Autonomic Nervous System: Divisions, Receptors, and Physiological Effects

What are the two divisions of the Autonomic Nervous System (ANS)?

Sympathetic and Parasympathetic

What is the primary function of the Sympathetic Nervous System (SNS)?

To prepare the body for 'fight or flight' responses during stress or exercise.

What does the Parasympathetic Nervous System (PNS) primarily promote?

Rest and digest functions.

How do the sympathetic and parasympathetic systems work together?

They maintain homeostasis by adjusting body functions according to physical activity levels.

What role does the hypothalamus play in the ANS?

It stimulates both the sympathetic and parasympathetic systems and monitors body conditions.

What type of neuron originates from the CNS in the ANS?

Preganglionic neuron (pre).

What characterizes postganglionic neurons in the ANS?

They are unmyelinated and innervate effector cells.

What is the effect of the SNS on heart rate?

Increases heart rate and force of contraction.

What neurotransmitter is released by all preganglionic neurons in the SNS?

Acetylcholine (ACh).

What neurotransmitter is primarily released by postganglionic neurons in the SNS?

Norepinephrine.

What is the physiological effect of alpha-1 adrenergic receptors?

Stimulates contraction of blood vessels, increasing blood pressure.

What is the effect of beta-2 adrenergic receptors on bronchial smooth muscle?

Causes bronchodilation, increasing oxygen intake.

What happens to GI motility during sympathetic activation?

Decreased motility and increased constriction of sphincters.

What is the primary function of the PNS on the heart?

Decreases heart rate and blood pressure.

What type of receptors do all PNS neurons use?

Cholinergic receptors.

What is the role of muscarinic receptors in the PNS?

They can be stimulatory or inhibitory, affecting various effector cells.

What are the effects of beta-1 adrenergic receptors on the kidneys?

Increase renin release, promoting water and sodium retention.

What is the function of alpha-2 adrenergic receptors?

Inhibit the release of norepinephrine, acting as a negative feedback loop.

What is a common side effect of beta-2 agonists used in asthma treatment?

Tachycardia or tremors due to systemic effects.

What happens to blood flow during exercise according to the ANS?

Blood flow is redistributed to skeletal muscles.

What is the effect of the PNS on salivary glands?

Increases salivary secretion.

What is the effect of sympathetic activation during a stressful event?

Increased heart rate, dilated pupils, and decreased GI motility.

What is the role of the adrenal medulla in the SNS?

Releases epinephrine and norepinephrine into the bloodstream.

What is the significance of cholinergic neurons in the PNS?

Both preganglionic and postganglionic neurons release acetylcholine.

How does chronic stress affect the gastrointestinal system?

It can contribute to GI disorders by inhibiting normal digestive processes.

What is the physiological advantage of pupil dilation during stress?

Enhances vision and awareness of surroundings.

What is the effect of beta-3 adrenergic receptors?

Stimulate lipolysis in adipose tissue and relax the bladder.

What is the role of the cauda equina in the PNS?

Contains preganglionic neurons that innervate pelvic organs.