Human Biology (Nervous System) Flashcards
What are Neurons?
Specialised cells that pass along nerve impulses.
What does the Sensory Nervous System do?
Takes information from the body to the brain:
External conditions: e.g. temperature, hearing, touch
Internal conditions: Blood temperature, pressure, blood gas & pH.
What does the Central Nervous System do?
Takes information to and from the brain and co-ordinates spinal reflexes.
What do motor neurons do?
Takes information from the brain to the body about responses.
- Stimulates movement or glandular secretions
- Has both voluntary and involuntary secretions.
Where are synapses present?
At muscles and glands.
What is the cell body of a neuron?
Contains a nucleus and carries impulses to the body.
What are the dendrites of a neuron?
Describe their structure and function.
Short extensions of the body that are highly branched.
Receive stimulus and carry impulses to all the body.
What are axons? Describe their structure and function.
Longer extensions from the cell body.
Carries nerve impulses away from the cell body
Usually covered with a myelin sheath
What is the gaps along an axon called?
Nodes of Ranvier
What are 3 functions of the myelin sheath?
- Acts as an inuslator for impulses.
Protects axon from external damage
Speeds movement of nerve impulses
What is the neurilemma?
The outermost layer of schawnn cells and helps to repair injured fibres by guiding regrowth.
What is the difference between grey matter and white matter?
Grey:
- Cell bodies
- Unmyelinated fibres
White:
- No cell bodies
- Myelinated fibres
What are sensory neurons?
Carries messages from receptors to the CNS.
What are interneurons?
The link between sensory and motor neurons.
What are motor neurons?
Carries messages from CNS to muscles and glands.
What does autonomic and somatic mean?
Somatic: Means under voluntary control
e.g. skeletal muscles movement, eye movement
Autonomic: Means under involuntary control
e.g. Muscle lining in blood vessels, and glands
What are the 3 types of neuron structure?
Multipolar, Bipolar, Pseudopolar
What are 4 features of multipolar neurons?
- Most common
- One axon, multiple dendrites
- Axon may have multiple terminals
- Interneurons and motor neurons are of this type
What are 2 features of bipolar neurons and 2 examples?
- One axon and one dendrite, branching at ends
- Generally, part of special sense organs
e.g. in eye, ear, nose
What is a feature of pseudopolar neurons?
- Cell body to side
What is a synapse?
A point where nerve impulses are passed from one neuron to another.
There is no join because of a small gap for chemical messages neurotransmitters to cross.
Also occur at neuromuscular junctions.
What are nerves and the 3 types and their directions?
Bundles of neuron fibres extending from the CNS.
3 Broad Types:
Sensory, Motor, Mixed
Sensory take information from the body to the CNS.
Motor takes information to the body from the CNS.
Mixed takes information from both ways.
