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
Feb 23, 2016
Coordination and ResponseNervous 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
We think about this action/ We don’t think about this action
Coughing
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.
Which system is responsible for the detection?Which system is responsible for the coordination of responses ?
sensory
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.
Human Nervous SystemBrainProtected by?Spinal CordProtected by
CranialNerves connected in pairs to the brain
.
i
Spinal nerves connected in pairs to the spine
CNS
PNS 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• Voluntary responses are under the
control of our brains. For example;
Stimulus
Effector
Motor Neuron
Sensory
neuron
Receptor
Spinal Cord
.
Response
Coordinator
Transmits electrical impulses @ 1-120m/s
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!Receptor --> sensory neurone → CNS(relay neuron) → motor neurone → effector.
coordinator
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 For example;
Stimulus
Effector
Motor Neuron
e
Sensory neurone
Receptor
Spinal Cord
Transmits impulses
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 diagram1.Receptor - - - - - - - - - - - - - - - - - - -2. What are five senses in your body?
Control of a possible football situationRISU 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.
In a reflex action:
A reflex action is a fast, automatic response to a stimulus.
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 Arc1. Stimulus picked up by
Receptor cells in finger (skin)
2. Impulse passed on to sensory neuron
3. Sensory neuron passes impulse to spinal cord
4. Spinal cord sorts out response and send message to motor neuron
5. Motor neuron sends impulses to finger muscles to pull away
Relay neuron
effector
stimulus
Stimulus (change) picked up by receptor
Impulse carried along nerve cell (Sensory neurone) to spinal cord
Spinal cord or brain sorts out message
Impulse carried along nerve cell (motor neurone) to effector organ
Effector organ brings about a response
Arrange them in right order
1
2
3
4
5
Neurones
Objectives:*Describe and distinguish between three types of neuron**Describe the functioning of these neurons in a reflex actionStarter:How many neurons are there? Name them.
Neurons •It carries information from the nervous system as electrical impulses.•These cell that carry this information are called nerve cells or neurones.
•This is a sensory neuron.•It carries information from the receptor to the CNS.
•This is a motor neuron.•It carries information from the CNS to the effector.
Nerve ending in a sense organ
Neurone ending in an effector(muscle or gland)
nucleus
(Insulation)
cytoplasm
in CNS
Relay neurons short pass on impulses from sensory to motor neuron located inside the CNS
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 12/05/11Complete the following table
STRUCTURE FUNCTIONMyelin sheath
Axon
Cell body
Dendrites
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.
In a reflex action:
A reflex action is a fast, automatic response to a stimulus.
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 waysStarter:Reflex actions are a…….., f… and usually p………
automaticfast protective
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/sleep/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!!!
NOTE : To work out the average you add all the result up, then divide by three…….EASY!!
Name Result 1 Result 2 Result 3 Average
Name Average reflex (cm)
PeaceYashKidusAmandaLairKatrinaBryanRachael
How else can we display our results?
Graph
0
Remember Title,
label axis,