Nervous system Flashcards
This structure regulates voluntary movements
Cerebellum
The primary motor area is located here
frontal lobe
This structure is a major sensory relay centre
thalamus
hypothalamus
Thirst and safety centres are located here
the lobes of the brain
frontal, parietal, temporal and occipital.
Central Nervous system includes
- brain
- spinal cord
Peripheral nervous system
- nerves
- ganglion
Dendrites VS Axons
Dendrites: signal input (receiving end)
- Short, thick, unmyelinated
Axons: signal output (transmitting end
- Long (mm to over 1cm)
Axonal Transport
Passage of proteins, organelles and other materials along an axon = axonal transport
Anterograde transport
soma to end of axon
(e.g. mitochondria, vesicles, proteins for
Retrograde transport
Retrograde transport = axon end to soma
(e.g. waste, materials for recycling)
Resting State
A neuron at rest has a negative charge inside compared to the outside. Due to the difference in ions inside and outside the cell
Triggering an action potential
When the neuron gets a strong enough signal, it causes special channels to open, allowing positive sodium ions to flow in. This makes the inside of the neuron more positive.
Depolarisation
As more sodium ions enter, the inside of the neuron quickly becomes positive. This positive charge is the electrical signal.
Repolarization
After the peak of the signal, sodium channels close, and potassium (K⁺) channels open, letting potassium flow out. This returns the inside of the neuron to a negative charge.
Resetting
The neuron briefly becomes even more negative than at rest, then goes back to its normal resting state. It’s now ready to send another signal.
3 types of neurons
- sensory (afferent)
- interneurons
- motor (efferent)
action potential
momentary reversal of membrane potential
What makes the myelin sheath
- oligodendrocytes in CNS
- Schwann cells in PNS
oligodendrocytes
forms myelin sheath in CNS
ependymal cells
line internal areas of brain
secrete and circulate cerebrospinal fluid
microglia
detect debris and damage
astrocytes
Forms a supportive framework between neurons and blood vessels
Schwann cells
produce myelin sheath in PNS
brain
sulci = grooves
gyri = folds
folia = thin folds
midbrain
- Houses visual and auditory control centres (reflexes)
- Roles in motor control and suppression of unwanted body movement
pons
- Connects the 2 sides of the cerebellum
- Carries sensory and motor information up and down the brainstem
medulla oblongata
- All nerve fibres connecting the brain and spinal cord passes through
90% of nerve fibres cross over at the pyramidal decusstion
Occulumotor nerve (III)
Narrows pupils and focus lens
Facial nerve (VII)
tear, nasal and salivary glands
Glossopharyngeal nerve (IX)
paratid salivary glands
Vagus nerve (x)
heart, lung, digestive tract
Autonomic Reflexes
visceral reflexes : unconscious, autonomic, responses to stimulations involuntary visceral receptors and effectors
hormones
- Carried by blood to distant targets
- Slow and not particularly specific
neurotransmitters
- Released at synapses between neurons and targets
- Fast and specific
Autonomic Nervous System
- Regulates fundamental states and life practices
- e.g. heart rate, blood pressure, body temperature
Maintains homeostasis
What are the three properties of a neuron?
excitability
conductivity
secretion
What type of neurons are sensory neurons?
unipolar
What type of neurons are motor neurons?
Multipolar
Where does the visceral sensory division send signals from?
Viscera od the thoracic and abdominal cavities
Where does information from the somatic sensory division come from?
Skin, muscles, bones and joints
What do Satellite cells do?
Provide support and nutrition to cell bodies in ganglia
Frontal lobe
abstract thoughts
## mood and motivation
Parietal lobe
taste
somatic sensation
sensory integration
language processing
Occipital lobe
visual awareness
Temporal lobe
- auditory processing
- comprehension
- memory
- visual
What are the divisions of the spinal cord?
five main regions: cervical, thoracic, lumbar, sacral, and coccygea
Number of spinal nerves in each region
Cervical: 8 pairs
Thoracic: 12 pairs
Lumbar: 5 pairs
Sacral: 5 pairs
Coccygeal: 1 pair
Where is CSF found in the brain?
cerebrospinal fluid is primarily found in the subarachnoid space, the ventricles of the brain, and the central canal of the spinal cord.
What two neurons are involved in motor contraction?
motor contraction involves upper motor neurons, which originate in the brain and send signals down to the spinal cord, and lower motor neurons, which connect directly to muscles to induce contraction.
What is the parasympathetic neurotransmitter?
- ## primary neurotransmitter of the parasympathetic nervous system is acetylcholine (ACh)
What are the receptors for adrenaline and noradrenaline?
adrenaline and noradrenaline interact with alpha (α1 and α2) and beta (β1, β2, and β3) receptors to mediate a wide range of physiological responses.
What are the sympathetic neurotransmitters
the two main neurotransmitters of the sympathetic nervous system are norepinephrine (primarily from post-ganglionic neurons) and epinephrine (released from the adrenal medulla).
What is a tract?
a tract is a bundle of nerve fibers in the central nervous
What are the layers of meninges?
the dura mater (outer layer), arachnoid mater (middle layer), and pia mater (innermost layer)
What are the 3 functions of cerebrospinal fluid?
protection
cushioning
buoyancy
facilitates nutrient and waste exchange
Speed of signals in myelinated fibres
myelinated fibers transmit signals significantly faster than unmyelinated fibers,
Speed of transmission in unmyelinated fibres
unmyelinated fibers have a conduction speed of approximately 0.5 to 2 m/s, which is significantly slower than the speeds seen in myelinated fibers.
How many neurons are in the sensory pathway?
the first-order neuron (from the receptor to the spinal cord or brainstem),
the second-order neuron (from the spinal cord or brainstem to the thalamus)
the third-order neuron (from the thalamus to the cerebral cortex).
Sensory pathway
the sensory pathway involves a series of neurons (first-order, second-order, and third-order) that transmit sensory information from receptors through the spinal cord and brainstem to the thalamus and finally to the cerebral cortex
Where does the sensory pathway decussate? Which neuron is it?
second-order neuron decussates in the medulla.
Motor pathway
upper motor neurons (which originate in the brain and project to the spinal cord)
lower motor neurons (which innervate skeletal muscles).
Where does the motor pathway decussate? Which neuron?
medullary pyramids for the corticospinal tract (involving upper motor neurons
