2.1.1

Role of the Nervous System

Controls and coordinates all body functions by transmitting signals between the brain and body.

Voluntary Actions

Conscious, intentional movements controlled by the brain (e.g., walking, writing, speaking).

Involuntary Actions

Automatic, unconscious responses not under conscious control (e.g., breathing, heartbeat, digestion).

Brain

The control center of the nervous system that processes information, controls voluntary movements, and regulates involuntary functions like breathing and heart rate. It is responsible for cognition, memory, emotions, and sensory processing.

Spinal Cord

A long, tubular bundle of nervous tissue that extends from the brainstem down the vertebral column. It serves as the main pathway for transmitting signals between the brain and the rest of the body, and coordinates reflex actions.

Cranial Nerves

12 pairs of nerves that emerge directly from the brain and brainstem. They control sensory and motor functions of the head and neck, including vision, smell, taste, facial movement, and eye movement.

Spinal Nerves

31 pairs of nerves that branch off from the spinal cord. They transmit sensory information from the body to the CNS and carry motor commands from the CNS to muscles and glands throughout the body.

Peripheral Nerves

Network of nerves that extend throughout the body beyond the brain and spinal cord. They connect the CNS to limbs and organs, facilitating communication between the central nervous system and the rest of the body.

Sensory Neurons

Nerve cells that transmit sensory information (touch, temperature, pain, etc.) from receptors in the body to the CNS for processing.

Motor Neurons

Nerve cells that carry signals from the CNS to muscles and glands, controlling voluntary movements and involuntary responses.

electrical signals - action potentials

neurons transmit info through electrical impulses that travel along the length of the nerve cell at high speeds (up to 120 meters per second)

chemical signals - neurotransmitters

at synapses, electrical signals trigger release of chemical messangers called neurotransmitters that cross synaptic gap to communicate with next neuron

Cerebrum

The largest part of the brain, divided into two hemispheres. It controls higher brain functions including thought, reasoning, memory, voluntary movement, language, and sensory processing. The outer layer (cerebral cortex) is responsible for consciousness and complex cognitive processes.

Cerebellum

Located at the back of the brain below the cerebrum. It coordinates voluntary movements, maintains balance and posture, and plays a role in motor learning and fine motor control.

Brainstem

Connects the brain to the spinal cord and controls vital automatic functions such as breathing, heart rate, blood pressure, and sleep-wake cycles. It consists of three parts: the midbrain, pons, and medulla oblongata.

Pons

Part of the brainstem located above the medulla oblongata. It serves as a bridge connecting different parts of the nervous system, relays signals between the cerebrum and cerebellum, and helps regulate breathing, sleep, and arousal.

Medulla Oblongata

The lowest part of the brainstem that connects the brain to the spinal cord. It controls vital autonomic functions such as heart rate, blood pressure, breathing, swallowing, and reflexes like coughing and vomiting.

Temporal Lobe

Located on the sides of the brain near the temples. It processes auditory information, is involved in memory formation, language comprehension, facial recognition, and emotional responses.

Motor Cortex

A strip of cortex located in the frontal lobe that controls voluntary muscle movements throughout the body. Different regions of the motor cortex correspond to movements of specific body parts.

Sensory Cortex

Located in the parietal lobe, it receives and processes sensory information from the body including touch, pressure, temperature, and pain. Different areas correspond to sensations from different body parts.

Corpus Callosum

A thick band of nerve fibers that connects the left and right cerebral hemispheres. It enables communication and coordination between the two sides of the brain, allowing them to share information and work together.

Pituitary Gland

A small, pea-sized gland located at the base of the brain. Often called the "master gland," it produces and releases hormones that regulate growth, metabolism, reproduction, stress response, and controls other endocrine glands.

Thalamus

A structure located in the center of the brain that acts as a relay station for sensory information. It receives sensory signals (except smell) and transmits them to appropriate areas of the cerebral cortex for processing.

Hypothalamus

Located below the thalamus, it regulates body temperature, hunger, thirst, sleep-wake cycles, and emotional responses. controls the pituitary gland and links the nervous system to the endocrine system.

Frontal Lobe

Controls executive functions such as reasoning, planning, problem-solving, decision-making, personality, emotional regulation, voluntary movement, and speech production.

Parietal Lobe

Processes sensory information including touch, temperature, pain, and spatial awareness. It also plays a role in mathematical reasoning and body position awareness.

Temporal Lobe

Processes auditory information, is involved in memory formation, language comprehension, facial recognition, and emotional responses.

Occipital Lobe

Primarily responsible for processing visual information, including color, shape, distance, and motion detection.

Carpal Tunnel

A condition caused by compression of the median nerve as it passes through the carpal tunnel, a narrow passageway in the wrist. This compression leads to numbness, tingling, weakness, and pain in the hand and fingers (especially thumb, index, middle, and part of the ring finger).

Causes: Repetitive hand motions (typing, using tools), prolonged wrist flexion or extension, wrist injuries, fluid retention during pregnancy, rheumatoid arthritis, diabetes, thyroid dysfunction, and anatomical factors like a naturally smaller carpal tunnel. Risk increases with activities that involve repetitive gripping, vibration exposure, or awkward wrist positions.

Radial Nerve

Controls extension of the wrist, fingers, and thumb; provides sensation to the back of the hand and thumb side. Affects the thumb, index finger, middle finger, and the radial (thumb) side of the ring finger on the back of the hand.

Median Nerve

Controls flexion of the wrist and fingers, thumb opposition, and fine motor movements; provides sensation to the palm side of the hand. Affects the thumb, index finger, middle finger, and the radial (thumb) side of the ring finger on the palm side.

Ulnar Nerve

Controls fine motor movements of the hand, finger abduction and adduction, and some wrist flexion; provides sensation to the ulnar side of the hand. Affects the little finger and the ulnar (pinky) side of the ring finger on both palm and back of the hand.

Hippocampus

C shaped curve in temporal lobe, Essential for forming new memories and spatial navigation. Converts short-term memories into long-term memories and helps with learning and recall of information

Amygdala

almond shaped near hippocampus, Processes emotions, particularly fear and anxiety. Plays a key role in emotional memory, threat detection, and the fight-or-flight response