27. Nervous System Flashcards
What is the function of a nervous system?
Enables animals to sense and react to changes in the internal and external environment. Made out of many nerve cells
What are nerve nets and what animal has them?
The simples form of a nervous system. Diffusing nerve nets control contraction and expansion of gastrovasular cavity. Neutrons are not grouped together like in a nervous system. - Cnidarians
Define a nerve. What is their function
Bundles or tracts of fibre like extensions of neurons. Improves control of more complex animals
Define cephalisation
The clustering of sensory organs and neurons in the brain
What is the central nervous system
Consists of the brain and longitudinal nerve cord
Define the peripheral nervous system (PNS)
Consists of nerves connecting the central nervous system (CNS) with the rest of the body
What are ganglia?
Clusters of neurons
In vertebrates, wha does the central nervous system consist of?
The brain and spinal cord
In vertebrates, what does the Peripheral nervous system consist of?
Nerves and ganglia
What are three stages of information processing in the nervous system? How is it handled?
Sensory input
Integration
Motor output
Handled by a specific population of neurons
What triggered the development of more complex CNS and cephalisation?
Bilateral symmetry!
How is information processed within the nervous system? 6 steps
- sensor which is the effector
- sensor will tell the periphial nervous system (PNS)
- PNS will tell the CNS (central nervous system).
- The CNS (the brain) will integrate the information and make a solution
- CNS will communicate with the PNS
- motor input back to the sensor
image will help!
what is contained within the cell body of a neuron and what extenstions arise from the cell body?
cell body: contains nucelus and most of the neurons organelles
extentions: axon and dendrites
what is an axon?
a slender projection that conducts electrical impulses which transmits signals to other neurons.
what is the axon hillock?
the area where the cell body and axon are joined together
what are dendrites?
highly branched reciever signals from other neurons. more branches, the more connections with other neurons so more synapse
what is synapse?
what is a myelin sheath?
a lipid membrane that wraps itself around axons to insulate and enables proper function of the neuron by helping the speed of neural impulses
what are oligodendocytes?
a type of gilia cell (supporting cells) which supports the nervous system in the CENTRAL NERVOUS SYSTEM. oligodendocytes form myelin sheaths which is essential for nerve impulses. can wrap around up to 50 axons
what are schwann cells?
a type of gilia (supporting cell) that is in the PERIFERIAL NERVOUS SYSTEM. essential for production of myelin sheaths that transimit nerve impules in the neuron. the schwann cell can only wrap itself around one axon (opposed to 50 in oligodendrocytes)
what is the node of raniver?
a gap between the myelin sheaths in neruons.
