Overview of the Nervous System

30 flashcards covering CNS vs PNS, SNS vs ANS, neurotransmitters, and homeostasis based on the nervous system lecture notes.

What does the CNS stand for and what are its main components?

Central Nervous System; consists of the brain and spinal cord, with the brain handling conscious and unconscious processing and the spinal cord linking the brain to the body and mediating simple reflexes.

What are the two major divisions of the nervous system?

Central Nervous System (CNS) and Peripheral Nervous System (PNS).

Which structures are part of the CNS?

Brain and spinal cord.

What is the brain the site of according to the notes?

Conscious thought and much unconscious processing.

What is the role of the spinal cord?

A conduit between the brain and body and it can mediate simple reflexes (e.g., knee‑jerk).

What does the Peripheral Nervous System (PNS) do?

Relays sensory information to the CNS and carries motor instructions away from it.

What is the difference between afferent and efferent neurons?

Afferent neurons transmit data to the CNS; efferent neurons transmit data from the CNS.

Which division of the PNS controls skeletal muscles and is it voluntary?

The Somatic Nervous System (SNS); it is voluntary.

Give an example of an SNS action.

Raising your arm.

What does the Autonomic Nervous System (ANS) regulate?

Internal organs and glands; it is involuntary.

What are the two divisions of the ANS?

Sympathetic division (Fight‑or‑Flight) and Parasympathetic division (Rest‑and‑Digest).

What activates the sympathetic division?

Stress, danger, and intense activity.

What is the primary neurotransmitter of the sympathetic division?

Noradrenaline (norepinephrine).

Name some physiological effects of sympathetic activation.

Increased heart rate and force of contraction; increased breathing rate; dilation of pupils; decreased digestive activity.

What is the purpose of the sympathetic division?

To mobilize energy and prepare the body for rapid action.

What activates the parasympathetic division?

Calm states, post‑meal, and recovery states.

What is the primary neurotransmitter of the parasympathetic division?

Acetylcholine.

Name some physiological effects of parasympathetic activation.

Decreased heart rate and breathing rate; constricted pupils; increased digestive activity (peristalsis and enzyme release).

What is the purpose of the parasympathetic division?

To conserve energy and promote maintenance and repair.

What does homeostasis refer to in this context?

Dynamic balance maintained by the coordinated actions of the sympathetic and parasympathetic divisions; internal variables stay within optimal ranges.

How do the two branches maintain homeostasis under normal conditions?

They offset each other to keep internal variables within optimal ranges.

What is the enteric nervous system and how many neurons does it contain?

The “gut brain”; it contains about 100 million nerve cells.

What is notable about the enteric system's processing?

It can process and digest food independently of the CNS.

What are typical triggers for autonomic responses listed in the notes?

Stress, danger, and exercise (activate sympathetic); relaxation and digestion (activate parasympathetic).

Which neurotransmitters are associated with the sympathetic and parasympathetic divisions?

Sympathetic: noradrenaline (norepinephrine); Parasympathetic: acetylcholine.

What effect does sympathetic activation have on the heart?

Increases heart rate and force of contraction.

What effect does parasympathetic activation have on the heart and respiration?

Decreases heart rate and decreases breathing rate.

What effect does the sympathetic division have on digestion?

Inhibits digestive activity.

What effect does the parasympathetic division have on digestion?

Stimulates digestion (peristalsis and enzyme release).

What is the overall contrast between the sympathetic and parasympathetic divisions?

Sympathetic: fight‑or‑flight, energy mobilization; Parasympathetic: rest‑and‑digest, energy conservation and maintenance.