Ever wonder how you can do everything you do? The Nervous System Ever wonder how you can do everything you do?

4 main functions Allows us to sense our external environment as well as sense changes internally. Movements (actions both involuntary and voluntary) Allows us to have memory and intelligence – Thinking! Helps maintain homeostasis by detecting changes either on the outside or inside and allowing your body to react appropriately.

Divided into two main sections Central Nervous System (CNS) = brain and spinal cord Peripheral Nervous System (PNS) = cranial and spinal nerves and are information lines (like corded telephones)

CNS and PNS The CNS is the control center. It houses the brain and spinal cord. The PNS is the message center. It connects the CNS to the rest of the body.

What makes up the Nervous System? Neurons: the basic cell and functional unit of the nervous system. They transmit information to the body in the form nerve impulses. Nervous Tissue: Bundles of neurons or nerve cells put together. Neuroglial cells: supporting cells in the nervous tissue.

Neuron: Conducts impulses to the neuron Conducts impulses to the body

Neuron structure explained: 1. Cell body: Contains the nucleus and organelles. 2. Dendrites: The part that receives the signal from sensory neurons or other neurons. 3. Axon: The part that conducts the nerve impulse (The highway it travels down) 4. Myelin sheath: protects the axon 5. Nodes of Ranvier: The gap where there is no sheath protecting it. 6. Axon Terminal: The end where impulses are sent out to another nerve.

Neuroglial cells: Function: Fill in spaces, provide structural frameworks, produce myelin, carry on phagocytosis 2. Types: Microglial, Oligodendrocites, Astrocytes, Ependymal, Schwann cells

Specific types of neurons: Depending on what your body needs to do- there are different types of neurons. 1. Bipolar (interneuron) 2. Unipolar (Sensory) 3. Multipolar (motor)

Each neuron is either a Sensory Neuron, a Motor Neuron or an Interneuron. SENSORY NEURON: Your body senses something and sends a message to your brain or spinal cord. Afferent= bring messages into the brain. MOTOR NEURON: It stimulates muscles to contract, or your body to “do” something either voluntarily or involuntarily. Efferent= send information away from brain to body. INTERNEURON: Lie within the CNS and link other neurons together. They transmit impulses from one part of the brain or spinal cord to another. Neurons continued

Autonomic vs. Somatic nervous system 1. Autonomic nervous system – controls everything we don’t think about.. Smooth muscles, glands, breathing, etc. = involuntary movement 2. Somatic nervous system – controls the skeletal muscle = voluntary movement

Neuron activity: Use the book and your notes to create a foldable about the different types of neurons. You may fold it anyway you like as long as on the outside you have three flaps (1 for each of the types of neurons) The outside you will need to draw what each neuron looks like and label it. The inside will answer the following info: Where it is located. Something about the number of axons and dendrites. If it is a sensory neuron, interneuron, or motor neuron and what that means. Is it afferent or efferent. One piece of other information.

The brain: The brain is composed of about 100 billion multipolar neurons and even more nerve fibers to communicate. Divided into three major portions: The cerebrum, cerebellum, and the brain stem

The Brain: Cerebrum controls sensory and motor functions, higher mental functions – memory and reasoning (Divided into sections) Cerebellum coordinates voluntary muscle activity Brain stem regulates visceral activities and connects various parts of the nervous system

The Brain Lobes: The Frontal Lobe The Parietal Lobe The Occipital Lobe The Temporal Lobe

1. The Frontal Lobe Functions: Forms the anterior portion of each hemisphere (Your brain is divided into left and right portions). Functions: How we know what we are doing within our environment (Consciousness). Controls our emotional response. Controls our expressive language.

The Frontal Lobe Observed Problems: Loss of simple movement of various body parts (Paralysis). Inability to plan a sequence of complex movements needed to complete multi-stepped tasks, such as making coffee (Sequencing). Inability to express language (Broca's Aphasia).

2. Parietal Lobe Location: Posterior to the frontal lobe, on the top part of the cerebrum. Function: Location for visual attention. Location for touch perception.

Parietal Lobe Observed Problems: Inability to locate the words for writing. Problems with reading. Difficulty with drawing objects. Difficulty in distinguishing left from right. Difficulty with doing mathematics. Inability to focus visual attention. Difficulties with eye and hand coordination.

3. Occipital Lobe Location: Most posterior, at the back of the head/brain. Function: Vision control center. Observed Problems: Defects in vision Difficulty with identifying colors Production of hallucinations Difficulties with reading and writing.

4. Temporal Lobe Location: Laterally (each side of brain close to the ears. Function: Hearing ability Memory Observed problems: Difficulty in recognizing faces. Short-term memory loss. Right lobe damage can cause persistent talking. Increased aggressive behavior.

BRAIN STEM Deep in Brain, leads to spinal cord. Functions: Breathing, Heart Rate, Swallowing, Reflexes to seeing and hearing, controls sweating, blood pressure, digestion, temperature (Autonomic Nervous System). Anything you Can’t Control. Sense of balance (Vestibular Function). Observed Problems: Decreased vital capacity in breathing. Problems with balance and movement. Dizziness and nausea. Sleeping difficulties (Insomnia, sleep apnea).

Brain Stem Includes midbrain, pons, and medulla oblongata Midbrain –vision reflex and auditory reflex Pons – relay sensory impulses from peripheral nerves to the brain Medulla oblongata –controls the cardiac center, blood vessel constriction, and respiratory center.

CEREBELLUM Located at the base of the skull. Functions: Coordination of voluntary movement Balance and equilibrium Observed Problems: Loss of ability to coordinate fine movements. Loss of ability to walk. Slurred Speech

The Spinal Cord

The Spinal Cord Spinal Cord connected to the brain descends down the middle of the back and is surrounded and protected by the bony vertebral column surrounded by a clear fluid called Cerebral Spinal Fluid (CSF), that acts as a cushion to protect the delicate nerve tissues against damage from banging against the inside of the vertebrae transmit electrical information to and from the limbs, trunk and organs of the body, back to and from the brain Spinal Cord

Cerebral Spinal Fluid:

Spinal Nerves There are four main groups of spinal nerves which exit different levels of the spinal cord. These are in descending order down the vertebral column: Cervical Nerves "C" : (nerves in the neck) supply movement and feeling to the arms, neck and upper trunk. (8 total) Thoracic Nerves "T" : (nerves in the upper back) supply the trunk and abdomen. (12 total) 3. Lumbar Nerves "L" and Sacral Nerves "S" : (nerves in the lower back) supply the legs, the bladder, bowel and sexual organs. (5L and 5S)

Cranial Nerves Olfactory 2. Optic 3. Oculomotor 4. Trochlear Pair of nerves What is does Olfactory smell 2. Optic vision 3. Oculomotor Raise eyelids, move the eye, controls involuntary muscles of the eye, adjusts amount of light into the eyes 4. Trochlear Carries motor impulses to the fifth voluntary muscle of the eye 5. Trigeminal Ophthalmic division = sensory fibers from the surface of the eye, tear glands, anterior scalp, forehead, upper eyelids Maxillary division = upper teeth, upper gum, upper lip Mandibular division = scalp behind ears, skin of jaw, lower teeth, lower gum, lower lip

6. Abducens 7. Facial 8. Vestibulocochlear 9. Glossopharyngeal Pair of nerves What is does 6. Abducens Moves the rest of the eye 7. Facial Taste, anterior two-thirds of tongue, facial expression 8. Vestibulocochlear Vestibular branch = maintain equilibrium Cochlear branch = hearing 9. Glossopharyngeal Tongue and pharynx, tonsils, posterior third of tongue 10. Vagus Somatic= Larynx, swallowing, speech Autonomic = heart and smooth muscles 11. Accessory Cranial branch = soft palate, pharynx, larynx Spinal branch = neck muscles 12. Hypoglossal Move the tongue for speaking, chewing, swallowing

How does your brain send out signals?

Membrane Potential The surface of a cell membrane is usually electrically charged. When the charges are not equal it is said to be polarized and is VERY IMPORTANT in sending Nerve impulses to and from the body CNS to the PNS!

Resting Potential: The difference in electrical charge between the inside and outside of a cell is called the POTENTIAL DIFFERENCE. In a nerve cell that is “RESTING” or not sending impulses this difference in charges is called the RESTING POTENTIAL As long as the nerve cell remains undisturbed or the charges do not change it will remain in a resting potential state.

Action Potentials Action Potential: Electrical charges change by sodium channels opening and allowing positive sodium into the cell. This makes it positive. And is called DEPOLARIZATION Soon after potassium channels open and allow potassium in ions in again bringing the charge back to negative. This is called REPOLARIZATION The action potential is the rapid change from Depolarization to Repolarization which causes an impulse to be sent through the neuron

Action Potential

Nerve Impulses A wave of action potentials that move down the neuron and axon until they hit either another neuron or body cell to transmit the impulse. Nerve Pathways- when nerve impulses travel from neuron to neuron.

Synapse The junction between two communicating neurons is called the synapse. The neurons DO NOT TOUCH- there is a gap that separates them

Impulse Pathway: An Impulse (action potential) travels from the dendrite to the cell body and then the axon to the axon terminals (or end of the neuron). At the end of a neuron or synapse, NEUROTRANSMITTERS are released from the axon terminals. Neurotransmitters diffuse to the next neuron or body cell.

How Neurotransmitters are released:

Reflexes The simplest nerve pathways that are only a few neurons long are called REFLEXE ARCS. Reflexes are automatic subconscious responses to changes within or outside the body. Example: The Knee-Jerk reflex: Only 2 neurons. A sensory neuron communicating directly with a motor neuron.

Knee Jerk Reflex Page 221-222 in book Knee Jerk activity