coordination Flashcards
(27 cards)
what is a stimulus
a stimulus is a change in an animals surroundings
what is a response?
a reaction to a stimulus
example of stimulus and response
a ball being thrown - stimulus
movement to avoid the ball - response
what is a receptor organ?
detects the stimulus
what is an effector organ
your body responding to the stimulus (muscles moving)
order of stimulus and response chain
stimulus- receptor-coordination-effector-response
what is the role of receptors
to detect stimulus by changing its energy into the electrical energy of the nerve impulses.
receptor examples and type of energy received
eye (retina) - light
ear (organ of hearing) - sound
ear(organ of balance) -mechanical (kinetic)
tongue (taste buds) chemical
nose (organ of smell) - chemical
skin (touch/pressure/pain receptors)- mechanical (kinetic)
skin (temperature receptors)- heat
muscle (stretch receptors) -mechanical (kinetic)
what is the central nervous system
impulses from receptors pass along nerves containing sensory neurons until they reach the brain and spinal chord. These two organs together are the central nervous system
what do motor neurons do?
transmit impulses to the muscles and glands
difference between sensory neurons and motor neurons
sensory- carry impulses from the receptors to the brain and spinal chord
motor- transmit impulses to the muscles and glands
some nerves contain both or only one of these neurons
structure of an eye and function of the parts
sclera- tough outer coat of the eye- visible white part
cornea- at the front of the eye the sclera becomes a transparent window- lets light into the eye
iris- behind the cornea is the colored ring of tissue
pupil- in the middle of the iris a black whole that lets no light through- its black because there is no light escaping from the inside of the eye
choroid- underneath the sclera, dark layer because contains many pigment cells as well as blood vessels. The pigment stops light being reflected around the inside of the eye
retina- innermost layer of the back of the eye- light energy converted into electrical impluses
what happens in the retina?
the retina contains receptor cells called rods and cones.
These cells react to light and produce impulses in sensory neurons
the sensory neurons then pass these impulses to the brain through the optic nerve.
rod cells and cones functions
rod cells- work well in dim light but cant distinguish between different colors. Brain sees image produced by rods in black and white This why we cant see colors very well in the dark- only rods working properly
cones cells- only work in bright light.
Three types of cones which respond to different colors of light: red green and blue. We see all the colors because these three cones are stimulated to different degrees.
how do we form an image
to form an image on the retina, light needs to be refracted
refraction happens when light passes from one medium to another of a different density
in the eye this happens first at the air/cornea boundary and again at the lens.
cornea acts as first lens of the eye
as a result of refraction at the cornea and lens, the image on the retina is inverted. The brain interprets the image the right way up
the role of the iris
to control the amount of light entering the eye by changing the size of the pupil.
The iris contains 2 muscles:
circular muscles- form a ring shape in the iris
radial muscles- lie like the spokes of a wheel.
bright light dim light iris
bright light
1) circular muscles contract
2) radial muscles relax
3) pupil constricts
dim light
1) circular muscles relax
2) radial muscles contract
3) pupil dilates
what is the iris reflex
whenever our eyes look from a dim light to a bright light, the iris rapidly adjusts pupil size.
what is the blind spot?
area in retina where an image cant be formed- where the optic nerve leaves the eye- no rods or cones, called blind spot.
The brain can put images together of each eye cancelling out the blind spots of both eyes.
what is accommodation?
the changes that take place in the eye that allow us to see objects at different distances
how does accommodation work?
1) focusing on a distant object: ciliary muscles relax, suspensory ligaments pulled tight, lens ‘flat’
2) focusing on a nearby object: ciliary muscles contract, suspensory ligaments slack, lens more rounded
what does a reflex arc mean?
the pathway goes into the CNS and then straight back out again
describe the process of a reflex arc
stimulus detected by temperature or pain receptors in the skin
these generate impulses in sensory neurons
the impulses enter the CNS through a part of the spinal nerve called dorsal root
in the spinal chord, the sensory neurons connect by synapses with short relay neurons which in turn connect with motor neurons.
the motor neurons emerge from the spinal chord through the ventricle root and send impulses back out to muscles of the arm
these muscles contract pulling the arm away from harmful stimulus
how does our brain know about the reflexes
in the spinal chord, the reflex arc neurons also form connections called synapses with nerve cells leading to and from the brain, the brain receives info abt stimulus therefore how we fell pain
