chap 15

what is the somatic nervous system

is a component of the peripheral nervous system, regulates voluntary movements, transmits sensory information to the central nervous system. It controls skeletal muscles and is responsible for reflexes and conscious motor control.

what is somatic sensory

refers to sensory input from the skin, muscles, and joints that is processed by the central nervous system to create perceptions of touch, pain, temperature, and body position.

what is somatic motor

involves the output signals that control voluntary movements of skeletal muscles, enabling actions like walking and grasping.

what is the autonomic nervous system

part of the peripheral nervous system that regulates involuntary bodily functions, including heart rate, digestion, and respiratory rate. It has two main divisions: the sympathetic and parasympathetic nervous systems.

what is autonomic moter

manages involuntary functions.

what are the functions of the lower motor neurons of somatic nervous system

They transmit signals from the spinal cord to skeletal muscles, enabling voluntary movement and reflex actions.

what are preganglionic neuron

neurons that originate in the central nervous system and synapse with postganglionic neurons in autonomic ganglia, facilitating communication within the autonomic nervous system.

what is a postganglionic neuron and its function

A neuron that transmits signals from autonomic ganglia to target tissues such as smooth muscle and glands, playing a key role in the autonomic nervous system.

difference between pre and postganglionic neurons

originate in the central nervous system and connect to postganglionic neurons in autonomic ganglia; neurons transmit signals from the ganglia to target tissues.

what is an autonomic neuron

A type of neuron that is part of the autonomic nervous system, responsible for involuntary functions such as heart rate, digestion, and respiratory rate.

what neuronal convergence

The process by which multiple presynaptic neurons communicate with a single postsynaptic neuron, allowing for the integration of signals and modulation of neuronal output.

what is neuronal divergence

The process by which a single presynaptic neuron communicates with multiple postsynaptic neurons, allowing for the amplification of a signal and distribution of neuronal influence across different pathways.

what is the difference between the lower motor neurons of the somatic vs the autonomic nervous system

innervate skeletal muscle fibers for voluntary movement; innervate smooth and cardiac muscles or glands for involuntary functions.

hypothalamus role in the autonomic nervous system

regulates autonomic functions such as heart rate, blood pressure, and temperature control, integrating signals from the body and coordinating responses through the sympathetic and parasympathetic divisions.

what is the role of the brainstem in the autonomic nervous system

responsible for controlling many autonomic functions including heart rate, respiratory rate, and blood pressure, linking higher brain functions with autonomic regulation.

what is the roll of the spinal cord in the autonomic nervous system

conduit for autonomic signals, transmitting information between the brain and the autonomic targets in the body. It contains pathways for both the sympathetic and parasympathetic divisions, facilitating reflex arcs and responses.

what is the parasympathetic division of the autonomic nervous system

a branch of the autonomic nervous system that promotes rest and digest functions, conserving energy by slowing down the heart rate and increasing intestinal activity.

what is the sympathetic division of the autonomic nervous system

a branch of the autonomic nervous system that prepares the body for fight or flight responses, increasing heart rate, dilating airways, and inhibiting digestive functions.

anatomic differences between parasympathetic and sympathetic divisions

characterized by long preganglionic and short postganglionic fibers; has short preganglionic and long postganglionic fibers, leading to distinct anatomical and functional differences.

what is the degree of response from the parasympathetic division

localized and specific, as it primarily affects individual organs rather than the body as a whole, allowing for precise regulation of functions such as digestion and heart rate.

what is mass activation

a widespread activation of the sympathetic division that prepares the entire body for rapid responses to stress or danger.

what is the terminal ganglia

ganglia located near or in the target organs of the parasympathetic nervous system, where preganglionic fibers synapse with postganglionic neurons.

what is a intramural ganglion

ganglia located within the walls of target organs of the parasympathetic nervous system. They allow for direct communication between the nervous system and the organ.

what is the organization of the sympathetic division

consists of a network of preganglionic neurons that originate in the thoracic and lumbar regions of the spinal cord and synapse in ganglia close to the spinal cord, known as sympathetic ganglia.

what is white rami

the myelinated preganglionic fibers that carry signals from the spinal cord to the sympathetic ganglia. They are part of the sympathetic nervous system.

what is gray rami

the unmyelinated postganglionic fibers that carry signals from the sympathetic ganglia back to the spinal nerves. They help distribute sympathetic signals throughout the body.

what are white rami communicantes

the myelinated preganglionic fibers that connect the spinal nerves to the sympathetic ganglia, facilitating communication within the sympathetic nervous system.

what are gray rami communicants

the unmyelinated postganglionic fibers that connect sympathetic ganglia to spinal nerves, enabling the transmission of sympathetic signals.

what is the anatomy if the sympathetic divison

the sympathetic chain ganglia, preganglionic fibers originating from the thoracolumbar spinal cord, and postganglionic fibers that extend to various target organs, facilitating the 'fight or flight' response.

what are the steps for the sympathetic chain ganglia

The process involves preganglionic neurons exiting the spinal cord, synapsing in the sympathetic chain ganglia, and then postganglionic fibers traveling to target organs.

what is the sympathetic splanchnic nerves

Nerves that arise from the sympathetic chain and innervate abdominal and pelvic organs, transmitting sympathetic signals.

what is the prevertebral ganglia

Ganglia located anterior to the vertebral column, associated with the sympathetic division, which innervate the digestive, urinary, and reproductive organs.

what is the celiac

A cluster of nerve cells located near the abdominal organs that innervates the stomach, spleen, pancreas, and liver, transmitting sympathetic signals.

what is the superior mesenteric

A cluster of nerve cells located in the abdomen that innervates the small intestine and parts of the large intestine, transmitting sympathetic signals.

what is the inferior mesenteric ganglia

A cluster of nerve cells located in the abdomen that innervates the large intestine, rectum, and portions of the urinary bladder, transmitting sympathetic signals.

Where do sympathetic preganglionic neurons originate?

Thoracolumbar region (T1–L2) of the spinal cord.

Where do parasympathetic preganglionic neurons originate?

Brainstem and sacral spinal cord (craniosacral division).

Chronic sympathetic overactivity can contribute to which condition?

Hypertension (high blood pressure).

What part of the brainstem is vital for autonomic functions like breathing and heart rate?

Medulla oblongata.

A stroke affecting autonomic centers can impair

Heart rate, respiration, and digestive control.

What is the main symptom of autonomic neuropathy?

Impaired regulation of blood pressure, heart rate, digestion, and urination.

What can cause autonomic neuropathy?

Diabetes mellitus.

What is multiple system atrophy (MSA)?

A progressive neurodegenerative disorder affecting autonomic functions.

What is Raynaud phenomenon?

Excessive sympathetic vasoconstriction in fingers and toes in response to cold or stress.

What is orthostatic hypotension?

A sudden drop in blood pressure upon standing, due to ANS dysfunction.

What is Horner syndrome?

Loss of sympathetic innervation to the face, causing drooping eyelid and pupil constriction.

What is autonomic dysreflexia?

A dangerous condition of uncontrolled sympathetic output, often after spinal cord injury

What is autonomic tone?

Continuous low-level activity of the autonomic nervous system.

Which division is dominant after eating a meal?

Parasympathetic division.

Which division is dominant during exercise?

Sympathetic division.

Parasympathetic stimulation causes the bladder to

Contract and promote urination.

Sympathetic activation of sweat glands leads to

Increased sweating.

Parasympathetic stimulation ______ heart rate.

Decreases.

Sympathetic stimulation ______ pupil size.

Dilates

Parasympathetic stimulation of the digestive system ______ activity.

Increases gastrointestinal

Sympathetic stimulation of the adrenal medulla causes release of ______.

Epinephrine and norepinephrine.

How is neurotransmitter action terminated in the sympathetic nervous system?

Reuptake of norepinephrine or enzymatic breakdown (MAO, COMT).

Activation of beta-2 receptors causes ______.

Bronchodilation and vasodilation in skeletal muscles.

Activation of beta-1 receptors increases ______.

heart rate and contractility.

Activation of alpha-1 receptors usually causes ______.

Vasoconstriction.

Where are nicotinic receptors found?

On postganglionic neurons and adrenal medulla cells.

What receptors bind norepinephrine?

Alpha and beta adrenergic receptors.

What receptors bind acetylcholine?

Nicotinic and muscarinic receptors.

What is an adrenergic neuron?

A neuron that releases norepinephrine (NE).

What is a cholinergic neuron?

A neuron that releases acetylcholine (ACh).

Parasympathetic ganglia are located ______ to the target organ.

Near or within

Sympathetic ganglia are located ______ to the spinal cord.

Close (in the sympathetic chain).

What neurotransmitter is typically released by sympathetic postganglionic neurons?

Norepinephrine (NE).

What neurotransmitter is primarily released by sympathetic preganglionic neurons?

Acetylcholine (ACh).

Where do parasympathetic preganglionic neurons originate?

Brainstem and sacral spinal cord (craniosacral division).