Overview
This lecture covers the basic organization of the nervous system, its cooperation with the endocrine system, and key divisions within the central and peripheral nervous systems.
Nervous System Functions and Comparison to Endocrine System
- The nervous system and endocrine system work together to control other body systems.
- The nervous system responds quickly using action potentials (electrochemical signals).
- The endocrine system responds more slowly via hormones released into the blood.
Central Nervous System (CNS)
- The CNS consists of the brain and spinal cord.
- The CNS integrates and processes incoming sensory information.
- Integration allows the brain to interpret and combine signals from various senses for context and meaning.
Peripheral Nervous System (PNS)
- The PNS connects the CNS to the rest of the body.
- Sensory (afferent) nerves carry incoming information to the CNS.
- Motor (efferent) nerves transmit commands from the CNS to effectors (muscles and glands).
Sensory (Afferent) Division
- Special senses involve unique organs: vision (eye), taste (tongue), smell (nose), hearing and balance (ear).
- Somatic senses involve signals from the body, such as touch, pain, temperature, and awareness of muscle/joint positions (proprioception).
- Visceral senses originate from internal organs, conveying information like fullness, pain, or pressure.
Motor (Efferent) Division
- The somatic motor system controls voluntary movements via skeletal muscle.
- The autonomic motor system controls involuntary responses in cardiac muscle, smooth muscle, and glands.
Autonomic Nervous System (ANS)
- The sympathetic division controls "fight-or-flight" responses (increased heart rate, respiration, sweating, pupil dilation, redirected blood flow, increased glucose).
- The parasympathetic division controls "rest-and-digest"/"feed-and-breed" activities (slowed heart and breathing rates, normal digestion, relaxed pupils).
Key Terms & Definitions
- Central Nervous System (CNS) — brain and spinal cord; integrates sensory input and coordinates responses.
- Peripheral Nervous System (PNS) — nerves outside the CNS; connects CNS to limbs and organs.
- Afferent (Sensory) Nerves — carry information to the CNS.
- Efferent (Motor) Nerves — carry commands from the CNS to muscles/glands.
- Somatic — relating to the body, especially skeletal muscles and voluntary control.
- Visceral — relating to internal organs.
- Autonomic Nervous System (ANS) — controls involuntary bodily functions.
- Sympathetic Division — prepares the body for stressful activities.
- Parasympathetic Division — conserves energy and promotes housekeeping functions during rest.
Action Items / Next Steps
- Prepare for the next lecture on neural tissue, focusing on neurons and glial cells.