AAP Nervous System 2 Flashcards
1
Q
What is the voltage across the neuronal membrane when a neuron is at rest?
A
- -60 to -70 mV
- this is called resting membrane potential
2
Q
Distribution of ions across cell membrane
A
- the voltage difference between the 2 sides of the cell mbn in a neuron is largely due to distribution of different ions on the two sides of the membrane
- in the resting state, the outside has more positive charges
- the inside has more negative charges
3
Q
What is the membrane current?
A
- membrane current is known as the flow of ions (electrical charge) across the membrane
- there are ion channels located at the cell membrane
- ions such as sodium & potassium flow through the ion channels
4
Q
Types of ion channels
A
- Voltage-gated ion channels: open/close in response to the change in membrane potential(voltage)
- Ligand-gated ion channels: open/close in response to chemical binding (e.g. hormone, neurotransmitter)
5
Q
Depolarization
A
- redistribution/flow of ions across the cell membrane will increase/decrease the membrane potential
- the increase in the membrane potential (the inside becomes less negative, e.g. -70 becomes -20) is called depolarization
- depolarization leads to the activation of the neuron which increases the probability to fire
6
Q
Hyperpolarization
A
- decrease in membrane potential )the inside becomes more negative) is called hyperpolarization
- hyperpolarization leads to the inhibition of the neuron which decreases the probability to fire
7
Q
Action Potential
A
- depolarized neurons generate the electrical impulse travelling along the axon which is known as action potential or “spike”
- AP is mainly due to the flow of NA+ into the cells (through voltage-gated sodium channels)
8
Q
Repolarization
A
- the return of membrane potential from depolarized stage towards resting membrane potential (potassium ions flow out)
9
Q
What are the two major types of voltage-gated channels involved in the generation of action potential?
A
- sodium channels
- potassium channels
10
Q
Conduction of action potential along the axon
A
- As the axon is wrapped by myelin intermittently, the sodium channels are blocked by the myelin sheath
- therefore, action potential can only be generated in the gaps between the adjacent myelin sheath
- the gap between the myelin sheath is known as the nodes of Ranvier which is the area that the ion channels are not covered
- The ions (sodium and potassium) can flow through the membrane in the areas
- new action potential is always generated at the Ranvier node
- conduction of action potential along an axon is like “jumping” from one node of Ranvier to the next
11
Q
Conduction of action potential between the neurons (at a synapse)
A
- when an action potential reaches the axon terminal, neurotransmitter (NT) is released from the axon terminal
- NT is a molecule generated by a neuron
- the receptors on the dendrite of the next neuron are stimulated by the NT, leading to the excitation of the next neuron
- a new action potential would be generated in the next neuron
12
Q
What are the types of neurotransmitters?
A
- excitatory neurotransmitters: usually cause an influx of sodium so that the neurons will be depolarized (inside of cell more positive)
- inhibitory neurotransmitters: cause entry of chloride ions which leads to hyperpolarization (make inside of cell more negative)
13
Q
Common neurotransmitters that are excitatory NT
A
- Acetylcholine
- Catecholamines (Norepinephrine & Epinephrine)
- Dopamine
- Serotonin (5-HT)
- Glutamate
14
Q
Common inhibitory NTs
A
- gamma-aminobutyric acid (GABA)
- glycine
15
Q
What are the regions of the brain?
A
- cerebrum (cerebrum cortex)
- Diencephalon: thalamus & hypothalamus
- Brain stem: Midbrain, Pons, Medulla oblongata
- Cerebellum
16
Q
What is the brain ventricle?
A
- empty space below the cerebrum
- filled by fluid known as Cranial Spinal Fluid (CSF)
- continue at the back with spinal channel/spinal cavity
17
Q
How many pairs of spinal nerves are there in dogs?
A
-36 pairs of spinal nerves
18
Q
Cortex
A
- highly developed into different functional areas, especially in higher species
- the surface area of cortex in higher species is much larger than that of the lower species due to folds/gyrus
19
Q
What are the different areas of the cortex that have different functions?
A
- sensory areas: responsible for receiving and processing sensory information coming from the body
- motor areas: initiates/coordinates motor activity in the muscles
- auditory areas: receives hearing information from the ears
- visual areas: receive visual information from eyes
- higher functional areas (e.g. prefrontal cortex): solving complex tasks
20
Q
What does the cerebrum do?
A
- controls most key functions in the body: conscious activities, intelligence, memory, language, muscle movement
21
Q
What does the cerebellum do?
A
- area of the brain responsible for coordination of movement, balance, posture
- if the cerebellum is injured, movements become jerky
22
Q
What is the brain stem?
A
- consists of the medulla oblongata, pons and midbrain
- brain stem is responsible for vital life functions such as breathing, heartbeat, and blood pressure
- many of the cranial nerve pairs originate from the brain stem
23
Q
What is the diencephalon?
A
- key components below the cortex
- relay station between brain stem and cerebrum
- thalamus: acts as a relay station for sensory inputs to the cerebrum
- hypothalamus: interface between the nervous system and the endocrine system
24
Q
What are meninges?
A
- coverings of the brain and spinal cord
- three layers
- dura mater (surface): double-layered external covering below the bone of skull
- Arachnoid layer: middle web-like layer
- Pia mater: internal layer (blue)
25
Q
Cerebrospinal fluid (CSF)
A
- the composition of CSF is similar to blood plasma
- circulated in brain ventricles and spinal cavity in arachnoid space (space below the arachnoid layer)
26
Q
What are the functions of CSF?
A
- primary function is to cushion the brain within the skull and serve as a shock absorber for the central nervous system
- also circulates nutrients and chemicals, removes waste products from the brain and spinal cord
27
Q
How many cranial nerve pairs are there?
A
- 12 nerve pairs that originate directly from the brain stem
- each nerve may contain axons of motor neurons, axons of sensory neurons, or combinations of both
28
Q
State the names and the functions of the cranial nerves.
A
I: olfactory --> smell II: optic --> sight III: oculomotor --> moves eye, pupil IV: trochlear --> moves eye V: trigeminal --> face sensation VI: abducens --> moves eye VII: facial --> moves face, salivate VIII: vestibulocochlear --> hearing, balance IX: glossopharyngeal --> taste, swallow X: vagus --> heart rate, digestion XI: accessory --> moves head XII: hypoglossal --> moves tongue
29
Q
What is a reflex?
A
- an involuntary and nearly instantaneous movement/response to a stimulus
- a reflex is made possible by neural pathways called reflect arcs which are organized at the spinal cord level without involvement of brain
- protects the body against potential damage by its fast response, due to the short neuronal circuit involved
30
Q
Neuronal circuit involved in reflex
A
- sensory neuron forward sensory information to spinal cord via dorsal nerve root
- motor neurons located in spinal cord forward information to muscle (effectors)
31
Q
What does a reflex arc consist of?
A
- receptor (nerve endings)
- sensory neuron
- spinal cord
- motor neuron
- effector (muscles pulling back the hand
32
Q
Examples of relfex
A
- patella reflex: tapping the patella (ligament) results in extension of the leg due to muscle contraction
- Corneal reflex: gentle touch of the cornea results in reflex closure of the eyelids
- pupillary light reflex: constriction of pupil in response to shining light
33
Q
Review and identify pictures in anki
A
all done!
