Explain how Jessica heard the sound of a dog growling and was able to respond rapidly to the
touch of its nose on her leg.
HEARING
When the person hears the sound of a dog growling,
The pinna traps and directs the sound waves into the auditory canal
The sound waves strike the tympanic membrane (eardrum) and
cause it to vibrate,
The vibrating membrane causes the ossicles
to vibrate
This sets up waves in the perilymph and endolymph
The organ of Corti in the cochlea becomes stimulated
The stimulus is converted to a nerve impulse
The nerve impulse is carried by the auditory nerve to the cerebrum where
the sound is Interpreted
The pressure in the cochlea is then eased out though the round window
Into the Eustachian tube.
REFLEX ACTION
Reflex action may be defined as rapid,
automatic response to a stimulus received
by an organ, in this case, the leg
When the dogs nose touches the leg
Receptors in the skin receive the stimulus
The stimulus is converted into a nerve impulse
The Impulse travels along the sensory neuron
Towards the spinal cord along the dorsal root
of the spinal nerve
In the spinal cord, the sensory neuron
makes synaptic contact with the connector neuron
and then the impulses are transmitted
along the motor neuron along the ventral
root of the spinal nerve to the effector
organ/muscle which contracts and pulls the leg away
touch of its nose on her leg.
HEARING
When the person hears the sound of a dog growling,
The pinna traps and directs the sound waves into the auditory canal
The sound waves strike the tympanic membrane (eardrum) and
cause it to vibrate,
The vibrating membrane causes the ossicles
to vibrate
This sets up waves in the perilymph and endolymph
The organ of Corti in the cochlea becomes stimulated
The stimulus is converted to a nerve impulse
The nerve impulse is carried by the auditory nerve to the cerebrum where
the sound is Interpreted
The pressure in the cochlea is then eased out though the round window
Into the Eustachian tube.
REFLEX ACTION
Reflex action may be defined as rapid,
automatic response to a stimulus received
by an organ, in this case, the leg
When the dogs nose touches the leg
Receptors in the skin receive the stimulus
The stimulus is converted into a nerve impulse
The Impulse travels along the sensory neuron
Towards the spinal cord along the dorsal root
of the spinal nerve
In the spinal cord, the sensory neuron
makes synaptic contact with the connector neuron
and then the impulses are transmitted
along the motor neuron along the ventral
root of the spinal nerve to the effector
organ/muscle which contracts and pulls the leg away
