the nervous system Flashcards
(22 cards)
What is the spinal cord?
A long column of neurons that run from the base of the brain down to the spine at several places down the cord, neurons branch off and connect with the other parts of the body.
Function of the spinal cord
The spinal cord relays information between the brain and the rest of the body.
How does the CNS coordinate a response?
The sense organs contain receptors which detect a stimulus. This information is converted to an electrical impulse and sent along the sensory neurons to the CNS which then coordinates a response and the impulses travel along the motor neurons to the effector which responds for example by contracting a muscle.
what do the receptors eyes ear tongue and skin detect?
Light
sound
chemicals
touch and temperature change
what is your reaction time and what can speed this up
Time taken to respond to a stimulus and caffeine
steps to measure the reaction time after caffeine consumption
1) The person being tested should sit with their arm resting on the edge of a table
2) Holding a ruler vertically between that thumb and four finger and ensure that the zero end of the ruler is level with that thumb and finger and let go without warning
3) The person should try to catch it as quickly as they can
4) Reaction time is measured by the number on the ruler where it’s caught
5) Repeat the test several times and calculate the main distance that the ruler fell
6) Repeat steps 1 - 5, 10 minutes after the person being tested has had a caffeinated drink
what is the control variable to ensure that the reaction time caffeine test is fair?
Using the same person and same hand to catch the ruler
Ruler should be dropped from the same height every time Ensure that the person tested has not had any caffeine before the start of the experiment
what is a synapse and what occurs there
The junction between two neurons
The nerve impulse is transferred by chemicals which diffuse across the gap the chemicals then set off a new electrical signal to the next neurone
why will the transmission of a nervous impulse slowdown at the synapse?
As diffusion of chemicals across the gap takes time
what are the three characteristics of reflexes and what do they reduce the chances of and give an example?
Automatic and rapid response responses to the stimuli
They can be protective which reduce chances of injury
An example is the withdrawal reflex arc in response to a pain stimulus like moving a hand away from a bee after it stings
What happens in the reflex arc?
When a stimulus is detected by receptors impulses are sent along the sensory neuron to the relay neuron in the CNS
what happens when the impulses reach a synapse between the sensory neuron and relay neuron and the relay neurone and motor neuron in the reflex arcn
They trigger its chemicals to be released which cause impulses to be sent along the relay neuron under the same thing happens from the relay to the
motor neuron
what is the sclera
The white tough out of coats that covers unprotects the eye
What is the cornea?
The transparent part of the sclera at the front of the eye which refract light through the pupil
what is the iris?
The coloured part of the eye which contains muscles that allow it to control the size of the pupil and how much light and the eye
what does the lens do
Changes shape to focus the light onto the retina
what is the retina and what does it do?
A light sensitive layer which has receptor cells that detect light intensity and colour
what does the optic nerve do?
Carries impulses from the retina to the brain the brain then uses this information to form an image
what is the choroid?
A pigmented layer which absorbs light to prevent reflection and contains blood vessels to supply the retina with oxygen and nutrients
What is the blindspot?
The points where the retina is attached to the optic nerve where there are no light sensitive cells so light can’t be detected
example of a protective reflex
blinking
