Section 2.1

Question 1

What are the main functions of the Autonomic Nervous System (ANS)?

Answer 1

The ANS influences the heart, smooth muscle, and glands to maintain homeostasis and dynamic equilibrium.

Question 2

How does the ANS maintain homeostasis?

Answer 2

The ANS maintains homeostasis through its two subdivisions, the sympathetic and parasympathetic systems, which are constantly active

Question 3

Where does the output of the ANS originate from, and how is it sent to the periphery?

Answer 3

The output of the ANS originates from the hypothalamus, brainstem, and spinal cord and is sent to the periphery through sympathetic and parasympathetic pathways.

Question 4

What are some key systems controlled by the ANS, apart from the heart and smooth muscles?

Answer 4

Other key systems under the control of the ANS include the enteric nervous system, reproduction, and thermoregulation.

Question 5

What is the primary role of the sympathetic nervous system, and when does it become particularly active?

Answer 5

The primary role of the sympathetic nervous system is to stimulate the fight-or-flight response. It becomes particularly active during stressful or threatening situations.

Question 6

What are the main activities controlled by the parasympathetic nervous system, and what is its primary role?

Answer 6

The parasympathetic nervous system is primarily responsible for the body’s “rest-and-digest” activities, including processes like digestion, urination, and salivation. It helps the body function efficiently when at rest.

Question 7

How do autonomic nerve pathways typically operate in terms of the number of neurons involved and their locations?

Answer 7

Autonomic nerve pathways consist of a two-neuron chain connecting the Central Nervous System (CNS) to the effector.

The first neuron’s cell body is within the CNS, and its axon, known as the preganglionic fiber, synapses with the cell body of the second neuron.

The second neuron’s cell body is located in a cluster of neuronal cells known as a ganglion, and its axon, called the postganglionic fiber, innervates the effector organ.

Question 8

Look at the picture you took on your phone

Answer 8

Put it into goodnotes if you haven’t already

Question 9

Where do the preganglionic fibers of the sympathetic nervous system originate, and how are they distributed?

Answer 9

The preganglionic fibers of the sympathetic nervous system originate in the thoracic and lumbar regions of the spinal cord. They tend to be short and terminate in ganglia located in chains on both sides of the spinal cord. Some preganglionic fibers pass through these ganglia and terminate in collateral ganglia, located roughly halfway between the CNS and the effector organs.

Question 10

What are preganglionic fibers of the parasympathetic nervous system, and where do they arise from?

Answer 10

The preganglionic fibers of the parasympathetic nervous system arise from the brain or lower spinal cord. They are long and terminate in ganglia known as terminal ganglia, located close to the effector organ. As a result, the postganglionic fibers of the parasympathetic system are very short.

Question 11

hat are the key differences between the sympathetic and parasympathetic nervous systems in terms of the origin and length of preganglionic fibers, as well as the location of ganglia?

Answer:

Answer 11

Sympathetic Nervous System:
- Preganglionic fibers originate in the thoracic and lumbar regions of the spinal cord.
- Preganglionic fibers tend to be short.
- They terminate in ganglia located in chains on both sides of the spinal cord.
- Some preganglionic fibers pass through these ganglia and terminate in collateral ganglia located roughly halfway between the CNS and the effector organs.

Parasympathetic Nervous System:
- Preganglionic fibers arise from the brain or lower spinal cord.
- Preganglionic fibers are long.
- They terminate in ganglia known as terminal ganglia, located close to the effector organ.
- Consequently, the postganglionic fibers of the parasympathetic system are very short.

Question 12

What neurotransmitter is used by preganglionic fibers in both the sympathetic and parasympathetic nervous systems?

Answer 12

Preganglionic fibers in both the sympathetic and parasympathetic nervous systems use acetylcholine (ACh) as their neurotransmitter.

Question 13

How do the neurotransmitters differ in the postganglionic fibers of the sympathetic and parasympathetic nervous systems?

Answer 13

• In the parasympathetic system, the postganglionic fibers use acetylcholine (ACh) and are therefore called cholinergic fibers.
• In the sympathetic system, most postganglionic fibers use norepinephrine (also known as noradrenaline) and are called adrenergic fibers. However, some sympathetic postganglionic fibers may use epinephrine.

Question 14

What is the concept of dual innervation, and how does it relate to the sympathetic and parasympathetic systems?

Answer 14

Dual innervation is the concept that almost all effector organs receive input from both the sympathetic and parasympathetic systems. However, some organs, like the kidneys and adrenal glands, do not have direct innervation from both systems.

Question 15

What is the fate of most afferent nerve traffic from visceral organs and activities such as digestion, sweating, and circulation?

Answer 15

Most of the afferent nerve traffic from visceral organs and activities like digestion, sweating, and circulation do not reach the level of consciousness. They are instead regulated by autonomic efferent output, meaning they are controlled by the autonomic nervous system without conscious awareness or control.

Question 16

How would you describe the general roles of the sympathetic and parasympathetic nervous systems in terms of excitatory and inhibitory actions?

Answer 16

In general, the sympathetic nervous system tends to be excitatory, while the parasympathetic system is inhibitory. For instance, the sympathetic system increases heart rate, while the parasympathetic system decreases it.

However, there are exceptions, such as in the digestive system, where the sympathetic system decreases gastric motility, and the parasympathetic system increases it.

Question 17

Why is it important for the sympathetic and parasympathetic systems to have opposite regulatory actions?

Answer 17

Having opposite regulatory actions is crucial because it allows for precise regulation of homeostatic parameters. This balance ensures that the body can respond appropriately to various physiological demands and maintain overall stability.

Question 18

Look on goodnotes for the chart on the effects of sympathetic and parasympathetic stimulation on various organs of the body

Question 19

What is the effect of sympathetic stimulation vs parasympathetic stimulation in the eye?

Answer 19

Sympathetic:
Dilation of pupil
Adjustment of eye for far vision

Parasympathetic:
Adjustment of eye for near vision

Question 20

What is the effect of sympathetic stimulation vs parasympathetic stimulation in the digestive tract?

Answer 20

Sympathetic:
Decreased motility (movement)
Contraction of sphincters (to prevent
forward movement of contents)
Inhibition of digestive secretions

Parasympathetic:
Increased motility
Relaxation of sphincters (to permit
forward movement of contents)
Stimulation of digestive secretions

Question 21

What is the effect of sympathetic stimulation vs parasympathetic stimulation in the heart?

Answer 21

Sympathetic:
Increased rate, increased force of
contraction (of whole heart)

Parasympathetic:
Decreased rate, decreased force of contraction (of atria only)

Question 22

What is the effect of sympathetic stimulation vs parasympathetic stimulation in the blood vessels?

Answer 22

Sympathetic:
Constriction

Parasympathetic:
Dilation of vessels supplying the penis and clitoris only

Question 23

What is the effect of sympathetic stimulation vs parasympathetic stimulation in the lungs?

Answer 23

Sympathetic:
Dilation of bronchioles (airways)
Inhibition of mucous secretion

Parasympathetic:
Constriction of bronchioles. Stimulation of mucous secretion.

Question 24

What is the effect of sympathetic stimulation vs parasympathetic stimulation in the urinary bladder?

Answer 24

Sympathetic:
Restriction

Parasympathetic:
Contraction (emptying)

Question 25

What are sympathetic tone and parasympathetic tone, and how do they influence organ activity?

Answer 25

Sympathetic tone and parasympathetic tone refer to the baseline, or tonic, activity of both the sympathetic and parasympathetic nervous systems in a particular organ.

At any given time, both systems are generally active to some degree. When one system becomes more activated than its tonic activity, it becomes the dominant influence on the organ, while the other system decreases its firing. This allows for either sympathetic or parasympathetic dominance, depending on the physiological need or advantage at the time.

Question 26

What are some of the effects the
sympathetic system will have on the body in order to fight a bear or run away?

Answer 26

1. Increase heart rate and force of heart contraction
2. Constrict your arterioles to increase blood pressure
3. Dilate the respiratory airways to bring in more oxygen
4. Breakdown carbohydrate and fat stores to make sure there is plenty of glucose for your muscles
5. Arterioles in the muscles dilate so there is increased oxygen and glucose delivery
6. Inhibit digestion and renal function
7. Increased sweating to prepare for the excess heat generation of physical activity
8. Vision and hearing are heightened

Question 27

what are some of the effects the
parasympathetic system has on the body in order to calm your body down?

Answer 27

• Decreased heart rate and force of heart contraction
• Dilate your arterioles to decrease blood pressure
• Constrict the respiratory airways as not as much oxygen is needed
• The liver stops producing glucose and focuses on digestion, i.e. produces bile
• Arterioles in the muscles constrict as not as much oxygen and glucose delivery
• Promote digestion and renal function
• Pupils constrict back to normal
• Adrenal glands stop producing epinephrine and norepinephrine

Question 28

What are the three exceptions to the concept of dual innervation, where both the sympathetic and parasympathetic systems innervate the same organ?

Answer 28

Blood Vessels: Most arterioles and veins receive only sympathetic stimulation. Their regulation is achieved solely by increasing or decreasing sympathetic activity. Dual innervation is found in blood vessels in the penis and clitoris.

Sweat Glands: Most sweat glands receive sympathetic innervation only. Interestingly, the sympathetic postganglionic fibers release acetylcholine (ACh) instead of norepinephrine.

Salivary Glands: The salivary glands receive dual innervation, meaning both the sympathetic and parasympathetic systems can stimulate salivary secretion.

Question 29

What are the two distinct regions within each adrenal gland?

Answer 29

The adrenal glands are closely associated with the kidneys and have two distinct regions: the outer cortex and the inner medulla

Question 30

How does the adrenal medulla function in the context of the sympathetic nervous system?

Answer 30

The adrenal medulla functions like a sympathetic ganglia in that it is innervated by a sympathetic preganglionic fiber.

However, it does not give rise to a postganglionic fiber. Instead, upon sympathetic stimulation, the adrenal medulla releases chemical transmitters into the blood, which qualify as hormones since they are released into the circulation.

Question 31

What are the primary chemical transmitters released by the adrenal medulla upon sympathetic stimulation?

Answer 31

About 20% of these hormones are norepinephrine (the neurotransmitter associated with sympathetic postganglionic fibers), and 80% are epinephrine, a closely related compound.

Consequently, the adrenal medulla acts as a global amplifier of the sympathetic system upon sympathetic stimulation.

Question 32

What are the two main classes of receptors that play a crucial role in defining how a tissue will respond to ANS (Autonomic Nervous System) stimulation?

Answer 32

Cholinergic Receptor: These receptors are found on the cell membrane and respond to the neurotransmitter acetylcholine (ACh).

Adrenergic Receptor: These receptors are G-protein coupled receptors located on the cell membrane. They respond to catecholamine neurotransmitters, primarily epinephrine and norepinephrine.

Question 33

What are the two types of cholinergic receptors, and what activates them?

Answer 33

Muscarinic Receptors: These receptors are activated by the mushroom poison muscarine. They are found on the effector cell membranes and respond to acetylcholine (ACh) released by parasympathetic postganglionic fibers. Binding of ACh or muscarine to muscarinic receptors triggers a G-protein coupled reaction, leading to the opening of cation channels and depolarization potential.

Nicotinic Receptors: These receptors are activated by the tobacco plant derivative nicotine. They are also found on the effector cell membranes and bind ACh released from both sympathetic and parasympathetic preganglionic fibers. Binding of ACh or nicotine to nicotinic receptors on cation channels leads to the opening of the channel and the subsequent response.

Question 34

What are adrenergic receptors, and how can they be classified?

Answer 34

Adrenergic receptors are receptors that respond to catecholamine neurotransmitters, primarily norepinephrine and epinephrine, and play a crucial role in defining how a tissue or organ responds to sympathetic stimulation.

Adrenergic receptors can be classified as either alpha (α) or beta (β) receptors and further subclassified as α1, α2, β1, β2, and β3 receptors.

Question 35

What is the significance of norepinephrine and epinephrine in relation to adrenergic receptors?

Answer 35

Norepinephrine is released from postganglionic fibers and the adrenal medulla, while epinephrine is released from the adrenal medulla. These two neurotransmitters have different effects when binding to adrenergic receptors.

Question 36

What are some defining features of α and β receptors in terms of their cellular actions?

Answer 36

The α and β receptors have different cellular actions when activated by norepinephrine and epinephrine.

Question 37

What are some key characteristics of alpha (α) receptors, and how do they respond to norepinephrine and epinephrine?

Answer 37

• Both α1 and α2 receptors have a greater sensitivity for norepinephrine than epinephrine.
• All adrenergic receptors, including α receptors, activate G-proteins.
• Activation of α2 receptors suppresses the cAMP pathway.
• Activation of α1 receptors activates the Ca2+ second messenger system.

Question 38

What are some key characteristics of beta (β) receptors, and how do they respond to norepinephrine and epinephrine?

Answer 38

• β2 receptors have a greater affinity for epinephrine than β1 receptors.
• β1 receptors respond equally to norepinephrine and epinephrine.
• β3 receptors are generally only found in adipose (fat) tissues.
• All adrenergic receptors, including β receptors, activate G-proteins.
• Both β1 and β2 receptors enhance the cAMP pathway.

Question 39

How do the effects of sympathetic stimulation vary depending on the number and type of adrenergic receptors in target tissues and organs?

Answer 39

The effects of sympathetic stimulation are determined by the presence and type of adrenergic receptors in target tissues and organs.

• α1 receptors are almost always excitatory, and their stimulation, found in the smooth muscle cells of blood vessels, causes contraction.
• α2 receptors, primarily expressed in the smooth muscle cells of the digestive system, are inhibitory, causing a decrease in contraction.
• β1 receptors are generally excitatory and are mainly found in the heart.
• β2 receptors are generally inhibitory and are primarily found in smooth muscle cells of arterioles and the respiratory airway.

Question 40

How does the activation of β1 and β2 receptors differ in terms of their effects, and how is salbutamol used in the treatment of asthma?

Answer 40

• Stimulation of β1 receptors is generally stimulatory and is mainly found in the heart.
• Stimulation of β2 receptors is generally inhibitory and is primarily found in smooth muscle cells of arterioles and the respiratory airway.
• Salbutamol, which activates β2 receptors, is a bronchodilator commonly used to treat asthma because it opens the airways without significantly affecting heart rate.

Question 41

Which neurotransmitter(s) is involved in increased heart rate and force of heart contraction?

Answer 41

Epi and NE

Question 42

Which neurotransmitter(s) is involved in constriction of arterioles to increase blood pressure?

Answer 42

NE

Question 43

Which neurotransmitter(s) is involved in dilation of respiratory airways to bring in more oxygen?

Answer 43

Epi

Question 44

Which neurotransmitter(s) is involved in inhibition of digestion and renal function?

Answer 44

NE

Question 45

Which receptor(s) is involved in Increased heart rate and force of contraction?

Answer 45

beta 1

Question 46

Which receptor(s) is involved in Constriction of arterioles to increase blood pressure

Answer 46

alpha 1

Question 47

Which receptor(s) is involved in dilation of respiratory airways to bring in more oxygen?

Answer 47

Beta 2

Question 48

Which receptor(s) is involved in inhibition of digestion and renal function?

Answer 48

alpha 2

Question 49

Compare and contrast the parasympathetic and sympathetic nervous systems.

Answer 49

The parasympathetic and sympathetic nervous systems are two branches of the autonomic nervous system. The parasympathetic system is responsible for “rest-and-digest” activities, while the sympathetic system initiates the “fight-or-flight” response. They often have opposing effects on the body’s functions, such as heart rate, digestion, and pupil size.

Question 50

Describe what is meant by sympathetic tone and parasympathetic tone and what is their relationship.

Answer 50

Sympathetic tone and parasympathetic tone refer to the ongoing, baseline activity of each system in the absence of a dominant signal. They are balanced to maintain homeostasis. If one system becomes more active than the other, it can shift the balance, leading to either sympathetic dominance or parasympathetic dominance.

Question 51

Compare and contrast sympathetic dominance and parasympathetic dominance.

Answer 51

Sympathetic dominance occurs when the sympathetic nervous system becomes more active than the parasympathetic system, leading to increased heart rate, reduced digestion, and other “fight-or-flight” responses. Parasympathetic dominance, on the other hand, involves increased parasympathetic activity, leading to decreased heart rate and increased digestion, typical of a “rest-and-digest” state.

Question 52

Describe the role of the adrenal glands in the autonomic nervous system.

Answer 52

The adrenal glands are closely associated with the kidneys and play a significant role in the sympathetic nervous system. The adrenal medulla, when stimulated by the sympathetic nervous system, releases hormones, including epinephrine and norepinephrine, into the bloodstream, amplifying sympathetic responses throughout the body.

Question 53

Describe the receptors of the autonomic nervous system.

Answer 53

The autonomic nervous system primarily uses cholinergic receptors (respond to acetylcholine) and adrenergic receptors (respond to norepinephrine and epinephrine). Cholinergic receptors include muscarinic and nicotinic receptors, while adrenergic receptors are further classified as alpha (α) and beta (β) receptors, with subtypes like α1, α2, β1, β2, and β3, each having distinct effects on target tissues.