Science test neurons

• Neurotransmitters are chemicals that transmit signals across the synapse from one neuron to another.
• Axons are covered by myelin sheath which insulates them to speed up signal transmission
• The three main parts of a neuron are the cell body (soma), dendrites, and axon.
• Axons are covered by myelin sheath which insulates them to speed up conduction
• Neurons are the basic building blocks of the nervous system, responsible for transmitting information through electrical and chemical signals.
• The axon is the long, thin projection that carries electrical signals away from the cell body.
• Coordination


  Different parts of the body working together smoothly, like a team, to get things done
• Humans are multicellular organisms
• Multicellular organisms are made up of different body systems that must communicate with one another and work together to keep the organism alive
• Homeostasis


  The ability of the body to maintain a stable internal environment despite changes in external conditions
• These systems work together to achieve homeostasis
• Nervous system


  Responsible for controlling our thoughts and actions, including protecting us from all sorts of dangers
• Nervous system function


  1. Recognising a change to the environment

  2. Sending a message about it

  3. Processing this information

  4. Telling our body what to do in response
• Neurons


  Nerve cells that make up the nervous system
• Parts of the nervous system

  • Central nervous system
  • Peripheral nervous system
• Central nervous system (CNS)


  Composed of the brain and spinal cord, detects sensory information and coordinates the body's actions
• Peripheral nervous system (PNS)


  Collection of neurons that connect the CNS to the rest of the body
• Brain


  • Complex organ that controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger and every process that regulates our body
  • The control centre of the body
  • Interprets messages about our internal and external environments and plays a key role in maintaining homeostasis
• Spinal cord


  Long, thin, tubular structure made up of nerves that extends from the brainstem to the bottom of the backbone, connects the brain to the peripheral nervous system
• What are the 2 parts of the nervous system

  • Central Nervous System (CNS)
  • Peripheral Nervous System (PNS)
• Neurons


  • Transmit messages (electrical signals) between the PNS and CNS
  • Have long bodies and many receptors called dendrites, allowing for fast transmission
  • Message moves as an electrical impulse through the cell body and then through a long structure called an axon
  • Axons are covered with a white insulating substance called myelin which helps speed up the signal
• Types of neurons


  • Sensory neurons - carry the impulse to the central nervous system
  • Interneurons (relay) - carry the impulse through the central nervous system
  • Motor neurons - take the impulse to effectors such as muscles or glands
• Synapse


  Gaps between neurons where chemicals called neurotransmitters are released to carry the signal across
• The structure of a neuron includes

  • cell body, nucleus, dendrites, axon, myelin sheath, axon terminals
• Transmission of message between neurons


  1. Nerve impulse travels along a neuron until it arrives at the synaptic junction

  2. Neurotransmitters are released from the axon terminal of one neuron into the synapse

  3. Neurotransmitters carry the signal across the synapse, triggering an electrical signal in the dendrite of next neuron which passes the impulse on
• Transmission of a nerve impulse

  How is a nerve impulse transmitted from neuron to neuron?
• Poisons


  Can stop neurotransmitters from being produced or detected in the body, interfering with the neurotransmitters' job of carrying the message to the next neuron, causing spasms and paralysis
• Responses guided by the nervous system can be either voluntary or involuntary
• Voluntary actions


  Conscious decisions requiring thought from the brain that you know you are completing
• Involuntary actions


  Occur unconsciously and without thought, which can make them super quick
• Stimulus-response model


  1. Changes (stimuli) in the environment need to be detected by receptors

  2. If a response is required, this needs to be communicated to effectors to bring about some type of change or correction so the conditions can be brought back to normal
• Parts of the endocrine system

  • main control glands
• Receptors


  Structures found on neurons and other cells that detect stimuli
• Reflex actions


  May involve only a few neurons and require no conscious thought, once the stimulus is detected by a receptor, the message is sent via the sensory neuron to the interneuron in the spinal cord and then from the motor neuron to the effector to bring about a response, the message does not go to the brain, usually in dangerous situations
• The Endocrine System uses chemical messages called hormones produced in endocrine glands to control and coordinate activities in the body
• Hormones


  Control and regulate functions like metabolism, growth, development and sexual reproduction, the effects are usually slower and generally longer lasting than those of the nervous system
• Only particular cells have receptors for particular hormones, these target cells are attuned to the hormones carried through the body and respond in a particular way
• Hormone binding


  A hormone and its matching receptor are like a lock and key, the hormone (key) triggers a response when it fits precisely into the receptor (lock)
• Negative feedback


  Whenever the internal environment deviates from its normal state, what feedback causes a series of actions that return it to its normal state, it is how the body keeps conditions within it constant at the optimum level (homeostasis)
• Positive feedback


  A deviation from normal conditions is amplified, leading to a further deviation, positive feedback is rare in biology because it tends to produce harmful, unstable conditions