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

4 main functions Sensory receptors allow us to sense our external environment as well as sense changes internally. Coordinates body activities (actions both involuntary and voluntary) Assimilates experiences in order 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 unite of the nervous system. They transmit information to the body in the form of nerve impulses. Nerves: are bundles of axons. 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- either covered by a Schwann cell or Oligodendrocytes 5. Nodes of Ranvier: The gap where there is no sheath protecting it. 6. Axon Terminal: The part where impulses are sent out to another nerve.

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: Is considered Afferent or it brings information from the body into the neurons located in the brain or spinal cord (CNS). Stimulated by changes from inside or outside the body- the sense it and act on it. MOTOR NEURON: Is considered Efferent or it brings messages away from the CNS and sends them to the body. It stimulates muscles to contract, or your body to “do” something either voluntarily or involuntarily. 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

Neuroglial cells: Function: Fill in spaces, provide structural frameworks, produce myelin, carry on phagocytosis 2. Types: Microglial: scattered throughout, support neurons, phagocytize bacterial cells and cellular debris Oligodendrocites: occur in rows, provide insulating layers of myelin around axons within the brain and spinal cord

Neuroglial cells Types Cont. 3. Astrocytes: found between neurons and blood vessels, provide structural support – form scar tissue that fills spaces within the CNS 4. Ependymal: epithelial like membrane that covers specialized brain parts and forms inner linings that enclose spaces within the brain. 5. Schwann cells – in PNS, form covering of myelin around axons

Examples of cells:

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.

Review work for Nervous system: Neuron you are working on the following questions: * Check your recall pp. 207, 208, 209, 212 (1 &2) * Review exercises p 249 Q1, 2, 3, 4, 6, 7

CNS: Gray: Cell bodies that are non-myelinated Composed of Gray matter and white matter. Gray: Cell bodies that are non-myelinated White: axons that are myelinated

The brain: The brain is composed of about 100 billion 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 activities and connects various parts of the nervous system

Cerebrum: Divided into 2 hemispheres called the Left and Right Cerebral Hemispheres. The two hemispheres communicate by the corpus callosum: acts like a bridge between the two.

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 Functions: How we know what we are doing within our environment (Consciousness). Controls our emotional response. Controls our expressive language. Memory for habits and motor activities.

The Frontal Lobe Observed Problems: Loss of simple movement (Paralysis). Inability to plan a sequence of complex movements, such as making coffee (Sequencing). Inability to focus on task (Attending) Changes in social behavior. Changes in personality. 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. Goal directed voluntary movements. Manipulation of objects.

Parietal Lobe Observed Problems: Inability to attend to more than one object at a time. Inability to name an object (Anomia). Inability to locate the words for writing (Agraphia). Problems with reading , drawing and math(Alexia). 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 (Visual Field Cuts). Difficulty with identifying colors (Color Agnosia). Production of hallucinations Visual illusions - inaccurately seeing objects.

4. Temporal Lobe Location: Laterally (each side close to the ears. Function: Hearing ability Memory acquisition Categorization of objects. Observed problems: Difficulty in recognizing faces. Short-term memory loss. Inability to categorize objects (Categorization). 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 (Startle Response). Controls sweating, blood pressure, digestion, temperature (Autonomic Nervous System). Affects level of alertness. Ability to sleep. Sense of balance (Vestibular Function). Observed Problems: Decreased vital capacity in breathing, important for speech. Swallowing food and water (Dysphagia). Difficulty with organization/perception of the environment. Problems with balance and movement. Dizziness and nausea (Vertigo). Sleeping difficulties (Insomnia, sleep apnea).

Brain Stem Includes midbrain, pons, and medulla oblongata Midbrain – several masses of gray matter that serve as reflex centers = vision reflex and auditory reflex Pons – relay sensory impulses from peripheral nerves to higher brain centers Medulla oblongata – similar to the pons, but also controls the cardiac center, vasoconstriction and vasodilatation, and respiratory center.

CEREBELLUM Located at the base of the skull. Functions:\ Coordination of voluntary movement Balance and equilibrium Some memory for reflex motor acts. Observed Problems: Loss of ability to coordinate fine movements. Loss of ability to walk. Inability to reach out and grab objects. Tremors. Dizziness (Vertigo). Slurred Speech (Scanning Speech). Inability to make rapid movements.

Hypothalamus and Thalamus Hypothalamus is important in maintaining homeostais by regulating: Heart rate Water and electrolyte balance Hunger and body weight Body temp Sleep and wakefulness Controls pituitary gland Thalamus: receives All sensory information

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

The 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)

Activities: Labeling and vocab worksheets. Brain/Neuron packet. Brain and Spines board game

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

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.

Potential Changes Nerve cells are EXCITABLE: they can respond to changes in their environment. In order to do this their potential difference must change (The balance of Na+ and K- ions must change) In order for this to happen a certain “Degree” or “level” of change must occur called the Threshold. Once the threshold level is reached the neuron can now go from a resting potential to an ACTION POTENTIAL

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 called the synaptic cleft 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). There the impulse encounters a synapse separating it from another neuron. At the synapse NEUROTRANSMITTERS are released from the axon terminals. Neurotransmitters diffuse across the synaptic cleft to the next neuron or body cell.

Neurotransmitters They can either inhibit the action potential (stop it- lessens the chance that a nerve impulse will continue) Or they can excite and trigger a nerve impulse and stimulus to occur. 50 different types: Acetylcholine: stimulates skeletal muscle contractions Norepinephrine: Autonomic nervous system actions. Creates a sense of feeling good (Low levels cause depression) Endorphins: Inhibits; reduces pain.

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

1. what is an action potential in your own words 2. Resting potential 3. How is an impulse sent