Autonomic Nervous System (Unit 4)

Autonomic Nervous System

Controls involuntary muscle and body processes. Part of the PNS.

Examples of functions regulated by the Autonomic Nervous System:

To Generalize, the autonomic system helps regulate homeostasis. Therefore, functions include:

• Breathing Rate

• Sneezing

• Temperature Sensation

• Sweating when Exercising

• Monitoring Changes in Blood Pressure

• Heart & Breathing Rate

• Movement of Food Through the Gut

The 2 subdivisions of the ANS are:

• Sympathetic

• Parasympathetic

Sympathetic Subdivision

Prepares the body to perform optimally at physical tasks.

AKA “fight or flight”

Begins from the in the Thoracic and Lumbar regions

Parasympathetic Division

Regulates body activities under resting, peaceful conditions.

AKA “rest and digest”

Begins in the Cranial and Sacral regions

How many consecutive neurons do the 2 subdivisions use to innervate targets?

Both use 2 neurons

In the sympathetic subdivision, the preganglionic neuron is _____ than the postganglionic neuron.

shorter

In the parasympathetic subdivision, the preganglionic neuron is _____ that the postganglionic neuron.

longer

All preganglionic neurons in the ANS, and all postganglionic neurons that innervate sweat glands, are ____.

cholinergic

All sympathetic postganglionic neurons, besides sweat glands, are

adrenergic

The __________ is found on all postganglionic neurons & adrenal medulla cells.

nicotinic AChR subtype

The _________ is found on all target organs of the parasympathetic branch and on sympathetic sweat glands.

muscarinic AChR subtype

The effect of nAChR activation is _____.

excitation

mAChR activation tends to be ____________________.

excitatory, but is inhibitory in the heart

Adrenergic receptors have ____ subtypes.

alpha and beta

α1 adrenergic receptor

• Found in all sympathetic target organs except the heart and bronchioles

• Overall effect is excitatory, causes smooth muscle contraction

α2 adrenergic receptor

• Found in the pancreas, CNS, and GI

• Can be excitatory or inhibitory

  • Inhibits insulin release in the pancreas

  • Inhibits sympathetic activity

  • Causes GI sphincter contraction

β1 adrenergic receptor

• Found in the heart and kidneys

• Overall effect is excitatory

  • Increases heartrate and force of contraction

  • Stimulates renin release in the kidneys

β2 adrenergic receptor

• Found in coronary arteries and bronchioles

• Mostly inhibitory

  • Causes relaxation and dilation

β3 adrenergic receptor

• Found in adipose tissue and the urinary bladder

• excitatory or inhibitory

  • relaxes the bladder wall

  • stimulates fat breakdown

Beta Blockers (ex. Metoprolol)

• Class of pharmaceutical that serves as a competitive antagonist to norepinephrine.

• Causes decreased stimulation of the heart and is therefore used to treat tachycardia

Beta Agonists (ex. Albuterol)

• Class of pharmaceutical that stimulates β receptors

• Causes bronchodilation and bronchoconstriction and is therefore used to treat the symptoms of a asthma attack

Parasympathetic postganglionic neurons are ______.

cholinergic