1. THE NERVOUS SYSTEM

2. EXAMPLES? HOW DOES IT WORK? Sensory Input - stimulus is gathered.
Integration - interpret the information, and decide what to do with it
Motor Output - carry out the decided action
EXAMPLES?

3. What Does It Do?
The Nervous System is in charge of controlling almost everything you can think of with the body.
Thoughts
Feelings
Sensation
Action
Reaction
Emotion
Communication

4. The Central Nervous System (CNS) is comprised of the brain and the spinal cord.

5. The Peripheral Nervous System (PNS) is comprised of all the nerves that are in the body. They all connect to the brain via the spinal cord.

6. Functional Classification
Afferent Division
Also called Sensory Division
Sends information to the brain from the body
Somatic sensory fibers send impulses from skin, skeletal muscle, and joints
Visceral sensory fibers send impulses from organs.

7. Functional Classification
Efferent Division
Also called Motor Division
Sends information to the brain from the body
Carries impulses from the CNS to organs, muscles, and glands
Causes a physical response.

8. Functional Classification
Efferent Division
Has 2 sub-divisions
Somatic Nervous System
Also called “Voluntary Nervous System”
Primarily controlled by us
Reflex actions are the exception (choking, flinching, yawning)
Autonomic Nervous System
Also called “Involuntary Nervous System”
Controls things we cannot
Gland function, smooth muscle function, cardiac muscle function

9. Tell Me How You Feel!
Proprioceptors are found in muscles and tendons, and react to pressure and tension / stretching. They help maintain posture and balance. If enough are stimulated at once, they can also trigger pain.

10. Tell Me How You Feel!
Fine touch sensors are found close to the surface of the skin. The amount in a given area varies.

11. Tell Me How You Feel!
Temperature and pain are monitored by bare dendrite endings, and are the most overall abundant.

12. Structural Classification
Based off of number of processes extending from the cell body.
Multipolar has several, usually dendrites
Bipolar has an axon and a dendrite
Unipolar has one extension that immediately divides

13. SUPPORTING CELLS Referred to as Neuroglia, or simply “GLIA”
ASTROCYTES provide structure and manipulate blood flow to active neural sites. They also comprise the blood-brain barrier.
OLIGODENDROCYTES and SCHWANN CELLS help form the myelin sheaths

14. SUPPORTING CELLS
Microglia dispose of debris, like dead cells and bacteria.
Ependymal Cells line the brain and spinal cord cavities, using their cilia to circulate cerebrospinal fluid
Satellite Cells act as protective, cushioning cells.

15. Neuron Structure
All organelles are found in the cell body except centrioles
Dendrites are branch-like structures that receive signals from the body
Axons are the long “tail” that transmit signals, and are encased in a myelin sheath
Axons end in axon terminals, also called synaptic terminals, and the communication site is called a synapse, which is located at the dendrites of the next neuron in line
Neurotransmitters are chemicals that are used to transmit messages, released at the end of axon terminals into a synaptic cleft

16. Neuron Structure
Remember, nerve cells never actually touch other nerve cells. There is a small gap between them (the Synaptic Cleft) and that gap never closes!

17. Neuron Structure
The axons are covered in a myelin sheath for protection, which is a part of the Schwann cell.
The gaps between the Schwann cells are called the Nodes of Ranvier.

18. Neuron Structure
The destruction and hardening of the myelin sheath results in multiple sclerosis.

19. ACTION POTENTIAL
Na+ moves inward along the membrane at one location through voltage-gated channels
As this action spreads, the axon repolarizes behind it, almost pushing it along
This occurs the length of the axon

20. NEURAL SYNAPSES
When the action potential reaches the end of the axon, the information is transmitted to either the CNS, or the dendrites of the next neuron in the chain.
The voltage change from the action potential depolarizes the voltage-gated channels at the synaptic terminal, allowing for the neurotransmitters to pass.

21. NEURAL SYNAPSES
The neurotransmitter binds to the ligand-gated channels, causing them to open.
Na+ and K+ ions pass through the gate, which closes when the neurotransmitter detaches.
This is called “Direct Synaptic Transmission”

22. NERVE SIGNALING
Stimuli can polarize (hyperpolarize) or depolarize a neuron.
The larger the stimulus, the larger the change in membrane potential.
If the change is large enough, it triggers a response called the Action Potential.
The Action Potential is a brief information signal that travels along the axon to your CNS.

23. SO TELL ME…………………. FEELINGS, NOTHING MORE THAN FEELINGS....
When the action potential reaches the next nerve cell, it isn’t always strong enough to transfer the signal down the line
Multiple action potentials will add together and force it down the line. This is called Temporal Summation.
Repetitive stimuli on the same nerve cell will also build up an action potential that will carry down.
SO TELL ME………………….
Why don’t we feel every little thing that touches us?
Explain hypersensitivity
How does Chinese Water Torture work?

24. NEUROTRANSMITTERS
Acetylcholine – extremely common. Found in both CNS and PNS. Medically used for lowering heart rate. Also found in conjunction with learning, memories, and dreaming.
Biogenic Amines – derived from amino acids. Category encompassing some of the transmitters responsible for mood, sleep, love, hate, satisfaction, and other “feelings”.
Amino Acids – several amino acids function as neurotransmitters in the CNS, including regulating how we feel pain.

25. THE CNS AND PNS
The brain is surrounded by and filled with cerebrospinal fluid, which aids in nutrient delivery and provides protective cushioning.
Cranial nerves start in the brain, and terminate mainly in the organs
Spinal nerves start in the spine, and cover the body below the head
Somatic nervous system is mainly muscular, and is responsible for dealing with external stimulus
Autonomic nervous system handles internal issues, and is broken up into three parts

26. THE CNS AND PNS

27. THE AUTONOMIC NERVOUS SYSTEM
Sympathetic Division: responsible for “fight or flight” (heart rate, adrenaline levels)
Parasympathetic Division: regulatory, keeps levels normal, levels out the sympathetic response
Enteric Division: controls digestive secretions and peristalsis
All 3 systems work together to maintain homeostasis.

28. THE BRAIN

29. WHITE MATTER vs GREY MATTER
Both are found in the brain
Grey matter is made up of nerve cell bodies, and is grey due to the color of the nuclei
Grey matter cells have no myelin
sheath
Grey matter controls processing of
incoming sensory information
White matter is made up of fibers
White matter controls communication
between grey matter and the body
Both are delicious.

30. THE BRAINSTEM
The brainstem is made up of the midbrain, pons, and medulla oblongata
The medulla oblongata controls respiration, heart rate, and reflexes (vomiting, swallowing, sneezing, and coughing)
The pons helps regulate the medulla oblongata
The medulla oblongata and pons work together to help regulate large-scale body motions, like walking
The midbrain receives and processes information from the body.
The pons and medulla can induce sleep, while parts of the midbrain regulate it

31. THE CEREBELLUM & THE DIENCEPHALON
The cerebellum regulates motor control, coordination, and precision. It also plays a part in cognitive functions, such as attention levels and language.
The diencephalon is made up of the thalamus, the hypothalamus, and the epithalamus
The thalamus is like the secretary for the cerebrum, monitoring information coming in and out.
The hypothalamus regulates homeostasis. It does so by acting as a thermostat, and signaling for basic urges like being tired, hunger, mating desire, fight-or-flight.
The epithalamus houses the pineal gland, which produces sleep-regulating melatonin.
This also helps in regulating our circadian rhythm, which is our response to the light cycle of the day. Our brain produces different hormones for different things depending on the light cycle.

32. THE CEREBRUM
The cerebrum is split into 2 hemispheres (cerebral hemispheres) and is comprised of several other structures (hippocampus, basal ganglia, olfactory bulb)
It controls the conscious and voluntary motor functions

33. THE CEREBRUM It also controls memory, thoughts, and judgment
It is responsible for processing the information we bring in through our senses (sight, sound, smell, touch, taste)
The outermost layer is the neocortex, which is the area we see the most of, and relate to when we picture the brain.
The corpus collosum is the large group of axons that allows for communication between the left and right hemispheres.

34. PROCESSING IN THE CEREBRAL CORTEX

35. PROCESSING IN THE CEREBRAL CORTEX
The Somatosensory Homunculus

36. CERTAIN SECTIONS CONTROL CERTAIN ACTIONS
Language and speech are controlled by Broca’s Area in the frontal lobe (face muscles) and Wernicke’s Area in the temporal lobe (speech comprehension)
The Limbic System controls almost all base instincts and emotions
Bonding, fear, right vs wrong, excitement, cognitive skills, learning, attention, social interaction and understanding, emotional processing and reaction
The Limbic System is made up of the amygdala, hippocampus, and olfactory bulb, as well as sections of the thalamus and hypothalamus
What are some past, current, and possible future uses of this knowledge?

37. LEARNING Short-Term Memory is stored in the frontal lobe
Long-Term Memory is stored in the hippocampus
The more we retrieve long-term memories and bring them to short-term, the easier they are to recall.
Muscle habits are formed over repetition, and very hard to break.
Repetition strengthens neural links and quickens response times.
Learning something new creates new neural connections.
It is easier to learn something new than to fix something wrong.

38. CONSCIOUS vs UNCONSCIOUS
Our brain does things consciously and unconsciously at the same time
After new experiences, our unconscious brain forms new neural connections to establish memories and motor skills
Using fMRI imaging, we can see what parts of the brain are active during stimuli, and how the brain process it during and after.

39. NEURAL DAMAGE AND REPAIR
The CNS cannot make direct repairs. Instead, new neurons grow and create new neural paths.
The paths are determined by chemical signaling, causing the axons to curve toward or away from the signal and make new connections.
Humans are capable of constant creation of new brain cells, which was previously thought to be impossible
What possible complications could arise during new growth after an injury?

40. DISEASES AND DISORDERS
SCHIZOPHRENIA
Loss of conception of reality, coupled with hallucinations, skewed emotions, voices, inability to tell the difference between right and wrong.
Genetic in nature
Treated with medications that bind to dopamine receptors, or inhibit the production of dopamine.

41. DISEASES AND DISORDERS
DEPRESSION
Bipolar depression is characterized by extreme mood swings.
Genetic in nature, influenced by environment, and found in a high percentage of people
Treatments include medical (increasing biogenic amine activity) and non-medical (therapy, coping techniques)

42. DISEASES AND DISORDERS
ALZHEIMER’S DISEASE
Age-sensitive disorder in which neurons die in massive amounts, triggering loss of memory and sometimes function.
Genetic in nature, but also triggered by age.
Treatments are in development. Due to the difficulty of diagnosis, and complexity of the illness, the most we can do is care for those suffering.

43. DISEASES AND DISORDERS
PARKINSON’S DISEASE
Disorder where motor skills are effected. Loss of stability (shaking) and inability to initiate movement are signs.
Triggered by the death of midbrain neurons.
Currently no cure. Treatments include surgery to help increase brain longevity, medications, and physical therapy.