Nervous system Flashcards
What does The Nervous System consist of?
- The central nervous system (CNS) – the brain and spinal cord
- The peripheral nervous system – nerve cells that carry information to or from the CNS
What are nerve cells called?
Nerve cells are also called neurones.
How are nerve cells adapted?
They are adapted to carry electrical impulses from one place to another:
- They have a long fibre (axon) which is insulated by a fatty sheath.
- They have tiny branches (dendrons) which branch further as dendrites at each end.
What are receptors?
Receptors are groups of specialised cells.
What can receptors detect?
They can detect a change in the environment (stimulus) and produce electrical impulses in response. Sense organs contain groups of receptors that respond to specific stimuli.
Name the five skin sensors.
Skin Touch, temperature
Tongue Chemicals (in food and drink, for example)
Nose Chemicals (in the air, for example)
Eye Light
Ear Sound
What are effectors?
Effectors are parts of the body - such as muscles and glands - that produce a response to a detected stimulus.
Give three examples of an effector.
- A muscle contracting to move an arm
- Muscle squeezing saliva from the salivary gland
- A gland releasing a hormone into the blood
What is a reflex action?
A reflex action is a way for the body to automatically and rapidly respond to a stimulus to minimise any further damage to the body.
Why do reflex actions not involve the brain?
After the brain realises the body is in pain, it will be too late to prevent the body from harm.
What is the sequence for a reflex action- not involving the brain?
Stimulus → Receptor → Sensory neurone → Relay Neurone → Motor neurone → Effector → Response.
What is the reflex arc?
The nerve pathway followed by a reflex action.
What do muscles work in?
Muscles work in antagonistic pairs.
What does muscles working in antagonistic pairs, allow muscles to do? Name some examples.
It ensures that when a part of the body is moved, it can move back to its original position.
- The biceps and triceps in the arm
- The quadriceps and hamstrings in the leg
