Central Nervous System 1 Flashcards
What is the central organ of the nervous system?
Brain
What makes up the CNS?
Brain & spinal cord
What does the surface anatomy include?
- Cerebral hemispheres
- Cerebellum
- Brainstem
What is the average weight of a
- new born?
- adult human brain?
- 350-400g
- 1300-1400g
What are the functions of the CNS?
- Form a communication network
- Coordinates all the systems of body & allow to function
- Integrates the info that it receives
What do neurons receive messages from other neurons through?
dendrites
What are dendrites?
Carry message to neurons cell body
What do axons do?
Carry outgoing messages
What is a nerve?
A group of axons bundled together in the PNS
What is a nerve fascicle(fasciculus)?
Bundle of funicili
Funiculus (bundle of axons)
What is a tract?
A group of axons bundled together in CNS
What is a nucleus?
Collection of neural cell bodies in CNS
What is a ganglion?
Collection of neuron cell bodies in the PNS (except basal ganglia)
List the 2 functions of a myelin sheath
- Increases neuron efficiency
- Provides insulation
Name two demyelinating diseases
- Multiple sclerosis
- Guillain-Barre syndrome
What is white matter?
Bundle of axons each coated with a sheath of myelin
What is gray matter?
Masses of cell bodies and dendrites - each covered with synapses
List the 3 types of nerve tracts
- Association fibers
- Commissural fibers
- Projection fibers
List the 3 groups nerves are categorised by based on direction of the signals
- Afferent nerves (signals from sensory neurons to CNS)
- Efferent nerves ( CNS to target muscles & glands)
- Mixed nerves (both afferent & efferent axons)
What is the ascending/afferent pathway?
Neurons projecting from the periphery toward the brain
What is the descending/efferent pathway?
Neurons projecting from brain toward periphery
What does the dorsal root ganglia contain?
Cell bodies of sensory neurons
What does the dorsal horn contain?
First point of synapse of sensory neurons
How many pairs of spinal nerves are there?
31
Name the two roots the spinal nerve branches into
- Anterior (ventral relays sensory info)
- Posterior (dorsal root relays motor info)
______ transport substances from cell body to axon terminal toward the ____ end of microtubule (______ transport)
Kinesin
plus
Anterograde
______ transport substances from the axon terminal to the cell body toward the ____ end of the microtubule (_____ transport)
Dyenin
minus
retrograde
What is the function of microtubules?
- Transport of nutrients, proteins & other important substances from neuron cell body to other parts of nerve cell
What do neurofibrillary tangles consist of ?
Insoluble twisted fibres
What does a synapse consist of?
- Presynaptic ending
- Postsynaptic neuron
- Synaptic cleft/space
Differences in ____ concentration on opposite sides of the membrane produce a _________ (______)
ion
voltage difference
membrane potential
What does the sum of EPSP & IPSP dictate?
Neuron gets depolarised/hyperpolarised
What is the function of the axon hillock?
Controls the firing of the neuron
What does a gate keeper or a sensor do?
Sums the total inhibitory & excitatory signals
If the sum of the signals exceeds a certain threshold what happens?
Action potential triggered & electrical signal transmitted down the axon away from cell body
List the 3 different types of neurons
- Sensory (signals from outer parts of body into CNS)
- Motor ( signals from CNS to outer parts of body)
- Interneurons (connect neurons within brain & spinal cord)
The ______ the nerve fiber the _____ information travels
thicker
faster
C-nerve fibers are unmyelinated/myelinated?
unmyelinated
What are sensory recptors?
Specialised endings of afferent neurons/seperate cells
List the functions of sensory receptors
- Detect & respond to physical/chemical stimuli
- Convert one form of energy into another (heat> electrical)
Many types of sensory receptors.
List what osmoreceptors, proprioceptors, polymodal receptors & nociceptors are
- Osmoreceptors: changes in osmotic pressure
- Proprioceptors: joint position sense
- Polymodal receptors: More than one type of stimulus
- Nociceptors: damage/distortion of tissues
List the 3 types of membrane-bound receptors
- Ligand-gated ion channel (have a channel through which ions move inside & outside of cells)
- GPCR receptors (act through both LGIC & enzyme-linked pathways)
- Kinase-linked receptors (transmembrane receptors, binding of extracellular ligand causes enzymatic activity on intracellular)
What are nuclear receptors and where are they located?
Non-membrane bound receptors, located in nucleus of cells
When are nuclear receptors activated?
When ligand molecules enter the nuclear membrane e.g. estradiol
Are GABAA inhibitory/excitatory?
inhibitory
What is an autoreceptor?
Receptor located on the neuron and bind a specific ligand released by that same neuron
Are autoreceptors inhibitory/excitatory?
inhibitory
List autoreceptors
- dopamine D2 receptor
- alpha 2a & alpha 2c adrenoreceptors
- M2 and M4 muscarinic receptors
- H3 receptors
