Overview
This lecture introduces the human nervous system, detailing its main functions, structures, and subdivisions, focusing on both the central and peripheral components.
Main Functions of the Nervous System
- Coordinates all body activities.
- Enables response and adaptation to internal and external changes.
- Distinguishes humans through consciousness and intelligence.
Central Nervous System (CNS)
- Composed of the brain and spinal cord.
- Brain is located in the skull (cranium) and has six main sections: cerebrum, cerebellum, diencephalon, midbrain, pons, and medulla oblongata.
Brain Sections and Functions
- Cerebrum: Largest section; divided into right and left hemispheres, and four lobes:
- Frontal (reasoning, thought)
- Parietal (sensory integration)
- Temporal (auditory processing)
- Occipital (visual processing)
- Cerebellum: Controls muscle coordination, balance, posture, and tone.
- Diencephalon: Contains thalamus (sensory relay) and hypothalamus (autonomic functions, emotions).
- Midbrain: Manages eye and auditory reflexes.
- Pons: Controls reflexes like chewing, tasting, saliva production.
- Medulla Oblongata: Regulates heart, blood vessels, digestion, respiration, and reflexes (swallowing, coughing, sneezing).
Spinal Cord
- Connects brain to body through nerves.
- Divided into cervical, thoracic, and lumbar regions.
- Afferent nerves carry signals to the brain; efferent nerves carry signals from brain to body.
Peripheral Nervous System (PNS)
- All nerves outside the brain and spinal cord.
- Subdivided into somatic and autonomic systems.
Somatic Nervous System
- Conducts voluntary control of muscles and processes sensory information.
- Uses afferent (to CNS) and efferent (from CNS) neurons.
Autonomic Nervous System
- Divided into sympathetic (activates fight or flight) and parasympathetic (restores normalcy) systems.
- Controls involuntary actions and regulates body’s internal environment.
Key Terms & Definitions
- Neuron — Nerve cell transmitting electrical signals.
- Cerebrum — Largest brain part; handles higher functions.
- Afferent neuron — Carries information to CNS.
- Efferent neuron — Carries commands from CNS to muscles.
- Sympathetic nervous system — Activates body in response to stress.
- Parasympathetic nervous system — Restores body to restful state.
Action Items / Next Steps
- Review the six main sections of the brain and their functions.
- Learn the differences between afferent and efferent neurons.
- Prepare for detailed study of the peripheral nervous system in future lessons.