Autonomic nervous system Lec 17

Autonomic Nervous System (ANS)

A system that innervates organs whose functions are generally not under voluntary control.

Sympathetic Nervous System (SNS)

Part of the ANS that prepares the body for 'fight or flight' responses.

Parasympathetic Nervous System (PNS)

Part of the ANS that promotes 'rest and digest' activities.

Dual Innervation

Most organs receive input from both SNS and PNS, allowing for balanced physiological responses.

Afferent Division

The part of the nervous system that carries sensory information to the CNS.

Efferent Division

The part of the nervous system that carries motor commands from the CNS to the periphery.

Cranial Nerves

A set of twelve nerves that directly connect the brain to various body parts, some of which have parasympathetic functions.

Epinephrine

A hormone released by the adrenal medulla that acts as a neurohormone, often associated with the 'fight or flight' response.

Acetylcholine (ACh)

A neurotransmitter released by both preganglionic and postganglionic fibers in the PNS.

Ganglion

A mass or group of neuronal cell bodies located outside the CNS.

Negative Feedback

A process where the output of a system dampens or reduces the effect of the initial stimulus.

Convergence in ANS

The process where each postganglionic neuron receives synapses from multiple preganglionic neurons.

Divergence in ANS

The process in which a preganglionic neuron branches to synapse on multiple postganglionic neurons.

Visceral Organs

Organs that are not typically under voluntary control and often regulated by the ANS.

CNS Centers

Areas in the brain and spinal cord that regulate autonomic functions such as hunger and thirst.

Reflex Arc

A neural pathway that controls reflex actions, typically involving sensory neurons, an integrating center, and efferent pathways.

Glucose Release

The process stimulated by the SNS to enhance blood sugar levels during stressful situations.

Mass Action

The phenomenon in which SNS activation leads to simultaneous responses across many organs.

Muscarinic Receptors

A type of receptor in the PNS that responds to acetylcholine and is involved in parasympathetic effects.

Adrenergic receptors

Receptors that respond to the neurotransmitters norepinephrine and epinephrine in the SNS.