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Nervous System

Explore the evolutionary journey of the nervous system from simple nerve nets to complex brains in humans. Learn about the different types of neurons, transmission of nerve impulses, synapses, and the structures and functions of the brain and spinal cord. Discover disorders like Parkinson's disease, cerebral palsy, and Alzheimer's disease that affect the nervous system.

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Nervous System

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  1. By: Allie Dunn & Sarah Leitnaker Nervous System

  2. Evolution of Nervous system • Hydra (Cndarian)- have one or more nerve net, made up of neurons. • Flatworm (planarians)- have ladder like nervous system • with two nerve cords that run the length of the body. • Connected by transverse nerves • Cephalization • Ganglion- a cluster of neurons

  3. Hydra and Flatworm

  4. Evolution of Nervous system • Earthworms (annelids) (Also molluscs and arthropods/insects) • True nervous systems • A brain, well developed sense organs, multiple ganglia, and increased number of neurons.

  5. Evolution of Nervous system • Humans (vertebrates)- • Central nervous system with brain and spinal cord • With ascending and descending tracts. • Peripheral nervous systems

  6. Neurons • Cell body, dendrite, and axon • Bundled axons form nerves and are sometimes covered by myelin sheath • Spiral neuroglia form myelin sheath membrane.

  7. Types of Neurons • Motor (efferent): • Nerve impulses for CNS to muscles • Shape- have many dendrites and a single axon (multipolar). • Sensory (afferent): • Takes impulses from sensory receptors to CNS • Cell body divides into two directions, periphery CNS (unipolar). • Interneurons: • Only CNS • Typical multipolar

  8. Transmission of nerve impulses • At resting potential the axon has negative voltage • Action potential gated channels allow positive sodium ions to move freely into axon, voltage becomes positive. • Myelinated axons: action potential concentrated at the nodes. • *refractory period

  9. Synapse • Gap in between neurons (synaptic cleft) • Neurotransmitter carry impulses across synaptic cleft. They are released when calcium gates are open. • The neurotransmitters bind with the receptors. • Neuromodulators block the neurotransmitter or modifies its response.

  10. Intermission

  11. Brain and Spinal Cord • Protected by bone i.e. skull and vertebrae • Wrapped in meninges, three protective membranes. • Spaces in between are filled cerebrospinal fluid

  12. Spinal Cord • Bundle of nerve tissue from brain to below rib cage. • Reflex action center and communication.

  13. Brain • Four chambers called ventricles • Cerebrum is the largest portion in humans. Communicates and coordinates activities in the brain. • Divided into lobes. • Diencephalon • Hypothalamus regulates hunger sleep and temperature. And controls the pituitary gland. • Thalamus receives sensory input.

  14. Brain • Limbic system: blends emotions and mental functions. • Two different parts: • Hyppocampus: awareness of past experiences • Amygdala: emotional overtones on these experiences

  15. Peripheral Nervous System • Outside central nervous systems with nerves. • Cranial nerves and spinal nerves and be sensory or motor. • Somatic system: serves the skin, joint, and skeletal muscles. • Reflex arc: sensory receptors generate nerve impulses. Info is integrated. Impulses travel along motor axons to an effector which brings about a response.

  16. Autonomic System • Regulates cardiac and smooth muscles. • Involuntary • Use two neurons and one ganglion for each impulse. • Sympathetic division for emergency situations. • Parasympathetic division for relaxed state.

  17. Parkinson’s Disease • Degenerative disease process that affects the basel ganglia of the brain • Caused by a deficiency of the neurotransmitter and aging • Effects are a tremor, rigidity, and difficulty with spontaneous movements. • Also expressionless face, monotone voice and a shuffling walk.

  18. Cerebal Palsy • A loss or deficiency of motor control • Caused by injury to the brain before, during or after birth. • Can also be caused by hypoxia, jaundice, and infection. • Effects are involuntary spasms and lack of balance. • Intelligence, posture and speech are frequently • impaired. • May also be associated with visual impairment, • reduced hearing and behavioral problems • May have fixed abnormalities

  19. Alzheimer’s Disease • Associated with a deficiency of ACh. • Form of dementia that gets worse overtime. • Affects memory, thinking and behavior. • Causes abnormal clumps (amyloid plaques) and tangled bundles of fibers (neurofibrillary tangles). • There is no cure • Three different stages: • Mild • Moderate • Severe

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