Nervous system

What do these four celebrities have in common?

Botox! (and plastic surgery)

• Botox!

• Used to paralyze muscles in the face to prevent wrinkles from showing

• Unfortunately botox is short for botulinum toxin

• Produced by bacteria Clostridium botulinum

• The most deadly toxin known

• It would take about 0.000001 grams of this toxin to kill you if you breath it in

• Despite paralysis of muscles, botox actually directly affects the nervous system.

Nervous System.

The nervous system has several divisions Central Nervous System (CNS)

Consists of brain and spinal cord.

Peripheral Nervous System (PNS) Nerves and Ganglia outside the central

nervous system

The nervous system is made up of neurons and associated cells

Neurons

Many types of neurons but most have the same basic features

Cell body Contains nucleus and cell organelles

Dendrites Receive signals from other neurons

Axon Sends signals to other neurons or to muscles

Axon terminals

Axon Terminal Branch out from axon ending in synaptic

end bulbs

Synaptic end bulbs allow transfer of electrical or chemical impulses from nerve cells to other nerve cells or muscles

Signals can either excite muscles to contract, or inhibit to contract.

Botulism

Botulinum toxin works by blocking release of neurotransmitters at neuromuscular junctions (where nerve meets muscle cell)

This permanently prevents the muscle from contracting The toxin binds permanently to the synaptic end bulb

It can take months to years to recover from the toxin

Neurons firing

http://www.dailymail.co.uk/sciencetech/article-2581184/The-dynamic-mind-Stunning-3D-glass-brain-shows-neurons-firing-real-time.html

https://www.youtube.com/watch?v=C4Gt322-XxI

CNS (Central Nervous System)

The Brain is divided into several different areas The largest part of the brain is called the cerebrum Externally the cerebrum is divided into:

Frontal Lobe

Parietal Lobe

Occipital Lobe

Temporal Lobe

Cerebellum

Internally there are several other structures including: Thalamus

Problems with speech

Wernike’s and Broca’s areas

Wernike’s aphasia Fluent speech but not comprehensible Often people with Wernike’s aphasia don’t know they can’t be understood https://www.youtube.com/watch?v=B-LD5jzXpLE

Broca’s aphasia Broken speech but comprehensible https://www.youtube.com/watch?v=kOqtIrwyLbw

Frontal lobe

Responsible for: Movement Speech Personality

Parietal lobe

Sensations related to touch Pain Temperature Pressure

These sensations are received in the parietal lobe and interpreted.

Occipital lobe

Vision Interprets signals from the eyes Optic nerves cross over and images

on the left are interpreted by the right brain and vice versa

Temporal Lobe

Sound processing and recognition Memory storage

Cerebellum

Cerebellum Coordination of fine motor

movements

Balance and posture.

Looks kind of like cauliflower

https://www.youtube.com/watch?v=5eBwn22Bnio

Thalamus

Thalamus Responsible for sleep regulation Relay centre for motor and sensory

signals Signals are routed through the

thalamus to appropriate areas in the brain or the body

Cranial Nerves

12 cranial nerves Control of muscles in the face and

neck area Receive input from sensory organs

Vagus nerve Sensory and motor functions of many

vital body functions including:

Heartbeat, breathing, swallowing, digestion.

How does the brain work?

Good question!

https://www.youtube.com/watch?v=BKVv6v-Hd0A

https://www.youtube.com/watch?v=cbqjxmTNivQ

Cerebrovascular accident (stroke)

50,000 strokes in Canada every year 3rd leading cause of death Occurs when blood-flow to the brain is interrupted

Two kinds of stroke: Ischemic stroke – due to blockage of an artery Hemorrhagic stroke – bleeding into the brain

Stroke signs and symptoms

Numbness in the face or extremities, typically on one side only Face may droop

Slurred speech Blurred vision Sudden headache Loss of coordination

Stroke Diagnosis

Physical exam looking for the symptoms of stroke

Listen to the carotid arteries with a stethoscope Checks to see if there is reduced blood-flow

CT scan will likely be ordered This allows the doctor to see bleeding or damage done to brain cells

CT scans can also look at large blood vessels of the brain to look for blockage

MRI May be used in conjunction with CT scan

Stroke Diagnosis

Blood tests Low blood glucose can give similar symptoms Blood clotting factors may be looked at

Electrocardiogram Looks at electrical activity of the heart Looks for heart problems that may have lead to stroke

Carotid angiograph Allows imaging of the carotid arteries

Treatment - Ischemic stroke

Works best within 3 hours of stroke Medication given to remove the clot

Typically through a vein in the arm Can be done directly to the brain through a catheter (tube) in the groin region

Aspirin is given to prevent blood clots from forming to prevent another stroke at the time of treatment

Mechanical removal of blood clot Catheter used to physically break up or remove the clot. May not actually be beneficial

Treatment – Ischemic stroke

Surgery to remove plaques from carotid arteries Angioplasty and stents

A balloon is inserted into the carotid arteries to expand the opening A stent is then put in place to support the opened artery

Treatment – Hemorrhagic stroke

Aim is to reduce bleeding and pressure in the brain Drugs which can lower blood pressure

Supportive medical care while the body absorbs the blood

Surgery may be required if the bleeding is excessive to relieve pressure

Stroke video

https://www.youtube.com/watch?v=pcmrgwNCPwM

Recovery

Recovery depends on what part of the brain is affected but could include any of the following:

Speech therapy Physical therapy Recreational therapy Occupational therapy Psychiatric services

Prevention:

Eat a healthy diet Low in trans and saturated fats, and low cholesterol High fibre (helps lower cholesterol) Low sodium

Maintain a healthy weight Exercise Stop smoking (or just don’t start)

Smokers have increased risk of stroke

Limit drinking Drinking too much alcohol raises blood pressure

Alternative/complementary approaches

Acupuncture Ease pain and treat paralysis caused by stroke

Massage May help mood, lower blood pressure, relax body and mind

Yoga Low impact exercise Smooth physical movements and improved breathing

Aromatherapy Relieve pain and relax

Rosemary, lavender, and peppermint

Alternative/complementary approaches

Change in diet Naturopathic doctors may suggest many specific foods

High in potassium, magnesium, calcium, and omega 3-6 fatty acids

First Nations traditional healers may suggest a diet including foods which have been traditionally consumed by First Nations people in North America.

Alternative/complementary approaches

Herbal medicine and vitamin supplements May be used to improve blood circulation and brain function First Nations traditional healers may suggest willow bark

Has been used historically and lowers blood pressure

Naturopathic doctors may suggest vitamins to supplement those lacking in the diet

Herbal medicine may be suggested to help with proper circulation Ex. Ginko biloba – increase circulation in the brain by dilating cerebral blood

vessels

Spinal Cord

Bundles of ascending sensory nerves and descending motor nerves

Extends from the brain stem to the first and second lumbar vertebrae Spinal nerves enter and exit

between vertebrae

Peripheral Nervous System

Peripheral Nervous System (PNS)

31 spinal nerves emerge from the spinal cord Spinal nerves belong to the Autonomic or Somatic nervous systems

Autonomic Nervous System (ANS) responsible for sensory information from internal organs and control of smooth muscle

Somatic Nervous System (SNS) responsible for sensory information, and control of skeletal muscle.

Sensory signals travel up the spinal cord to the brain Motor signals travel down the spinal cord, exit and travel to the desired

muscles Sensory neurons are located in dorsal root ganglions

Reflex arc

A reflex arc is an automatic movement in response to stimuli

Stretch reflex

Sensory signal does not ascend to the brain in this case

Signal transmission

Signal transmissions occur through action potentials Action potentials are electrochemical

signals that travel through axons ending at the synaptic end bulb resulting in signals sent to any cells in contact with the end bulb

1. Sensory receptors send signals to the dorsal root ganglion

2. sensory neurons relay the information into the spinal cord

3+4. sensory information is relayed to the brain.

Signal transmission

5. reflex arcs send the signal to a motor neuron

6. signals from the brain stimulate motor neurons in the anterior of the spinal column

7. motor neuron receives signal from 5 or 6 and relays the signal to the muscle.

8. autonomic nervous system sends motor signals to smooth muscle

Reflex arc video

https://www.youtube.com/watch?v=wLrhYzdbbpE

Alzheimer's disease

Characterized by: Loss of memory

Begins with loss of short-term memory and expands

Change in personality Confusion Become suspicious easily

6th leading cause of death in North America

Alzheimer’s disease

No known cure Medications can reduce symptoms to

improve quality of life

Exact cause is unknown Plaques of protein deposits within the

brain Nervous tissue starts to disappear

Tangles of protein found within neurons preventing proper function.

Heat stroke

Not related to the types of strokes we have been discussing Due to exposure to high temperatures and possibly dehydration

Temperature higher than 105 F or 40.5 C

The body can not maintain homeostasis Complications with the nervous system

Can cause brain damage

Elderly (over 65) and very young (less than 4) are more susceptible