Chapter 9- The nervous system (1) Flashcards
What is a nervous system?
An organism’s control centre
What is the nervous system responsible for?
1- Sensory input- monitoring the internal and external world via millions of receptor cells
2- Integration- processing and interpreting sensory information. Deciding what to do.
3- Motor output- activating effector organs (muscles, glands)
What are the two principal divisions of the central nervous system?
1- The central nervous system- Includes the brain and spinal cord
2- The peripheral nervous system- Includes motor nerves and sensory nerves.
What nerves form the efferent system?
Motor nerves
What nerves form the afferent system?
Sensory nerves
What is the efferent system further subdivided into?
Somatic (voluntary) and autonomic (involuntary)
What can autonomic pathways be further subdivided into?
Sympathetic and parasympathetic
What is sympathetic?
Activates the fight or flight mode response
What is parasympathetic?
Initiates the rest and digest response
What are the nerve arrangements?
43 pairs of nerves connect the CNS to the rest of the body.
12 cranial nerves exit the brain
3 are sensory nerves
5 are motor nerves
4 are mixed
A further 31 pairs of nerves exit at various levels of the spinal cord. They are all mixed.
What is the nervous system primarily composed of?
Nervous tissue- main tissue of the nervous system. It monitors and regulates the function of the body.
What is a neuron made up of?
A neuron is made up of a plasma membrane, a nucleus, and various other organelles in the cytoplasm.
What is the structure of the neuron?
1- Has a soma (cell body)
2- Has various neurites which can be subdivided into dendrites and one long axon
The neuron structure supports a specialised function which is what?
The transmission and processing of information via electrical impulses.
What are dendrites?
Dendrites are neurites that receive incoming signals.
What do dendrites have to assist with its function?
Lots of branching
What does the soma do?
Sums incoming electrical signals from the dendrites.
What is situated in the soma?
The nucleus and other organelles are situated, including key organelles that are required for protein synthesis, including:
1- The protein producing rough endoplasmic reticulum
2- The nucleus including a prominent nucleolus
Where do most cell bodies like to hide?
In the CNS.
Clusters of cell bodies in the CNS are called nuclei.
What is the ganglia?
Clusters of cell bodies lying along the nerves of the PNS
What is the axon?
This is a neurite that generates and transmits electrical impulses (action potentials) away from the soma.
They are the conducting region of the neuron
Where does the axon join with the soma?
At the axon hillock
What does the axon end in?
Axon terminals (synapses) that make contact with other neurons.
The axon is coated in between with what?
A myelin sheath- an insulating layer of fat and protein
