The Nervous System
Ramona, Sarah, Laura, Zunaira & Hibba
What Exactly Is The Nervous System?
- Responsible for everything you do!
- Three basic parts: brain, spinal cord, nerves
- Think of your brain as a control centre
- Think of your spinal cord as a highway information can travel up and down
- Think of your nerves as sub-roads that connect to the highway
Function #1
Sends signals around your body.
Function #2
Lets you respond to everything around you.
Function #3
Coordinates movement and processes senses.
What Does Your Nervous System Do?
- Everything you consciously and subconsciously do - breathing, your heart beating, blinking, etc.
- Intelligence, memory, learning, movement, basic bodily functions, and the senses are possible because of the nervous system
The Nervous System, Part 1: Crash Course A&P #8
Central Nervous System
- Consists of brain and spinal cord
- Primary commanding system
- Protected by skull and spinal column
- Parts are covered by tough tissues called meninges
- Cerebrospinal fluids also provide protection
Peripheral Nervous System
- Nerves that connect the rest of your body to the CNS
- Relays information from a part of your body, up through your spinal cord, and registers it in your brain
- Autonomic sub-system responsible for functions you don't think about, e.g., blood pumping
- Somatic sub-system responsible for things you control at will
Pain
Pain is our body's response to get us out of a potentially dangerous situation. It helps us prevent damage to our bodies. When we experience pain, we go through several stages.
#1: Contact with the "stimulus" - the object that endangers us.
#2: Reception - the nerve ending registers the information
#3: Transmission - the nerve relays this to the spinal cord
#4: Pain reception - the brain registers this information, and decides what to do, such as moving your hand away from the hot object you just touched
A problem concerning nerve damage is the body's inability to react to pain.
Nerves and Neurons
- A neuron is an individual cell, and a nerve is a group of neurons
- Sensory neurons send signals to the CNS
- Motor neurons receive signals from the CNS
- Neurons are the longest lived cells in your body
Diagram Parts
- Dendrites receive information from other neurons, or surrounding area
- Axons transmit electrical impulses away from cell body to other cells
- Information travels down axon, and hops from cell to cell
- This process is called 'synapse'
- Myelin sheath surrounds axon and transmits nerve impulses
The Brain
- mass of soft nerve tissue protected by the skull
- made up of neurons (grey matter) and cell processes (white matter)
- grey matter found at periphery of brain and centre of spinal cord
- white matter found deep within brain
- very compact, and weighs about three pounds
Cerebrum
- largest part of the brain
- centre for thought and intelligence
- divided into right and left hemispheres
- right hemisphere controls the movement on the left side of your body, and vice versa
- responsible for senses, learning, and motor functions
- cerebral cortex is outside of cerebrum
- function is learning, reasoning, knowledge, and memory
Vertebra
- 33 interlocking small bones that form the backbone or spine
- each bone has a hole where your spinal cord passes through
- a misalignment can cause information to not pass through correctly, or pain
Cerebellum
- lies below cerebrum at back of skull
- controls voluntary muscles
Medulla
- controls heart rate, breathing, swallowing, coughing, and vomiting
- forms brainstem that connects cerebrum to spinal cord
Spinal Cord
- 45 cm long
- goes from medulla to second lumbar vertebrae
- acts as pathway between brain and rest of body
Breakdowns of the System
Alzheimer's Disease
- risk increases with age
- symptoms include progressive inability to remember facts or events, and later even friends and family
- runs in families
- lesions of proteins are found in the brain
Narcolepsy
- individuals are extremely drowsy at all times
- weakness in muscles is experienced
- occurs at random
- dream stage of sleep can occur when person is awake, resulting in temporary paralysis
Charcot-Marie Tooth Syndrome
- slow progressive degeneration of muscles in limbs
- people experience loss of feeling
- symptoms occur by age 30
- not fatal
Fun Facts
There are more nerve cells in the human brain than there are stars in the milky way
Your brain loses a gram of weight per gear
The nervous system relays information at about 100 metres per second
A baby's brain triples in size in its first year
If injured, nerves at the bottom of the spinal cord can cause paralysis
An octopus, an invertebrate, has 500 million neurons
Nervous System Case Study
What you're seeing here...
- Immune system has begun to erroneously attack myelin, or protective sheath that covers neurons, causing damage in the brain.
- This damages nerve signals in the brain! No wonder Ramona was experiencing forgetfulness and mood swings.
- Inflammation has occurred, preventing the brain from communicating with the rest of the body.
- Hint: you now know which part of the nervous system the disease affects.
- Hint #2: we prescribed corticosteroids to stall inflammation of the brain.
What you're seeing here...
- Plot twist! We did a test, and found out that the patient recently had measles.
- This virus weakens the brain, and causes swelling. It also makes younger people more susceptible to diseases.
What You're Seeing Here...
- High amounts of estrogen were found in the patient's urine samples.
- This hormone helps regulate a female's sex drive.
- Hint #3: Did you know, women are 2-3 times more likely to get a certain disease than men?
What You're Seeing Here...
- The x-rays are in... And it has been confirmed. Only the patient's central nervous system has been affected by whatever it is she has.
- Here, the spinal cord has been slightly impacted due to myelin sheaths in its neurons being worn away.
- The extent of her symptoms show that her disease has progressed really far!
What you're seeing here...
- More scans of the brain showing how warped it is.
- You can see how poor her immune system is at defending against... Something.
What you're seeing here...
- There is inconsistent damage between the patient's eyes - specfically her optic nerves. That explains the blurry vision!
- Your final hint: Something has been targeting her nerves in particular. Any guesses?