Chapter 10: Autonomic and Somatic Nervous System

Question 1

What does the ANS innervate

Answer 1

The autonomic nervous system innervates smooth muscle, cardiac muscle and glands (often referred to as visceral effectors) because they are associated with the internal organs of the body

Question 2

what type of control does ANS operate under

Answer 2

without unconscious control by either increasing (exciting) or decreasing (inhibiting) ongoing activities in their effectors

Autonomic = autonomous, without control of the CNS

Question 3

dual innervation

Answer 3

an organ or tissue is controlled by both divisions of the autonomic nervous system: the sympathetic and parasympathetic systems

Question 4

parasympathetic nervous system

Answer 4

• Enhances rest and digest activities, which conserve and restore body energy during times of rest and recovery
• Also known as the craniosacral division of the ANS

Question 5

What does “craniosacral” mean?

Answer 5

Cranio” = comes from the brainstem (cranial nerves III, VII, IX, X)

“Sacral” = comes from the sacral region of the spinal cord (S2–S4)

• restore rest and restorable body functions

Question 6

sympathetic nervous system

Answer 6

Produces the fight or flight response which prepares the body for emergency situations

Question 7

What are the two main divisions of the ANS and their functions?

Answer 7

Parasympathetic (craniosacral): Rest and digest—conserves energy

Sympathetic (thoracolumbar): Fight or flight—prepares body for stress

Question 8

What is the enteric nervous system (ENS)?

Answer 8

A third branch of the ANS that independently controls the GI tract, with its own sensory, motor, and interneurons

• involuntary
• contains sensory neurons, interneurons and motor neurons

Question 9

How does the autonomic nervous system usually operate?

Answer 9

Without conscious control, increasing (exciting) or decreasing (inhibiting) ongoing activities in their effectors

Question 10

What are the two main branches of the autonomic nervous system?

Answer 10

• Parasympathetic nervous system
• Sympathetic nervous system

Question 11

What is the primary function of the parasympathetic nervous system?

Answer 11

Enhances rest and digest activities, conserving and restoring body energy during rest and recovery

Question 12

What is the main function of the sympathetic nervous system?

Answer 12

Produces the fight or flight response, preparing the body for emergency situations

Question 13

What is the role of sensory neurons in the enteric nervous system?

Answer 13

Monitor chemical changes and stretching within the GI tract

Question 14

What are the two types of autonomic motor pathways?

Answer 14

• Preganglionic neuron
• Postganglionic neuron

Question 15

Where does the first neuron, the preganglionic neuron, originate?

Answer 15

In the brain or spinal cord

Question 16

describe the autonomic motor pathway

Answer 16

prganglionic neuron (CNS) –> autonomic ganglion (PNS) –> postganglionic neuron –> visceral effector

Question 17

What is a ganglion?

Answer 17

A cluster of neuronal cell bodies in the PNS

Question 18

What characterizes the postganglionic neuron?

Answer 18

Lies entirely in the PNS and relays action potentials from autonomic ganglia to visceral effectors

Question 19

Where do parasympathetic and sympathetic neurons originate?

Answer 19

Parasympathetic: Brainstem & S2–S4 spinal cord

Sympathetic: T1–L2 spinal cord

Question 20

Where are their ganglia located?

Answer 20

Parasympathetic: Near or in target organs (terminal ganglia)

Sympathetic: Near spinal cord (sympathetic trunk/collateral ganglia)

Question 21

What is the role of chromaffin cells in the adrenal medulla?

Answer 21

They are modified sympathetic neurons that release epinephrine (80%), norepinephrine (20%), and dopamine into the blood

Question 22

What is a cholinergic neuron and what receptors does it act on?

Answer 22

A neuron that releases ACh, acting on nicotinic (ganglia/skeletal muscle) and muscarinic (effectors) receptors

Question 23

What are nicotinic acetylcholine receptors?

Answer 23

Receptors present in the plasma membrane of parasympathetic & sympathetic postganglionic neurons

Question 24

What enzymes break down neurotransmitters in the ANS?

Answer 24

Acetylcholinesterase (AChE) breaks down ACh

Monoamine oxidase (MAO) inactivates NE

Question 25

What is an adrenergic neuron?

Answer 25

A neuron that releases norepinephrine (NE); acts on alpha (α) and beta (β) adrenergic receptors

Question 26

What are the two main types of adrenergic receptors?

Answer 26

* Alpha receptors * Beta receptors

Question 27

What is the function of chromaffin cells?

Answer 27

Produce and release catecholamines such as epinephrine and norepinephrine

Question 28

What is autonomic tone?

Answer 28

The balance between sympathetic and parasympathetic activity, regulated by the hypothalamus

Question 29

What does SLUDD stand for in parasympathetic responses?

Answer 29

used for effects: * S → salvation * L → lacrimation * U → urination * D → digestion * D → defecation

Question 30

What are the three decreases associated with parasympathetic responses?

Answer 30

1) Decreased heart rate 2) Decreased diameter of bronchial tubes 3) Decreased diameter of pupils

Question 31

What are "E" situations and sympathetic responses?

Answer 31

Exercise, Emergency, Excitement, Embarrassment → Fight or flight: ↑HR, ↑BP, bronchodilation, ↑glucose, pupil dilation

Question 32

Why are the effects of sympathetic stimulation longer lasting?

Answer 32

1. Widespread axon divergence 2. ACh quickly inactivated; NE lasts longer 3. Epinephrine/NE from adrenal medulla prolong effect

Question 33

What are autonomic reflexes?

Answer 33

Fast, involuntary responses occurring when action potentials pass through an autonomic reflex arc

Question 34

Q18: What are the components of an autonomic reflex arc?

Answer 34

1. Sensory receptor 2. Sensory neuron 3. Integrating center (CNS) 4. Motor neurons (pre & postganglionic) 5. Effector (smooth muscle, cardiac muscle, glands)

Question 35

Which structures receive only sympathetic innervation?

Answer 35

* Sweat glands * Aerector pili muscles * Kidneys * Spleen * Most blood vessels

Question 36

What is the major control and integration center of the ANS?

Answer 36

Hypothalamus

Question 37

What does the somatic nervous system control?

Answer 37

Voluntary movement of skeletal muscles

Question 38

What is the neuromuscular junction (NMJ)?

Answer 38

is the synapse (connection) between a motor neuron and a skeletal muscle fiber. where a nerve signal is converted into a muscle contraction.

Question 39

What are the steps of signal transmission at the NMJ?

Answer 39

1. AP arrives at end bulb 2. Ca²⁺ enters 3. ACh is released 4. ACh binds to nicotinic receptors 5. Na⁺ enters → End plate potential (EPP) 6. EPP → muscle AP → contraction 7. ACh broken down by AChE

Question 40

What is the effect of ACh at the NMJ?

Answer 40

Causes skeletal muscle fiber to contract

Question 41

What can alter events at the NMJ?

Answer 41

* Botulinum toxin * A-latroxin * Curare * Organophosphates

Question 42

What is the role of motor neurons in the autonomic nervous system?

Answer 42

Propagate action potentials from the CNS to effectors

Question 43

What is the main difference between the autonomic and somatic nervous systems?

Answer 43

The autonomic nervous system operates involuntarily, while the somatic nervous system operates voluntarily

Question 44

What are the two types of autonomic motor neurons in the autonomic motor pathways?

Answer 44

Pre-ganglionic neuron and postganglionic neuron

Question 45

Where does the pre-ganglionic neuron extend from and to?

Answer 45

From the CNS to an autonomic ganglion

Question 46

What is the function of the postganglionic neuron?

Answer 46

Extends from the autonomic ganglion to the visceral effector

Question 47

What are terminal ganglia associated with?

Answer 47

Parasympathetic nervous system

Question 48

What are the two types of autonomic ganglia in the sympathetic nervous system?

Answer 48

* Sympathetic trunk * Collateral ganglia

Question 49

What do chromaffin cells in the adrenal medulla release?

Answer 49

Epinephrine and norepinephrine

Question 50

What are varicosities?

Answer 50

Varicosities = swollen areas along autonomic axons Function: Release neurotransmitters diffusely Found in: Smooth & cardiac muscle, glands Common in: Autonomic nervous system (especially sympathetic)

Question 51

What triggers the exocytosis of synaptic vesicles at a varicosity?

Answer 51

An action potential reaching the varicosity

Question 52

What type of responses can ACh and NE cause in the visceral effectors?

Answer 52

Excitatory or inhibitory responses

Question 53

Give examples of excitatory responses in the ANS.

Answer 53

* Contraction of smooth muscle * Increased rate and force of contraction of cardiac muscle * Increased secretions of glands

Question 54

Give examples of inhibitory responses in the ANS.

Answer 54

* Relaxation of smooth muscle * Decreased rate and force of contraction of cardiac muscle * Decreased secretions of glands

Question 55

What does the parasympathetic nervous system regulate?

Answer 55

Activities that conserve and restore body energy

Question 56

What does the sympathetic nervous system favor?

Answer 56

Body functions that support vigorous physical activity and rapid production of ATP

Question 57

What does the somatic nervous system innervate?

Answer 57

Skeletal muscles of the body

Question 58

What does a somatic motor pathway consist of?

Answer 58

A single somatic motor neuron extending from the CNS to the skeletal muscle

Question 59

What neurotransmitter is released by somatic motor neurons?

Answer 59

Acetylcholine (ACh)

Question 60

What is the effect of ACh at the neuromuscular junction?

Answer 60

Always excitatory, causing contraction of skeletal muscle

Question 61

What happens when an action potential reaches the synaptic end bulbs of a somatic motor neuron?

Answer 61

Triggers exocytosis of synaptic vesicles, releasing ACh

Question 62

What can alter events at the neuromuscular junction?

Answer 62

Botulinum toxin: blocks ACh release α-latrotoxin: overstimulates release Curare: blocks ACh receptors Organophosphates: block AChE, causing overstimulation → paralysis