Unit 3: Behaviour, Populations and environment

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Unit 3 Behaviour, Populations and environment
Higher Human Biology

• Chapter 26 Organisation of the nervous system

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• Learning Intentions

• Success Criteria

• To examine the workings of the brain and the
  nervous system.

• Define the terms
• Central nervous system
• Peripheral nervous system
• Somatic nervous system
• Autonomic nervous system

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The Nervous System
The nervous system is a network of specialised
cells that communicate information about an
individuals surroundings and itself. It
processes this information and causes reactions
in other parts of the body.

Image source www.drstandley.com
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Summary The Nervous System
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Structural Division The Nervous System
CNS (central nervous system)
PNS (peripheral nervous system)
Brain
Spinal Cord
Based on the structure and location of the
component parts, the nervous system can be
divided as shown in the diagram.
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Central Nervous System
Peripheral Nervous System

• Somatic some involuntary reflex actions, mostly
  voluntary actions
• Autonomic - involuntary actions

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Functional Division The Nervous System
PNS (peripheral nervous system) Crainial nerves
spinal nerves)
Autonomic (involuntary - muscles)
Somatic (mostly voluntary)
A further method of dividing up the nervous
system is based on different functions performed
by the two separate branches of the peripheral
nervous system as shown in the diagram
Parasympathetic
Sympathetic
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The Somatic Nervous System
The peripheral nervous system has 2 branches,
called the somatic and the autonomic nervous
systems. The somatic nervous system (including
spinal nerves) controls the skeletal muscles.
Most movements that it controls are voluntary but
it also controls certain involuntary reflex
actions (e.g. limb withdrawal).
C.N.S
STIMULUS
RESPONSE
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The Autonomic Nervous System
The autonomic nervous system (ANS) controls
involuntary responses to stimuli by the body, so
there is no conscious control, but under
exceptional some people can suppress certain
autonomic responses intentionally.
Autonomic nerves regulates the heart, blood
vessels, bronchial tubes, alimentary canal
sweat glands.
The nerves start at the nerve cells in the brain,
pass down the spinal cord then emerge at the
appropriate organ.
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Autonomic Nervous System
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Antagonistic nature of the Autonomic Nervous
System

• The sympathetic and parasympathetic systems which
  make up the autonomic nervous system are
  described as being antagonistic.
• i.e. They affect many of the same body structures
  but exert opposite effects on them.

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Parasympathetic v Sympathetic
ANTAGONISTIC have opposite effects
Homeostasis
Response to stress

• Tries to maintain a stable internal environment

• Flight or flight response

• Calms the body down after stress

• Helps body conserve resources store energy

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Harmonious Balance

• The autonomic nervous system is concerned with
  maintaining a stable internal environment by
  playing a part in homeostasis.
• The sympathetic and parasympathetic nervous
  systems are constantly working in an opposite but
  equal manner (neither wins).

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Fight or flight

• In response to a crisis the sympathetic system
  prepares the body for action and the expenditure
  of energy by
• Increasing heart rate and blood pressure.
• Diverting blood to skeletal muscle.
• Increasing perspiration.
• The hormone ADRENALINE helps to sustain this
  state till the emergency is over.

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Calming Down

• When the crisis is over, the parasympathetic
  system briefly takes over by
• Returning heart rate and blood pressure to
  normal.
• Peristalsis in the digestive tract increases.
• Blood is diverted away from skeltal muscles and
  back to the intestine (allowing digestion to
  resume).
• THIS ALLOWS THE BODY TO STORE ENERGY AND CONSERVE
  RESOURCES.

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Task Torrance-TYK pg 215 Qus 1-4
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Task Torrance AYK pg215/216 Qus 1-4