central nervous system
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Central Nervous System. National 4 & 5: Multicellular Organisms. M ulticellular organisms are made up of many different tissues and organs Cells do not work independently, so they communicate with each other Also, different tissues and organs need to communicate with each other - PowerPoint PPT PresentationTRANSCRIPT
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Central Nervous System
National 4 & 5:Multicellular Organisms
Multicellular organisms are made up of many different tissues and organs
Cells do not work independently, so they communicate with each other
Also, different tissues and organs need to communicate with each other
Communication is usually carried out in 2 ways:
- hormones - nerve signals
Internal Communication
Identify the discrete areas of the brain and understand their functions
Identify the different typed of nerves/neurones in the human body
Examine the role of each type of nerve/neurone
Explain how a reflex action works, and identify examples of this
Examine how information is passed from one neurone to another
Learning Outcomes
What is the nervous system composed of? The nervous system is composed of: - the brain - the spinal cord - nerves
Cerebrum - conscious
thought, reasoning, imagination
Cerebellum- balance and co-ordination
Medulla (brain stem)- heart rate and breathing rate
The Brain
The brain is approximately 75% water It weighs about 3 pounds, BUT uses between 20%-25% of
your energy supplies each day Your brain can survive without oxygen for 4-6 minutes
before it starts to die There are over 100, 000 miles of blood vessels in your brain There are over 100 billion neurons in your brain
It’s not true that humans only use 10% of their brains; each part of the brain has a purpose
The slowest speed information passes around your brain is approximately 260 mph
The number of internal thought pathways that your brain is capable of producing is one followed by 10.5 million kilometers of standard typewritten zero’s!
Brain facts
Stimulus (change) picked up by receptor
Impulse carried along nerve cell (Sensory neurone) to spinal cord
CNS processes info & sends a response
Impulse carried along nerve cell (motor neurone) to effector organ
Effector organ brings about a response
Central Nervous System (CNS)Consists of the brain and spinal cord
1)
2)
3)
4)
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Receptors are found all over the body, often as part of sense organs
E.g. eyes, ears, skin They work in response to a stimulus The more receptors, the more sensitive an
area usually is to a stimulus
Effectors are also found all over the body They act in response to the CNS The more effector cells are in a body part,
the more it can move or the faster it can act
Effectors are often either muscles or glands - muscles respond rapidly - glands respond more gradually
Receptors and effectors
Sense Stimulus Sense organSight light eyes
Sight
Sense Stimulus Sense organSmell chemicals nose
Smell
Sense Stimulus Sense organTemperature heat / cold skinPain damage skinPressure force skinTouch contact skin
Skin
Hearing/balance
Sense Stimulus Sense organHearing sound earsBalance movement
/ positionpart of inner
ear
Sense Stimulus Sense organTaste chemicals tongue and
throat
Taste
The Reflex Arc A reflex is a rapid, unconscious response to a stimulus e.g. blinking, pulling a hand off a hot surface
Relay neurone
motor neurone
sensory neurone
• Receptor cells send an impulse along the sensory neurone to the CNS
• The relay neurone transfers the impulse to the motor nerve
• The motor neurone transfers the impulse to the effector cells, to carry out the response
What happens in a goalie’s body as he tries to save a goal?
The greatest goals of all time
What happens in a goalie’s body as he tries to save a goal?
Mark each other’s work:
1 point if they have used any of these words:Eye(s) Brain
2 Points:Nerve(s) Muscle(s)
3 Points:Neurone(s) Receptor(s) Spinal cord
4 Points:Motor (neurone) Sensory (neurone)
Use your judgement – any other scientific words that they have used correctly that should get points?
You have been given a series of cards for a series of reflex actions
You must arrange them under the following headings
Reflex responses
Stimulus
Receptor
Response Co-ordinator
Effector Response
How fast are your reflexes??
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
Name Result 1 Result 2 Result 3 Average
Name Average reflex (cm) Graph
0
Remember Title,
label axis,
Pupil Name
Aver
age
refle
x (c
m)
Information is carried through the CNS by a series of neurones
Information is picked up by a neurone through a dendrite Then it is passed to the cell body It then gets passed towards the next neurone by an axon
fibre
Transfer of information along neurones
Structure of a synapse• Between each
neurone is a small gap called a synapse
• To pass information between neurones, a chemical passes across this synapse
• These chemicals are called neurotransmitters
Re-Cap
1. What is meant by the term reflex action?2. Give an example of a reflex action.3. What is the function of the sensory nerve?4. What part of the brain controls our breathing rate?5. What part of the brain controls our balance?6. What part of the brain is responsible for our memory?