What are four general functions of nervous tissue?
- Detect and analyze sensory input
- Coordinate body activities
- Store experiences
- Learning and memory
What are the two parts of the nervous system?
- 1) Peripheral Nervous System (PNS): all the nerves of the body ie. spinal, autonomic, enteric
- 2) Central Nervous System (CNS): brain and spinal cord
How does the nervous system divide tasks?
Somatotopic organization- there are ways that labour can be divided at the body level, systems level, circuit level, and cell level.
What is a gyri?
"Bump" on the brain surface
What is a sulci?
"groove" on the brain surface
Provide an example of somatotopic organization?
There is a gyrus on either side of the central sulcus. The precentral gyrus is the primary motor cortex. The postcentral gyrus is the primary sensory cortex.
How is the precentral gyrus different from the postcentral gyrus?
The precentral gyrus contains a layer of Betz cells which are specifically involved in motor function.
How is the spinal cord organized?
Sensory info enters at the dorsal horn while motor info exits at the ventral horn.
What is white matter (in the spinal cord)?
Ascending and descending tracts of myelinated nerve fibers
What is gray matter?
Nerve cell bodies
What type of information do peripheral nerves carry?
Both sensory (afferent) and motor (efferent) information
What are somatic nerves?
- Nerves of the PNS where sensory info is consciously perceived
- Motor activity is voluntary (skeletal muscle)
- Usually a single neuron connection
What are visceral nerves?
- Aka autonomic nerves
- Nerves of the PNS where sensory info is perceived unconsciously (ie. propioception- positions of the limbs)
- Motor activity is involuntary
- Multiple connections
What are the two types of autonomic nerves?
- 1) Sympathetic: flight or fight, catabolic, mobilize energy stores
- 2) Parasympathetic: rest and repose, anabolic, growth, tissue repair/maintenance
Name two important differences between sympathetic nerves and parasympathetic nerves.
- 1) Function (sympathetic=catabolic, parasympathetic=anabolic)
- 2) Origin of nerve cell bodies (sympathetic= thoracic and lumbar, parasympathetic= sacral and cervical/cranial)
What are the three broad categories of nervous tissue?
- 1) Neurons: excitable cells that carry out information transfer
- 2) Glia: non-excitable cells of neural origin that enhance efficiency of transmission
- 3) Support cells : include cells of the blood vessels and microglia (immune cells of the CNS)
What is Nissl substance?
Ribosome-rich RER in a neuron (found in the soma)
Name the four major parts of a neuron.
Describe the dendrites of a neuron.
- Receptive region of the cell
- Conduct afferent info towards the cell body
- Some contents similar to soma - mitochondria and SER, microtubules and neurofilaments
- Lack Golgi complexes
Describe the axon of a neuron.
- Conductive region of the cell
- Sends impulses away from the cell
- Contains mitochondria and SER (no RER)
- Microtubules - axonal transport- moves vesicles and proteins, recycles structural components, anterograde and retrograde transport
What is the effector region?
Wherever the neuron contacts/effects target gland, muscle, or neuron
What are the three parts to a synapse?
- Presynaptic terminal
- Postsynaptic terminal
- Synaptic cleft
Name two types of synapses.
Axosomatic and axodendritic