B10. The Nervous System Flashcards
What is homeostasis?
Homeostasis in the regulation of the internal conditions of a cell or organism to maintain optimum conditions for function in response to internal and external changes.
e.g. control of blood glucose concentration
What are the 2 automatic control systems of the body?
1) The Nervous System
2) Endocrine system
2) The Endocrine System
What type of messages travel via the nervous system?
Electrical impulses
What is a neuron?
A neuron is a nerve cell along which an electrical impulse can travel.
Name 3 types of neuron.
1) Sensory neuron
2) Relay neuron
3) Motor neuron
The nervous system is made up of 2 parts. What are these 2 parts?
The central nervous system (brain and spinal cord) and the peripheral nervous system (all other nerve cells).
Describe how a neuron is adapted for it’s function.
- Thin projections called dendrites extend from the cell body and connect with other neurones, allowing electrical impulses to pass from one to the other.
- The axons of most neurones are insulated by a layer called the myelin sheath. This ensure the impulses travel rapidly along the axon.
What happens if the myelin sheath degenerates?
The electrical impulse can not travel as smoothly down the axon. The person may experience tremors.
Describe the pathway of an electrical impulse during a conscious action e.g. putting up your hand to answer a question.
Stimulus –> Receptor –> Sensory neuron –> CNS (brain) –> Motor neuron –> Effector (muscle/gland) –> response.
What is a stimulus?
A change in your environment e.g. hearing a loud bang.
What parts of the body detect stimuli.
Sense receptors in the sense organs i.e. ears, eyes, nose, mouth, skin.
What is a synapse?
A synapse is a gap between two neurons. Electrical impulses can not cross the synapse.
Describe how electrical impulses can cross the synapse.
1) Electrical impulse reaches the end of the first neuron.
2) This stimulates the release of neurotransmitter chemicals.
3) The neurotransmitter chemicals diffuse across the synapse.
4) They bind to receptors on the next neuron.
5) This binding of the neurotransmitters to the receptors stimulates the second neuron to transmit an electrical impulse (same message) along its axon.
What are the names of the chemicals that diffuse across the synapse?
Neurotransmitter chemcials.
Describe the pathway of an electrical impulse during a reflex action.
Stimulus –> Receptor –> Sensory neuron –> CNS (spinal cord) –> Motor neuron –> Effector (muscle/gland) –> response.