AIMS
1. Review the Peripheral Nervous System
2. Review The Somatic Nervous System
3. Introduce an understanding of the Autonomic Nervous System
 Sympathetic Nervous System
 Parasympathetic Nervous System
NERVOUS SYSTEM
Peripheral
•
Somatic NS
•
Sensory neurons
•
Moto neurons
•
Neurotransmitters
Central NS
includes the brain
and the spine
Peripheral NS
includes
everything outside
of the CNS
THE NERVOUS SYSTEM
Central Nervous
System
Brain
Spine
Peripheral Nervous
System
Somatic Nervous
System
Autonomic Nervous
System
Sensory
function
Motor function
Sympathetic
Nervous System
Parasympathetic
Nervous System
CNS & PNS – HOW ARE THEY RELATED?
The role of the CNS is to integrate and
coordinate all incoming neural information
and to initiate messages sent to different
parts of the body.
The PNS is the complete network of neurons
located outside the CNS.
FUNCTIONS OF THE PNS
There are two main functions of the PNS
1.
To carry information from the sensory organs and internal organs to the CNS
2.
To carry information from the CNS to the muscles, organs and glands.
Messages can only travel in one direction along the neurons. That is sensory
neurons carry information to the brain and motor neurons carry information
from the brain.
PERIPHERAL NERVOUS SYSTEM
The peripheral nervous system (PNS)
is a network of nerves located
outside the central nervous
system (CNS)
How does the CNS rely on the PNS?
How does the PNS rely on the CNS?
SOMATIC
SYSTEM
The PNS is divided into two subdivisions,
theNERVOUS
somatic nervous
system and the autonomic nervous system.
Somatic nervous system
Responsible for
initiating movement
of the skeletal
muscles.
Sometimes the somatic nervous
system is referred to as the
skeletal nervous system.
Neurotransmitters relay
messages from the neuron to
the muscle, causing it to
expand or contract. They also
relay messages from sensory
receptors to the CNS, allowing
us to feel sensations like heat
or pain.
THE SOMATIC NERVOUS SYSTEM
The word soma means body!
Motor information from the brain
Voluntary movement
Sensory information to the brain
Sense data from skin, body etc.
Afferent – to the brain
Efferent – from the brain
Sensory nerves are afferent, motor nerves are efferent
(Look at the handout from yesterday, how do we remember aff and eff?)
Neural pathways
Messages can only travel in one direction along a neuron. Three different neurons make
up neural pathways to make sure messages reach all parts of the body.
Explain the function of the
sensory neuron on the left
and the motor neuron on
the right.
Neural pathways
Messages can only travel in one direction along a neuron. Three different neurons make
up neural pathways to make sure messages reach all parts of the body.
Explain the function of the
sensory neuron on the left
and the motor neuron on
the right.
Neural pathways
Interneurons create connections
between sensory and motor neurons,
and relay messages from one type of
neuron to another type of neuron. They
exist only in the central nervous system
(brain and spinal cord).
In this scenario, you would
automatically withdraw your
hand before any intervention
from the brain.
THE SOMATIC NERVOUS SYSTEM
The somatic nervous system is also known as the skeletal nervous system (make sure you are
aware of this).
It has both a sensory and motor function:
 It transmits messages to the senses (sensory receptors eg ears, eyes) to the CNS eg hearing
an alarm go off
 It controls voluntary movement of the skeletal muscles (those attached to the
skeleton/bones) via messages sent from the CNS (most likely from the motor cortex. Eg
turning your head to work out wear the alarm is coming from)
THE SNS
Neural impulses from the CNS are carried along the motor neurons
of the somatic nervous system to the muscles causing them to
contract or expand resulting in the required movement.
The nerves of the SNS DO NOT operate on the non skeletal muscles
such as the heart, stomach of intestines.
THE SNS & PARAPLEGIA/QUADRAPLEGIA
If the spinal cord is severed, the somatic nervous system, below the
point of severance, becomes paralysed because the messages
between the CNS and PNS cannot connect.
Such damage is permanent because the nerves in the spinal cord
do not regenerate.
The higher up the damage is to the spinal cord the more extensive
the paralysis.
GLOSSARY OF TERMS
Individually find the definitions for:
•
Pg.274 Autonomic Nervous System
•
Pg.274 Visceral Muscles
•
Pg.274 Biofeedback
•
Pg.276 Sympathetic Nervous System
•
Pg.278 Parasympathetic Nervous System
•
Pg.278 Homeostasis
You have 8 minutes…….
THE AUTONOMIC NERVOUS SYSTEM
• The ANS is a network of neurons that connect the CNS to all the
body’s internal, non-skeletal muscles and organs (eg heart,
stomach, liver) and to the body’s many glands (sweat, saliva,
adrenal glands).
• Most of the actions controlled by the ANS occur automatically,
without our conscious control. Eg heart beat, digestion.
ANS
• Although influenced by the CNS, the ANS appears to work
independently in a self-regulating way
• It functions continuously whether you are awake, asleep, under
anaesthetic or in a coma
• It may be the only part of the nervous system keeping a person
alive after all other parts of the CNS have shut down.
THE ANS
The ANS is then subdivided into:
 Sympathetic Nervous System
 Parasympathetic Nervous System
THE AUTONOMIC NERVOUS SYSTEM
Connected to internal organs, not consciously controlled. Keeps us alive – automatically.
Sympathetic branch controls arousal, fight or flight response / fires us up. Release of
adrenaline, heart up, breathing up etc.
Parasympathetic calms back down, keeps at stable level. Digestion resting etc.
THE AUTONOMIC NERVOUS SYSTEM
•
Autonomic Nervous System
•
Self regulation vs voluntary control
•
Visceral muscles
•
Biofeedback
Remember that the autonomous
ANS likes to regulate your body
even when you are asleep.
LIVING WHILE BRAIN DEAD… THANKS TO THE PNS
•
Carol Ann Quinlan
•
April 1975 became unconscious after coming
home from a party
•
Consumed sedatives and alcohol
•
stopped breathing twice for 15 minutes or
more
•
Went into a persistent vegetative state
•
Kept alive on a ventilator for several months
•
Removed from mechanical ventilation during
1976
•
Persistent vegetative state for almost a
decade until her death from pneumonia in
1985.
Autonomic branch of the ANS kept her ‘alive’
DIVISIONS OF THE ANS
•
Sympathetic NS
•
Parasympathetic NS
•
While the sympathetic and parasympathetic nervous systems are both active at
the same time, one system usually dominates at any given time.
THE SYMPATHETIC NERVOUS SYSTEM
• The SympNS is responsible for activating internal muscles,
organs and glands at times of vigorous activity, stress or
threat.
• Some physiological functions will be heightened (eg.
Increase heart rate) and others will be lowered (eg
digestion) in order to redirect oxygen and blood flow to
where it is needed.
• That is, it provides the body with energy to deal with the
situation and enhance survival.
• http://www.youtube.com/watch?v=we9_CdNPuJg
THE ACTIVITIES OF THE SYMPNS
• Pupils dilate (expand)
• Decrease salivation (related to digestion)
• Heart rate increases
• Increase release of glucose (from the liver)
• Inhibition of release of bile (gall bladder)
• Adrenal glands – stimulates hormone secretion resulting in
increased heart rate, blood pressure, breathing rate.
• Genitals – excites
• Sweat Glands – increases production of perspiration
THE SYMPATHETIC NERVOUS SYSTEM
•
Sympathetic NS role
•
Organs
•
Glands
•
Adrenaline & Noradrenaline
In pairs come up with examples of the SNS at work with organs/glands.
THE PARASYMPATHETIC NERVOUS SYSTEM
The Parasympathetic nervous system generally counterbalances the
effects of the sympathetic nervous system.
It has two main functions
 At times of minimal stress or threat it helps maintain a constant
internal body environment (homeostasis)
 It restores the body to a state of calm, once the need for activity
initiated by the sympathetic nervous system has ceased. Meaning
it helps conserve energy.
THE ACTIVITIES OF THE PARASYMPATHETIC NERVOUS
SYSTEM
•
Pupils – contract
•
Salivation – increase
•
Heart rate – slows
•
Digestion – increases
•
Glucose release from Liver – decrease
•
Bile released from gall bladder – stimulated
•
Adrenal Glands – inhibits hormone secretion
•
Bladder – increase
•
Genitals – relax
•
Sweat Glands – decrease production of persperation.
THE PARASYMPATHETIC NERVOUS SYSTEM
•
Parasympathetic NS role
•
Homeostasis
Draw out table pg.278 including pupils, glands, heart, stomach, liver etc
AUTONOMIC NERVOUS SYSTEM FUNCTIONS
FIGHT OR FLIGHT
•
It is sympathetic arousal!
•
In response to a real or imagined threat
•
Physical or psychological danger
STRESS & AROUSAL – THE FIGHT OF FLIGHT
RESPONSE
• Arousal – the overall
alertness and activation
of the individual.
• Without us actually
being conscious of it,
our body responds to
perceived threats
automatically.
• This is caused by
activating our fight/flight
response
FIGHT OR FLIGHT
The fight or flight response is response that occurs automatically
resulting in a state of physiological arousal that prepares our
body to either deal with the perceived threat (fight ) or to run
away to maintain safety (flight).
FIGHT OR FLIGHT
Some individuals are programmed to fight and some are
programmed to run away. Usually it depends on two main factors
 Genetics
 The specifics of the situation.
Example – Chickens will run if they perceive danger they can escape
from, however if they perceive the situation as inescapable they
will crouch and freeze, hoping they won’t be harmed.
It is therefore considered to be adaptive.
FIGHT OR FLIGHT
It can be triggered by both perceived physical and psychological threat (eg
performance anxiety)
The sympathetic nervous system plays the greatest role in the fight/flight response.
 Explain how.
HOME STUDY
•
Write out definitions and add examples to any terms or concepts that you feel you
did not fully understand from today’s lesson.
•
Homework sheet
• Unit 3 SAC 1 = Wednesday 7th March 3pm-4.30pm
• Prepare for SAC by completing Psychbook activity 5 on
sleep study Oswald. It will be on Research Methods,
States of Consciousness and Sleep.
(Email Emi and Niusha this info)