Nervous system Flashcards
Why does the retina contain cones
To enable colour vision
Give two ways that the nervous system controls the action of the eye to enable effective sight
•Changes the shape of the lens- focus image on the retina
•Controls eye muscles- change direction of vision
Advantages of eye positioning in sheep
• Eyes on the side of the head
• A wide angle of vision
•Early detection of danger
Give a function of the iris
Controls pupil size
Give a function of the lens
Focuses light
Give a function of the retina
• Absorbs light
• Detects colour
• Detects movement
Give a function of the cornea
• Protection
• Refracts light
Role of the tapetum lucidum
Bounces light back to improve night vision in nocturnal animals
Explain how the structure of the tapetum lucidum helps its function
• Layer at the back of the eye
• Reflects light
• Provides better light absorption
State two parts of the CNS
• Brain
• Spinal cord
Give two functions of the parasympathetic nervous system
• Slows heartbeat
• Homeostasis
• Constricts pupils
• Breathing rate back to normal
State two symptoms and treatments of listeriosis in ruminants
• Loss of appetite
• Fever
• Lack of coordination
• Salivation
• Circling
• Seizures
Treatments:
-Isolation
-Antibiotics
Explain eye positioning in owls
• Front of face and close together - better to focus
State the photoreceptors in the eye
• Rods
• Cones
Explain two adaptions that help animals see in the dark
• Large eyes - see more clearly
• Slit pupils - easier to constrict
• More rods - react to lower light levels
State a function of the fovea
Provides sharp, central vision
State a function of the sclera
Provide strength, structure and protection
Give the name of a hormone released when an animal is stressed
Adrenaline / cortisol
Describe how organs respond to stimuli
• Receptors detect stimuli
• Send impulses to the CNS
• CNS processed the message
• Messages sent to the effector
• Effector generates a response
Give two functions of the sympathetic nervous system
• Dilates pupils
• Increased heart rate
• Relaxes bladder
• Prepares body for fight or flight
Describe vasoconstriction
• Happens when an animal is cold
• Blood vessels constrict
• Less blood to the skin
• Reduces heat loss
Describe vasodilation
• When an animal gets hot
• Blood vessels dilate
• Increased blood flow to the skin
• Cools down
State two types of neuron
• Sensory
• Motor
• Relay
Describe binocular vision
• Each eye overlaps - single 3D image
• Eyes at front of face - narrow field of vision
• Better to focus
• Predator animals
