Chapter 15 & 16 (nervous sys) : part 1 Flashcards
1
Q
What are the three basic steps the nervous system follows?
A
The three basic steps are sensory function, interpretation (analysis), and motor response (reaction).
2
Q
What is the sensory function of the nervous system?
A
The sensory function detects changes inside (e.g., blood pressure, temperature) and outside (e.g., touch, sound) the body.
3
Q
How does the nervous system gather sensory information?
A
Information is gathered through sensory receptors and sent to the brain and spinal cord.
4
Q
What happens during the interpretation (analysis) step?
A
The central nervous system (CNS) processes and analyzes the sensory input to decide how to respond.
5
Q
What is the motor response (reaction) in the nervous system?
A
After processing, the CNS sends signals back through motor neurons to respond, resulting in movements or changes in actions.
6
Q
What does the Central Nervous System (CNS) include?
A
The CNS includes the brain and spinal cord, which process and analyze information.
7
Q
What is the Peripheral Nervous System (PNS)?
A
The PNS includes all nerves outside the CNS that send signals to and from the brain and spinal cord.
8
Q
What are the divisions of the Peripheral Nervous System (PNS)?
A
The PNS is divided into the Somatic Nervous System (SNS), Autonomic Nervous System (ANS), and Enteric Nervous System (ENS).
9
Q
What does the Somatic Nervous System (SNS) control?
A
The SNS controls voluntary movements, such as moving a muscle.
10
Q
What does the Autonomic Nervous System (ANS) manage?
A
The ANS manages involuntary actions, such as heartbeat and digestion.
11
Q
What is the role of the Enteric Nervous System (ENS)?
A
The ENS regulates the digestive system.
12
Q
What is the summary of how the nervous system works?
A
The nervous system senses changes, interprets them in the CNS, and responds with actions, either voluntary or involuntary.
13
Q
What is the role of the CNS and PNS in the nervous system?
A
The CNS is the control center, while the PNS acts as the communication network connecting the body to the brain and spinal cord.
14
Q
What is a synapse?
A
A synapse is the site where one neuron communicates with another neuron or an effector cell like a muscle or gland.
15
Q
Which neuron sends the signal at the synapse?
A
The presynaptic neuron sends the signal.
16
Q
Which cell receives the signal at the synapse?
A
The postsynaptic neuron or an effector cell receives the signal.
17
Q
What is the synaptic cleft?
A
The synaptic cleft is the tiny gap between the presynaptic and postsynaptic cells.
18
Q
What crosses the synaptic cleft to carry the signal?
A
Neurotransmitters (chemical messengers) cross the synaptic cleft.
19
Q
What happens when neurotransmitters bind to the postsynaptic neuron?
A
They stimulate the postsynaptic cell to create a new electrical signal.
20
Q
What triggers the release of neurotransmitters in the presynaptic neuron?
A
An electrical signal in the presynaptic neuron causes the release of neurotransmitters from vesicles.
21
Q
Why is the synaptic cleft important?
A
It ensures precise signal transmission from one cell to another.
22
Q
What do synaptic end bulbs contain?
A
Synaptic end bulbs contain many tiny membrane-enclosed sacs called synaptic vesicles.
23
Q
What do synaptic vesicles store?
A
Synaptic vesicles store packets of neurotransmitter chemicals.
24
Q
How many types of neurotransmitters can neurons contain?
A
Many neurons contain two or even three types of neurotransmitters.
25
What is the charge outside and inside a resting neuron?
The outside is positive, and the inside is negative.
26
What causes the charge difference in a resting neuron?
The unequal distribution of Na⁺ and K⁺ ions, trapped anions, and the sodium-potassium pump.
27
Where are sodium ions (Na⁺) more concentrated in a resting neuron?
Outside the cell.
28
Where are potassium ions (K⁺) more concentrated in a resting neuron?
Inside the cell.
29
Why can’t most anions leave the cell?
They are too large to pass through the membrane.
30
How does the sodium-potassium pump work?
It pumps 3 Na⁺ out of the cell and 2 K⁺ in.
31
Why is there more Na⁺ outside the cell?
The membrane has fewer Na⁺ leakage channels, and the pump actively removes Na⁺.
32
How is the charge difference helpful to the neuron?
It prepares the neuron to send electrical signals quickly.
33
What is the all-or-none principle?
The all-or-none principle states that if a stimulus reaches threshold, the action potential is always the same.
34
Where do graded potentials originate?
In the dendrites or cell body.
35
Where do action potentials originate?
At trigger zones and travel along the axon.
36
What types of channels are used for graded potentials?
Ligand-gated or mechanically-gated ion channels.
37
What types of channels are used for action potentials?
Voltage-gated channels for Na⁺ and K⁺.
38
How do graded potentials conduct signals?
They do not propagate and only work over short distances.
39
How do action potentials conduct signals?
They propagate, allowing communication over long distances.
40
What is the amplitude of graded potentials?
It varies based on the stimulus strength (1 mV to more than 50 mV).
41
What is the amplitude of action potentials?
It is all-or-none, typically about 100 mV.
42
How long do graded potentials last?
From milliseconds to minutes, depending on the stimulus.
43
How long do action potentials last?
0.5 to 2 milliseconds.
44
Can graded potentials be hyperpolarizing or depolarizing?
Yes, they can be either inhibitory (hyperpolarizing) or excitatory (depolarizing).
45
Are action potentials hyperpolarizing or depolarizing?
They always start with depolarization, followed by repolarization.
46
Do action potentials have a refractory period?
Yes, ensuring signals do not overlap.
47
What is the direction of signal transmission at the synapse?
Signal transmission at the synapse is a one-way transfer from a presynaptic neuron to a postsynaptic neuron.
48
What happens when an action potential (AP) reaches the end bulb of axon terminals?
When an AP reaches the end bulb of axon terminals, voltage-gated Ca2+ channels open and Ca2+ flows inward from the extracellular fluid, triggering release of the neurotransmitter.
49
What occurs after the neurotransmitter is released?
The neurotransmitter crosses the synaptic cleft and binds to ligand-gated receptors on the postsynaptic membrane.
50
What are electrical synapses?
Electrical synapses allow the action potential to spread through gap junctions in smooth muscle, cardiac muscle, and the brain.
51
What is the advantage of electrical synapses?
Electrical synapses allow for faster and synchronized communication.
52
What are chemical synapses?
Chemical synapses involve neurotransmitter released into the synaptic cleft, which crosses and binds to receptors on the postsynaptic cell, where it becomes an electrical signal.
53
What is acetylcholine (ACh), and where is it found?
Acetylcholine is a well-studied neurotransmitter found in many PNS and some CNS neurons.
54
Is acetylcholine excitatory or inhibitory?
It can be excitatory or inhibitory depending on the receptor and location.
55
Name the two excitatory amino acid neurotransmitters.
Glutamate and aspartate.
56
What are the main inhibitory amino acid neurotransmitters?
GABA (gamma-aminobutyric acid) and glycine.
57
Which important biogenic amines can act as neurotransmitters?
Norepinephrine, epinephrine, dopamine, and serotonin.
58
Are biogenic amines excitatory or inhibitory?
They can be excitatory or inhibitory based on the receptors they act on.
59
What purines serve as neurotransmitters?
ATP (energy molecule) and adenosine and its derivatives.
60
What is one role of adenosine as a neurotransmitter?
Adenosine promotes relaxation and sleep.
61
What is nitric oxide (NO), and what does it do?
NO is a gas neurotransmitter that is excitatory and has widespread effects like improving blood flow and aiding memory.
62
What is carbon monoxide (CO) as a neurotransmitter?
CO is a gas neurotransmitter that acts as an excitatory signal in the brain.
63
What is the primary function of inhibitory neurotransmitters like GABA and glycine?
They calm or stabilize the nervous system by preventing excessive nerve activity.
64
What role does dopamine play as a neurotransmitter?
Dopamine influences movement, motivation, and reward.
65
How does serotonin affect the body?
Serotonin regulates mood, appetite, and sleep.
66
What is norepinephrine responsible for?
It plays a role in alertness and the stress response (fight or flight).
67
What are neuropeptides?
Neuropeptides are small chains of 3–40 amino acids linked together by peptide bonds, used by neurons to send signals. They are found in both the central nervous system (CNS) and peripheral nervous system (PNS) and can excite or inhibit activity depending on the receptor they bind to.
68
How do neuropeptides work?
Neuropeptides are made in the cell body of neurons, packaged into vesicles, and transported to the axon terminals. They bind to metabotropic receptors, creating slower, long-lasting effects compared to fast-acting neurotransmitters. Many neuropeptides also act as hormones controlling body functions.
69
What are enkephalins?
Enkephalins are natural painkillers that reduce pain perception and are 200 times more powerful than morphine.
70
What are endorphins and dynorphins?
Endorphins and dynorphins, also known as 'opioid peptides', work as the body’s natural pain blockers and are linked to euphoria, memory, learning, temperature regulation, hormone release, and mental health conditions.
71
What is substance P?
Substance P is released by neurons that transmit pain signals from the body to the brain, increasing pain perception. Enkephalins and endorphins can suppress its release, reducing pain signals.
72
What happens when you hurt yourself?
Substance P enhances the pain signal to make you aware of the injury, while endorphins and enkephalins kick in to dull the pain.
73
How do neuropeptides benefit the body?
Neuropeptides are involved in memory and learning, body temperature control, regulating hormones and reproduction, and potential nerve protection.
74
What do sensory neurons in the somatic nervous system do?
Sensory neurons carry information from your environment to your brain. They detect touch, pain, temperature, proprioception, and special senses like sight, hearing, taste, smell, and balance.
75
What are the functions of sensory neurons?
They are responsible for detecting touch, pain, temperature, proprioception, and special senses.
76
What do motor neurons in the somatic nervous system do?
Motor neurons send signals from your brain to your skeletal muscles to make them contract and move.
77
What is the difference between the somatic and autonomic nervous systems?
The autonomic nervous system controls automatic, involuntary actions, such as heart rate, digestion, and breathing.
78
How does the autonomic nervous system receive input?
The ANS receives input from sensory receptors in organs, blood vessels, and muscles to regulate automatic bodily functions.
79
What is a summary of the somatic nervous system?
The somatic nervous system involves sensory neurons to perceive the environment and motor neurons to control skeletal muscles for movement.
80
What are somatic motor neurons?
Somatic motor neurons are nerve cells that directly control skeletal muscles.
81
What does innervation mean?
Innervation means these neurons connect to and communicate with your muscles, allowing them to move.
82
What is the nature of the signal sent by somatic motor neurons?
The signal sent by somatic motor neurons always excites skeletal muscles, making them contract.
83
Can skeletal muscles contract on their own?
No, skeletal muscles cannot contract on their own; they need the somatic motor neurons to 'turn them on.'
84
How are somatic motor neurons usually controlled?
Most of the time, you consciously control somatic motor neurons.
85
What role do integrating centers in the brainstem and spinal cord play?
They handle automatic actions such as maintaining posture, balance, and reflexes.
86
What is the function of sensory neurons in the somatic nervous system?
Sensory neurons detect information from somatic senses, such as touch, pain, temperature, and body position.
87
What is the summary of the somatic nervous system's function?
The somatic nervous system controls the movement of skeletal muscles through motor neurons, which are mostly under voluntary control. Some actions, like maintaining posture, balance, or reflexes, happen automatically.
88
What is the Motor (Efferent) Division of the PNS?
The motor division is the part of the peripheral nervous system (PNS) that controls how your body responds to signals from the central nervous system (CNS). It sends instructions from the brain and spinal cord to muscles and glands to react to situations.
89
What are the two systems of the Motor Division?
The motor division is split into two systems: Somatic Nervous System (SNS) and Autonomic Nervous System (ANS).
90
What does the Somatic Nervous System (SNS) control?
The SNS controls voluntary movements of skeletal muscles, such as walking or smiling.
91
What does the Autonomic Nervous System (ANS) control?
The ANS automatically controls involuntary actions like heart rate, digestion, and breathing.
92
What are the two divisions of the Autonomic Nervous System (ANS)?
The ANS is divided into the Sympathetic Division and the Parasympathetic Division.
93
What is the function of the Sympathetic Division?
The Sympathetic Division prepares your body to handle stressful or emergency situations.
94
What are some actions of the Sympathetic Division?
Actions include increasing heart rate, releasing energy by breaking down stored sugars, dilating pupils, and slowing digestion.
95
What is the function of the Parasympathetic Division?
The Parasympathetic Division promotes relaxation and helps the body recover when the stress is gone.
96
What are some actions of the Parasympathetic Division?
Actions include slowing heart rate, enhancing digestion, and conserving energy.
97
How does the ANS maintain homeostasis?
The ANS maintains homeostasis by responding to subconscious visceral sensations and exciting or inhibiting visceral effectors.
98
What are subconscious visceral sensations?
These are signals from internal organs that your brain processes without you being aware of them.
99
What are visceral effectors?
Visceral effectors include smooth muscles, cardiac muscles, and glands.
100
How can the ANS affect visceral effectors?
The ANS can either excite (stimulate them to act) or inhibit (slow them down) depending on the situation.
101
What is the summary of the ANS function?
The Sympathetic Division helps the body react quickly to stress, while the Parasympathetic Division brings the body back to a calm state.
102
How does the ANS ensure stability?
The ANS balances the sympathetic and parasympathetic divisions to maintain homeostasis by managing subconscious sensations and controlling involuntary muscles and glands.
103
What are the components of the ANS?
The ANS includes autonomic sensory neurons, integrating centers in the CNS, and autonomic motor neurons.
104
What is the role of autonomic motor neurons in the ANS?
Autonomic motor neurons regulate visceral activities by increasing (exciting) or decreasing (inhibiting) activities in effector tissues.
105
Can you provide examples of autonomic motor neuron activities?
Examples include vasoconstriction and vasodilation of blood vessels, and the rate and force of heartbeat.
106
What is the primary function of the ANS?
The ANS usually operates without conscious control.
107
Which parts of the brain regulate ANS reflexes?
Centers in the hypothalamus and brain stem provide regulation for ANS reflexes.
108
What are interoceptors?
Sensory receptors located in blood vessels, visceral organs, muscles, and the nervous system that monitor conditions in the internal environment.
109
What are examples of interoceptors?
Chemoreceptors that monitor blood CO2 level and mechanoreceptors that detect the degree of stretch in the walls of organs or blood vessels.
110
What is the autonomic motor pathway?
It is a system that controls involuntary actions of smooth muscles, cardiac muscles, and glands.
111
What are the two types of neurons in the autonomic motor pathway?
Preganglionic Neuron and Postganglionic Neuron.
112
What is a Preganglionic Neuron?
It is the first neuron in the pathway that starts in the CNS and ends at a ganglion.
113
Where does the Preganglionic Neuron start and end?
It starts in the central nervous system (CNS) and ends at a ganglion.
114
What does the Preganglionic Neuron do?
It transmits a signal from the CNS to the ganglion.
115
What is a Postganglionic Neuron?
It is the second neuron in the pathway that starts at the ganglion and extends to the target organ.
116
What does the Postganglionic Neuron do?
It transmits the signal from the ganglion to the organ or tissue.
117
What is the significance of the two-neuron chain in the autonomic nervous system?
It allows the autonomic nervous system to be more controlled and efficient at maintaining homeostasis.
118
What is Dual Innervation?
Most organs in your body receive signals from both the sympathetic and parasympathetic divisions of the ANS. These divisions work in opposite ways to maintain balance and control organ functions.
119
How does the Sympathetic Division work?
Stimulates organs to prepare the body for action, like increasing heart rate or dilating airways.
## Footnote
Example: If you're scared, this division makes your heart beat faster.
120
How does the Parasympathetic Division work?
Slows down or relaxes organ activity to conserve energy, like decreasing heart rate or promoting digestion.
## Footnote
Example: After a meal, this division helps digest food by increasing stomach activity.
121
How does the balance of control vary by organ?
Some organs are more influenced by one division than the other, depending on the system's need.
## Footnote
Example: In an emergency, sympathetic control dominates to keep you alert. After the situation calms down, parasympathetic signals take over to restore the body to normal.
122
What is the summary of Dual Innervation?
Most organs get signals from both sympathetic and parasympathetic nerves. One division increases activity (e.g., action during stress), while the other decreases it (e.g., resting and conserving energy). This balance ensures proper control and adaptation based on what the body needs at any moment.
123
What are the two functional categories of ANS responses?
The responses of various organs to ANS stimulation group into the sympathetic and parasympathetic divisions.
124
What is the role of the sympathetic division?
The sympathetic division contributes to actions for a 'fight or flight' response.
125
What is the role of the parasympathetic division?
The parasympathetic division is responsible for 'rest and relax' (or rest and digest) actions.
126
How do the sympathetic and parasympathetic divisions differ?
Different neurotransmitters and receptors result in different effects on various systems.
127
How does the sympathetic system work?
A single sympathetic preganglionic fiber connects to many postganglionic neurons, forming a diverging circuit that allows widespread signal travel to various parts of the body.
128
Why is sympathetic stimulation so intense?
Postganglionic fibers spread the signal to many visceral effectors simultaneously, ensuring a massive response during stressful situations.
129
What happens to the body when the sympathetic system is activated during anger?
Heart rate increases, breathing rate speeds up, blood vessels constrict while others dilate, and pupils dilate. This diffused response makes emotions like anger hard to control.
130
What are the key points about the sympathetic nervous system?
The sympathetic system uses a diverging circuit to activate multiple organs at once, creating a strong, widespread response effective for emergencies but making emotions harder to contain.
131
How does the parasympathetic response compare to the sympathetic system?
The parasympathetic response is more controlled.
132
How many postsynaptic neurons do presynaptic parasympathetic neurons usually synapse with?
Presynaptic parasympathetic neurons usually synapse with only 4–5 postsynaptic neurons.
133
Which areas do the sympathetic division affect in the body?
Wide regions of the body, including skin, sweat glands, arrector pili muscles, adipose tissue, smooth muscle of hair follicles, and blood vessels.
134
Where are the cell bodies of sympathetic preganglionic neurons located?
In the lateral gray horns of spinal cord segments T1–L2, part of the thoracolumbar outflow.
135
Where are the cell bodies of parasympathetic preganglionic neurons located?
In the nuclei of cranial nerves III, VII, IX, and X, and the lateral gray matter of spinal cord segments S2–S4 (craniosacral outflow).
136
What are the ganglia associated with the sympathetic division?
Sympathetic trunk ganglia and prevertebral ganglia.
137
Which ganglia are associated with the parasympathetic division?
Terminal ganglia.
138
Where are sympathetic ganglia typically located?
Close to the CNS and distant from visceral effectors.
139
Where are parasympathetic ganglia located?
Typically near or within the wall of visceral effectors.
140
How do axons of sympathetic neurons differ in length and divergence?
Preganglionic neurons have short axons and synapse with many postganglionic neurons with long axons that target many visceral effectors.
141
How do axons of parasympathetic neurons differ in length and divergence?
Preganglionic neurons have long axons that synapse with 4–5 postganglionic neurons with short axons targeting one specific visceral effector.
142
Are white and gray rami communicantes present in the sympathetic system?
Yes, white rami communicantes contain myelinated preganglionic axons, and gray rami communicantes contain unmyelinated postganglionic axons.
143
Are white and gray rami communicantes present in the parasympathetic system?
No, they are not present.
144
What neurotransmitters are used by the sympathetic division?
Preganglionic neurons release acetylcholine (ACh), while most postganglionic neurons release norepinephrine (NE). Postganglionic neurons controlling sweat glands release ACh.
145
What neurotransmitters are used by the parasympathetic division?
Both preganglionic and postganglionic neurons release acetylcholine (ACh).
146
How many neurotransmitters does the nervous system use?
The nervous system uses over 100 different neurotransmitters to send signals between neurons or to other cells.
147
What are the two major neurotransmitters used in the autonomic nervous system (ANS)?
The two major neurotransmitters used in the ANS are Acetylcholine (ACh) and Norepinephrine (NE).
148
What is Acetylcholine (ACh)?
Acetylcholine (ACh) is one of the most commonly used neurotransmitters in the ANS, playing a key role in sending nerve signals in both the parasympathetic division and certain parts of the sympathetic division.
149
What are Cholinergic Synapses?
Cholinergic synapses are communication points between neurons or cells where acetylcholine (ACh) is released. The neurons that use ACh are called cholinergic neurons.
150
What is Norepinephrine (NE)?
Norepinephrine (NE) is another main neurotransmitter used in the sympathetic division of the ANS, helping the body handle stressful or emergency situations by increasing heart rate, blood pressure, and energy availability.
151
What are Adrenergic Synapses?
Adrenergic synapses are communication points where norepinephrine (NE) is released. The neurons that use NE are called adrenergic neurons.
152
What is the primary reliance of the autonomic nervous system on neurotransmitters?
The autonomic nervous system primarily relies on acetylcholine (ACh) and norepinephrine (NE). Cholinergic synapses use ACh, while adrenergic synapses use NE.
153
What are cholinergic receptors?
Cholinergic receptors are receptors that respond to acetylcholine (ACh), a neurotransmitter released by cholinergic neurons. When acetylcholine binds to these receptors, it initiates specific actions in the nervous system or target organs.
154
What are the two types of cholinergic receptors?
The two types of cholinergic receptors are nicotinic receptors and muscarinic receptors.
155
Where are nicotinic receptors found?
Nicotinic receptors are found in the plasma membranes of dendrites and cell bodies of sympathetic and parasympathetic postganglionic neurons, chromaffin cells of the adrenal medulla, and motor end plates at the neuromuscular junction.
156
What do nicotinic receptors do?
Nicotinic receptors are always excitatory. When acetylcholine binds to them, they stimulate the next neuron or muscle cell to activate.
157
Where are muscarinic receptors found?
Muscarinic receptors are found on the plasma membranes of effectors, such as smooth muscle, cardiac muscle, and glands innervated by parasympathetic postganglionic neurons.
158
What do muscarinic receptors do?
Muscarinic receptors can be excitatory or inhibitory, depending on the type of tissue.
## Footnote
Example: They may stimulate digestion or slow the heart rate during rest.
159
Summarize cholinergic receptors.
Cholinergic receptors respond to acetylcholine and are classified into nicotinic receptors (always excitatory) and muscarinic receptors (excitatory or inhibitory depending on the organ).
160
What are adrenergic receptors?
Adrenergic receptors respond to norepinephrine (NE) and epinephrine (E). They are found on visceral effectors activated by the sympathetic nervous system.
161
What is norepinephrine (NE)?
Norepinephrine (NE) is released as a neurotransmitter by sympathetic postganglionic neurons.
162
What is epinephrine (E)?
Epinephrine (E) is released as a hormone into the blood by chromaffin cells of the adrenal medulla.
163
What are the main subtypes of adrenergic receptors?
Adrenergic receptors are split into two main subtypes: alpha (α) receptors and beta (β) receptors.
164
What are alpha receptors?
Alpha receptors are subdivided into alpha 1 (α1) and alpha 2 (α2) receptors.
165
What do alpha 1 receptors (α1) do?
Alpha 1 receptors (α1) are excitatory and cause vasoconstriction, increasing blood pressure.
166
Where are alpha 1 receptors (α1) found?
Alpha 1 receptors (α1) are found in places like smooth muscle of blood vessels.
167
What do alpha 2 receptors (α2) do?
Alpha 2 receptors (α2) are inhibitory and can reduce norepinephrine release, relaxing certain muscles.
168
What is an example of alpha 2 receptor (α2) action?
Alpha 2 receptors help dilate blood vessels in specific situations.
169
What are beta receptors?
Beta receptors are subdivided into beta 1 (β1) and beta 2 (β2) receptors.
170
What do beta 1 receptors (β1) do?
Beta 1 receptors (β1) are excitatory and increase heart rate and strength of heart contractions.
171
Where are beta 1 receptors (β1) found?
Beta 1 receptors (β1) are found in the heart.
172
What do beta 2 receptors (β2) do?
Beta 2 receptors (β2) are inhibitory and cause bronchodilation and relaxation of smooth muscle.
173
Where are beta 2 receptors (β2) found?
Beta 2 receptors (β2) are found in the lungs and smooth muscles of the airways.
174
How do drugs interact with adrenergic receptors?
Certain drugs can selectively activate or block these receptors to treat specific conditions.
175
What do alpha blockers do?
Alpha blockers lower blood pressure by relaxing blood vessels, affecting α1 receptors.
176
What do beta blockers do?
Beta blockers reduce heart rate and lower blood pressure, affecting β1 receptors in the heart.
177
What is the summary of adrenergic receptors?
Adrenergic receptors respond to norepinephrine (NE) and epinephrine (E) to trigger sympathetic effects.
178
What are the actions of alpha and beta receptors?
Alpha receptors: α1 excites (e.g., constricts blood vessels), α2 inhibits (e.g., relaxes blood vessels). Beta receptors: β1 excites (e.g., increases heart rate), β2 inhibits (e.g., dilates airways).
