Topic 5- Human nervous system Flashcards
What is the function of the nervous system?
The nervous system allows the body to react to its surroundings and coordinate an appropriate response
How des a stimulus lead to a response being carried out by the body?
-Stimulus is converted into an electrical impulse by the receptors
-The electrical impulse passes along sensory neuron’s to the the central nervous system (CNS)
-The CNS coordinates an appropriate response and an electrical impulse is sent along motor neurones to the effector, which carries out the response
What sequence of events describes how the nervous system works?
Stimulus–> receptor–> coordinator–> effector–> response
What is reflex action?
A reflex action is an automatic and rapid response which does not involve any conscious input from the brain
Why are reflex actions important?
Reflex actions aid survival by preventing harm to the body
Describe how a reflex action occurs via a reflex arc
-The stimulus is detected by a receptor
-An electrical impulse passes along a sensory neurone to the spinal cord (part of the CNS)
- At a synapse between a sensory neurone and a relay neurone, a chemical diffuses across the gap and stimulates a new impulse which passes along the relay neurone
-The same process occurs at a synapse between a relay neurone and a motor neurone
-At the effector, an appropriate response is carried out
What is the difference between a reflex pathway and a conscious pathway?
Within a reflex pathway, the coordination centre is a relay neurone found in the spinal cord/unconscious parts of the brain. In a conscious pathway, the coordination centre is in the conscious part of the brain
What is the function of the cerebral cortex?
Controls consciousness, intelligence, memory and language
What is the function of the cerebellum?
Controls muscular coordination
What is the function of the medulla
Controls unconscious activities (eg breathing, heart rate etc)
Why is the investigation and treatment of the brain difficult
-Its a complex and delicate organ
-The brain is easily damaged and destroyed
-Certain membranes prevent drugs from reaching the brain
- The exact function of each part of the brain is not known
What methods are used by scientists to determine brain function?
-Studying patients with brain damage
-Electrical stimulation of the brain
-MRI scans
What stimuli are the receptors of the eye sensitive to
Light intensity and colour
What are the two main functions of structures found within the eye?
Focusing on near or distant objects- accommodation
Adaptation to dim light
Describe the structure and function of the retina
The retina is a light-sensitive layer found at the back of the eye
Light stimulates the retinal cells, resulting in impulses being sent to the brain