Overview
This lecture introduces the basics of the nervous system, covering its main functions, structures, and divisions, with a focus on what students need to know for exams.
Functions of the Nervous System
- The nervous system detects stimuli (e.g., light, pain, sound) through sensory receptors.
- Sensory receptors send information to the central nervous system (CNS: brain and spinal cord).
- CNS integrates information and decides on a response (integrative function).
- Effectors (muscles or glands) carry out the response, such as movement or secretion.
Structure of the Central Nervous System (CNS)
- CNS consists of the brain and spinal cord.
- The brain and spinal cord are protected by three meninges: dura mater (outer), arachnoid (middle), pia mater (inner).
- Cerebrospinal fluid surrounds the CNS for protection and lubrication.
Regions of the Brain
- Cerebrum: largest part, responsible for voluntary movement, senses, intelligence, memory, and personality.
- Cerebellum: coordinates smooth voluntary movement, maintains muscle tone, posture, and balance.
- Corpus callosum: connects left and right brain hemispheres for communication.
- Medulla oblongata: controls vital functions (breathing, heart rate, reflexes like sneezing); damage can be fatal.
Spinal Cord Structure & Function
- Spinal cord extends from the medulla, down the vertebral column.
- Inner gray matter and outer white matter (difference due to myelin).
- Dorsal root (back) brings sensory info in; ventral root (front) sends motor commands out.
- Central canal contains cerebrospinal fluid.
- Spinal nerves branch off to the body; spinal cord controls primitive reflexes (e.g., knee-jerk).
Peripheral Nervous System (PNS) and Divisions
- PNS includes all nerves outside the CNS.
- Divided into somatic (voluntary movement, sense organs) and autonomic (involuntary functions) nervous systems.
- Autonomic nervous system splits into sympathetic (fight or flight, fast response) and parasympathetic (rest and digest, slow response) divisions.
Key Terms & Definitions
- Stimulus — incoming change in the environment detected by the body.
- Receptor — specialized cell or organ that detects stimuli.
- Integrator — CNS part (brain/spinal cord) that interprets information and decides a response.
- Effector — muscle or gland that acts in response to CNS instructions.
- Meninges — three protective layers around brain and spinal cord: dura mater, arachnoid, pia mater.
- Cerebrum — brain region for intelligence, senses, movement.
- Cerebellum — brain region for movement coordination and balance.
- Corpus callosum — structure connecting brain hemispheres.
- Medulla oblongata — brain region controlling vital involuntary functions.
- Dorsal root — spinal cord section carrying sensory inputs.
- Ventral root — spinal cord section carrying motor outputs.
- Somatic nervous system — controls voluntary muscles and sense organs.
- Autonomic nervous system — controls involuntary body functions.
- Sympathetic division — part of autonomic system for emergency responses.
- Parasympathetic division — part of autonomic system for relaxation and digestion.
Action Items / Next Steps
- Draw a flow diagram or family tree showing divisions of the nervous system.
- Review and memorize key terms using flashcards.
- Prepare to label diagrams of the brain, spinal cord, and their structures.