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
