Overview
This lecture introduces the basics of the nervous system, its functions, main structures, and divisions, with a focus on key concepts needed for exams.
Function of the Nervous System
- The nervous system detects stimuli (e.g., light, pain, sound) via sensory receptors.
- Information from receptors is sent to the central nervous system (CNS) for decision making (integration).
- CNS sends instructions to effectors (muscles or glands) to create a response.
- Responses allow the body to adjust to changes in the external environment.
Structure of the Central Nervous System (CNS)
- CNS is composed of the brain and spinal cord.
- The brain and spinal cord are protected by three layers called meninges: dura mater (outer), arachnoid, and pia mater (inner).
- Cerebrospinal fluid surrounds the CNS for lubrication and protection.
Regions of the Brain
- Cerebrum: Controls voluntary movement, senses, memory, personality, and intelligence.
- Cerebellum: Coordinates voluntary movements, maintains muscle tone, posture, and balance.
- Corpus Callosum: Connects left and right brain hemispheres for communication.
- Medulla Oblongata: Controls vital involuntary functions like heartbeat and breathing; damage can be fatal.
Spinal Cord Structure and Function
- Spinal cord extends from the medulla down the vertebral column.
- Central gray matter is surrounded by white matter (myelinated nerves).
- Main features: dorsal root (back, sensory input), ventral root (front, motor output), central canal (cerebrospinal fluid), spinal nerves.
- Controls reflexes (e.g., knee-jerk) and acts as a pathway for nerve impulses.
Peripheral Nervous System (PNS)
- PNS consists of all nerves outside the CNS, connecting the CNS to limbs and organs.
- Divided into:
- Somatic Nervous System: Controls voluntary movements and receives sensory input from sense organs.
- Autonomic Nervous System: Controls involuntary actions; subdivided into:
- Sympathetic Division: "Fight or flight," increases heart rate, dilates pupils, decreases digestion.
- Parasympathetic Division: "Rest and digest," slows heart rate, constricts pupils, increases digestion.
Key Terms & Definitions
- Stimulus — Change or signal from the environment detected by receptors.
- Receptor — Specialized cells/organs detecting stimuli.
- Integrator/Integration — CNS processing and decision-making.
- Effector — Muscle or gland carrying out the CNS response.
- Meninges — Three protective layers around the brain and spinal cord.
- Cerebrum — Largest brain region for voluntary and cognitive functions.
- Cerebellum — Coordinates movement and balance.
- Corpus Callosum — Band connecting left and right brain hemispheres.
- Medulla Oblongata — Controls essential involuntary functions.
- Spinal Cord — CNS part transmitting impulses and controlling reflexes.
- Somatic Nervous System — Controls voluntary actions.
- Autonomic Nervous System — Controls involuntary functions.
- Sympathetic Division — Prepares body for action.
- Parasympathetic Division — Promotes relaxation processes.
Action Items / Next Steps
- Draw a flow diagram or family tree to visualize the divisions of the nervous system.
- Create flashcards for key terms and definitions.