Human Body Systems (Nervous System)

Compare and contrast the endocrine system

• They both transmit information from one part of the body to another

• Nervous system is faster, electrical signals. Endocrine system is slower, chemical signals.

Nervous system

Transmits information very rapidly by nerve impulses conducted from one body area to another

Endocrine system

Transmits information more slowly by chemically secreted glands into the blood stream and then circulated from the glands to other parts of the body.

Central nervous system

Brain and spinal cord occupy a mid-line or central location in the body

Peripheral nervous system

Nerves extend to outlying or peripheral parts of the body

What are the 3 major components of a neuron?

Cell body, dendrites, axon

Cell Body

Main part of a neuron

Dendrites

One or more branching projections

Axon

One elongated projection

Sensory neuron

Transmit impulses to the spinal cord/brain from all parts of the body

• the input

Motor neurons

Transmit impulses in the opposite direction (away from the brain/spinal cord), conduct impulses to muscles and tissues

• output, all nerves go to muscles

Inter-neurons

Conduct impulses from sensory neurons to motor neurons

• connect to form complex, central networks of nerve fibers

• process information

Myelinated fibers

White, Fatty substance that wrap around some axons outside the central nervous system

Gila/Neuroglia

(Glial cells) - glue cells

One function is to hold the functioning neurons together and protect them

Astrocytes

Threadlike branches attach to neurons and to small blood vessels, holding these structures close to each other

Microglia

• Glial cells in the central nervous system

Usually, remain stationary but if inflamed/degenerating brain tissues, they enlarge and move

Oligodendrocytes

They help hold nerve fibers together and also serve another and more important function, they produce the fatty mylein sheath that involves nerve fibers located on the brain and in the spinal cord

White matter

Bundles of axons in the central nervous system, may be myelinated and form this

Gray matter

Brain and spinal cord tissues composed of cell bodies and unmyelinated axons and dendrites

Reflex arcs

Basic types of neuron pathways, and important to the nervous system functioning
- like one way streets, they allow impulse conduction in only one direction

Two neuron arc

Simplest type of reflex arc ( has sensory and motor neurons )

Three neuron arc

Next simplest type of reflex arc after the two neuron arc,( has sensory, inter-neurons and motor neurons )

How is an nerve impulse conducted?

First they have to be initiated by a stimulus ( pressure, temp or chemical change ), the inside of a membrane temporarily becomes positive and the outside becomes negative, leading to depolarization which then leads to re polarization, the action potential ( wave of electrical disturbance that travels along the length of a neuron ) can not go backward during the re polarization which leads to a nerve impulse

Synapse

Where nerve cells ( neuron ) communicates with another cell by passing signals across a tiny gap, using chemicals called neurotransmitters

Catecholamine

Group of neurotransmitters

• acetylcholine (Ach), norepinephrine (adrenline), dopamine and serotonin

Play a role in sleep, motor function, mood and pleasure recognition

Endorphins and enkephalins

Released in pain conduction pathways

• neurotransmitters

Blood brain barrier

Allows water, oxygen carbon dioxide and other substances ( Like alcohol ) to move between the blood and tissue of the brain

• many toxins and pathogens can not pass through this

• Protects vital nerve and tissues from damage

Neurotransmitters

Chemicals that allow neurons to communicate with each other throughout the body

X ray photos

Can reveal tumors or injuries, but do not show the detail or soft tissue

Computed tomography (CT Scan)

Involves scanning the head with a revolving X-Ray generator

(shows hemorrhages, tumors, lesions)

Positron emission tomography (PET Scan)

Variation of CT scanning, which is a radioactive substance is introduced into the blood supply, the radioactive material shows up as a bright spot on the image

Ultrasonography

Ultrasound waves are reflected off anatomical structures to form images, no harmful radiation

• often used in diagnosing hydrocephalus or brain tumors in infants

Magnetic resonance imaging ( MRI Scan )

A magnetic field surrounding the head induces brain tissue to emit radio waves

Electroencephalography (EEG)

Measurement of electrical activity in the brain (used for seizures, sleeping disorders, etc.)

Evoked potential (EP) test

Like an EEG, brain waves are observed by evoking a specific stimuli (light, sound)

Spinal cord

Tracts of gray and white matter that function as a two way tract between brain and body.

Function - It switches or transfers incoming sensory impulses to outgoing motor impulses, which makes reflex possible

Paralysis

Loss of ability to make voluntary movements

Meniges

Tough, fluid, cushioned set of membrane ( around spinal cord and brain )

Cerebrospinal fluid ( CSF )

Fills spaces in the brain and in the spinal cord, and fills spaces in the brain called cerebral ventricles, surrounds and cushions, protects from injury and removes waste

Hydrocephalus

“Water on the brain”, fluid can not drain away, so it accumulates in the ventricles or in meninges

Cranial nerves

• 12 of them

Emerge from under the surface of the brain, extending mostly from the brainstem, and conduct nerve impulses between the brain and structures in the head/neck/ thoracic or abdominal cavities

Lumbar puncture (Spinal tap)

Withdraw of some cerebrospinal fluid, useful to reduce pressure caused by swelling of the brain or spinal cord after injury or disease

Spinal nerves

Structure - 31 pairs of nerves emerge from the spinal cord

Function - Conduct impulses between the spinal cord and parts of the body not supplied by cranial nerves, make possible sensations and movements

Autonomic nervous system

Regulates involuntary functions

• heartbeat, secretions by glands

Somantic nervous system

Voluntary actions of skeletal muscles

• jerking hand away from a hot surface

Sympathetic nervous system

Our emergency system, sympathetic fibers take control when we feel strong emotions, when we cope with stress, fight or flight, strenuous exercise, etc.

Parasympathetic nervous system

Slow heartbeat, increase secretion of digestive juices and insulin, counter balance sympathetic function

Limbic system

Emotional brain controls basic emotion ( fear anger and pleasure ) and drives hunger, sex, dominance, and care of offspring

Parts of the brain stem

Medulla, pons and mid brain

Medulla oblongata

The vital centers ( control heart beat, breathing, etc)

Pons

Two way conduction path between areas of the brain and other regions of the body; influences respiration

Mid brain

Two way conduction pathways; relay for visual and auditory impulses

Hypothalamus

Helps control the functioning of every cell in the body and crucial for maintaining Body temp (pleasure, fear, anger, sexual arousal, pain)

Thalamus

Helps produce sensations, associates sensations with emotions, and arousal which is an alerting mechanism that keeps us awake

Cerebellum

Produce smooth coordinated movements, maintain equilibrium and sustain normal postures

Corpus callosum

Lets the 2 hemispheres share and communicate information with each other

Parkinson’s

Symptonms - Starts usally with tremor, then eventaully may cause stiffness, slowing of movement and trouble with balance 

Cause - Loss of neurons that produce dopamine

Treatment - No cure, but treatment includes trying to increase brain dopamine levels

Alzheimer’s

Symptonms - Memory loss, inability to do everyday taks, change in mood/behavior (depression, anger)

Cause - Buildup of protiens in the form of amyloid plauques and neurofibrallary tangles, causing brain cells to die and the brain to shrink 

Treatment - Clinical trials or some medicines for those with early on Alzheimers 

Epilepsy

Symptonms - Seizures ( short term confusion, stiff muscles, loss of conciousness, jerking of arm/legs) 

Cause - Brain injuries, genetics, infections, tumors or abnormal brain function 

Treatment - Anti seizure medicine, diterary changes, epilespy surgery and neurostimulation devices

Concussion/CTE

Symptonms - Headache, ringing in ears, nausea/vomitting, fatigue 

Cause -  Typically a traumatic injury or event to brain causing it to injure nerve cells 

Treatment - Physical and cognitive rest 

Stroke

Symptonms - Facial drooping, suddenweakness/numbness in arm/legs, difficulty speaking or understanding, dizziness, vision loss and headache 

Cause - Blood flow to a part of the brain is interupted or reduced, deprievning brain tissue of oxygen and nutrients 

Treatment - Clot busters, Emergcney medicine/proceudres ( differs for types of strokes )

Polio

Symptonms - Flu like symptoms (fever, headache, muscle aches, nausea/vomitting, loss of appetite)

Cause - Highly contagious virus often spreads through feces from poor hygeine or sometimes respiatory droplets 

Treatment - Bed rest, pain relievers, physical therapies or ventalatiors 

Clinical Depression

Symptonms - Fatigue, sleep disturbances (insomnia), appetite changes, low self worth, persistent sadness 

Cause - Genetic, biological, enviormental and physiological factors ( imbalance/change in neurotransmitters ) 

Treatment - Medications or psychotherapy 

Multiple Sclerosis

Symptonms - Vision problems, numbness or tingling, fatigue, balance issues, muscle weakness and occasional bladder issues 

Cause - Exact cause is unknown, but an autoimmune disease 

Treatment - Medications, physcial therapy and life style adjustments 

Huntington’s Disease

Symptonms - Movement disorders, causes trouble with thinking and planning, and mental health disorders 

Cause - Caused by a gene passed down from an parent, a person needs only one copy in order to get the gene, 

Treatment - No treatments but medicine can help with symptomns 

Meningitis

Symptonms - Sudden high fever, stiff neck, bad headache, nausea or vomiting, sensitivity to light, appetite change

Cause - Typically caused by infection but virsus are the most common cause 

Treatment - Antibiotics, bed rest, fluids and pain medicine 

Migraine

Symptonms -  Severe, throbbing head pain, nausea/vomitting, sensitivity to light, sound or smell

Cause - Abnormal brain activity, genetic/enviormental factors 

Treatment - Medications and pain relievers, therapies designed to attack frequent headaches 

Cerebral Palsy

Symptonms -  Life long issues with movement, muscle tone and posture 

Cause - Abnormal brain development or brain damage affecting motor function 

Treatment - Physical, occupational and speech therapy, medication and surgery 

Opioid Addiction

Symptonms -  Chnage in attitude/personality, isolation, irratibltiy and nervousness 

Cause - Opioids are additvive and trigger high reward systems in the brain, trigger endorphins which make you feel good

Treatment - Medications, therapy or rehab 

ALS (Lou Gehrigs)

Symptonms -  Trouble walking or doing activites, weakness, tripping/falling, slurred speech, trouble swallowing, behaviroal changes 

Cause - Genes and factors of environment 

Treatment - No treatment but they do things to try to slow the progression of symptoms down (like medicine or therapies)

Creutzfeldt Jacob

Symptonms -  Rapid dementia, personality changes, memory loss, anxiety or depression 

Cause - Infectious protiens that cause normal brain protiens to malfunction and build up 

Treatment - There is no treatment avaliable