Coordination & Response
Topic 14
• Stimuli: a change in the environment that is detected by a sense organ
• Receptors: cells that detect the stimuli
• Effectors: organs that bring about responses
• Responses: the actions the effects take as a result
e.g. Glands usually secrete useful substances and muscles contract to bring about movement
• The sensory system: for detecting changes in our environment
• The nervous system: for coordinating our responses and initiating actions
The Human Nervous System:
The human nervous system consists of two parts:
• Voluntary actions are under
• The central nervous system (CNS)
conscious control and involve
- consists of the brain and spinal cord
the brain in decision making.
- the brain is protected by the skull and the spinal cord is protected by the
vertebral column
• The peripheral nervous system:
- all nerves outside brain and spinal cord
-Cranial nerves and spinal nerves are in pairs on either side of the brain and
spinal cord respectively.
- Cranial nerves link the brain with all the organs in the head and also some in
the thorax and abdomen
- Spinal nerves link the brain to the arms, thorax, abdomen and legs
- Spinal nerves leave the spinal cord in Pais through spaces between vertebrae
Neurones and Reflex arcs
Reflex actions:
Involuntary actions occur unconsciously. E.g. swallowing, blinking, breathing and beating of the heart. A simple reflex is very
quick and automatic response that the person does not need to think about. For example a person sitting on a sharp object such as
a pin, causing them to get up quickly - many reflexes are protective, they happen so you don’t hurt yourself
• Coordinator: the part of the body that connects information about the stimulus to the effector. This always happens inside the
central nervous system to allow connections with other parts of the body and the brain to be aware of stimuli
Stimulus Receptor Coordinator Effector Response
Neurones:
• Each nerve is made up of neutrons, surrounded by a protective fibrous tube. Neurones are highly specialised cells that can transmit
information in the form of nerve impulses over long distances, which are like pulse of electricity passing along a wire
• The cell body contains the nucleus and almost all of the cytoplasm
• There are thin extensions of cytoplasm that extend through the body
Sensory Neurones: transmit impulses from Motor Neurones: transmit impulses away from the brain
sense organs to the brain and spinal cord and spinal cord to effector organs - muscles & gland
Topic 14
• Stimuli: a change in the environment that is detected by a sense organ
• Receptors: cells that detect the stimuli
• Effectors: organs that bring about responses
• Responses: the actions the effects take as a result
e.g. Glands usually secrete useful substances and muscles contract to bring about movement
• The sensory system: for detecting changes in our environment
• The nervous system: for coordinating our responses and initiating actions
The Human Nervous System:
The human nervous system consists of two parts:
• Voluntary actions are under
• The central nervous system (CNS)
conscious control and involve
- consists of the brain and spinal cord
the brain in decision making.
- the brain is protected by the skull and the spinal cord is protected by the
vertebral column
• The peripheral nervous system:
- all nerves outside brain and spinal cord
-Cranial nerves and spinal nerves are in pairs on either side of the brain and
spinal cord respectively.
- Cranial nerves link the brain with all the organs in the head and also some in
the thorax and abdomen
- Spinal nerves link the brain to the arms, thorax, abdomen and legs
- Spinal nerves leave the spinal cord in Pais through spaces between vertebrae
Neurones and Reflex arcs
Reflex actions:
Involuntary actions occur unconsciously. E.g. swallowing, blinking, breathing and beating of the heart. A simple reflex is very
quick and automatic response that the person does not need to think about. For example a person sitting on a sharp object such as
a pin, causing them to get up quickly - many reflexes are protective, they happen so you don’t hurt yourself
• Coordinator: the part of the body that connects information about the stimulus to the effector. This always happens inside the
central nervous system to allow connections with other parts of the body and the brain to be aware of stimuli
Stimulus Receptor Coordinator Effector Response
Neurones:
• Each nerve is made up of neutrons, surrounded by a protective fibrous tube. Neurones are highly specialised cells that can transmit
information in the form of nerve impulses over long distances, which are like pulse of electricity passing along a wire
• The cell body contains the nucleus and almost all of the cytoplasm
• There are thin extensions of cytoplasm that extend through the body
Sensory Neurones: transmit impulses from Motor Neurones: transmit impulses away from the brain
sense organs to the brain and spinal cord and spinal cord to effector organs - muscles & gland
