Module 6: Nervous System Flashcards
(126 cards)
1
Q
What does the nervous system consist of?
A
Central nervous system (CNS) and peripheral nervous system (PNS).
2
Q
What is the CNS made up of?
A
Brain and spinal cord
3
Q
What is the PNS made up of?
A
The nerves outside of the CNS that go to muscles and organs.
4
Q
What can the PNS be divided into?
A
Somatomotor (going to skeletal muscles) and autonomic (going to other organs) nervous systems.
5
Q
What are some fun facts about the brain (4)?
A
1) Contains between 10 to 100 billion cells and weighs about 1.5 kilos (3.5 lbs)
2) If all the cells were laid out end to end, they would stretch ~1000 km
3) You have more brain cells when you are born than you do right now
4) Action potentials can travel down nerve cells at up to 400 km/hr (240mph)
6
Q
What are the 2 cerebral hemispheres of the brain?
A
Left and right hemisphere
7
Q
What does the left hemisphere activate?
A
Sends signals to activate muscles on the right side of the body.
8
Q
Where does sensory information from the side side of the body travel?
A
To the left hemisphere.
9
Q
What is the brain stem made up of? What does it control?
A
It is made up of the midbrain, pons, and medulla oblongata. The brain stem controls some of the most basic functions of the body like heart rate and respiration.
10
Q
What is the medulla continuous with?
A
The spinal cord
11
Q
Where is the cerebellum located? What is it responsible for?
A
Located above the brain stem at the posterior region of the brain. It is responsible for coordinated movement.
12
Q
What does the diencephalon consist of?
A
The thalamus and hypothalamus
13
Q
What are the bumps and dips on the surface of the brain called? What is their purpose?
A
Gyri and sulci, respectively. These folds increase the surface area of the brain.
14
Q
What are the 4 lobes each cerebral hemisphere can be divided into?
A
Frontal, parietal, occipital, and temporal lobes.
15
Q
What are the cortices/areas of the frontal lobe? What are their functions?
A
Primary motor cortex, motor association area (premotor cortex), and prefrontal cortex. Primary motor cortex processes input from skeletal muscles throughout the body. The premotor and prefrontal cortex integrate movement information with other sensory inputs to generate perception of stimuli.
16
Q
What are the cortices/areas of the parietal lobe? What are their functions?
A
Primary somatosensory cortex and association areas. Primary somatosensory cortex receives input from the major sense organs (skin, musculoskeletal system, and taste buds). The association areas of the parietal lobe integrate sensory information with other association areas of the cortex to form meaningful perceptions.
17
Q
What is the function of the cerebellum? Where does it receive input from?
A
Processes sensory information and coordinates execution of movement in the body. As structure with largest number of neurons in the brain, it receives input from somatic receptors, receptors for equilibrium, and balance and motor neurons from the cortex.
18
Q
What are the cortices/areas of the temporal lobe? What are their functions?
A
Primary auditory cortex and auditory association areas, which receive and process signals from the auditory nerve and integrate them with other sensory inputs. Other portions of the temporal lobe are involved in olfaction (smell) and mediating short-term memory storage and recall.
19
Q
What are the cortices/areas of the occipital lobe?
A
Primary visual cortex and visual association areas. Primary visual cortex receives input directly from the optic nerve and the visual association areas further process visual information and integrate it with other sensory inputs.
20
Q
What is the corpus callosum? What is its purpose?
A
The corpus callosum is a dense bundle of nerve fibers. It serves as a pathway and connection between the two cerebral hemispheres. This connection allows the brain to integrate sensory and motor information from both sides of the body and to coordinate the whole-body movement and function.
21
Q
What is the function of the pituitary gland?
A
Primarily regulates other endocrine organs.
22
Q
What are the anterior and posterior pituitary made of?
A
1) Anterior: epithelial tissue of the pharynx
2) Posterior: neural tissue of the hypothalamus
23
Q
Which hormones do the anterior and posterior pituitary release?
A
1) Anterior: LH, FSH, ACTH, TSH, GH, and prolactin
2) Posterior: Vasopressin and oxytocin
24
Q
What regulates the pituitary gland’s function?
A
Hypothalamus
25
What is the function of pons?
Act as a relay station for transferring information between the cerebellum and the cerebral cortex. Also coordinates and controls breathing.
26
What is the function of the thalamus?
Receives sensory input as it travels from the spinal cord and integrates sensory information before sending it to the cortex.
27
What is the function of the hypothalamus?
Controls a variety of endocrine functions (body temperature, thirst, food intake, etc.), mainly through directing the release of hormones.
28
Where is the midbrain (or mesencephalon) located? What is its function?
Bridges the lower brainstem with the diencephalon above. Function is in controlling eye movements and it also exerts control over auditory and visual motor reflexes.
29
What is the function of the medulla?
Portion of the brain stem that has primary control over involuntary functions such breathing, blood pressure, and swallowing. Also, here is where the fibers from the corticospinal tract cross over to the opposite side of the spinal cord to innervate muscles on the opposite side of the body.
30
Where do the optic nerves meet? Where do they go from there?
Optic chiasma, where they cross over and continue as optic tracts to the lateral geniculate bodies of the thalamus. From there, axons extend to their respective hemispheres on the primary visual area of the occipital lobe.
31
How many cranial nerves does the brain stem incorporate?
9
32
Where are the primary motor cortices located?
Posterior end of the frontal lobe
33
What is the function of primary motor cortices? What happens when this region is electrically stimulated?
Process information relating to skeletal muscle movement. When electrically stimulated, causes specific muscle to contract.
34
Where is the primary somatosensory cortex located?
Anterior end of the parietal lobe
35
What is the function of the primary somatosensory cortex?
Receives sensory information from the opposite side of the body. Sensations of pain, temperature, touch, and vibration are processed here.
36
Where is the language and mathematical area located?
Most often located in the left hemisphere (even for left-handed people)
37
What is the function of the language and mathematical area?
Serves as general interpretive centre, enabling a person to understand visual and auditory information and generate written and spoken responses.
38
How many neurons and glial cells is the brain made up of?
10s of billions of neurons and glial cells. Glial cells make up about 90% if the brain.
39
What is the function of the glial cells?
Provide necessary environment for neurons to function properly.
40
What are the 3 basic types of neurons?
1) Bipolar
2) Unipolar
3) Multipolar
41
What are bipolar neurons? Where are they found?
Have 2 processes extending from the cell body. Specialized neurons found in retina of the eye.
42
What are unipolar neurons? Where are they found? What is generally their function?
Have 1 process extending from the cell body. Located in the peripheral nerves outside the CNS and are generally sensory in nature, transmitting signals to and from spinal cord.
43
What are multipolar neurons? Where are they found?
Have many branching dendrites and one axon. Most common in the CNS.
44
What is the function of glial cells? How do they regulate this function?
Maintain delicate internal environment of the CNS. They also regulate nutrients and specific interstitial environment of brain. They perform this function by regulating passage of substances between the blood and the brain's interstitial space.
45
What are the types of glial cells?
Several types, including astrocytes, microglia, and oligodendrocytes (which produce myelin).
46
What is the language of the nervous system?
Action potentials
47
How does your brain know if you have a light object in your hand or heavy object? What is neural coding?
Special receptors detect pressure on the skin and send action potentials to the brain. Weight of the object is "coded" into the action potential. Heavier object, more action potentials per second. This is called neural coding.
48
What does the axon terminal of the presynaptic cell contain?
1) Voltage-gated calcium ion channels
2) Synaptic vesicles containing the neurotransmitter
3) Mitochondria
49
What does the postsynaptic cell contain?
1) Chemical receptors
2) Chemically gated ion channels (also called ligand-gated ion channels). These open when a chemical (neurotransmitter) attaches to them.
50
What does an excitatory response caused by a neurotransmitter lead to?
Leads to depolarization of the postsynaptic cell. If the depolarization is strong enough, it may fire an action potential.
51
What does an inhibitory response caused by a neurotransmitter lead to?
Leads to hyperpolarization of the postsynaptic membrane, making it harder to generate action potential.
52
What are the four different groups of neurotransmitters?
1) Acetylcholine (ACh)
2) Biogenic Amines
3) Amino Acids
4) Neuropeptides
53
List some examples of biogenic amines.
Catecholamines: dopamine, norepinephrine, epinephrine
54
List some examples of amino acids.
1) Excitatory: glutamate, aspartate
| 2) Inhibitory: gamma-amino-butyric acid (GABA), glycine
55
List some examples of neuropeptides.
Endogenous opioids (e.g. endorphin), Vasoactive Intestinal Peptide (VIP)
56
What is the difference between neuromuscular junction (NMJ) and the chemical synapse?
At the NMJ, a SINGLE action potential in motor neuron produced a SINGLE action potential in muscle cell, causing it to contract. At the chemical synapse, a single action potential on a presynaptic neuron will NOT produce an action potential on a postsynaptic neuron.
57
What is an EPSP?
Excitatory postsynaptic potential. This is a local depolarization of the membrane when an excitatory neurotransmitter causes chemically gated channels to open and select for only positive ions (Na2+). An EPSP is also called a graded potential.
58
Why is no action potential fired after influx of Na+ depolarizes region of the dendrite?
Because there are no voltage-gated channels on the dendrites or cell body of the neuron. Voltage-gated channels are essential for production of action potential.
59
Where does an action potential begin?
Begins at the axon hillock where there is the highest concentration of voltage-gated channels.
60
How does the EPSP generate an action potential?
EPSP must depolarize the axon hillock in order for an action potential to be fired. EPSP gets smaller with distance, so in order to cause depolarization to open voltage-gated Na+ channels in the axon hillock, the positive current of EPSP must be strong enough to spread all the way from synapse to axon hillock.
61
What are the 2 ways the strength of an EPSP can be increased?
Spatial summation of EPSPs and temporal summation of EPSPs.
62
Explain spatial summation.
Spatial summation of EPSPs is the additive effect produced by many EPSPs that have been generated at many different synapses on the same postsynaptic neuron at the same time.
63
Explain temporal summation.
Temporal summation of EPSPs is the additive effect produced by many EPSPs that have been generated at the same synapse by a series of high-frequency action potentials on the presynaptic neurons.
64
Distinguish between EPSP and action potential.
EPSP occurs only on the dendrites and cell body and will decrease with time and distance from its point of origin. Action potential is all-or-nothing and is usually only found on the axon. Also, EPSPs can be added one on top of the other while the action potential cannot.
65
How do inhibitory neurotransmitters produce IPSPs?
Inhibitory neurotransmitters produce hyperpolarization by opening different chemically gated channels. These channels (depending on the type of neurotransmitter) will either let chloride ions (Cl-) into the cell or let potassium ions (K+) out. This makes the membrane potential more negative, creating a hyperpolarization. This hyperpolarization is called an inhibitory postsynaptic potential (IPSP).
66
Can spatial and temporal summation occur with IPSPs?
Yes, but rather than producing stronger depolarizations, summation of IPSPs will produce larger hyperpolarizations.
67
What is synaptic integration?
Interaction of many IPSPs and EPSPs. Cell may fire an action potential if there are many more EPSPs than IPSPs. But if the number of IPSPs outnumber the EPSPs, the cell will be shut off. This battle of postsynaptic potential is called synaptic integration.
68
What does the motor system include?
Supplementary motor area, premotor area, primary motor cortex area, basal ganglia, various spinal pathways, motor nerves going to the muscles, and muscle receptors.
69
What is the function of the premotor cortex?
Premotor cortex develops the appropriate strategy for the movements necessary to perform an action, such as picking up a cup of coffee, after receiving signals from the prefrontal cortex.
70
What happened when people with damage to the premotor cortex were presented with food inside glass box with small opening in the side?
They did not reach through the opening, but aimed directly at the food and bumped their hand into the shield. They could not select the appropriate strategy to reach the food.
71
What is the function of the supplementary cortex? What is this area particularly important for?
Now that the premotor cortex has developed the appropriate sequence of muscle contractions, that information travels to the supplementary cortex. The supplementary cortex then programs the motor sequences necessary to perform the action. This area is particularly important for programming the muscles to open and close the hand and for repetitious movements like typing, since these can be complex movements. The more complex or repetitious the movement, the more the supplementary motor area is needed.
72
What happens when people with damage to the supplementary cortex try to pick up a peanut in a small well.
Their hand assumes an awkward position and they are unable to orient their hands and digits appropriately.
73
What is the function of the primary motor cortex? Where is it located?
To activate neurons that will essentially activate the appropriate muscles. It is located on the precentral gyrus in the frontal lobe and is arranged in a very specific manner.
74
What is the motor homunculus?
Topographical representation of the body on the surface of the primary motor cortex. As if the entire body was projected onto the surface like a map.
75
What is the arrangement of the motor homunculus?
Moving from medial to lateral: foot, ankle, knee, thigh, trunk, shoulder, elbow, wrist, hand, lots of room for fingers, face, lips, jaw, and tongue.
76
What is the corticospinal tract?
Major motor pathway from the primary motor cortex to the motor neurons that innervate the muscle cells.
77
What is the corticospinal tract made up of? Where is it located?
Made up of millions of axons whose cell bodies lie in the primary motor cortex. The tract begins in the motor cortex and descends down to the brain stem.
78
Where are nerves located in the medulla?
80% of all the nerve fibers cross to the contralateral (opposite) side of the body, while 20% remain on the same or ipsilateral side.
79
Where do the fibers from the brain stem go?
The fibers enter the spinal cord and continue their descent. Once they reach the level of the spinal cord where they synapse with the motor neurons, the fibers previously on the ipsilateral side cross to the contralateral side.
80
What is proprioception? How is this possible?
The "muscle sense" of the brain to be aware of the positions of the limbs and the extent of each muscle contraction at all times. This ability is possible because of the presence of special receptors in the muscle which send signals back to the brain.
81
What are the special receptors that help proprioception happen?
1) Muscle spindles, which detect muscle stretch, muscle length, and rate of change of muscle length.
2) Golgi tendon organs, which detect muscle tension.
82
What are muscle spindles? Where are they located? What do they consist of?
These spindles are sensory organs that sense the length and stretch of the muscle. They are located inside a whole muscle and adjacent to the real contractile muscle cells (called extrafusal fibers here). The muscle spindle consists of a series of intrafusal muscle fibers, a central sensory region, two sets of gamma motor neurons that activate the intrafusal fibers, and a sensory neuron that originates in the sensory region.
83
How do muscle spindles help proprioception happen?
When the whole muscle stretches, the sensory region of the spindles also stretches. This sensory region, which is sensitive to changes in shape, depolarizes and triggers action potentials in the sensory nerve, sending signals back to the brain. The more stretched the muscle, the more stretched the sensory region, the more it is depolarized, and the more action potentials sent back to the CNS. The brain receives this information and can interpret how stretched the muscle is. Since the muscle is attached to a limb, it will also "know" the position of the limb in space.
84
What does the central sensory region of the muscle spindle lack?
Myofibrils.
85
Signals sent to a whole muscle (e.g. biceps) causing it to contract travel from the spinal cord through which neurons?
Alpha motor neurons.
86
What happens when signals travel to the muscle through alpha motor neurons?
Only extrafusal muscle fibers would contract. Meanwhile, the intrafusal muscle fibers within the muscle spindles would go slack and information from the muscle spindle would stop.
87
What is needed to keep muscle spindles operating (in their sensitive range) during muscle contraction?
To keep muscle spindles operating, commands are simultaneously sent through gamma motor neurons to the intrafusal fibers. This causes contraction of the intrafusal fibers, which maintains stretch on the central region (where the stretch receptors are located) at the same rate as the whole muscle.
88
What is the purpose of alpha-gamma coactivation?
During a muscle contraction, alpha-gamma coactivation ensures that the muscle spindles continue to send information to the brain about muscle and limb position.
89
What happens with alpha motor nerve activation only? What happens with alpha-gamma coactivation?
a) No proprioceptive information travelling to brain.
| b) Proprioceptive information continues to travel to brain.
90
What is the reflex arc and what does it require?
A reflex arc is the most basic type of integrated neural activity. It requires a sensory receptor, a sensory (or afferent) neuron, one or more synapses (generally in the spinal cord), and may contain one or more interneurons. It also contains a motor (or efferent) neuron and an effector organ (e.g. muscle).
91
Describe the activity of the reflex arc.
The activity begins in the receptor with a receptor potential that produces an action potential in the afferent neuron. The action potential enters the spinal cord where it will produce action potentials on the interneurons and, eventually, on the efferent neuron. The efferent neuron will activate an effector (e.g. muscle).
92
Does the reflex arc require any output by the brain to cause the effector (e.g. muscle) to contract?
No, it does not.
93
List the events of the stretch reflex (an example of a reflex arc).
1) Tapping the tendon produces a very small stretch of the quadriceps muscle.
2) Stretching the muscle also stretches the muscle spindles.
3) Muscle spindles trigger action potentials in the afferent neuron that enters the spinal cord.
4) The motor nerve of the quadriceps is activated, while the muscles of the hamstring are inhibited.
5) Quadriceps contract and the hamstring relaxes; lower leg kicks out.
94
How many neurons does the cerebellum contain?
More neurons than the rest of the brain combined.
95
What is the cerebellum's function?
Its functions include contributing to the generation of accurate limb movements, correcting ongoing movements, and modifying the strength of some reflexes. It is also involved with classical Pavlovian conditioning, the learning of new muscle movements, and the vestibular occular reflex (VOR) - one of our important eye movements.
96
From where must the cerebellum receive information in order to assist in making accurate limb movements and correcting ongoing movement?
It must receive the same information from the motor cortex that is travelling out to the muscles being activated and it must receive information dealing with the position of limbs in space (proprioception).
97
How does the cerebellum analyze movements and make sure they are correct?
The cerebellum compares the actual signal from the brain with the proprioceptive information from the muscle itself. As a result, it can make sure that the muscle is actually doing what it's supposed to do. If the movement is not what it should be, the cerebellum will modify the signals from the primary motor cortex.
98
Which parts of the brain receives proprioceptive information?
Proprioceptive information from muscle spindles travels to cerebellum and somatosensory cortex.
99
What is the limbic system composed of? Where is it located?
Hypothalamus, amygdala, hippocampus, cingulate complex, and septum. Most of these structures are found deep within the brain and form a ring around the brain stem.
100
What is the key function of the limbic system?
The key function is to link the higher thought processes of the brain with the more primitive emotional responses of fear, rage, and sexual pleasure. It is also involved with behaviours dealing with feeding, drinking, pain, motivation, and learning. Overall, the limbic system allows us to respond correctly to changes in our environment.
101
Where is the hypothalamus located?
At the base of the brain, just anterior to the brain stem.
102
What are the functions of the hypothalamus? How does it perform these functions?
Major functions include temperature control, body water regulation, regulation of food intake, cardiovascular regulation, regulation of the circadian clock, coordination of emotional behaviours, and control of hormones released from the anterior and posterior pituitary gland. The hypothalamus performs most of these functions through negative feedback control.
103
How does the hypothalamus control body temperature?
If the body temperature rises from 37 to 39 degrees C (or 98.6 to 102.2 degrees F), regions in the hypothalamus would detect this change and initiate mechanisms to return temperature to normal. These mechanisms include diverting blood to the skin and sweating, both of which would lead to cooling of the skin and body temperature returning to normal.
104
Where is the pituitary gland located? What is its function?
It is roughly the size of a large pea and hangs below the hypothalamus. It is very important in the control and release of hormones and is closely regulated by the hypothalamus.
105
What is the difference between the the autonomic nervous system (ANS) and the somatomotor system?
Unlike the somatomotor system, the ANS is not under voluntary control.
106
What does the autonomic nervous system control?
The ANS controls heart rate, the pupils in the eye, smooth muscle in walls of arteries and veins, glands like the adrenals, and many other organs.
107
What are the two divisions of the ANS?
The sympathetic (SYN) and parasympathetic (PSYN) nervous systems.
108
What is the sympathetic nervous system (SYN) responsible for?
The SYN is responsible for activating body functions involved in fight or flight situations. When activated, it will increase your heart rate and blood pressure, dilate your airways and blood vessels to the muscles, and shut down your digestive system.
109
What is the parasympathetic nervous system (PSYN) responsible for?
The PSYN is responsible for storage and conservation of energy -- functions associated with rest and relaxation. This system would slow down the heart rate and lower blood pressure.
110
Which organ only receives input from the SYN?
The adrenal only receives input from the SYN.
111
Where do nerves of the SYN exit?
Nerves of the SYN exist the spinal cord in the thoracic and lumbar (central) regions of the cord. These preganglionic neurons will synapse in ganglia onto a second postganglionic nerve that will travel to the effector/travel organ of interest.
112
Where do nerves of the PSYN exit?
Nerves of the PSYN exit at the brain stem and the very lower sacral region of the spinal cord. These preganglionic nerves will synapse onto a postganglionic nerve very near the effector organ of interest. This nerve will then synapse onto the target organ.
113
What neurotransmitter is released by the preganglionic neurons that leave the spinal cord in both the SYN and PSYN?
The preganglionic neurons that leave the spinal cord in both the SYN and PSYN release the neurotransmitter acetylcholine (ACh). The ACh will then stimulate the second postganglionic neuron.
114
Why are the axons of the PSYN preganglionic fibers longer?
The axons are longer since the synapse occurs closer to the effector organ.
115
What neurotransmitter is released by the sympathetic postganglionic neuron?
The neurotransmitter released by the sympathetic postganglionic neuron onto the target organ is usually norepinephrine (NE), but in some cases it is ACh.
116
What neurotransmitter is released by the parasympathetic postganglionic neuron?
The neurotransmitter released by the parasympathetic postganglionic neuron is always ACh.
117
What is the response of the ANS on the adipose (fat) tissues?
Parasympathetic response: No effect
Sympathetic response: Stimulates lipolysis (fat breakdown), which increases free fatty acids in the blood to be used as a source of energy.
118
What is the response of the ANS on the adrenal glands?
Parasympathetic response: No effect
Sympathetic response: Increased secretion of epinephrine (adrenaline), which increases cardiac output.
119
What is the response of the ANS on the lungs?
Parasympathetic response: Bronchioles constrict
Sympathetic response: Bronchioles dilate, which lets more into alveoli.
120
What is the response of the ANS on the salivary glands?
Parasympathetic response: Watery saliva
Sympathetic response: Thick mucus -> dry mouth
121
What is the response of the ANS on the pupils?
Parasympathetic response: Constrict
Sympathetic response: Dilate, which lets more light in
122
What is the response of the ANS on the heart?
Parasympathetic response: Heart rate slows
Sympathetic response: Heart rate and force of contraction increase -> cardiac output increases
123
What is the response of the ANS on the kidneys?
Parasympathetic response: No effect
Sympathetic response: Increased secretion of renin, which stimulates RAS to increase blood pressure
124
What is the response of the ANS on the bladder?
Parasympathetic response: Release of urine
Sympathetic response: Retention of urine
125
What is the response of the ANS on the digestive system?
Parasympathetic response: Increased activity of digestive tract - motility and enzyme secretions
Sympathetic response: Decreased activity of digestive tract - motility and enzyme secretions -> blood flow diverted to working muscles
126
What is the response of the ANS on the blood vessels, arterioles, and veins?
Parasympathetic response: No significant changes
Sympathetic response: Constriction in non-exercising organs and dilation in skeletal and cardiac muscle -> increase blood flow to working muscles
