What is the primary responsibility of the Autonomic Nervous System (ANS)?
The ANS is responsible for maintaining homeostasis and regulating subconscious body activities.
What are the two main divisions of the ANS?
The two main divisions are the Sympathetic Nervous System (SNS) and the Parasympathetic Nervous System (PSNS).
How do the SNS and PSNS typically work together?
They have opposite functions and work together to balance body responses.
What is the SNS commonly known as?
It is known as the “fight or flight” response system.
When is the SNS activated?
It is activated during times of stress to prepare the body to either fight or flee from it
What neurotransmitters/hormones are released during SNS activation and where do they come from?
Epinephrine (Epi) and norepinephrine (NE) are released into the bloodstream from the adrenal gland, spreading their function as hormones throughout the body.
What are the primary effects of SNS activation on the body? It causes increases in:
-Mental alertness
-Metabolic rate and energy release from fat reserves
-Respiratory rate and bronchial dilation
-Heart rate, blood pressure, and vasoconstriction
-Sweat gland activity
-Pupil dilation
What are the primary effects of SNS activation on the body? It causes decreases in:
-Digestive function
-Urine production
Where do the neurons that supply the SNS leave the CNS, and where are the ganglia located?
Neurons leave the CNS at the thoracic and lumbar regions. The ganglia lay close to the spinal cord
Are the preganglionic or postganglionic fibers longer in the SNS?
The preganglionic fibers are short, and the postganglionic fibers are long.
What is the PSNS commonly known as?
It is known as the “rest and digest” system.
When is the PSNS activated?
It is activated during times of rest to help the body relax and digest food.
What is the most significant cranial nerve component of the PSNS?
Cranial nerve X: the vagus nerve.
What are the primary effects of PSNS activation on the body? A: It causes increases in:
-Digestive and salivary secretions
-GI tract mobility and blood flow
-Production of urine and feces
What are the primary effects of PSNS activation on the body?It causes decreases in:
-Pupil Size
-Metabolic rate
-Heart rate and blood pressure
-Respiratory rate
Where do the neurons that supply the PSNS leave the CNS, and where are the ganglia located?
Neurons leave the CNS at the cranial and sacral regions. The ganglia are distant from the spinal cord, laying close to the effectors
Are the preganglionic or postganglionic fibers longer in the PSNS?
The preganglionic fibers are long, and the postganglionic fibers are short
What are the receptors of the PSNS called, and why are they named this way?
They are called cholinergic receptors (subtypes: muscarinic and nicotinic) because they respond to the neurotransmitter acetylcholine (ACh).
What are the receptors of the SNS called, and why are they named this way?
hey are called adrenergic receptors (subtypes: alpha and beta because epinephrine is also known as adrenaline.
What happens when acetylcholine (ACh) binds to a muscarinic receptor?
The cell responds according to its PSNS genetic program (e.g., increased GI mobility).
What happens when epinephrine (Epi) or norepinephrine (NE) binds to an alpha or beta receptor?
The cell responds according to its SNS genetic program (e.g., increased heart rate).
Where are nicotinic cholinergic receptors most commonly found?
They are most common in the ganglia between preganglionic and postganglionic nerve fibers in both the SNS and PSNS.
What is the function of acetylcholine (ACh) within the sympathetic ganglia?
Within the ganglia, ACh is the neurotransmitter that binds to nicotinic cholinergic receptors to carry nerve impulses.
Quiz Questions: Which of the following neurons typically releases acetylcholine at the intestines?
Parasympathetic postganglionic
