Neurobiology and Behaviour Flashcards
Define the terms stimulus, response and reflex in the context of animal behaviour
stimulus - change in the environment (internal/external) that is detected by a receptor and elicits a response
response - change in organism produced by stimulus
reflex - rapid, unconscious (innate) response to stimulus
Explain the role of receptors, sensory neurons, relay neurons, motor neurons, synapses and effectors in the response of animals to stimuli
Receptors - detect a stimulus; can by sensory cells or nerve endings of sensory neurons
Sensory neurons - receive messages from receptors across synapses; carry message to CNS (spinal cord/brain)
Relay neurons - receive messages from sensory neurons across synapses; pass message to motor neurons that can use appropriate response
Motor neurons - receive message from CNS relay neurons across synapses; carry message to effectors
Synapses - spaces between adjacent neurons; bridged by neurotransmitters which diffuse from presynaptic to postsynaptic neuron
Effectors - carry out response after receiving message from motor neuron
• muscles - contract
• glands - secrete substances (ie. hormones)
Draw and label a diagram of a reflex arc for a pain withdrawal reflex, including the spinal cord and its spinal nerves, the receptor cell, sensory neuron, relay neuron, motor neuron and effector
- white/grey matter
- ventral/dorsal roots
Explain how animal responses can be affected by natural selection, using two examples
- White-tailed deer (mate selection)
- males fight in the fall (competition), results in breeding by stronger, determined males
- females ovulate in fall, stimulated by photoperiod (shortening day length)
- fawns are born in spring when more food available and warmer temperatures; easier to escape from predators
- innate behaviours determine “survival of fittest” - Northern cardinals
- non-migratory species
- males change calls in spring to attract mates
- communicate in winter using whistles
- mate in March and May-July; lay eggs when weather is warm and more food, gives chicks time to mature/fledge before winter
- female sings from nest so male knows when to bring food
- brighter red males hold territories with denser vegetation, feed at higher rates, greater reproductive success
Outline the diversity of stimuli that can be detected by human sensory receptors, including mechanoreceptors, chemoreceptors, thermoreceptors and photoreceptors
Mechanoreceptors - energy in form of movement, sound, pressure, gravity (eg. hair cells in inner ear detect sound, pressure receptors in skin detect touch)
Chemoreceptors - dissolved substances (tongue), airborne vapours (nose) (eg. taste receptors and olfactory cells detect molecular shapes/changes)
Thermoreceptors - temperature (eg. warm/cold receptors in skin send messages to CNS at rate determined by surface temperature)
Photoreceptors - electromagnetic radiation, usually in visible range (eg. rod/cone cells in eye absorb light to detect intensity/colour)
Label a diagram of the structure of the human eye
- sclera
- cornea
- conjunctiva
- eyelid
- choroid
- aqueous humour
- pupil
- lens
- iris
- vitreous humour
- retina
- fovea
- optic nerves
- blind spot
Annotate a diagram of the retina to show the cell types and the direction which light moves
Cone Cells - 3 types to sense colours of red, blue, green light; function better in bright light
Rod Cells - still function well in dim light; monochromatic vision only
Pigmented Cells (choroid) - contain melanin to absorb light rays that escape photoreceptors, prevent internal reflection that distort visual image
Bipolar Cells - combine stimulation from photoreceptors and transmit impulses to ganglion cells
Ganglion Cells - sensory neurons that are stimualted by bipolar cells, transmit impulses through optic nerve fibres
Nerve Fibres - combine to form optic nerve
Light goes from optic nerve to photoreceptors
Compare rod and cone cells
Rod Cells
- monochrome vision
- absorb all wavelengths
- high light sensitivity, see better in dim light
- high convergence as groups of 200 cells synapse to one bipolar cell
- high sensitivity at low light b/c bipolar cell stimulation by many rod cells makes action potential more likely
- wide distribution in retina (absent in fovea) so larger fov
Cone Cells
- colour vision
- absorb red, green, blue light via 3 different types
- low light sensitivity, required bright light to “fire” and see colour
- no convergence as each cell synapses with own bipolar cell
- high visual resolution b/c adjacent parts of image are detected by separate cells
- distribution in retina controlled in fovea so acute vision has small fov
Both are photoreceptors located in the retina
Explain the processing of visual stimuli, including edge enhancement and contralateral processing
Edge Enhancement
- lateral inhibition makes neighbourhood of dark object appear lighter and vice versa
- leads to better contrast near boundaries of light/dark; human eyes are good at processing information
- retina uses contrast rather than absolute light intensity to recognize objects
Contralateral Processing
- stimuli is processed on the opposite side of where it was detected
- Information from left half of visual field is detected by right half of retina + processed by right hemisphere; vice versa
- at optic chiasma, information from both eyes may swap so left/right visual field processed together
- impulses continue to the thalamus where the optical information is processed before an image forms in the visual cortex
Label a diagram of the ear
- pinna
- eardrum
- bones of the middle ear
- oval window
- round window
- semicircular canals
- auditory nerve
- cochlea
Explain how sound is perceived by the ear, including the roles of the eardrum, bones of the middle ear, oval and round windows, and the hair cells of the cochlea
Eardrum - vibrates with sound waves transmitted through air; rapidly toward/away from middle ear; transmits to inner ear
Bones of Middle Ear (ossicles) - transmit sound waves from eardrum to oval window; amplify sound
Oval and Round Windows (membranes) - oval window transmits sound waves to fluid in cochlea; fluid is incompressible and needs to vibrate freely; round window moves away from cochlea when oval moves toward
Hair Cells of Cochlea - receptors in membrane of cochlea tube contain hair bundles stretching from one membrane to other; detect sound waves passing through cochlea as vibrations move hair (cilia) bundles with different frequency which are interpreted by brain as different pitches; induce nervous impulses across synapses + via auditory nerve to brain (when vibrations detected)
Sound waves (compressed waves of air particles)
Vibration of oval window
Fluid movement within cochlea -> vibration of round window -> dissipation of energy (no sound perception), pressure is depleted
Vibration of basilar membrane (floor of cochlear duct)
Binding of cilia of receptor hair cells
Graded potential changed (receptor potential) in receptor cells
Changes in rate of actions potentials generated in auditory nerve
Propagation of action potentials to auditory cortex of brain
Sound is perceived by brain
Distinguish between innate and learned behaviour
Innate - develops independently of environmental context; from birth; all
Learned - develops as result of experience; not initially; only some
Design experiments to investigate innate behaviour in invertebrates, including either a taxis or kinesis
Taxis - change in movement in response to stimulus
eg. chemotaxis in Planaria
Kinesis - change in activity rate in response to stimulus
eg. hygrokinesis in Woodlice
Analyse data from invertebrate behaviour experiments in terms of the effect on chances of survival and reproduction
- Graph axes, then relationship
- Read description below
- Overall conclusion
Discuss how the process of learning can improve the chance of survival
- modifies/develops new behaviour patterns
- can improve chances of survival, particularly in diverse/changing environments
eg. chimpanzees learn to catch termites by poking sticks into mounds
eg. foxes avoid electric fences after being shocked
eg. hedgehogs learn to run across busy roads instead of curling up (Britain)
eg. birds avoid eating black/orange cinnebar moth caterpillar after tasting unpleasant
