Week 2 Lecture 1: The Central Nervous System Flashcards
What is the central nervous system (CNS)?
The brain and the spinal cord
What is the peripheral nervous system (PNS)?
All neurons and parts of neurons (cell bodies in the CNS and axons in PNS) outside of the CNS
What two nervous systems is the PNS comprised of?
The somatic nervous system and the autonomic nervous system
What is the function of the somatic nervous system?
Controlling voluntary action via skeletal muscle
What is the function of the autonomic nervous system?
Visceral functions (involving internal organs) such as heart rate and breathing
What is a part of the autonomic nervous system?
The enteric nervous system
What is the function of the enteric nervous system?
Controls digestion and the movements of the gut, it gets input from the CNS but can also work independently
Where are most neurons?
In the CNS, 86 billion in the brain and 1 billion in the spinal cord
What cells other than neurons are found in the nervous system?
Glial cells
What is the function of glial cells?
Support and protect neurons.
What is considered grey matter?
Nerve cell bodies, unmyelinated axons and dendrites
What is a cluster of neurons in the CNS called?
Nuclei
What is a bundle of axons in the CNS called?
Tracts
What is a cluster of neurons in the PNS called?
Ganglia
What is a bundle of axons in the PNS called?
Nerves
Does the CNS use a lot of energy?
Yes, despite the brain being less than 2% of the body’s mass, it receives 15% of the blood pumped by the heart and consumes 1/2 the body’s glucose
Does the CNS use more energy than a computer?
No, the CNS requires substantially less energy than a computer (40 watts = brain)
How does the CNS save energy?
Communication between neurons (action potentials/spikes) is expensive and the energy supply to the CNS only supports low level firing therefore the CNS has to use its energy sparingly (only 4% of neurons are firing at any given moment, one spike per neuron every 6 seconds)
What type of signals do the dorsal and ventral root in spinal nerves carry?
The dorsal (back) root carries afferent (incoming, sensory) signals and the ventral (front) root carries efferent (outgoing) signals from the CNS to the body e.g. motor signals
Where is grey matter located in the spinal cord?
It is found mainly in the middle of the spinal cord and has butterfly shape with a dorsal and ventral horn on each side
What are the types of nuclei found in the grey matter of the spinal cord and what is their respective positions? (2)
- Somatic and visceral sensory nuclei are in the dorsal horn
- Autonomic efferent nuclei and somatic motor nuclei are found in the ventral horn
Where does somatic sensory nuclei get signals from?
The skin
Where does visceral sensory nuclei get signals from?
The viscera (internal organs)
Where does autonomic efferent nuclei send signals to?
Glands and smooth muscle
Where does somatic motor nuclei send signals to?
Skeletal muscle
What are ascending tracts and where can they be found in the spinal cord?
Carry sensory signals to the brain and are mainly dorsal
What are descending tracts and where can they be found in the spinal cord?
Carry signals from the brain and are mainly ventral
What are the tracts that stay in the spinal cord called?
Propiospinal tracts
What is a spinal reflex (example)?
When the spinal cord responds to stimuli without consulting the brain e.g. knee-jerk reflex
What are 6 major divisions of the brain?
The cerebrum, diencephalon, midbrain, pons, medulla and cerebellum
What structures make up the brain stem and what is it’s function?
The midbrain, pons and medulla make up the brain stem which is the main control center of autonomic function and reflexes e.g. breathing, swallowing, vomiting
Which cranial nerves start in the brains stem?
3, 10 and 12
What are cranial nerves?
Nerves that enter or leave the brain rather than the spinal cord
What structures make up the diencephalon?
Hypothalamus, thalamus, pituitary gland and pineal gland
What is the function of the thalamus?
Processes information going in and out of the cerebral cortex i.e. relay centre
What is the function of the hypothalamus?
Regulates behavioural drives e.g. fight or flight and endocrine and autonomic homeostasis
What is the function of the pituitary and pineal glands.
Secreting hormones
What structures are included in cerebral grey matter?
Cortex, limbic system and the basal ganglia
How are the two hemispheres of the cerebrum connected together?
The connected via the corpus callosum, a large bundle of myelinated axons
Do the functions of the two hemisphere differ?
Yes, we have cerebral lateralization. The left hemisphere is associated with language and math while the right hemisphere is associated with spatial and touch analysis
What are the 4 lobes of the brain (found in each hemisphere)?
Frontal, parietal, temporal and occipital
What structure is found in each hemisphere and is apart of the limbic system?
The cingulate gyrus
