Coordination and Response
Nervous control in Humans
*Describe the structure of the nervous
system
**Distinguish between voluntary and
involuntary actions
Homework:
Revise Homeostasis and Excretion for test on 3/5/11
Blinking
We think about this action/ We don’t think about this action
Coughing
We think about this action/ We don’t think about this action
Kicking
We think about this action/ We don’t think about this action
Pupils changing size
We think about this action/ We don’t think about this action
All living organisms are sensitive to changes in their environment. The
changes they detect are called stimuli. E.g. ?
The cells that detect these changes are called receptors. E.g.?
The responses are brought about by muscles and glands because of a stimuli
and they are called effectors.
sensory
Which system is responsible for the detection?
Which system is responsible for the coordination of responses ?
nervous
Match the words with the definitions
Stimulus
The part of a control system that brings
about a change to the system
Effector
Action or behaviour that is caused by a
stimulus.
Response
A change in the environment that
causes a response.
Receptor
The part of a control system that
detects changes in the system and
passes this information to the
processing centre.
CNS
Brain
Protected
by?
Spinal
Cord
Protected
by
Human Nervous System
Cranial
Nerves
connected in
pairs to the
brain
PNS
Spinal nerves
connected in
pairs to the
spine
i
The nerves are
made up of
specialised cells
called neurons
Cranial nerves link
the brain to all
organs in the head
and some organs of
the abdomen and
thorax
.
Spinal nerves link
brain to legs ,arms ,
thorax and
abdomen
Voluntary Response
.
Effector
• Voluntary responses are under the control
of our brains.
Response
For example;
Motor
Neuron
Stimulus
Coordinator
Receptor
Transmits electrical
impulses @ 1120m/s
Sensory
neuron
Spinal
Cord
Some facts

Bundles of neurons are called nerves.
The neurons joining the sensory and the
motor neurons are called relay neurons

Effectors are muscles or glands.

Putting it all together!
coordinator
Receptor --> sensory neurone → CNS(relay neuron) → motor neurone → effector.
Write one more examples of voluntary action.
In the last example who was the receptor and who was
the effector?
Involuntary Response or Reflex Action
• What is an involuntary response?
• What do you think will happens to the
man’s hand?
•
http://www.bbc.co.uk/schools/gcsebitesize/science/ocr_gateway/ourselves/3_keeping_in_touch6.shtml
Involuntary Response or Reflex Action
• An involuntary response bypasses the
brain to give a fast response to a
stimulus.
• This helps protect the body from harm.
Involuntary Response
Effector
For example;
Motor
Neurone
Stimulus
Receptor
Transmits impulses
Sensory
neurone
Spinal
Cord
Give one more examples of reflex action.
Draw one of your examples from both voluntary
and involuntary actions as a flow diagram.
Sense Organs and Reflex Arcs
Objectives:
*Define sense organs
** Describe their functioning in a reflex action
Starter: Complete the flow diagram
1.Receptor
-----------------2. What are five senses in your body?
Control of a possible football situation
RISU are trailing 1-0 to ISU in the final of the Rainbow Cup. All of a
sudden (student A) pulls up with a suspected torn hamstring. (Student B)
spots this and immediately sends a message to Mr Colley what happens.
Mr Colley makes a decision. He decides to replace (student A) with
(Student C). Student C went on to score a hat trick.
Final Score RISU 3 ISU 4
In terms of response:
1.What kind of response is this?
2. What was the stimulus?
3. What was the effector?
4. What was the response?
Nervous system
Parts of our body we use to sense things are called
SENSE ORGANS – eye, ear, mouth, skin, nose.
Each SENSE ORGAN has special cells called RECEPTOR
CELLS. Each receptor cell is sensitive to different
things.
SENSE ORGANS are a group of receptor cells that
respond to a particular stimuli
Senses
• Receptors in eye sensitive to light
• Receptors in ear and sensitive to sound
• Receptors on tongue and sensitive to
chemicals
• Receptors in nose and sensitive to chemicals
• Receptors in the skin and sensitive to touch,
pressure, pain, temperature
Reflex actions
•
•
•
•
•
The tap on the knee in the knee jerk
test is a stimulus.
Its detected by receptors in the thigh
muscle connected to your knees.
The receptor sends signals to your
spinal cord.
The spinal cord sends nerve impulses
to your leg muscles.
The leg muscles respond by
contracting which pulls your lower leg
upwards.
A reflex action is a fast, automatic
response to a stimulus.
In a reflex action:
A receptor detects a stimulus.
The receptor sends an electrical
impulse along a sensory neuron
These impulses are sent to the
CNS.
The CNS sends an electrical
impulse along a motor neuron to
an effector.
The effector responds to the
stimulus.
Reflex Arc
1. Stimulus picked up by
Receptor cells in finger
(skin)
stimulus
Relay neuron
2. Impulse passed on to
sensory neuron
3. Sensory neuron passes
impulse to spinal cord
effector
4. Spinal cord sorts out
response and send
message to motor neuron
5. Motor neuron sends
impulses to finger muscles
to pull away
3
4
Spinal cord or brain sorts out message
Impulse carried along nerve cell (motor neurone) to
effector organ
5
1
2
Effector organ brings about a response
Stimulus (change) picked up by receptor
Impulse carried along nerve cell (Sensory neurone) to spinal cord
Arrange them in right order
Neurones
Objectives:
*Describe and distinguish between three types
of neuron
**Describe the functioning of these neurons in a
reflex action
Starter:
How many neurons are there? Name them.
Relay neurons short pass on
impulses from sensory to motor
neuron located inside the CNS
Neurons
•It carries information from the nervous system as electrical impulses.
•These cell that carry this information are called nerve cells or neurones.
Nerve ending in a
sense organ
cytoplasm
nucleus
(Insulation)
•This is a sensory neuron.
•It carries information from the receptor to the CNS.
in CNS
•This is a motor neuron.
•It carries information from the CNS to the effector.
Neurone ending in
an effector(muscle
or gland)
The Structure of the Neuron
• Cell body contains nucleus cytoplasm and nerve
fibres
• Fibres carrying impulses away from cell body are
Axons
• Fibres carrying impulses towards cell body are
Dendrons with smaller Dendrites extending from
cell body
• The Myelin Sheath is a thick insulating material (fat)
that encloses the axon. It enables fast conduction of
impulses up to 100m/s
• to fast transmission)
•The neurones do not touch each other. The gap between them is called
synapse
•Impulse arrives at a synapse in a particular direction
•Chemical molecules released by the sensory neuron diffuses across and fits
on to the receptor molecules on the membrane of the motor neuron
•Nerve impulse passes from sensory neuron to motor neuron
•The chemical is absorbed back in the sensory neuron
•Since chemicals are produced on one side impulses travel in only one
direction
•Many drugs produce their effects by acting at synapses
Some facts:
Synapses are 20 nm wide and
slows down the speed of your
impulse by 15m/s
Homework: due 12/05/11
Complete the following table
STRUCTURE
Myelin sheath
Axon
Cell body
Dendrites
FUNCTION
Reflex actions
•
•
•
•
•
The tap on the knee in the knee jerk
test is a stimulus.
Its detected by receptors in the thigh
muscle connected to your knees.
The receptor sends signals to your
spinal cord.
The spinal cord sends nerve impulses
to your leg muscles.
The leg muscles respond by
contracting which pulls your lower leg
upwards.
A reflex action is a fast, automatic
response to a stimulus.
In a reflex action:
A receptor detects a stimulus.
The receptor sends an electrical
impulse along a sensory neurone
These impulses are sent to the
CNS.
The CNS sends an electrical
impulse along a motor neurone to
an effector.
The effector responds to the
stimulus.
Reflexes and Reaction time
Objectives:
*Explain the importance of reflex action in the
body
** Calculate reaction time
*** Represent data in different ways
Starter:
fast
protective
automatic
Reflex actions are a…….., f… and usually p………
Reaction time
The time between a stimulus and a response
Eg. If someone is driving and they see a cow in
the middle of the road. Their reaction time is
the time taken to see the cow (stimulus) and
to press the brake (response).
Reaction time: Practical
http://www.bbc.co.uk/science/humanbody/sle
ep/sheep/
How fast are your reflexes??
• How can we measure our reflexes?
Practical experiment….Using a ruler
1.Using a ruler you have to see how quickly you can catch it.
2. Each person will try three times and record their results in a
table
3. We will then collect the class data and find out who has the
fastest reflexes!!!
Name
Result 1
Result 2
Result 3
Average
NOTE : To work out the average you add all the
result up, then divide by three…….EASY!!
Name
Peace
Yash
Kidus
Amanda
Lair
Katrina
Bryan
Rachael
Average
reflex (cm)
How else can we display
our results?
Graph
Remember
Title,
label axis,
0