Date post: | 02-Jul-2015 |
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Science |
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HOMEOSTASIS & THE
NERVOUS SYSTEM
Objective
• F. Describe the structure of the brain, spinal cord, sensory
and motor neurons and sensory receptors and relate to
their function
• The brain is the control center of the body. The numerous
sections of the brain carry out specific tasks that function
in maintaining homeostasis.
• The nervous system is responsible for relaying messages
to/from the brain to the body.
Guiding Ideas
Question!
• Examine the diagrams below. Do you think this is a
survivable injury? Why or why not? Please explain.
Phineas Gage
THE BRAIN
External Features of the Brain
Cerebral Cortex
Cerebral
Cortex
Cerebral Cortex - The outermost layer of
gray matter making up the superficial
aspect of the cerebrum.
The Brain Stem
What does the light blue shaded region
refer to?
What does the green shaded organ refer
to?
Lobes of the Brain
Based on the diagram, damage to which of the
following lobes would result in hallucinations?
Based on the diagram, damage to which of the
following lobes would result in mood changes
and/or social differences?
Brain Cap Activity: Step 1
Step 2:
• Wear and share your caps!
NERVOUS SYSTEM
The Importance of the
Nervous System
• Communication system that contains 100 billion nerve cells in the brain alone
• Your nervous system is active all the time
• It gets information about the depth of your breathing, pressure on your skin, temperature, light, odours etc.
• It controls muscle movements such as blinking, scratching your nose.
• Memory and language are functions of the nervous system.
• Hormones require more time than nerves do
Vertebrate Nervous Systems
CNS PNS
• Consists of the nerves of the brain and spinal cord
• Coordinating Center for incoming/outgoing information
• Nerves that carry information between the organs of the body and the CNS
• Subdivided into: somatic and autonomic nerves
• Somatic nerves: skeletal muscle, bones and skin
• Autonomic nerves: special motor nerves that control internal organs of the body
• Autonomic nerves sympathetic and parasympathetic nervous system
The Types of Neurons
Neurons:
• Are the functional units of the nervous system.
• These specialized nerve cells are categorized into three groups:
1.The sensory neurons
2.Interneurons
3.Motor Neurons
1. Sensory Neurons (afferent neurons)
• Sense and relay information (stimuli) from the
environment to the CNS for processing• Example: photoreceptors, chemoreceptors and
thermoreceptors
2. Interneurons
• Link neurons within the body
• Predominantly located in the brain and spinal cord
• Integrate and interpret sensory information and connect neurons to outgoing motor neurons
3. Motor Neurons (efferent neurons)
• Relay information to the effectors
• Effectors include muscles, organs and glands because they produce responses
Let’s suppose you touch a hot stove…
1. Heat is detected by temperature receptors in the skin
2. A nerve impulse is carried to your spinal cord
3. Sensory neuron interneuron motor neuron
4. Motor neuron causes the hand to contract and pull away from the stove
5. All this happens in less than 1 second, before information travels to your brain
Neural Circuits: Reflex Arc
• Reflexes are involuntary and often unconscious
• The simplest nerve pathway is the reflex arc
• Most reflexes occur without brain coordination
• Reflex arcs contain 5 essential components:
1.Receptor
2.Sensory Neuron
3.Interneuron in the spinal cord
4.The motor neuron
5.Effector
Sequence of Events1. Stimulus causes signal in
sensory receptors
2. Message travels along sensory
neuron
3. Message reaches interneuron
4. Message goes to brain
5. Message travels in the motor
neuron
6. Message causes response
(muscle to contract)
Test your reflexes!!
• http://reflextest.net/
• Extra practice and review
• http://www.bbc.co.uk/schools/gcsebitesize/science/aqa/ne
rvesandhormones/thenervoussystemact.shtml