Nervous System Overview Quiz

Introduction to Nervous System

• The nervous system is highly complex, divided into two major parts: the central nervous system (CNS) and the peripheral nervous system.
• The nervous system controls other organ systems, maintaining balance within those systems.
• Nervous system disorders are often difficult to diagnose and treat.

Nervous System Objectives

• Explain the difference between the central and peripheral nervous systems.
• Describe the functions of the nervous system.
• Describe the structure of a neuron.
• Describe the structure and function of a synapse.
• Describe the function of the blood-brain barrier.
• Describe the functions of meninges.
• Describe the functions of the spinal cord.
• List the major divisions of the brain and their general functions.
• Explain the two divisions of the autonomic nervous system.

Organization of the Nervous System

• The nervous system is composed of two main parts: Central Nervous System (CNS) and Peripheral Nervous System (PNS).
• CNS includes the brain and spinal cord.
• PNS includes nerves that connect the CNS to other parts of the body.

Peripheral Nervous System

• The PNS is divided into two main functional classifications: Sensory (afferent) and Motor (efferent).
• Sensory division carries information from the body to the CNS.
• Motor division carries impulses away from the CNS to muscles and glands. This further divided into two subdivisions: Somatic (voluntary) and Autonomic (involuntary).

Functions of the Nervous System

• Sensory input: gathering information from inside and outside the body.
• Integration: processing and interpreting sensory input and deciding if an action is needed.
• Motor output: responding to integrated stimuli by activating muscles or glands.

Functional Classification of the Peripheral Nervous System

• Sensory (afferent) division: Nerve fibers that carry information to the CNS.
• Motor (efferent) division: Nerve fibers that carry impulses away from the CNS.
• Motor division is further subdivided into somatic (voluntary) nervous system and autonomic(involuntary) nervous system

Spinal Cord and Brain Tracts

• The spinal cord carries information to and from the brain.
• Ascending tracts carry sensory information up to the brain.
• Descending tracts carry motor information down from the brain to muscles and glands.

The Brain

• The brain is composed of four main parts: Cerebrum, Diencephalons, Brain stem, and Cerebellum.

Functions of the Cerebrum

• Largest part of the brain, composed of different lobes (frontal, temporal, parietal and occipital), each controlling different functions.
• Frontal lobe: important for personality.
• Parietal lobe: center for sensory reception and interpretation of sensation (touch, temperature, pressure, and pain).
• Occipital lobe is responsible for the sense of vision.
• Temporal lobe: responsible for hearing, smell.

Layers of the Cerebrum

• Basal ganglia are internal islands of gray matter.
• Basal ganglia regulate voluntary motor activities.
• Dysfunction of the basal ganglia leads to problems controlling muscles, rigidity, and tremors (e.g., Parkinson's Disease).

The Cerebellum

• Located at the back of the brain.
• Coordinates posture, equilibrium, and voluntary muscle activity.
• Damage leads to loss of control of fine movements, posture and motor learning.

The Brainstem

• Composed of midbrain, pons, and medulla oblongata.
• Plays a central role in respiration and cardiovascular control.

The Diencephalon

• The Thalamus: Relay station for all sensory stimuli to the brain.
• The Hypothalamus: Controls body temperature, appetite, body fluids, and endocrine functions.

Limbic System

• A series of structures involved in learning, memory, and emotional responses (e.g., pain, pleasure, affection, anger).

Cerebrospinal Fluid (CSF)

• Supports, protects, and exchanges materials.
• Forms a cushion to protect the brain.
• Monitors CO2, O2, and pH.
• Produced by the choroid plexus.
• Located in the subarachnoid space around the brain and spinal cord.

Blood-Brain Barrier

• Includes the least permeable capillaries in the body.
• Excludes many potentially harmful substances.
• Useless against fat-soluble molecules, respiratory gases, alcohol, nicotine, and anesthesia.

Apply Your Knowledge - Trauma to Pons

• A brain trauma to the pons can cause problems with breathing.

The Synapse

• Communication occurs between two neurons or a neuron and a target cell.
• A neurotransmitter is released to transmit signals.

Transmission of Chemical Signals Across the Synapse

• Presynaptic membrane releases neurotransmitters.
• Neurotransmitters bind to receptors in the next neuron.
• This triggers a new electrical signal.

The Autonomic Nervous System

• Innervates cardiac muscle, smooth muscle, and glands.
• Functionally divided into two parts: sympathetic and parasympathetic.

Sympathetic Nervous System

• Prepares the body for stressful situations("fight or flight").
• Increases pulse and blood pressure.
• Slows down digestive system.
• Uses epinephrine and norepinephrine as neurotransmitters.

Parasympathetic Nervous System

• Associated with relaxation.
• Decreases pulse and blood pressure.
• Stimulates digestive system.
• Uses acetylcholine as a neurotransmitter.

Nerve Physiology

• Nerve cells are excitable cells.
• Any stimulus can change the membrane potential (impulse/action potential).
• Myelin sheath increases nerve transmission speed.

Starting a Nerve Impulse

• Stimulus depolarizes the neuron's membrane.
• Sodium ions flow into the membrane.
• This exchange causes an action potential in the neuron.

The Action Potential

• Nerve impulse (action potential) is propagated across the entire axon.
• Potassium ions rush out of the neuron.
• The sodium-potassium pump restores the original configuration.
• This process requires ATP.

Action Potential (Nerve Impulse) details

• Depolarization: Na+ passes into the neuron.
• Repolarization: K+ passes out of the neuron.
• Return to resting potential: by closure of K channels and activation of Na-k pump.
• Local anesthetic blocks sodium channels.

Nerve Impulse Propagation

• Impulses travel faster in fibers with a myelin sheath.
• Multiple Sclerosis involves myelin sheath destruction.

The Reflex Arc

• Reflex is a rapid, predictable, and involuntary response to stimuli.
• Reflex arc is a direct route from a sensory neuron, to an interneuron, to an effector.

Traumatic Brain Injuries

• Concussion: Slight brain injury, no permanent damage.
• Contusion: Nervous tissue destruction, tissue does not regenerate.
• Cerebral edema: Swelling from inflammation, can compress and kill brain tissue.

Cerebrovascular Accident (CVA)

• Commonly known as a stroke.
• Results from a ruptured or obstructed blood vessel in the brain.
• Brain tissue deprived of oxygen dies.

Alzheimer's Disease

• Progressive degenerative brain disease.
• Mostly seen in the elderly, can start in middle age.
• Abnormal protein deposits within neurons.
• Victims experience memory loss, irritability, confusion, and ultimately, hallucinations and death.

Classification of Sensation

• General sensations: superficial (touch, heat, cold), deep, and visceral (under abnormal conditions).
• Special senses: taste, smell, vision, and hearing.

Pain

• An unpleasant sensory and emotional experience.
• Gives conscious awareness of tissue damage.
• Protection: removes body from danger, promote healing, and avoid noxious stimuli.

Nociceptors

• Special receptors responding to noxious stimuli.
• Generate nerve impulses interpreted as pain.

Fast Pain

• Occurs rapidly after stimuli (0.1 second).
• Sharp pain like needle puncture or cut.
• Not felt in deeper tissues.
• Transmitted to the brain by type A (myelinated) nerve fibers.

Slow Pain

• Begins more slowly, increases in intensity in both superficial and deeper tissues.
• Smaller C nerve fibers.
• Transmitted to the brain by slowly C nerve fibers (unmyelinated).

Visceral Pain

• Often accompanied by strong autonomic and/or somatic reflexes.
• Poorly localized, may be "referred".
• Usually caused by distension of hollow organs or ischemia.

Referred Pain

• Pain originating from organs perceived as coming from the skin.
• Site of pain may be distant from the actual location of the organ.

Additional Notes

• Various university logos, specific dates or instructor names will be ignored as these are not relevant to student study notes.