Module 10:

• Drugs can be antagonists, antagonists, or reuptake inhibitors.

  • Agonists: make neurons fire

  • Antagonists: stop neural firing

  • Reuptake inhibitors: block reuptake

• The nervous system is the body’s speedy electrochemical communication network, consisting of all the nerve cells of the peripheral and central nervous systems, that takes in information from the world and the body’s tissues, makes decisions, and sends back information and orders to the body’s tissues.

  • The central nervous system (CNS): the brain and spinal cord.

    • The spinal cord is a two-way information highway, connecting the PNS and brain.

  • The peripheral nervous system (PNS): the sensory and motor neurons that connect the central nervous system to the rest of the body. 

    • All nerves are not encased in bone; everything but the brain and spinal cord; is divided into two categories: somatic and autonomic.

  • Nerves: bundled axons that form neural cables, connecting the central nervous system with muscles, glands, and sense organs.

• Sensory (afferent) neurons: neurons that carry incoming sensory information from the body’s tissues and sensory receptors to the brain and spinal cord.

• Motor (efferent) neurons: neurons that carry outgoing information from the brain and spinal cord to the muscles and glands, controlling voluntary and involuntary physical processes.

• Interneurons: neurons within the brain and spinal cord that communicate internally and process information between the sensory inputs and motor outputs.

• The somatic nervous system (also known as the skeletal nervous system): the division of the peripheral nervous system that controls the body’s voluntary skeletal muscles. Uses motor (efferent) neurons.

• The autonomic nervous system (ANS): the part of the peripheral nervous system that controls the glands and the muscles of internal organs (such as the heart). Controls the body’s automatic functions, and is split into two branches:

  • Its sympathetic division arouses; its parasympathetic division calms.

  • Sympathetic nervous system: the division of the ANS that arouses the body, mobilizing its energy.

    • Accelerates heart rate, breathing, dilates pupils, slows down digestion.

  • Parasympathetic nervous system: the division of the ANS that automatically slows and calms the body after a stressful event. 

    • Heart rate and breathing slow, pupils constrict, and digestion speeds up.

• The Endocrine System: the body’s slow chemical communication system; a set of glands that secrete hormones into the bloodstream.

  • Hormones are chemical messengers that are manufactured by the endocrine glands, travel through the bloodstream, and affect other tissues.

  • Controlled by the hypothalamus, which is the brain region controlling the pituitary gland (the pituitary gland is the most influential gland).

    • This gland deals with growth hormones, contractions in childbirth, milk production in women, etc.

• Some hormones are chemically identical to some neurotransmitters, as the endocrine system and nervous system are very closely related.

  • Similarity: Both produce molecules that act on receptors elsewhere. 

  • Difference: The nervous system zips messages from eye to brain to hand in a fraction of a second, while the endocrine system’s messages take several seconds to travel from the gland to the target tissue.

• Adrenal glands: a pair of endocrine glands that sit just above the kidneys and secrete hormones (epinephrine and norepinephrine) that help arouse the body in times of stress.

  • Part of the sympathetic nervous system division of the ANS.