»Ever wonder how you can do everything you do?

1 Allows us to sense our external environment as well as sense changes internally.

2 Movements (actions both involuntary and voluntary)

3. Allows us to have memory and intelligence – Thinking!

4. Helps maintain homeostasis by detecting changes either on the outside or inside and allowing your body to react appropriately.

» Nervous tissue consists of:˃ Neurons

+ Main functional unit of nerve tissue+ Transmit nerve impulses+ Comprised of: cell body, dendrites, and axons

˃ Neuroglia+ Provide to the neurons:

– Support– Insulation– Nutrients

+ Relay signals for differentiation of neurons from progenitor cells

»Central Nervous System (CNS) Central Nervous System (CNS) = brain and spinal cord»Peripheral Nervous System (PNS) Peripheral Nervous System (PNS) = cranial and spinal nerves and are information lines (like corded telephones)

» 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.

1.1. Neurons: Neurons: the basic cell and functional unit of the nervous system. ˃ They transmit information to the body in the

form nerve impulses.

2.2. Nervous Tissue: Nervous Tissue: Bundles of neurons or nerve cells put together.

3.3. Neuroglial cells: Neuroglial cells: supporting cells in the nervous tissue.

» Sensory receptors˃ At the end of peripheral nerves˃ Gather in formation

+ Inside and outside of the body+ Monitor temperature and O2 levels+ Monitor external environmental factors

˃ Convert information to nerve impulses that transmit over the PNS to the CNS+ Integration occurs to translate sensation into perception

– Create sensations– Add memory– Help produce thoughts

˃ Because of this we make conscious or subconscious decisions and then use motor functions

» Motor functions˃ Employ PNS, which carry information from the CNS to the effectors˃ Effectors are outside of the nervous system and controlled by the nervous

system+ Muscles or glands

˃ Divided into two categories+ Somatic nervous system

– Voluntary motions– Skeletal muscle

+ Autonomic nervous system– Involuntary motions– Cardiac muscle, smooth muscle, and various glands

˃ Actions counteract changes detected, therefore helping to maintain homeostasis

1.1. FunctionFunction: : Fill in spaces, provide structural frameworks, produce myelin, carry on phagocytosis

2. 2. TypesTypes:: ˃ Microglial, Oligodendrocites,

AstrocytesAstrocytes, , EpendymalEpendymal, , Schwann cellsSchwann cells

» Microglial cells˃ Scattered throughout CNS˃ Phagocytize bacterial cells and other cellular debris˃ Form scars in areas of damage

» Oligodendrocytes˃ Align along nerve fibers˃ Provide the insulating layer of myelin – myelin sheath

» Astrocytes˃ Found between neurons and blood vessels˃ Provide structural support˃ Join parts by abundant cellular processes˃ Regulate concentrations of nutrients and ions˃ Can also form scar tissue within CNS

» Ependymal cells˃ Form an epithelial-like membrane

+ Covers specialized brain parts+ Form inner linings of enclosed spaces in brain and spinal cord

» Schwann Cells˃ Found in PNS˃ Produce myelin sheath around axons of myelinated neurons

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.

» Myelinated axons – The myelin sheath that envelopes the nerve cell is crucial for faster conduction of action potential. Found in the PNS (sensory and motor neurons) and white matter of CNS.

» Unmyelinated axons - The unmyelinated nerve pertains to any of the nerve cells without myelin sheath. They are slower in conducting impulses and are found in the PNS (visceral nervous system) and gray matter of CNS.

Depending on what your body needs to do- there are different types of neurons. 1. Bipolar2. Unipolar 3. Multipolar

1. Each neuron is either a Sensory Neuron, a Motor Neuron or an Interneuron.

1. SENSORY NEURON: Your body senses something and sends a message to your brain or spinal cord. Afferent= bring messages into the brain.

2. 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.

3. INTERNEURON: Lie within the CNS and link other neurons together. They transmit impulses from one part of the brain or spinal cord to another.

1. Use the book and your notes to create a foldable about the different types of neurons.

2. 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)

3. The outside you will need to draw what each neuron looks like and label it –bipolar, unipolar, multipolar.

4. The inside will answer the following info: 1. Where it is located. 2. Something about the number of axons and

dendrites. 3. If it is a sensory neuron, interneuron, or motor

neuron and what that means. 4. Is it afferent or efferent. 5. One piece of other information.

Book Work: p216 Q’s 3-5, 8; p221 9-12

How does your brain How does your brain send out signals?send out signals?

» The junction between two communicating neurons is called the synapsesynapse.

» The neurons are separated by a synaptic cleft

» The neurons DO NOT TOUCH- there is a gap that separates them

» Neuron transmitting the impulse into the synpase – presynaptic neuron

» Neuron receiving the impulse – post synaptic neuron» As the message crosses the synaptic cleft - synaptic

transmission

» Neurotransmitters – biochemicals that move one way » Distal ends of axon terminals = synaptic knobs (not found in

dendrites)˃ Contain membranous sacs called synaptic vesicles

» When impulse reaches synaptic knob, vesicles release neurotransmitters, which diffuse across the synaptic cleft to receptors in the postsynaptic neuron

Action of the Neurotransmitter» Excitatory

˃ Turns a process on+ Dopamine + Norepinephrine+ Noradrenaline+ Glutamate + Histamine + Acetylcholine + Aspartate

» Inhibitory˃ Turns a process off

+ GABA - Gamma amino butyric acid + Glycine

» Net effect on the postsynaptic neuron depends on the combined effect of the excitatory and inhibitory inputs˃ Inputs range from one to 10,000 presynaptic neurons

» 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!

» The difference in electrical charge between the inside and outside of a cell is called the POTENTIAL DIFFERENCE. POTENTIAL DIFFERENCE.

» In a nerve cell that is “RESTING” or not sending impulses this difference in charges is called the RESTING POTENTIALRESTING POTENTIAL

» As long as the nerve cell remains undisturbed or the charges do not change it will remain in a resting potential state.

» Action Potential: Action Potential: 1. Electrical charges change by sodium channels

opening and allowing positive sodium into the cell. This makes it positive. And is called DEPOLARIZATION

2. 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 The action potential is the rapid change from Depolarization to Repolarization which Depolarization to Repolarization which causes an impulse to be sent through the causes an impulse to be sent through the neuron neuron

» 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.

TO DO» P. 227

˃ Copy down table 9.1˃ Questions 14 & 15

» P. 228˃ Questions 17-19˃ Questions 20-22

» P229˃ Copy down table 9.3, but take one of the neurotransmitters from 9.2 and

try to integrate it into the what you are writing down from 9.3. (In other words, you would need to add a step 5 and 6)

» P 230˃ Questions 25-26

» The simplest nerve pathways that are only a few neurons long are called REFLEXE ARCS.

Several Interneurons

in CNSaka Reflex

center

» Reflexes are automatic subconscious responses to changes within or outside the body.

» Helps to maintain homeostasis» Example: The Knee-Jerk reflex: Only 2 neurons.

A sensory neuron communicating directly with a motor neuron.

Page 221-222 in book

Knee Jerk activity

» Example of the withdrawal reflex

» Practice problems on back of notes» Worksheet» On Back of worksheet:

˃ P. 232 27-30

1. The brain is composed of about 100 billion multipolar neurons and even more nerve fibers to communicate.

2. Divided into three major portions: The cerebrum, cerebellum, and the brain stem

1.1. CerebrumCerebrum controls sensory and motor functions, higher mental functions – memory and reasoning (Divided into sections)

2.2. Cerebellum Cerebellum coordinates voluntary muscle activity

3.3. Brain stem Brain stem regulates visceral activities and connects various parts of the nervous system

1. The Frontal Lobe2. The Parietal Lobe3. The Occipital Lobe4. The Temporal Lobe

1. Forms the anterior portion of each hemisphere (Your brain is divided into left and right portions).

Functions:Functions:• How we know what we are doing

within our environment (Consciousness).

• Controls our emotional response. • Controls our expressive language.

Observed Problems: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).

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

Observed Problems: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.

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

Location: Location: Laterally (each side of brain close to the ears. FunctionFunction: •Hearing ability •Memory

Observed problemsObserved problems: •Difficulty in recognizing faces. •Short-term memory loss. •Right lobe damage can cause persistent talking. •Increased aggressive behavior.

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

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).

» 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.

Cranial NervesPair of nerves What is does

1.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 eyelidsMaxillary division = upper teeth, upper gum, upper lipMandibular division = scalp behind ears, skin of jaw, lower teeth, lower gum, lower lip

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 equilibriumCochlear branch = hearing

9. Glossopharyngeal Tongue and pharynx, tonsils, posterior third of tongue

10. Vagus Somatic= Larynx, swallowing, speechAutonomic = heart and smooth muscles

11. Accessory Cranial branch = soft palate, pharynx, larynxSpinal branch = neck muscles

12. Hypoglossal Move the tongue for speaking, chewing, swallowing

The Spinal CordThe 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 Cerebral Spinal Fluid (CSF),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 informationelectrical information to and from the limbs, trunk and organs of the body, back to and from the brain

The Spinal Cord

» Cerebral Spinal Fluid:

Spinal NervesThere are four main groups of spinal nerves which exit

different levels of the spinal cord.

These are in descending order down the vertebral column:

1.1. Cervical Nerves "C"Cervical Nerves "C" : (nerves in the neck) supply movement and feeling to the arms, neck and upper trunk. (8 total)

2.2. Thoracic Nerves "T"Thoracic Nerves "T" : (nerves in the upper back) supply the trunk and abdomen. (12 total)

3. Lumbar Nerves "L" and Sacral Nerves "S"Lumbar Nerves "L" and Sacral Nerves "S" : (nerves in the lower back) supply the legs, the bladder, bowel and sexual organs. (5L and 5S)