1 / 15

The Nervous System

Explore the specialized cells of the nervous system, the structure of neurons, and the different regions of the nervous system. Learn about the types of neurons, nerve impulses, action potentials, and the organization of the nervous system. Discover the functions of the central nervous system (CNS) and the peripheral nervous system (PNS), as well as the two divisions of the autonomic nervous system. Additionally, understand the effects of drugs on the nervous system and common disorders such as meningitis and multiple sclerosis.

inelln
Télécharger la présentation

The Nervous System

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. The Nervous System

  2. Neurons: specialized cells of the nervous system. • 3 major regions: • 1) Dendrites: receive signals from other neurons • 2) Cell Body: contains the nucleus and organelles • 3) Axon: Carries impulse signal to other neurons/muscles • 4) Myelin sheeth – surrounds portions of the axon to protect and insulate.

  3. Types of neurons: • Sensory: Send impulses from receptors in the sense organs to the spinal cord and brain. • Motor: Carry a signal from brain and spinal cord to glands/muscles. • Interneuron: Found in the spinal cord and brain. Sends messages between sensory and motor neurons.

  4. Reflex arc • A reflex is an preprogrammed response to a certain stimulus. • In a reflex a sensory neuron sends a message to the spinal cord which immediately relays a response to a motor neuron. • The brain does not interpret the response until after it has happened!

  5. Nerve Impulse – charge traveling through a neuron. • 1. A stimulus is received by a sensory neuron. • 2. The impulse is sent towards the spinal cord and then up to the brain to receive the message. • 3. The brain sends a response to a motor neuron with reaction instructions.

  6. Action-Potential Nerves: All or nothing! • In order for nerves to send an impulse, they rely upon the concentration of ions to function properly. Specifically Sodium and Potassium ions control impulses. • At rest: Slightly negative inside the cell, slightly positive outside. • Stimulus causes pumps to activate, dumping positive sodium ions outside the cell and pulling in less potassium – reversing the charges on either side of the membrane.

  7. Sodium-Potassium Pumps • To allow for action potentials, a protein pump is used. • The one protein dumps 3 positive charges out of the cell (Na+) and pulls in 2 K+ ions. • Each time the pump makes this switch, ATP is used.

  8. Impulses • The impulse travels the length of the nerve cell’s axon until it reaches the end. • Between 2 neurons there is a gap called a synapse. • The impulse causes the axon to send neurotransmitters to the dendrites of the next neuron to continue the message.

  9. Organization of the Nervous System: 2 Divisions • The nervous system has 2 divisions: • Central Nervous System (CNS) • Brain and spinal cord • Mostly interneurons • Peripheral Nervous System (PNS) • Sensory and motor neurons that carry info to and from CNS.

  10. CNS - Brain • Cerebrum: Largest portion. • Involved with learning, memory, speech/language, senses and voluntary movement. • Cerebellum: Found in the back. • Controls balance and coordination, smooth muscle (involuntary movement). • Medulla Oblongata: Relays signals between brain and spinal cord. • Controls breathing rate, heart rate, and blood pressure.

  11. CNS – Spinal Cord • Extends from the brain to the lower back • Protected by the spinal column or vertebrae. • Reflexes are processed by the spinal cord.

  12. PNS - • Subdivided into Somatic and Autonomic. • Somatic Nervous System relay info from sensors to CNS. • comprises voluntary actions • Autonomic carries impulses from CNS to heart and other internal organs. • Comprise involuntary actions (out of your control).

  13. Autonomic Divisions • Sympathetic and Parasympathetic divisions. • Sympathetic Nervous System act in times of stress: High heart rate and breathing. • Parasympathetic Nervous System active when the body is relaxed. • Both relay messages to the same organs, but the over responses depends on which division is in control.

  14. Drug Effects • A drug is a substance that alters some function of the body. • Certain drugs: • change the amount of neurotransmitters released. • Block receptors of neurotransmitters. • Imitate neurotransmitters. • Types of drugs: • Stimulants: Increase activity • Caffine • Nicotine • Depressants: Decrease CNS, blood pressure and heart rate. Often raise levels of dopamine  creating a happy feelings. • Alcohol • Inhalants • Illegal drugs

  15. Disorders • Meningitis – and inflammation of the meninges. • This can be life threatening and lead to a number of other disorders if not treated. Multiple Sclerosis – Breakdown of the myelin protective coverings around neurons. Can cause paralysis, loss of function, cognitive issues and death if untreated.

More Related