B3.1 The Nervous System

• Accommodation is when you change the lens shape to fine focus the image of an object regardless of its distance from the eye
• the central nervous system (CNS) is the brain and the spinal cord
• the cerebellum is the region of the brain that controls unconscious functions such as posture, balance and muscular movement
• the cerebral cortex is the outer layer of the cerebrum
• the cerebrum is highly folded region of the brain that is responsible for controlling voluntary actions such as learning, personality and memory. it is divided into the

  left and right hemisphere
• the ciliary body is an extension of the iris, it contains the ciliary muscle which can contract or relax, allowing the eye to focus
• colour blindness is when a person has a defect in the receptors or a lack of receptors in the retina
• coordination is the ability to use different parts of the body together smoothly and efficiently
• the cornea is the part of the eye that refracts light as it enters, focusing it onto the retina
• the effector is a gland or muscle that produces a response to a stimulus to restore optimum conditions
• the iris is the part of the eye that further refracts light to focus it onto the retina
• long-sightedness is when near objects seem out of focus due to the convergence of light rays in front of the retina (hyperopia)
• the medulla is the part of the brain responsible for non-voluntary movement such as breathing rate and heart rate
• the motor neurone is The neurone that transmits impulses from the relay neurone to the effector to produce a response
• the optic nerve is the nerve that carries impulses between the brain and the eye
• the pituitary gland is the gland that stores and releases hormones which regulate many bodily functions
• the pupil is a hole in the centre of the iris. is controlled by the muscle of the iris and changed size depending on the light intensity
• a receptor is a cell or organ that recognises the stimulus
• the reflex arc is the pathway of neurones involved in a reflex action
• the relay neurone is the neurone that transmits electrical impulses from the sensory neurone to the motor neurone
• the retina is the layer at the back of the eye that contains light receptors and is sensitive to light
• the sensory neurone is the neurone that detects the stimulus and transmits the electrical impulses from to the relay neurone located in the spinal cord
• short-sightedness is a defect of the eye where distant objects appear out of focus due to the convergence of light rays infront of the retina (myopia)
• suspenders ligaments attach the lense to the ciliary muscle
• the synapse is the junction between two neurones (nerve cells)
• the nervous system has two parts; the central nervous system and the peripheral nervous system
• the CNS is made of the spinal cord and the brain
• the nervous system is a network of nerve cells that transmit impulses between parts of the body
• the NS allows us

  • to react to our surroundings
  • to coordinate out behavior
• neurones are specialised cells that carry nerve impulses from one part of the body to another
• the 5 examples of sensory receptors

  1. hearing
  2. vision
  3. touch
  4. smell
  5. taste
• the 5 examples of stimuli

  1. light
  2. sound
  3. temperature
  4. pressure
  5. chemical
• examples of effectors

  1. muscles
  2. glands
• What type of neurone is this?

  Sensory neurone

  
• What type of neurone is this?


  Motor neurone

  
• The cell body (soma) contains the nucleus which

  controls the cell and also produces neurotransmitters
• the axon terminal transmits neurotransmitters from the presynaptic neurone into the synapse
• the myelin sheath insulates neurones, speeding up the impulse
• the nodes of ranvier are the “gaps” between the Schwann cells allow speed of transmittion to be further increased by allowing impulse to jump from node to node in a process called saltatory conduction
• dendrites have branched endings - connect with other neurones and carry nerve impulses towards cell body