The Nervous System

2. The Nervous System Nervous System: Hank

3. Word Parts • Ax- : axis • Dendr-: tree • Funi-: small cord or fiber • Gangli-: swelling • -lemm: peel or rind • Mening-: membrane • Peri-: around • Plex-: interwoven • Sens-: feeling • Syn-: together • Ventr-: belly or stomach • Moto-: moving

4. Vocabulary • Afferent: conducting toward the center • Efferent: conducting away from the center • Effectors: muscles, skin and glands • Nerveimpulse: transmission of information in the form of electrochemical signals • Neurons: nerve cells • Neurotransmitters: chemicals that carry nerve impulses • Acetylcholine, norepinephrine, epinephrine, dopamine, serotonin, endorphins • Synapse: the gap between 2 communicating neurons • Schwanncells: produce the myelin sheath

5. The Nervous System • Functions: • Sensory input – senses changes • Integration – interprets changes • Motor output – reacts to changes

6. Divisions of the nervous system • CNS: Central Nervous System • Brain & spinal cord: interprets incoming information • PNS: Peripheral Nervous System • Nerves that branch to the rest of the body

8. Types of Nervous Tissue • Neuroglia: support, insulate and nourish neurons • Outnumber neurons • Can divide (neurons cannot)

9. Neuroglia 1. Microglial cells: support neurons, phagocytize bacterial cells and debris and form scars: found throughout the CNS 2. Oligodendrocytes: provide the myelin sheath around axons: found along nerve fibers 3. Astrocytes: provide structure and regulate concentrations of nutrients: found between neurons 4. Ependymal cells: form a membrane that covers the parts of the brain and spinal cord

11. Neurons • Send signals in only one direction: do not touch each other • Three parts: • Dendrites – detect impulses • Cell body – interpret impulses • Axon – conduct impulses • Covered with a myelin sheath (fatty material)

13. Different Neuron Structures • Multipolar: (brain or spinal cord) have one axon and many dendrites • Bipolar: (eyes, nose and ears) have one axon and one dendrite • Unipolar: one end goes to the CNS and one end goes to the PNS

15. Types of Neurons • Sensory: (afferent) :transmit impulses from the PNS to the brain or spinal cord • Unipolar or bipolar 2. Interneurons: only in the CNS • Transmit impulses from one part of CNS to another part of the CNS • Multipolar 3. Motor: (efferent): transmit impulses out of the brain to effectors (muscles and glands) • multipolar

16. Nerve Physiology • How is a signal transmitted down a neuron? • Dendrites Cell Body Axon • NerveImpulse: an electrical signal that travels along an axon • Restingpotential: a neuron has a (+) charge outside the cell and a (-) charge inside the cell • resting potential

17. Action Potential • Resting neuron gets excited • Sodium channels open, allowing Na+ to enter & make the inside of the cell (+) & outside (-) • The impulse passes over the axon • Na+ channels close & potassium channels open, releasing K+ • Neuron is at rest again • Known as the Na+/K+ pump

20. nerve impulse

21. Connections Between Neurons • This is an extra slide and is not in the notes • When an impulse reaches the end of an axon: • Calcium channels open & Ca+ causing the release of neurotransmitters • Neurotransmitters diffuse across the synapse & bind to receptors on the dendrites of the next neuron initiating a new impulse

22. Synapses • Synapses

23. The Brain • TheBrain: The Control center of the body • Greymatter: non-myelinated axons • Whitematter: myelinated axons 1. The cerebrum or cerebral cortex • Largest part of the brain • Controls sensory and motor functions • Highly wrinkled to increase surface area

24. Cortex Lobes • FrontalLobe: reasoning, planning, speech, movement, emotions, language, memory, judgment, and problem solving • ParietalLobe: hand-eye coordination, orientation, touch, smell, speech and taste • TemporalLobe: emotions, smelling, tasting, perception, memory, music, aggressiveness and sexual behavior • OccipitalLobe: visual processing and recognition

25. Diencephalon 2. Diencephalon: between the cerebral hemispheres • Thalamus: relay station for sensory impulses (except smell) • Interprets pain, touch and temperature • Hypothalamus: heart rate, body temperature, blood pressure, hunger, thirst, weight, digestion, sleep and consciousness • Hippocampus: short to long-term memory • Limbic System: regulates emotion and memory

26. Brain Stem 3. BrainStem: connects the brain to the spinal cord • Midbrain: reflex centers • Pons: relays sensory impulses from PNS to brain • MedullaOblongata: every nerve passes through this • Cardiac controls • Respiration controls • Vasomotor controls • Coughing, sneezing swallowing and vomiting

27. Cerebellum 4. Cerebellum: communicates with other parts of the brain • Interprets: • Skeletal movements • Voluntary muscle movements • Loss of equilibrium

28. Right or Left Brained?

29. CNS: spinal cord • Spinalcord: the slender nerve column that passes downward from the brain into the vertebral canal • Consists of 31 segments that give rise to spinal nerves • Centralcanal: contains cerebrospinal fluid

30. Peripheral Nervous System • Nerves that carry messages to & from CNS • Afferent Division (Sense receptors) • sight, hearing, balance, smell, touch • Carry messages toward the spinal cord & brain • Efferent Division (Motor nerves) • Travel from the spinal cord & brain to muscles, telling them how to respond

31. Peripheral Nervous System • SomaticNervousSystem: Voluntary pathways • AutonomicNervousSystem: Involuntary pathways • Sympatheticnerves: stress, crisis • Increase heart rate, dilate airways and blood vessels, stimulate adrenaline release, inhibit digestive system • Parasympatheticnerves: relaxation • Slow down heart rate, lower blood pressure, stimulate digestive system

32. Cranial Nerves – PNS~12 pairs in the head & neck • Olfactory • smell • Optic • vision • Oculomotor • eyes • Trochlear • eyes • Trigeminal • face + nose + mouth • Abducens • eye roll • Facial • Taste, Face expression • Vestibulocochlear • Hearing & balance • Glossopharyngeal • Throat control • Vagus • Mouth, digestion • Accessory • neck • Hypoglossal • tongue

33. Nervous System Disorders • Poliomyelitis : viral infection that may lead to paralysis • Cerebralpalsy: affects hearing, learning, sight, speech and brain function • Parkinson’sdisease: leads to shaking and difficulty walking or moving • MultipleSclerosis (MS): Myelin sheaths are damaged so nerves don’t communicate correctly • Epilepsy: Characterized by seizers • Dyslexia: reading disorder where interpreting and processing is diminished • Tay-SachsDisease: inherited disease of the nervous system

34. Nervous System Disorders • Rabies – viral infection: convulsions, excitability, loss of sensation • Dementia – Loss of brain function that affects thinking, language, judgment, memory and behavior • Concussion: Violent jarring or shaking that results in a disturbance of brain function • Contusion: Bruise to the brain caused by injury • Cerebraledema: Swelling of the brain usually caused by traumatic injury

35. Brain Dysfunctions • Cerebrovascular accidents (Stroke): blood flow to the brain stops and brain cells die • Alzheimer’sDisease: brain function gradually diminishes over time