles and consciousness

Cerebellum

• Controls balance and equilibrium and damage to the cerebellum Cerebellar Ataxia.

Limbic System

• Functions: Emotions. Includes the Limbic System (or the limbic areas)

Cerebral Circulation

• Supplies the brain with blood.
• The circle of Willis (CoW) is an anatomotic structure that provides a connection between the anterior and posterior circulations to provide collateral flow to brain affected regions during arterial incompetency.

Spinal Cord

• Runs from the medulla oblongata to the T12 region. The cauda equina (a group of spiral nerves) is located below T12.
• Have major reflex centers.
• Contains 31 paired nerves.
• Cervical Nerves: Provide sense of motion to the arms, neck, and upper trunk.
• Thoracic Nerves (nerves in the upper back): Supply the trunk and abdomen.
• Lumbar and Sacral Nerves (from the lower back): Supply the legs, the bladder, bowel and sexual organs.

Peripheral Nervous System

• Contains both the nerves & scattered neuronal cell groups that are found outside the CNS
• Cranial nerves numbering is based on their sequence from the brain.

Reflex Arc

• The arc refers to the most basic neural pathway that manages a reflexive action to protect itself. The reaction is automatic, unintentional, and defensive to the situation.

Kinds of Reflexes

• Visceral reflexes: Cause smooth or cardiac muscles to contract or glands to secrete
• Somatic reflexes: Result in the contraction of skeletal muscle.
• Knee-jerk Reflexes: Known to be an ipsilateral and monosynaptic with the receptor and effector organs on the same side.

Flexor/Withdrawal Reflex

• The flexor, with a combination of 3 types of neurons: association, sensory and motor

Cross Extensor Reflex

• A cross-exertion reflex will stimulate specific muscles will stimulate opposing muscles.

Lesson 2: Neurological Disorders

A. Headache

• Also known as cephalagia.
• Primary headaches lack an identifiable organic cause, whereas secondary headaches result from an organic condition such as a brain tumor or aneurysm.
• Questions specific for a headache will relate to the origin, length of time the headache has lasted, family history and medication usage if any.

Types of Headache

• Tension arises from muscle contraction causes a tight band and unrelentless discomfort.
• Cluster happens in a pattern with 1-3 short lived attacks of pain.
• Sinus Pain is behind the browbone and checkbone
• Migraine can occur on either the face or in alternate with different attacks
• Lumbar comes from the loss of CSF Volume
• Post concussion results from seemingly trivial head injuries.

Categories of Migraine

• With aura is when the headache lasts 1days and aggravated
• Without aura is the development of 5-20 mins before the headache

Stages of Mighraine Headache

• Prodrone lasts for hours before and leads towards problems of concentration, irratbility and depression
• Aura takes place for 5-60 mins
• Headache persists after all this time and it can last up to 72 hours
• Prostdrome is just the after effects of the headache

Risk factors

• Consists of menstrual cycle, stress, depression, etc

Treatment

• Consists of history taking, complete physical/neurological examination

B. Intracranial Pressure (ICP)

• 7-15 mmHg is the normal pressure in the brain tissue and cerebrospinal fluid (CSF)
• Increased ICP is associated with altered states of consciousness. Referred to as Monro-Kellie Doctrine/Hypothesis.
• Cerebral Edema, brain surgery or lesions are all causes for the pressure incrasing.

Increases of of ICP

• Flattened Affect & decrease orientation
• Pupillary Change
• Impaired eye movement

Vitals

• Increase Systolic BP
• Vomitting

Complications

• Occurance of brained herniated leads towards eschemia/hypoxia
• CSF Analysis is needed
• Followed up a device to measure ICP Monitor

Treatment

• Usage of calcium blocker- Mannitol Suction the air way

Seizure Disorder

• Sudden, abnormal electrical discharge from the brain that results in changes in sensation, behavior, movements, perception, and consciousness. Epilepsy - chronic disorder of recurrent seizure.

Types of Seizures

• Focal begins in one area or the brain. Is Caused by any type of focal injury that leaves scar tangles and can be identified with a simple partial seziure. Not accompanied by loss of consciousness.
• Generalized Causes loss of consciousness and violent muscle contractions (Grand Mal Seziure).

C. Traumatic Brain Injury

• Common causes trauma, accidents
• Involves a brain insult.

Types of Head Injury

• Consists of scalp, bruises, fractures

Emergency Managment

• Immobilizing the head in an event as such as this

Medical and Surigal Managment

• Reducing Skeletral Fractures after a Trauma

Lesson 3: Autoimmune Disorders

A. Myasthenia Gravis

• Is sudden loss of motor control on one side of the face
• Is a chronic, progressive autoimmune neuromuscular disoder
• Acetylcholine cannot transfer to somatic nervous
• Females have are a higher chance of coming down with this

Clinical Manifesation

• Ptosis is the effect during most causes of the cases
• Dysphagia is the difficulty to swallow
• skeletal weakness

Diagnostic test

• Edrophonium Testing can show that with possibility the possiblilities of coming down with MG

Treatment

• Anticholinersterase drug is recomended and helps reduce
• Pyridostigmine/neostigne

Guillaine-Barre Syndrome

• Is an immune reaction attacking the Myelin Sheath with effect of conudction and this process if very fast.
• Also infects Gl tract
• Risk factor viral infection- HIV , Rubella etc

Clinical manifestation

• Starts to spread from the legs to upper body
• Dificult to move eyes in effect

Treatment and diagnostic

• Plasmapheresis- replacement of the plasma with albumin to remove all the bad
• PT/ PTTS needed to view antibodies