Nervous System Flashcards
1
Q
What two systems are the Nervous System divided into?
A
PNS - Peripheral Nervous System
CNS - Central Nervous System
2
Q
What is the role of the PNS?
A
Gather central information and then relay this information to intraneurons (CNS) and then send signal to muscles and glands for a voluntary (somatic) or involuntary (autonomic) response.
3
Q
What is another word for voluntary?
A
Somatic
4
Q
What is another word for involuntary?
A
Autonomic
5
Q
What are some key characteristics of the somatic system?
Myelinated or unmyelinated?
A
-Largely under voluntary control
-Sensory neurons carry info about the external environment inward from receptors in the skin, tendons, and skeletal muscles
-Motor neurons carry information to skeletal muscles
-Are all myelinated
6
Q
How are spinal nerves named?
A
Based on the region of the body where they are located; Cervical, Lumbral, Sacral
7
Q
What are some roles of the autonomic system?
A
- Homeostasis is maintained in the body by the often antagonistic actions of the sympathetic and parasympathetic nervous systems.
- The sympathetic nervous system prepares the body for flight or fight (ex: increasing heart rate), while the parasympathetic system returns organs to a resting state (ex: lowering heart rate)
- Depending on your environment, certain structures in your body react differently. Imagine being chased by a tiger vs. relaxing on the couch
8
Q
What is the role of the sympathetic nervous system?
What neurotransmitter(s) is released?
A
Fight or Flight
- Acts when the body is under stress
- Release the neurotransmitter norepinephrine
- Also triggers adrenal gland to release epinephrine and norepinephrine
9
Q
What is norepinephrine?
A
Has an excitatory effect on it’s target muscles
10
Q
What is epinephrine and it’s purpose?
A
Adrenaline - it triggers stress releases
11
Q
What is the role of the parasympathetic nervous system?
What neurotransimtter(s) is relased?
A
Rest and Digest
- Acts to restore and conserve energy
- Uses the neurotransmitter acetylcholine to control organ responses
12
Q
What is the basic functional unit of the nervous system?
A
Neuron
13
Q
What three parts does the Neuron consist of?
A
- Cell body
- Dendrites
- Axons
14
Q
What is the function of a nueron?
A
Transmit information
15
Q
Parts of Neuron: Cell Body
A
Contains nucleus and two extensions
16
Q
Parts of Neuron: Dendrities
A
Shorter, more numerous, receive information
17
Q
Parts of Neuron: Axons
A
Single, long fibers which conduct impulses away from the cell body; send information
18
Q
What is a Schwann Cell?
A
Axons usually contain a series of enclosing cells called Schwann cells.
19
Q
What is the purpose of Schwann Cells?
A
The presence of the Schwann Cells increases the speed of transmission because it limits the loss of chemicals.
20
Q
Long projections of a neuron conduct the electrical impulse; what is this electrical impulse called?
A
Action Potential
21
Q
What are gaps between the Schwann cells called?
A
Nodes of Ranvier
22
Q
What is the purpose of the Nodes of Ranvier
A
Speed up the impulse
23
Q
What is the speed of an impulse proportionate to?
A
The diameter of the axon
24
Q
If an axon has a greater diameter what happens to the speed of an impulse?
A
In increases
25
Do myelinated axons or unmyelinated axons conduct faster?
Myelinated axons conduct faster
26
What does Myelinated refer to?
It refers to white matter - myelinated axons conduct faster because the myelin sheath increases speed
27
What are collections of Schwann cells known as?
Myelin Sheath
28
What does Unmyelinated refer to?
Grey Matter - Lacks a Myelin Sheath
29
What are the three types of Neuron?
Sensory Neurons
Interneurons
Motor Neurons
30
What is the purpose of Sensory Neurons?
Gather information from receptors and pass onto interneurons (CNS)
31
What is the purpose of interneurons?
Process information and send to motor neurons.
32
What is the purpose of Motor Neurons?
Carry signals from CNS back to the body - organs, tissue, ect.
33
How do Sensory Neurons gather information?
They gather information from receptors (senses) and transmit impulses to the CNS (Brain and Spinal cord)
34
What do Interneurons act as?
They act as a link between sensory and motor neurons; process incoming info and relay outgoing info
35
What do motor neurons do?
Transmit information from CNS to muscles glands and other organs
36
What is the Nerve impulse pathway?
1. Sensory receptors gather information
2. Information gathered from sensory receptors is passed onto interneurons in the CNS
3. Motor neurons then transmit information from CNS to muscles, glands, and other organs (effectors)
37
What is a reflex ark?
Only includes a few neurons.
38
What is a reflex behaviour?
Autonomic, subconscious response.
39
What is an action potential?
Is an electrochemical message caused by the movement of ions (Potassium and sodium) through the cell membrane.
40
What is resting potential?
| How is it maintained?
Resting potential is the electrical charge difference across a neuron's membrane when it is not actively transmitting a signal, typically around -70 mV. This is maintained by the sodium-potassium pump, which pumps 3 sodium ions out and 2 potassium ions in, creating a net negative charge inside the cell.
41
What is the relationship of charged ions and the cell during resting potential?
There are more positively charged ions (mainly sodium) outside the neuron than inside. This creates a difference in charge across the cell membrane, with the inside of the cell being more negatively charged.
42
What are the steps in action potentials?
1. Stimulus received (must pass threshold potential)
2. Depolarization: Sodium gates open, sodium flows into neuron (makes it positive inside)
3. Repolarization: Potassium flows out of neuron, makes it negative again
4. Hyperpolarization: repolarization step overshoots resting potential, important to make sure impulse moves in One direction
5. Rest potential brought back by sodium-potassium pump (Uses ATP)
43
What is the first step in generating an action potential?
A stimulus is received that must pass the threshold potential.
44
What happens during depolarization in an action potential?
Sodium gates open, allowing sodium ions to flow into the neuron, making the inside of the neuron positive.
45
What is the role of sodium and potassium gates during repolarization?
Sodium gates close, and potassium gates open, allowing potassium ions to flow out of the neuron, making the inside of the neuron negative again.
46
What is hyperpolarization, and why is it important?
Hyperpolarization is when the repolarization step overshoots the resting potential, which is important to ensure the nerve impulse moves in one direction.
47
How is the resting potential restored during hyperpolarization?
The sodium-potassium pump restores the resting potential by using ATP to pump sodium (3) out and potassium (2) into the neuron.
48
What must a stimulus do to initiate an action potential?
The stimulus must pass the threshold potential to initiate an action potential.
49
What is the threshold stimulus?
The minimal stimulus required to cause the Na+ gates to open and impulse to be sent
50
What does the threshold stimulus lead to?
The all or none response
51
What is the synapse?
Junction between two communicating neurons.
52
What is Synaptic Transmission?
Synaptic transmission is the process by which a nerve signal is transferred from one neuron to another cell, typically another neuron or a muscle cell, across a synapse
53
What must be released at the gap to signal the next neuron?
Neurotransmitter
54
What makes up the CNS?
Brian and spinal chord
55
What makes up the PNS?
Sensory (afferent) division: Carries sensory information from the body to the central nervous system (CNS), including signals from sensory receptors (e.g., touch, pain, temperature) to the brain and spinal cord.
Motor (efferent) division: Carries motor commands from the CNS to the muscles and glands.
56
What is another word for sensory neurons?
Afferent Neurons
57
What does afferent mean?
Into something ex: afferent nerves go into CNS. eyes to brain
58
What is another word for motor neurons?
Efferent Neurons
59
What does efferent mean?
Out of someting - ex: Brain to muscles
60
What is the purpose of Sensory Neurons?
Carry information about external environment inward from recpetors in the skin, tendons, and skeltal muscle.
61
What is the purpse of motor neurons?
Carry information to skeletal muscles.
62
All neurons in the somatic system are __________
Myelinated
63
The PNS can be subdivided into two sub sections, what are these two sections?
Autonomic and Somatic
64
What is the difference between Autonomic and Somatic systems?
Somatic - Voluntary
Autonomic - involuntary
65
What is homeostasis?
Internal equilbrium.
66
What is antagonistic actions? Where is it applicable?
Often opposite. Ex: Sympathetic responses are antagonistic to parasympathetic respnoses. This is how homeostais is maintained.
67
What are some physiological effects of the sympathetic resonpse?
HR increases
Releases epinephrine
Bronchioles dialate (increase oxygen avaliable)
Blood pressure increases
Blood flow to muscles
**Increases energy avaliable**
68
What are some physiological effects of the parasympathetic resonpse?
HR decreases
Bronchoils constrict
Increase activity in organs (small intestine, rest and digest, ect)
69
How does the myelin sheath increase the speed of the action potential?
The myelin sheath increases the speed of the action potential by insulating the axon, preventing ion leakage. This allows the action potential to "jump" between the nodes of Ranvier in a process called saltatory conduction. Depolarization only occurs at these nodes, where Na+ gates open, allowing Na+ ions to rush into the cell, speeding up the transmission.
70
What is Saltatory conduction?
Saltatory conduction is the rapid method by which nerve impulses move down a myelinated axon with excitation occurring only at nodes of Ranvier.
71
What are the 4 types of Neurons?
Bipolar (Interneuron)
Unipolar (Sensory Neuron)
Multipolar (Motor Neuron, most common type of Neuron)
Pryimidal Cell
72
How are reflexs different when compared to other non-threating signals.
The signal is processed in the spinal chord rather than the brain. The spinal chord processes and sends out a signal before the signal reaches the brain. This is why you often react before you feel pain.
73
What is the purpose of the knee-jerk reaction.
It's autnomic and keeps you upright.
74
What is the purpose of a withdraw reflex?
The avoidance of a painful stimuli.
75
During what circumstance can the withdrawl reflex be overrided?
When a mother is protecting her offspring.
76
Another word for signal is:
Action potential
77
What is an action potential caused by?
The movement of ions across the cell membrane of the axon. Potassium and sodium.
78
What is resting potential?
Resting potential is the state of rest within a neuron. The average voltage of a neuron during rest is -70mV.
79
What is the resting potential determined by?
Concentrations of ions in the fluids on both side of the cell membrance (inside and outside of the cell). The inside of the cell is less positive than the outside due to more positive Na+ ions outside the axon compared to few K+ ions inside the axon.
80
How is the balance of ions kept during rest potential?
Sodium-Potassium pump. It pumps 3 Na+ out of the cell and takes 2 K+ into the cell. The Sodium-Potassium pump requires ATP.
81
How does the signal move UP the axon during depolarization.
The Sodium gates open one at a time allowing the signal to effectivly jump up the axon (Saltatory Conduction).
82
Why is hyperpolarization crucial?
To ensure the signal travles in the same direction up the axon.
83
Why does the sodium-potassium pump require ATP?
Because it goes against a concentration gradient.
84
How is level of pain percieved if every signal is the same speed and strength (all or nothing response)
The frequency of signals. If a signal is sent with high frequency more pain will be interpreted. A signal that is has a small frequency is less painful.
85
What is the refracory period?
Repolarization and Hyperpolarization - it's known as a refractory period becuase another signal cannot be sent until the voltage returns to normal resting potential.
86
What are the two major functions of the brain?
Organize and interpret information
Initiate impulses to be sent to the motor neurons or create thoughts
87
What are the three major parts of the brain?
Hindbrain
Midbrain
Forebrain
88
What is another name for the three major parts of the brain?
Vesicles
89
What is the hindbrain responsible for?
Survival
90
What is the midbrain responsible for?
Senses, alertness, and sleep
91
What is the forebrain responsible for?
Largest in humans, thinking, emotions, and memories
92
What is the purpose of wrinkles on the brain?
Increase SA
93
What are the 7 structures of the brain?
1. Cerebrum
2. Left Hemisphere
3. Right Hemisphere
4. Lobes - Frontal, Parietal, Occipital, Temporal
94
What is the cerebrum responsible for?
Thinking part of the brain, cerebral cortex is the outside wrinkly part
95
What is the outside wrinkly part of the brain?
Cerebral Cortex
96
What is the left hemipshere responsible for?
Right side of the body
97
What is the right hemipshere responsible for?
Controling left side of the body
98
What is the frontal lobe responsible for?
Fine motor skills, reasoning, higher thinking, speech, planing
99
What is the pareital lobe responsible for?
Recognition of stimuli, sensory input
100
What is the occipital lobe responsible for?
Visual information
101
What is the temporal lobe responsible for?
Auditory information, memory
102
What are the three part of the brainstem?
Medulla, pons, midbrain
103
What is the brainstem repsonsible for?
Vital funtions
104
What is the cerebellum responsible for?
Balace and movement
105
What is the thalmus responsible for?
Relay center for senses
106
What is the hypothalmus responsible for?
Regulates homeostasis, links nervous system and endocrine system, sends signal to pituitary.
107
What is the pons responsible for?
(Part of the brain stem) sleep, motor connection between hemispheres
108
What is th midbrain responsible for?
Senses, alertness, regultes temprature, eye movement (autonomic)
109
What is the medulla oblongata responsible for?
Vital body function; breathing, heart rate, blood pressure
110
What are sensory receptors?
Nerve endings that detect sensory information
111
What is sensation?
What we feel when the nerve impulses from sesnory neurons reach the cerebral cortex
112
What is perception?
How the cerebral cortex interprets the meaning of the sensory information
113
Why do optical illusions occur?
Sensory infromatino is not reintegrated precisly and what we sense is not what we percieve.
114
What are the 4 categories of receptors?
1. Photoreceptors - light
2. Chemeoreceptors - chemicals
3. Mechnoreceptors - detect touth, pressure
4. Thermoreceptors - temprature
115
What is the chimcal receptor for taste?
Taste bud
116
What are located in taste buds?
Papille
117
What does the tounge cotain that allows us to taste?
Chemoreceptors
118
How do we taste? Relating to a action potential
1. Taste cells depolarize in response to particular taste
2. This generates an action potential, which travels to the brain
3. The message travles to the brain-stem, then to the thalumus, and finally to the parietal lobe
119
What are the chemical receptors for smell?
Ofactory
120
How does smell differ from other senses?
Each odours chemical strucure fits into a particular chemeoreceptor
121
What is the cornea?
Transparent material, over pupil
122
Whats the purpose of the cornea?
Refract light towards the lens
123
Whats the Aqueous Humor?
Fluid between cornea and lens
124
Whats the pupil?
Opening in the iris that allows light to pass in
125
What is the iris?
Colored part of eye, controls the size of a pupil
126
What is the lens?
Focuses light onto the retina (can change shape to focus)
127
What is the vitreous humor?
Fluid in the eye, gives eye structure
128
Whats the sclera?
Most outer part of the eye, provides structure and protection
129
Whats the Choroid?
Middle layer of the eye, rich with blood vessels, nourishes eye and retina
130
What is the retina?
Senses light and sends signal through optic nerve to brain.
131
What two sensory receptors does the eye contain?
Rods - Detects light
Cones - Detects color (Red, Blue, Green)
132
At what structure are cones more abundent?
Near the Fovea Centralis
133
What is the Fovea Centralis?
An area of retina directly behind the lens. Lots of cones
134
What results in color blindness?
Deficency of a particular type of cone.
135
Where are rods more prominent?
Around edges of retina - peripheral vision
136
Aside from light, what else do rods detect?
Motion - responsible for peripheral vision
137
How do rods generate an action potential?
Rods contain pigment called rhodopin which when struct by light splits into two molecules.
Splitting causes an action potential which is carried to optic nerve
Two resulting molecules retinal and opsin must be recombined before another message can be sent
138
What is the pigment in rods called?
Rhodopsin
139
What are the two remaining molecules after the splitting of Rhodopsin?
Retinal and opsin
140
What is the area of the eye which contains no light receptors called?
Blind spot - due to optic nerve
141
What is the pinna?
Outer part of ear, some mammals control, function to funnel sound towards cannel
142
What is the auditory canal?
Tube that carries sound to ear drum
143
What is the tympanic membrane?
Ear drum, vibrates in response to sound wave
144
What are ossicles?
Three bones (smallest in the body) transmit and amplify vibration from ear to fluid filled cocheal through oval window
145
WHat is the Organ of Corti?
Inside thee cochela, has hair cells in fluid that move in response to vibrations from ossicles, send nerve impulse
146
What are the semi-circular canal?
Fluid filled canals that send signals concerning balance and head position
147
What is the Estacian tube?
Leads to throat, controls pressure inside the ear (ear popping)
148
How is sound converted from a pressure change to an action potential?
Compression waves in fluid of cochlea cause baislar membrane to vibrate this pressure pushes hair cells of organ of corti causing the stereocilia to bend against the tectorial membrane.
Stimulated hair cells send impulse to brain via auditory nerve for interpretation.
149
How do you distingush between pitches?
Low frequency sounds stimulate one section of hair cells farthest from oval window
High frequency stimiluates another section of hair cells near oval window
150
What are the semi-circular canals function?
Balance and orientation
151
What is the fluid in the Semi-circular canals
Endolymph
