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

http://photo.net/photo/pcd0865/rachel-mouth-8.4.jpg

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,