Coordination Flashcards
What does a coordinated response require?
- Stimulus
- Receptor
- Coordination
- Receptor
- Effector
- Response
- Effector
What is at the base of the brain?
Pituitary gland (secrets a number of chemical ‘messengers’ called hormones into the blood) just below the hypothalamus
Name the receptor and type of energy transduced
eye (retina) - light ear (organ of hearing) - sound ear (organ of balance) - kinetic tongue (taste buds) - chemical nose (organ of smell) - chemical skin (touch/pressure/pain receptors) - kinetic skin (temperature receptors) - heat muscle (stretch receptors) - kinetic
What do receptors do?
- Receptors change the energy into electrical energy of the nerve impulses (transduction)
- All receptors are transducers of energy
Give an example of the system?
light intensity–>eye(retina)–>neurones–>iris muscles–>change pupil size
What can be a stimulus?
A change in the organisms surroundings
What is a receptor?
Specialised cells that detect stimuli
What does the coordination do?
Links the stimuli and the response
What is the effector?
An organ carrying out the action
What is the response?
The reaction to the change
What is in the central nervous system? (CNS)
The brain and the spinal cord and is linked to sense organs by nerves
Sensory neurones carry information to the CNS whereas the motor neurones carry information from the CNS
What happens when receptors detect a stimulus?
- When the receptors detect a stimulus they send electrical impulses along sensory neurones to the CNS
- The CNS then sends electrical impulses to the effectors along a motor neurone
- The effector then responds accordingly. The CNS coordinates the response
- Because neurones transmit information using high speed electrical impulses the nervous system is able to bring about a very rapid response
What are synapses?
Synapses are gaps between two nerve cells, electrical signals are converted into chemical signals back into electrical signals
What happens in a synapse?
- Electrical impulses arrive down the axon of the first neurone
- Neurotransmitters diffuse across the synapse
- Neurotransmitters attach to the membrane of the second neurone
- Electrical impulses start in the second neurone
- Neurotransmitters are broken down by an enzyme from the second neurone after it has ‘passed on the message’
Other chemicals such as drugs may imitate neurotransmitters or block its action for good or bad.
What is a reflex action?
- A rapid involuntary response to a stimulus, the purpose is often to protect the body
- They are not started by impulses from the brain, but you are still aware (you feel pain). A voluntary action is under conscious control
What are examples of involuntary actions?
- Knee jerk
- Pupil reflex
- Hot surface
- Balancing and catching ones self
Describe a reflex arc
- Stimulus is detected by temperature or pain receptors in the skin
- These generate impulses in sensory neurones
- The impulses enter the CNS through a part of the spinal nerve called the dorsal root
- In the spinal cord the sensory neurone connects with the short relay neurones by synapses. The short relay neurones are connected with the motor neurones by synapses
- The motor neurones then emerge from the spinal cord through the ventral root, and send impulses back out tot he muscles of the arm which will contract pulling the arm (and thus the finger) away from the harmful stimulus
Describe the sclera
- Description: tough white outer coat
- Function: protection to inner parts of the eye and allows movement of the eye
Describe the conjunctiva
- Description: semi-transparent membrane
- Function: lubricates and protects the surface of the eye
Describe the choroid
- Description: thin vascular layer
- Function: the darkness of it prevents light from being reflected around the inside of the eye, by absorbing excess light
Describe the cornea
- Description: dome, outer covering of the eye, no blood vessels and is transparent
- Function: refracts light and protects the inner parts of the eye with several layers and oxygen diffuses in
Describe the pupil
- Description: opening in the centre of the eye
- Function: allows light in
Describe the iris
- Description: coloured part of eye in front of the lens
- Function: controls the amount of light entering the eye and so protects the eye from to much sunlight
Describe the lens
-Function: focuses light onto the retina
Describe the ciliary muscles
- Description: circular muscles that can relax of tighten the zonules (fibres that hold the lens suspended in position)
- Function: Helps change the lens shape in accommodation
Describe the suspensory ligaments
-Function: holds lens in place
Describe the retina
- Description: light sensitive layer that contains rods and cones
- Function: traduces light energy into electrical energy of nerve impulses
Describe the fovea
- Description: Highest concentrations of cones
- Function: allows us to have sharp vision, especially if the image is right in front as the image then focuses on the fovea
Describe the optic nerve
-Description and Function: bundle of sensory neurones that carry impulses to the brain
Describe what happens as light enters the eye
- Light enters the conjunctiva
- Light passes through the cornea where it is refracted a bit
- Light travels through the aqueous humour and the pupil
- When the light reaches the lens it is refracted even more
- The light then travels through the vitreous humour
- The light is then focused onto the retina
- The light sensitive cells traduce the light energy into electrical impulses
- These impulses travel through and along the optic nerve
- It is then interpreted by the brain
* Image on the retina is inverted but it is turned around it the brain and left to right
Describe the rod cells
- They are packed most tightly around the edge of the retina
- Provide black and white images
- They give greater sensitivity at low light intensity (night)
Describe the cone cells
- They are packed most tightly around the centre of the retina
- There are three types: red, green and blue
- Work under high light intensity
- Objects are seen most clearly during daylight, by looking directly at them
Describe the iris reflex in bright light
-Pupil constricts
-Radial muscles relax
-Circular muscles contract
This allows less light in
Describe the iris reflex in dim light
-Pupil dilates
-Radial muscles contract
-Circular muscles relax
This allows more light in
What is the blind spot?
Where the optic nerve meets and connects to the brain
What is accommodation?
Changes that take place in the eye which allow us to see objects at different distances
Describe accommodation for distant objects
- Ciliary muscles relax
- Suspensory ligaments contract
- Lens is flat (allows more refraction)
Describe accommodation for nearby objects
- Ciliary muscles contract
- Suspensory ligaments relax
- Lens is convex (allows less refraction)
What happens if you are long sighted?
- Your cornea or lens doesn’t bend enough
- Your eyeball may be too short
- Therefore nearby objects are brought into focus behind the retina
What happens if you are short sighted?
- Your cornea or lens bends too much
- You eyeball may be too long
- Therefore images of distant objects are brought into focus in front of the retina
What happens in the CNS?
The stimulation of receptors in the sense organs sends electrical impulses along nerves into and out of the central nervous system, resulting in rapid responses
