Somatic and Autonomic Nervous System: Key Concepts and Differences

What is the somatic nervous system responsible for?

It controls conscious, voluntary processes and the contraction of skeletal muscle cells.

What processes does the autonomic nervous system control?

It manages unconscious, involuntary processes, including cardiac muscle, smooth muscle, and glandular tissue activity.

How do cardiac muscle cells differ from skeletal muscle cells?

Cardiac muscle cells are shorter, branched, and have a single nucleus, while skeletal muscle cells are longer and multinucleated.

What is smooth muscle and where is it found?

Smooth muscle is non-striated, spindle-shaped, and contracts to propel food along the digestive tract.

What are the two subdivisions of the autonomic nervous system?

The sympathetic and parasympathetic nervous systems.

What is the primary function of the parasympathetic nervous system?

It is involved in anabolic processes that save energy and reduce heart activity and blood pressure.

What is the primary function of the sympathetic nervous system?

It is involved in catabolic processes that use up energy, increasing heart activity and blood pressure.

What are the two main reasons for the widespread effects of the sympathetic nervous system?

1. Circulating hormones like adrenaline and noradrenaline. 2. More divergence in sympathetic pathways.

What is the craniosacral division of the autonomic nervous system?

It refers to the parasympathetic system, which passes out from the brain and sacral region of the spinal cord.

What is the thoracolumbar division of the autonomic nervous system?

It refers to the sympathetic system, which passes out only from the thoracic and lumbar levels of the spinal cord.

What is the role of the somatic nervous system in muscle control?

It sends axons from the CNS to skeletal muscles, controlling voluntary movement.

How do axons travel to skeletal muscles?

Axons are grouped into bundles called nerves, which send multiple axons to each muscle.

What is the structure of smooth muscle cells?

Smooth muscle cells are short, spindle-shaped, tapering at both ends with a single nucleus.

What is the sliding filament mechanism?

It is the basic mechanism of contraction used by all muscle types, although the arrangement of filaments differs.

What is the significance of the fight-or-flight response?

It is activated by the sympathetic nervous system to prepare the body for confronting or escaping threats.

What types of muscle does the autonomic nervous system control?

It controls cardiac muscle, smooth muscle, and some glandular tissues.

What is the difference in effects between the sympathetic and parasympathetic systems?

The sympathetic system has widespread effects, while the parasympathetic system has more focused effects.

What are the levels of the central nervous system (CNS)?

The brain (cranial level) and the spinal cord, which is divided into cervical, thoracic, lumbar, sacral, and coccygeal sections.

Where do parasympathetic axons originate in the CNS?

They originate from the brain and the sacral region of the spinal cord.

Where do sympathetic axons originate in the CNS?

They originate only from the thoracic and lumbar levels of the spinal cord.

What are the two main divisions of the autonomic nervous system?

Sympathetic and parasympathetic nervous systems.

What is the role of parasympathetic axons in the body?

They control functions such as pupil diameter and gut muscle movement.

Where do sympathetic axons originate in the spinal cord?

From the thoracolumbar levels.

What is a ganglion?

A cluster of nerve cell bodies lying outside the central nervous system.

What are the two types of neurons in the autonomic pathway?

Preganglionic neurons and postganglionic neurons.

How do the lengths of axons differ in the sympathetic and parasympathetic systems?

In the sympathetic system, the preganglionic axon is shorter; in the parasympathetic system, it is longer.

What neurotransmitter is released by somatic nerve cells at the target tissue?

Acetylcholine (ACh).

What neurotransmitter do parasympathetic postganglionic neurons use?

Acetylcholine (ACh).

What neurotransmitter do sympathetic postganglionic neurons primarily release?

Noradrenaline (NA).

What is the exception to the rule regarding sympathetic postganglionic neurotransmitter release?

Sympathetic neurons to sweat glands release acetylcholine instead of noradrenaline.

What hormones are released by the adrenal medulla in response to sympathetic activation?

Noradrenaline and adrenaline.

What is the significance of divergence in the autonomic nervous system?

It allows a single preganglionic neuron to activate multiple postganglionic neurons, amplifying the response.

What physiological response is primarily associated with the sympathetic nervous system?

The fight-or-flight response.

How does the sympathetic nervous system prepare the body when threatened?

It activates widespread physiological responses to confront or escape the threat.

What distinguishes the autonomic nervous system from the somatic nervous system?

The autonomic system involves two nerve cells in its pathway, while the somatic system involves only one.

Where are ganglia typically located in the sympathetic nervous system?

Close to the spinal cord.

Where are ganglia typically located in the parasympathetic nervous system?

Close to or within the target tissue.

What is the role of the adrenal glands in the sympathetic response?

They release hormones into the bloodstream that enhance the sympathetic response.

What is the neurotransmitter released by sympathetic preganglionic neurons?

Acetylcholine (ACh).

What type of muscle does the sympathetic nervous system primarily affect?

Smooth muscle in blood vessels and cardiac muscle.

What is the relationship between the central nervous system and autonomic pathways?

Autonomic pathways consist of neurons that extend from the CNS to target tissues.