13. Coordination and response
13.1 coordination in animals
Terms in coordination system
o Changes in an organism’s environment that can be detected by sense
organs are called stimuli
o The stimuli are sensed by specialized cells called receptors
o The organism respond using effectors
o Muscles and glands are effectors
o The way in which receptors pick up stimuli and then pass information
on to effectors is called coordination
Animals need fast and efficient communication systems between their
receptors and effectors to be able to:
o respond very quickly
o catch food avoid predators
Methods of sending information from receptors to effectors
o Nerves system
Faster
o Endocrine system “hormones”
Slower
13.2 The human nervous system
Neurons
o Human nervous system is made up of specialized cells called neurons
o Neuron is a nerve cell specialized for the rapid transfer of electrical
impulses
o Neurons have normal cell parts
Cell membrane
Nucleus
Cytoplasm
o Neurons structure is adapted for their job
They have long thin fibers of cytoplasm stretching from the cell
body
, The longest fiber is called axon “it can stretch for
meters”
The shorter one is called dendrons/dendrites
Nerve impulses
Dendrites pick up electrical signals from other neurons
lying nearby
electrical signals sweeps along a neuron are called
nerve impulses
The signals pass to the cell body then the axon which
might pass to another neuron
Myelin
Myelin is a fatty substance surrounding the axons of
many neurons , enabling the nerve impulses to travel
faster
Myelin insulates the nerves fibers so they can carry
these impulses much faster
, The central nervous system
o All mammals have central nerves system and peripheral nervous
system
Central nerves system “CNS” is the brain and the spinal cord
Peripheral nervous system al the nerves and receptors in the
body not including the brain or spinal cord
o CNS is made up of neurons
The role for theses neurons is to coordinate the massages
travelling through the nervous system
o When the receptor detects stimulus it sends an electrical impulse to
the brain or spinal cord
o the brain or the spinal cord receives the impulses, and sends an
impulse on, along the appropriate nerve fibers, to the appropriate
effector
reflex arcs
o reflex action is a fast automatic response to stimulus
o reflex arc is the arrangement of neurons along which an impulse
passes during a reflex action
o Involuntary action is an automatic fixed action in response to
stimulus
o Steps for reflex action
An impulse is picked up by sensory receptor in your finger
The impulse travels through the sensory neuron to spinal cord
The relay neuron in the spinal cord picks the impulse
The relay neuron sends the impulse to the motor neuron
13.1 coordination in animals
Terms in coordination system
o Changes in an organism’s environment that can be detected by sense
organs are called stimuli
o The stimuli are sensed by specialized cells called receptors
o The organism respond using effectors
o Muscles and glands are effectors
o The way in which receptors pick up stimuli and then pass information
on to effectors is called coordination
Animals need fast and efficient communication systems between their
receptors and effectors to be able to:
o respond very quickly
o catch food avoid predators
Methods of sending information from receptors to effectors
o Nerves system
Faster
o Endocrine system “hormones”
Slower
13.2 The human nervous system
Neurons
o Human nervous system is made up of specialized cells called neurons
o Neuron is a nerve cell specialized for the rapid transfer of electrical
impulses
o Neurons have normal cell parts
Cell membrane
Nucleus
Cytoplasm
o Neurons structure is adapted for their job
They have long thin fibers of cytoplasm stretching from the cell
body
, The longest fiber is called axon “it can stretch for
meters”
The shorter one is called dendrons/dendrites
Nerve impulses
Dendrites pick up electrical signals from other neurons
lying nearby
electrical signals sweeps along a neuron are called
nerve impulses
The signals pass to the cell body then the axon which
might pass to another neuron
Myelin
Myelin is a fatty substance surrounding the axons of
many neurons , enabling the nerve impulses to travel
faster
Myelin insulates the nerves fibers so they can carry
these impulses much faster
, The central nervous system
o All mammals have central nerves system and peripheral nervous
system
Central nerves system “CNS” is the brain and the spinal cord
Peripheral nervous system al the nerves and receptors in the
body not including the brain or spinal cord
o CNS is made up of neurons
The role for theses neurons is to coordinate the massages
travelling through the nervous system
o When the receptor detects stimulus it sends an electrical impulse to
the brain or spinal cord
o the brain or the spinal cord receives the impulses, and sends an
impulse on, along the appropriate nerve fibers, to the appropriate
effector
reflex arcs
o reflex action is a fast automatic response to stimulus
o reflex arc is the arrangement of neurons along which an impulse
passes during a reflex action
o Involuntary action is an automatic fixed action in response to
stimulus
o Steps for reflex action
An impulse is picked up by sensory receptor in your finger
The impulse travels through the sensory neuron to spinal cord
The relay neuron in the spinal cord picks the impulse
The relay neuron sends the impulse to the motor neuron
