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Understanding the Nervous System: Components and Functions

Dive into the complexities of the nervous system, from the formation of neurons to the functions of the brain. Explore the types of neurons, nervous systems, and the role of the peripheral nervous system, all crucial for processing sensory input and generating motor responses.

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Understanding the Nervous System: Components and Functions

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  1. Nervous System

  2. So, we now know that the nervous system is the first one to form in an early embryo, so let’s talk about this in a little more detail…

  3. What is the Nervous System? • A network of specialized cells (nerve cells) which carry messages (impulses) throughout an organism • Two key components: • Receptors: sensitive to changes, physical forces, or chemicals both inside and outside the body • Effectors: where the impulse is sent • Responds to the receptor

  4. Nervous System Definitions • Ganglia- mass of nerve structures (cells, roots, etc.) • Ocellus- photoreceptor; “simple eyes” • Cerebral- brain • Neurons- nerve cells

  5. Neuron • Nerve Cell • Consists of: • Cell Body (largest part) • nucleus & organelles • Axon & axon terminals • transmit signals to other cells • Myelin • insulator surrounding the axon which allows for the conduction of impulses • Dendrites • receive signals from other cells

  6. Synapse

  7. Types of Neurons • Motor Neuron- transmit signals for muscle contractions • Sensory Neuron- associated with the 5 senses • Interneuron- occur entirely within the central nervous system • Mostly found within the brain • Make local connections

  8. Types of Nervous Systems…

  9. 1. Cephalization • Definition: A concentration of nervous tissue in the anterior (head) portion of an organism • Complexity increases throughout the animal kingdom

  10. 2. Nerve Net • A network of nerve cells which allows the organism to respond to the environment • Lack a brain or any cephalization • Found in hydra & other cnidarians

  11. 3. “Ladder” • Two lateral nerve cords joined by transverse nerves • Found in planarian and other flatworms • Ganglia present in the anterior end • Ocellus (eyespots) with photoreceptors sense lighting

  12. 4. Cerebral Ganglia • Ventral nerve cord with anterior ganglia • Annelids, Arthropods, and Mollusks • Brain= control center for the ganglia • Many exhibit eyes with lenses that create images • Receptors- sense touch • Increased overall number of neurons

  13. Vertebrate Brain • Central Nervous System (CNS) • Brain: the enlarged anterior end of the nerve cord • Has three parts: 1. Hindbrain- regulates organs below the level of consciousness ( , lungs) • Cerebellum & Medulla

  14. 2. Midbrain- sensory input & coordinates reflex responses • Optic Lobe 3. Forebrain- receives and integrates sensory and motor input • Cerebrum & Olfactory bulbs • Associated with higher mental capacity

  15. Cerebrum Cerebellum Brain Stem

  16. Spinal Cord • Dorsal nerve cord • Transmits impulses to and from the brain

  17. Peripheral Nervous System (PNS) • Lateral nerves: accessory nerves that transmit impulses to and from the spinal cord • Accessory sense organs: • Eyes • Ears • Nose • Taste buds • Skin 5 senses!

  18. Motor System

  19. Functions of the Nervous System • Receives sensory input • Integrate sensory input • Generate motor outputs (responses)

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