The Nervous System Flashcards
What are the 2 main parts of the Nervous System?
Central Nervous System (CNS) - brain + spinal cord, surrounded by shock-absorbing cerebrospinal fluid
Peripheral Nervous System (PNS) - nerves around rest of body, sensory + motor neurons
What are the 3 functions of the Nervous System?
- Receive stimuli from environment
- Analyse & interpret stimuli info
- Respond to stimuli as necessary
What are the sensory organs and their receptors?
Tongue - chemoreceptors (chemicals)
Ears - mechanoreceptors (vibrations)
Eyes - photoreceptors (light)
Skin - mechanoreceptors (pressure), thermoreceptors (temperature), nociceptors (pain)
Nose - chemoreceptors (chemicals)
Give 4 ways animals have adapted to see in the dark
- Larger eyes have wider pupils to capture more light
- More rod cells (type of photoreceptor) in retina for function in the dark
- Cats - tapetum lucidum (reflective layer behind retina) maximises available light by reflecting it back through photoreceptors = stimulate more receptor cells
- Slit pupils as easier to contract
Where are the eyes positioned on predators and prey?
Predator - eyes at front (like to hunt),
narrow field of vision
Prey - eyes at side (like to hide),
wide field of vision
Compare predator and prey eye adaptations
Predator - able to focus, better depth perception
Binocular vision
Prey - poor depth perception
Monocular vision
How is the owl adapted to seeing?
• Eyes elongated + can’t move in socket, so has to move head (180° turns)
• Lots of rod cells = hunt in low light
How is the sheep adapted to seeing?
• Eyes high up in skull = better vision when grazing
• Rectangular pupils increase depth perception when grazing
What is a function of the myelin sheath in neurons?
Provide protection + maintain health of axon
What is synaptic fatigue?
When the presynaptic neuron runs out of neurotransmitters
Explain the 5 stages of the reflex arc
- Receptors in skin detect stimulus
- Impulses sent along sensory neuron to spinal cord
- CNS integrates the information within the spinal cord
- Impulses sent along motor neuron from CNS to an effector
- Effector generates a response
What is the sympathetic nervous system?
‘Fight or flight’ response to stress
Focus energy on essential functions Prepares body for physical activity -
• heart rate increases
• pupils dilate
• inhibits digestion
• stimulates release of glucose in liver
What is the parasympathetic nervous system?
‘Rest and Digest’ - normal body functions, relaxed
• slow heartbeat
• stimulates digestion
• constricts pupils
What is the tapetum lucidum?
Reflective layer behind retina, reflects light back through photoreceptors stimulating more receptor cells, which maximises amount of light for night vision.
Name 3 things the body does to prepare for fight of flight.
Pupils dilate
Saliva production inhibited
Heart rate increase
Digestion inhibited
Stimulate release of glucose
Relaxed bladder
Name 3 changes in the body during rest and digest (parasympathetic)
Pupils constrict
Saliva production stimulated
Heart rate slows
Digestion stimulated
Stimulate release of bile
Bladder contracts
What are the 2 photoreceptors?
Rods and cones
What is the function of the node of ranvier?
Allow impulses to jump
What is the function of the Schwann cell?
Speed up transmissions, form the myelin sheath
Give 2 neurological disorders.
Listeriosis / degenerative myelopathy / seizures
