1 - Overview of the nervous system Flashcards
Planes of View of the Brain
sagittal, coronal, transverse
2 major divisions of the nervous system
Central Nervous System (CNS) and Peripheral Nervous System (PNS)
central nervous system
brain and spinal cord
peripheral nervous system
cranial and peripheral nerves
sensory function
Detect internal and external changes
Integrative function
analyses & makes decisions based on voluntary and involuntary responses
motor function
initiates motor movement & glandular secretions
gross anatomy of the brain
cerebrum, cerebellum, brainstem
cerebrum (LCS)
largest part of the brain. It contains the cerebral cortex and subcortical regions
Cerebellum (PBC)
located in the posterior region of the brain, it is mainly responsible for balance and coordination
Brainstem (MPMC)
contains the midbrain, pons and medulla oblongata. It communicates with the PNS to control involuntary processes such as breathing and heart rate.
cerebral cortex
FCC
The intricate fabric of interconnected neural cells covering the cerebral hemispheres; the body’s ultimate control and information-processing center.
corpus callosum
the large band of neural fibers connecting the two brain hemispheres and carrying messages between them
4 cortical lobes of the brain
frontal, parietal, occipital, temporal
frontal lobe (HDPLV)
higher cognitive functions, such decision-making and problem-solving.
It is also responsible for some features of language and voluntary movement
parietal lobe (ICI)
integrates information from the visual pathway, coordinates motor movement and interpretation of sensory information
temporal lobe (IOE)
interpreting speech and hearing, object recognition and emotion
occipital lobe
processing primary visual information
subcortical regions of the brain (RMEMS)
Brain regions that lie underneath the cortex
- Responsible for many functions including memory, emotions, motor movement & processing of sensory information
Important subcortical structures (HAHTB)
Hypothalamus, amygdala, hippocampus, thalamus and basal ganglia
Hypothalamus
brain region controlling the pituitary gland
amygdala (LMEFA)
A limbic system structure involved in memory and emotion, particularly fear and aggression.
Hippocampus (NLP)
A neural center located in the limbic system that helps process explicit memories for storage.
Thalamus (RLC)
relays messages between lower brain centers and cerebral cortex
basal ganglia (FC)
structures in the forebrain that help to control movement
Midbrain (CCTC)
Serves as a connection between the brainstem and subcortical regions
consists of: colliculi, tegmentum, cerebral peduncle
colliculi (EO)
directs eye movement towards objects of interest
Tegmentum (CA)
coordination of movement, alertness/sleep
cerebral peduncle
control of ocular muscles
Pons (BRB)
- A brain structure that relays information from the cerebellum to the rest of the brain
- forms bridge between midbrain and medulla
spinal cord
- Critical link between the CNS and PNS
* Nerves that branch off from the spinal cord form the PNS and innervate the rest of the body.
5 Sections of the spinal cord
cervical (neck) thoracic (chest) lumbar (lower back) sacral (hip) coccygeal (tail)
Divisions of PNS (Peripheral Nervous System)
somatic nervous system and autonomic nervous system
somatic (VCP)
Voluntary - controls the skeletal muscles and provides sensory information from the body and from the outside world
autonomic (IESP)
involuntary functions.
divided into enteric, sympathetic and parasympathetic
enteric
Regulates movement of water & solutes between gut and tissues
sympathetic
responsible for the ‘fight or flight’ reaction that occurs in response to a stressful stimulus
Parasympathetic
balances the sympathetic response by stimulating ‘rest and digest’ pathways
afferent pathway
carry sensory information from the periphery up to the brain via ascending nerve tracts
efferent pathway
The brain sends signals down to peripheral nerves along efferent descending nerve tracts to control motor output
2 cell groups in CNS
neurons and glia
4 glial cells in CNS
astrocytes, oligodendrocytes, microglia, ependymal cells
neurons
- Specialised cells that receive and send electrical signals within the CNS and between the CNS and PNS
- Input from other cells is received via dendrites, which relay info to the cell body
- The neuron may choose to then send a signal down the length of its axon, where chemicals will be released onto another neuron, muscle cell or other cell types at the synapse
bipolar neurons
one axon and one dendrite
Retina of the eye, inner ear, olfactory area of brain
unipolar neuron
Just 1 process from the cell body, part way down the axon
• Always sensory neurons (pain, temperature, touch, pressure)
multipolar neuron
A neuron with a single axon and multiple dendrites; the most common type of neuron in the nervous system.
Microglia
- Immune cells that survey the CNS and respond to signs of infection or damage
- Exist in a wide-range of morphologies depending on activation state
- either activated or surveillant
surveillant microglia
smaller, with multiple processes
activated microglia
larger, with rounded cell body & shorter processes
Astrocytes
- Small, star-shaped cells that support the development and homeostatic maintenance of the NS and cerebral blood vessels
- Heterogeneity (morphology, protein expression) across different brain regions
- Form ‘glial scar’ after severe injury
Ogliodendrocytes
- Cells that form the myelin sheath that wraps around some neurons to increase the speed of information transmission by the neuron
- In the PNS, these cells are called Schwann cells
White and grey matter in the brain
- Myelin increases the speed of axon potentials
- unmyelinated axon conduction velocities range from about 0.5 to 10 m/s
- myelinated axons can conduct at velocities up to 150 m/s
- white matter = myelinated areas
- grey matter = unmyelinated areas
Fluids of the CNS – cerebral blood vessels
- Neuronal health is critically dependent on adequate blood supply
- Blood vessels in the brain are made up the neurovascular unit
- Endothelial cells of the brain express form tight junction proteins, allowing the brain to create the blood-brain barrier (BBB)
- This gives the brain a high degree of selectively, thereby protecting it against entry by potentially harmful substances in the blood
neurovascular unit
- neurons
- endothelial cells
- pericytes (capillaries)
- astrocytes
- smooth muscle cell (arteries)
Fluids of the CNS – cerebrospinal fluid
- Cerebrospinal fluid (CSF) is contained within ventricles and in the subarachnoid spaces of the brain and spinal cord
- CSF provides buoyancy for the brain and cushions from injury, as well as waste removal
- CSF is produced from filtered blood by the choroid plexus in the ventricles
- Because CSF is shared between the brain and spinal cord, samples of CSF collected from the spinal cord are used to provide a ‘snapshot’ of the brain environment