BI103 Week 3 Lecture Notes

Sign Language Communication
- Different forms of communication exist beyond spoken languages; sign language is a significant form used by the deaf community.
Scientific Approach to Brain Research
- Ethical concerns limit methods used in studying brain function (e.g., live animal brain experiments criticized); affects studies involving memory and processing.
- Tests with animals (rats in mazes) are conducted to understand memory; however, results are not directly translatable to human experience.
- Functional MRI: Non-invasive way to observe brain activity; identifies active brain regions but lacks precision in terms of neural-level activity.

Components of the Nervous System
- Central Nervous System: Includes the brain and spinal cord.
- Peripheral Nervous System: Includes all other nerves and sensory organs.
Functionality of Nervous System
- Input: Receiving external stimuli (light, sound, etc.).
- Processing: Interpreting and understanding the stimuli.
- Output: Generating responses (like writing or speaking).
Subdivisions of Nervous System:
- Sensory Division: Carries information into the CNS (input).
- Motor Division: Carries commands out from the CNS (output).

Somatic vs. Visceral
- Somatic: Conscious control (e.g., movement); includes sensory input that can be consciously perceived.
- Visceral: Unconscious control (e.g., heart rate, digestion); includes processes we don't actively sense.
Divisions of Visceral Motor:
- Sympathetic: Involved in fight-or-flight responses (e.g., increased heart rate, blood flow to muscles).
- Parasympathetic: Involved in rest and recovery processes (e.g., decreased heart rate).

Basic Unit: Neuron, which has three basic parts:
- Input (Dendrites): Receive signals.
- Cell Body (Soma): Processes information.
- Axon: Sends signals out to other neurons or muscles.
Types of Neurons:
- Sensory Neurons: Carry signals to the CNS.
- Interneurons: Process information within the CNS.
- Motor Neurons: Carry commands from the CNS to the body.
Glial Cells: Supportive cells in the nervous system that maintain homeostasis, provide support and protection for neurons.

Main Brain Areas:
- Brain Stem: Controls basic life functions like heart rate and breathing.
- Cerebellum: Coordinates voluntary movements and balance.
- Cerebral Cortex: Higher brain functions like thought, memory, and reasoning.
Major Areas of the Brain:
- Frontal Lobe: Involved in decision-making, problem-solving, and control of behavior.
- Parietal Lobe: Processes sensory information like touch, temperature, and pain.
- Temporal Lobe: Involved in auditory processing and memory (where Wernicke's area is located for language comprehension).
- Occipital Lobe: Processes visual information.

Neurotransmitters: Chemicals that transmit signals across synapses.
- Excitatory Neurotransmitters: Increase likelihood of firing the next neuron (e.g., Glutamate).
- Inhibitory Neurotransmitters: Decrease likelihood of firing (e.g., GABA).
Action Potential: Neurons communicate via action potentials which are all-or-nothing responses. Once a threshold is reached, the neuron's signal propagates down the axon at a consistent strength.
Synapse: Connection point where neurotransmitters are released and received by the next neuron.

Memory Types:
- Short-term Memory: Briefly holds information for processing.
- Long-term Memory: Information consolidated over time in various brain regions.
Hippocampus: Crucial for forming new memories and learning; closely associated with emotional responses (via the amygdala).

Stages of Sleep:
- Stages include light sleep, deep sleep, and REM; each stage contributes differently to physical restoration and memory consolidation.
- Lack of sleep can lead to significant cognitive and physical impairments; critical for brain function and health.

Wernicke's Area: Involved in understanding language (both spoken and written).
Broca's Area: Involved in the production of speech and language articulation.
These areas communicate between, integrating comprehension and expression.

Brain functionality is often lateralized; for instance, the left hemisphere predominantly handles language processing and logical reasoning, while the right deals with creativity and emotional perception.

The nervous system is complex and integrates input, processing, and output to maintain homeostasis and respond to the environment. Understanding its mechanics contributes to comprehending human behavior and cognition. Further exploration of physiological responses will enhance knowledge of human biology.