Exam 2: Neuron Stuctures/Functions Flashcards
Which ends of a neuron receive information?
Dendrites
What is another name for the cell body?
Soma
Is there myelination on the dendrites?
Not much if any
Which end of a neuron sends information?
Axon
T/F Axons are not myelinated
False
What is the node of Ranvier?
The nodes between the myelin sheath where sodium can jump from one to another
Is the end of the axon presynaptic or postsynaptic?
Presynaptic
Where is the axon hillock?
The beginning part of the axon
Which neurotransmitter is used at the axon hillock?
GABA
What does GABA do to the cell?
Increases chloride permeability into the area of the neuron, suppressing activity or putting on the “brakes”
What happens if we ignore GABA?
We will have over-the-top crazy levels of activity including seizures
T/F Postsynaptic neural connections can be excitatory and inhibitory
True
Where are excitatory neural connections found?
In areas where the dendrites are
Are dendrites more positive or negative than the average membrane potential?
Positive
Are inhibitory connections more positive or negative than the average membrane potential?
Negative
What are the supporting cells of the nervous system?
Astrocytes
Ependymal Cells
Oligodendrocytes
Schwann Cells
Microglia
Which supporting cells are the smallest?
Microglia
What is the most abundant type of glial cell?
Astrocyte
What do astrocytes do?
They wrap around the true part of the blood brain barrier and provide a supporting structure. Astrocytes are helpful with maintaining electrolyte balance and repairing neurons after any neuronal injury.
Which nervous system do astrocytes support?
Central nervous system
What are ependymal cells?
Ependymal cells contain cilia which helps produce CSF and move the CSF to ensure it circulates around the brain and spinal cord in waves
What are microglia cells?
Microglia cells are cells that act as macrophages. They keep the area around the CNS clean and free of debris
What are the 4 types of neurons? (Hint: Schmidt said to only worry about 3 but there’s 4 in the PPT)
- Multipolar
- Pseudounipolar
- Bipolar
- True Unipolar (NOT WORTH EXPLAINING) - not found in humans
What are multipolar neurons?
Multipolar neurons have dendrites and connections with other parts of the CNS and play a role in decision making. They take lots of information and make a decision on whether to fire an action potential or not
Ex: Motor neurons or pain neurons that tell us to pull away from something painful
Think: decision maker
What are bipolar neurons?
Bipolar neurons are neurons that contain 2 projections and are designed to sense and pass along information as an action potential to another area of the brain
Think: Special sensory
Where do we find bipolar neurons?
Optic nerve; photoreceptors in the retina send messages through the optic nerve and create specialize senses
What are pseudounipolar neurons?
Neurons that make up the majority of sensory cells; the cell body (which mostly builds proteins and maintains things) does not make decisions and instead, it relays information from the dendrite to the axon and passes the information to the rest of the nervous system.
What are somatic sensory receptors?
Specialized structures designed to be good at sensing certain things
Somatic= can consciously sense, we are aware of it
Ex: Pain sensors, pressure sensors, etc.
What do free nerve endings do?
Sense Pain
What is another term for free nerve ending?
Nociceptor
Name 3 pressure sensors
Pacinian corpuscle, Meissner’s corpuscle, Golgi Tendon
What is a muscle spindle?
Stretch sensor that is woven into skeletal muscle that can confirm muscle contraction
Adaptation
A sensor’s ability to reset its baseline with prolonged exposure to a stimulus
Give an example of a a sensor that adapts to changing conditions
Baroreceptors readjusting to high blood pressure
What receptors undergo reverse adaptation? What does this mean?
Pain Receptors
The longer the pain is sensed, the worse the pain will feel
Another word for reverse adaptation
Sensitization
Superior/ inferior
Head/ feet
Dorsal/ Ventral
Back/ Front
Anterior Posterior
Front/ Back
Medial/ Lateral
Midline/ out to the side
Rostral/ Caudal
Front and upper/ Lower and bottom
Ex: on a bird the beak is Rostral and the tail is Caudal
Distal/ Proximal
Further from CNS/ Closer to CNS
Superficial/deep
How close to the skin surface
Sagittal Plane
Separates left from right
Coronal
Separates anterior from posterior
Horizontal
Separates superior from inferior
ex: magician would split their assistant here
Oblique
Separates at an odd angle
Major components of the CNS
Brain
Brainstem
Spinal Cord
Major divisions of the brain
Telencephalon
Diencephalon
(Waxman Table 1-1)
Major subdivisions of the brain stem
Midbrain (mecencephalon)
Pons
Medulla Oblongata
Function and location of Thalamus
“Relay center” in the middle of the brain, sends info where it needs to go
Function of the hypothalamus
Sensory control
Ex: temperature sensors, infection sensors
Four lobes of the brain
Frontal- thinking
Occipital- visual cortex
Parietal- sensory processing
Temporal- auditory processing
Separates the frontal lobe from parietal lobe
Central Sulcus
Separates the temporal lobe from parietal and frontal
Temporolateral Sulcus
Runs from the front of the brain to the back of the brain and separates the left and right hemispheres
Longitudinal Fissure
Major function of the corpus callosum
-Communication between the left and right sides of the brain
-highly myelinated
Part of the brain for language comprehension
-Wernicke’s Area in the temporal lobe
-Sensory function
Part of the brain involving word formation
-Broca’s area in the frontal lobe
-Motor function
Where is the primary motor cortex?
Pre Central Gyrus- Just anterior to the central sulcus (most posterior portion of frontal lobe)
Emotional centers of the brain
-Limbic System
-found in various areas of the brain
Grey matter
-Contains less myelin
- Decision making centers
-Cell bodies make it show up darker than white matter
White matter
-Contain much more myelin
- Transmitting centers
What is a benefit of having the grey matter on the superficial portion of the brain?
Close to the brain vasculature
Area in the grey matter that connects the left and right side of the spinal cord
Lamina 10
Area of the white matter that provides cross over between left and right sides of the spinal cord
Anterior White Commissure
Why is the anterior median fissure wider than the posterior?
The anterior spinal artery sits in the groove whereas the posterior does not have to make room for vasculature
What structure does CSF move down the spinal cord in?
Central Canal
Where information enters the spinal cord
-Sensory information goes into the dorsal horn (posterior)
-Cell bodies here have sensory function
Where motor function leaves the spinal cord
-Ventral Horn (anterior)
- Cell bodies here have motor function
What arteries supply the spinal cord arteries?
-Intercostal arteries
-Feed vessels near brain stem and upper neck
How is spinal cord blood supply regulated?
Autoregulation
How are the posterior spinal arteries oriented?
To either side of the posterior, one on the left and one on the right (2 total)
When info flows into the spinal cord, how does the signal travel?
Enters horizontally through the rootlets, interacts with cell bodies in the dorsal horns (decision making area), crosses over to ascending (white) columns so it can flow up to the brain
The anterior and posterior rootlets come together to form
Anterior and posterior roots that merge into the spinal nerve
What makes the posterior root unique?
The spinal ganglion present due to collection of cell bodies (pseudo unipolar)
Where are the anterior root cell bodies?
in the ventral horn
How many cervical vertebra and corresponding spinal nerves are there?
-7 vertera
- 8 sets of nerves
Where do C1 nerves exit the vertebra?
ABOVE C1 vertebra
How many thoracic vertebra and sets of spinal nerves are there?
12
How many lumbar vertebra and sets of spinal nerves?
5
How many sacral vertebra and sets of spinal nerves are there?
- At birth there are 5 separate vertebra that later fuse into 1
-5 sets of nerves
How many coccygeal nerves are there?
1 set
Dermatome
Are of the body that each spinal nerve is specialized to innervate
Lordosis
-Anterior curvature
- Physiologic in cervial and lumbar spine
Kyphosis
-Posterior curvature
-Physiologic in thoracic and coccyx
Scoliosis
Pathologic lateral curvature of the spine
Weight supporting structure of the spine
Vertebral body
