Label the parts of a neuron (9)
dendrite, soma, nucleus, axon hillock, axon, myelin, nodes of Ranvier, axon terminal, bouton
What chemicals originate inside a neuron at rest? (2)
1. A- which is a protein
2. K+ which is a potassium ion
What chemicals originate outside a neuron at rest? (2)
1. Na+ which is a sodium ion
2. Cl- which is a chlorine ion
What is the charge of a neuron at rest?
-70 millivolts
What is the charge of a neuron when it fires?
-55 millivolts
What is it called when the charge of a neuron changes from -55 to +30?
depolarization
What happens when the charge of a neuron reaches +30? (2)
1. Na+ gate closes
2. K+ gate opens
action potential
What is the exchange ratio of the sodium-potassium pump?
3 Na+ : 2 K+
Where are the sodium and potassium gates (ion channels) located? (2)
1. axon hillock
2. nodes of Ranvier (between the myelin sheaths)
What is it called when the charge of a neuron goes from +30 to -70?
repolarization
What is it called when the charge of a neuron goes from -70 to -90 to -70?
hyperpolarization
What happens when the charge of a neuron reaches -55? (2)
1. Na+ gates/channels open allowing sodium in
2. The neuron fires
How does local anesthesia work on a neuron?
It blocks sodium gates/channels from opening, preventing action potential.
How does hyponatremia impact neurons and a person's thinking?
The condition is a lack of sodium, which keeps action potentials from firing. It causes people to be very confused.
presynaptic neuron
neuron that delivers the synaptic transmission (in the form of neurotransmitter)
postsynaptic neuron
the neuron on the receiving end of the synapse (receives neurotransmitters)
Neurotransmitters are either...
excitatory or inhibitory
Where are neurotransmitters stored?
within synaptic vesicles of the bouton (axon terminal)
What happens when an action potential reaches the axon terminal (bouton)?
The bouton becomes receptive to Ca++ (calcium gates open), causing the neurotransmitter to spill out of the vesicles.
What can happen when a neurotransmitter is spilled into the synaptic cleft? (4)
1. Bind with receptors on the postsynaptic dendrites (which later separate)
2. Are taken back up into the presynaptic neuron
3. Diffuse away
4. Inactivated by chemical means
motor end plate
the point of synapse between a motor neuron and a muscle
CN I, olfactory function
sense of smell
CN II Optic Function
vision
Symptoms of problems with CN II Optic (1)
1. visual field cuts (contralateral)
CN III Oculomotor
motor adduction to the eyes
Symptoms of problems with CN III Oculomotor (4)
1. Problems keeping eyes looking in the same direction
2. Eyes are rolled outward (abducted)
3. Ptosis (drooping of eyelid)
4. Dilated and unreactive pupils
CN IV Trochlear
Innervates superior oblique muscle, which turns eye down & out
Symptoms of problems with CN IV Trochlear (1)
1. diplopia (double vision)
CN V Trigeminal - sensory (3)
1. touch to the whole face�forehead, cheeks, chin, mandible
2. touch within oral cavity--floor of mouth, anterior 2/3 tongue, teeth, & gums
3. touch to ear canal
CN V Trigeminal - motor (4)
1. depresses mandible (opens)
2. Tensor veli palatini- opens eustachian tube
3. Tensor tympani- dampens sound in middle ear
4. Suprahyoids- raise larynx
Symptoms of problems with CN V Trigeminal (sensory) (4)
1. Cannot feel touch to face
2. Cannot feel touch inside mouth
3. Drooling b/c unaware saliva is collecting inside mouth
4. Lesions on anterior 2/3 of tongue b/c of biting
Symptoms of problems with CN V Trigeminal (motor) (4)
1. Jaw crooked when opening
2. Inability to pop ears or middle ear infections
3. hyperacusis
4. unable to swallow safely or perform a pitch glide
CN VI Abducens (1)
Abducts the eye
Symptoms of problems with CN VI (2)
1. Eye rolls inward (internal strabismus)
2. Diplopia (double vision)
CN VII Facial (sensory) (1)
1. Taste to anterior 2/3 of tongue
CN VII Facial (motor) (3)
1. Muscles of face (forehead, eyebrows, close eyes, lips, cheeks)
2. Salivary glands
3. Stapedius muscle
Face�forehead/eyebrows
Wrinkle head, raise eyebrows, close eyes tightly and smile (inability to close eyelid)
Lips/cheek muscles�smile, pucker (stick
Symptoms of problems with CN VII Facial (sensory) (1)
1. Loss of taste (not due to smelling deficits)
Symptoms of problems with CN VII Facial (motor) (7)
1. Inability to raise eyebrows
2. Inability to close eyes tightly or produce tears
3. Inability to smile, pucker, or keep lips closed tightly
4. Cannot puff air into cheeks
5. Dry mouth
6. Hyperacusis
7. Bells palsy
CN VIII Vestibulocochlear (2)
1. hearing
2. balance
Symptoms of problems with CN VIII Vestibulocochlear (2)
1. loss of hearing (ipsilateral side)
2. vertigo & nystagmus