biology-nervous system

• what is the role of the nervous system

  to monitor and maintain a constant internal environment and to respond to the changes in our external environment
• what are the main 2 parts of the nervous system

  the central nervous system and the peripheral nervous system
• what is the role of a receptor

  to sense changes in the internal or external environment
• give some examples of sensory input

  pressure

  taste

  sound

  light

  blood ph
• what are mechanoreceptors

  receptors responsible for our hearing and balance
• what are nociceptors

  these are more commonly know as pain receptors
• what are photoreceptors

  responsible for us seeing light the are found in the eyes
• what are chemoreceptors

  found in ur nose and mouth they give use our sense of taste and smell
• what are thermoreceptors

  responsible for detecting changes in temperature
• describe the central nervous system

  • includes the brain and the spinal cord
  • surrounded by bones and vertebrae
  • fluid and tissue also insulate the brain and the spinal cord
  • the tissue is known as meninges and the fluid is known as cerebrospinal fluid
• describe the brain's structure and function: 3 parts: cerebrum, cerebellum, brainstem

  
• what are the origins of neuroscience

  • discovered by Paul Brocca in 1800
  • he studied the brains of aphasic (those who cant speak) paitents and realised different functions could be localised to different regions of the cerebrum
• what are astrocytes

  they are glial cells that are responsible for clearing excess transmitters
• what are oligodendrocytes

  glial cells that regenerate and maintain the meylin sheath
• what are microglia

  glial cells that are specialised macrophages
• what is the sensory neuron

  • it is an afferent neuron meaning it moves away from a central organ or point
  • it relays messages from receptors to the brain or spinal cord
• what is an interneuron

  • relays messages from sensory neurone to the motor neurone
  • it makes up the brain and the spinal cord
• what are motor neurons

  they are efferent neurons meaning they move towards a central organ or point. they relay messages from the brain or spinal cord to the muscles and organs
• what is a reflex response

  an automatic response to a stimulus
• give some examples of a reflex response

  knee jerk

  blinking

  response to pain
• what are the stages of a reflex response

  
• what neurons are involved in the reflex arc

  the sensory,inter and motor neurons

  the sensory carries the impulse from the stimulus to the cns where it synapes with the interneuron

  which then synapses with the motor which carries the nerve impulse to an effector

  
• how is the peripheral nervous system split

  it is split into the sensory divison which caries information to the central nervous system and into the motor division which carries information from the central nervous system
• how is the motor division split

  into the somatic and autonomic divison

  the somatic controls skeletal muscles where as the autonomic controls smooth muscle
• how is the autonomic division split

  into the sympathetic division which is responsible for the fight or flight response and into the parasympathetic division which stimulates relaxation
• describe the autonomic nervous system

  it regulates the bodys inoluentary actions such as the heart

  it is split into the parasympathetic and sympathetic divisions
• what are the roles of the sympathetic and parasympathetic systems

  the sympathetic prepares the body for violent activity where as the parasympathetic reverses these changes when the danger is over
• describe the fight or flight response

  • cortisol increases blood pressure and blood sugar
  • adrenaline facilitates physical reactions

  
• what are some common symptoms of fight or flight and how are these reversed

  during fight or flight the pupil dilates to reverse this the parasympathetic system constricts the pupil

  during flight or fight the bronchi dilates to reverrse this the bronchi is constricted

  during fight or flight peristalsis is inhibited to reverse this the parasympathetic system stimulates peristalsis
• what is a meylin sheath

  insulates the neuron and speeds up the rate of transmission
• label the nerve cell

  
• where are voltage gated ion channels found

  at the nodes of ranvier
• how do action potentials travel across a nerve

  the action potentials jump from one node to another in a process kown as saltatory propagation
• what is a resting potential

  • occurs when the neuron isnt sending a signal
  • the sodium potassium pump uses ATP to pump 3 sodium ions out and 2 potassium ions in
  • this makes the inside more negative that the outisde
  • the resting potential is about -70mv
• how is the resting potential determined

  by the concentrations of the ions in the fluids on both sides of the cell membrane
• explain this graph

  1.stimulus some Na+ being let out

  2.membrane potential reaches -55mv and the NA+ channels open so inside the neuron becomes less negative

  3.sodium close and potassium open

  4. potassium close causing hyperpolarisation making the inside of the cell more negative

  5.the sodium potassium pump returns to resting potential

  
• describe the synapse

  transmits information between neurons

  acts as a junction to divide impulses

  transmits impulses oly from the preysynaptic neuron to the postsynaptic neuron

  filiter out any low frequency impulses
• what does a neurotransmitter do

  diffuses across the synaptic cleft and fuses to the receptor on the postsynaptic membrane causing an influx of sodium ions generating an action potential
• how do impulses travel across the synaptic cleft

  action potential reaches the pre-synaptic terminal

  • voltage gated Ca2+ channels open

  • influx of Ca2+

  • synaptic vesicles fuse with membrane

  • neurotransmitter released into cleft

  • binds to receptor on postsynaptic membrane

  • action potential is initiated

  • neurotransmitter broken down

  
• what is summation

  a way of controlling the strength of action potentials

  2types: spatial and temporal