Nervous System: Structure and Function

• The nervous system facilitates communication between the brain and body.
• It is responsible for information storage and coordinates bodily activities like breathing, digestion, and pain sensation.

Central Nervous System (CNS) vs. Peripheral Nervous System (PNS)

• The CNS consists of the brain and spinal cord.
• The PNS comprises sensory neurons.

Components of the Nervous System

• The nervous system is made up of neurons, the brain, the spinal cord, and cerebrospinal fluid.
• Cerebrospinal fluid cushions the brain and spinal cord against injury.

Nervous System Divisions

• The two main divisions are the CNS (central) and PNS (peripheral).

Neuron Function

• Neurons process and transmit information.

Neuron Structure

• The main parts of a neuron are the dendrite, cell body, and axon.

Dendrites

• Dendrites are branched extensions of the cell body.
• They receive information and transmit impulses toward the cell body.

Cell Body

• The cell body contains the nucleus.
• The nucleus regulates protein production within the cell.
• DNA is located within the cell body.

Axon

• Axons transmit impulses away from the cell body.
• They send signals to other neurons, muscle cells, or glands.

Myelin Sheath

• The myelin sheath protects the neuron.
• It provides insulation and increases the speed of impulse transmission.

Brain Lobes

• The four lobes of the brain are the frontal, parietal, occipital, and temporal lobes.

Frontal Lobe

• The frontal lobe is responsible for judgment, impulse control, decision-making, intellect, and personality.

Parietal Lobe

• The parietal lobe processes sensory information such as temperature and pain.

Occipital Lobe

• The occipital lobe is responsible for visual processing.

Temporal Lobe

• The temporal lobe handles auditory processing.

Cerebrum

• The cerebrum is the largest, most complex part of the brain, responsible for thinking.
• It is divided into four lobes.

Cerebellum

• The cerebellum coordinates skeletal muscle movement.
• It maintains posture and balance.

Brain Stem

• The brain stem connects the brain to the spinal cord.
• It controls involuntary functions necessary for sustaining life.

Hypothalamus

• The hypothalamus regulates body temperature, thirst, appetite, and sleep.
• It also controls secretions from the pituitary gland.

Pituitary Gland

• The pituitary gland is the "master gland" that controls hormone production and secretion.

Corpus Callosum

• The corpus callosum is a bundle of nerve fibers connecting the right and left hemispheres.
• It allows communication between the two hemispheres.

Nervous System Care

• Regular physical activity and a healthy diet are important.
• Adequate sleep each night helps maintain nervous system health.
• Avoidance of substances like tobacco and limiting alcohol use are beneficial.

Alzheimer's Symptoms

• Symptoms include problems with memory, thinking, and completing daily tasks.

Alzheimer's Causes

• Proteins clump between neurons, causing buildup that impairs neuron communication.
• As neurons fail, the brain's function declines, leading to memory loss.

Parkinson's Symptoms

• Symptoms include resting tremors in the hands, arms, legs, or jaws.
• Other symptoms are stiff joints, loss of coordination, and difficulty with fine motor skills.

Parkinson's Causes

• Parkinson's is caused by a lack of dopamine production in the brain.

Epilepsy Symptoms

• The primary symptom of epilepsy is seizures.

Epilepsy Causes

• Epilepsy results from clusters of neurons in the brain sending out incorrect or abnormal signals.
• These signals alter a person's consciousness, movements, and actions.

Stroke Symptoms

• Stroke symptoms include slurred speech, blurred vision, and a droopy face.

Stroke Causes

• Occurs when blood flow to the brain stops, leading to the death of brain cells within minutes.

Stress vs. Stressor

• Stress is the body and mind's reaction to challenges and demands.
• A stressor is anything that causes stress.

Teen Brain Differences

• Teens typically react emotionally first, using the amygdala.
• Teens experience significant fluctuations in neurotransmitters.
• The prefrontal cortex is still developing in teens.

First Stage of Stress Response

• Alarm: The mind and body go on high alert, triggering the "fight or flight" response.

Second Stage of Stress Response

• Resistance: The body adapts and reacts to the stressor if the stressor remains.

Third Stage of Stress Response

• Fatigue: The body becomes tired and unable to handle stressors if the stressor persists for a long time.

Brain Response to Stress

• The hypothalamus releases a hormone that activates the pituitary gland.
• The pituitary gland releases hormones that stimulate the adrenal glands.
• The adrenal glands then release adrenaline.

Recommended Teen Sleep

• Teenagers should get 9.25 hours of sleep per night.

Stage 5 REM Sleep

• Stage 5 REM sleep is the restorative stage when neurons are repaired
• It is also when cells, tissues, and organs are restored, proteins are made, and growth hormone is released.

Consequences of Insufficient Sleep

• Consequences of not getting enough sleep include memory lapses, accidents, and injuries.
• Insufficient sleep can also lead to mood and behavior problems.
• It can also impact the time needed to process information.

Hemorrhagic Stroke

• A hemorrhagic stroke involves a brain bleed.

Ischemic Stroke

• An ischemic stroke involves clotting of a blood vessel, preventing blood from reaching the brain.

Stress Prevention

• Stress can be prevented through a healthy diet, adequate sleep, and regular physical exercise.

Body's Response to Stress

• The stress response proceeds from the hypothalamus hormone to the pituitary hormone.
• Then it goes to the adrenal glands, and finally to adrenaline.