Nervous System Overview

Nervous System Overview

• The nervous system is a complex network that allows communication between the body and the outside world
• The nervous system is made up of the central nervous system (CNS) and the peripheral nervous system (PNS)

Central Nervous System (CNS)

• The CNS consists of the brain and spinal cord
• The brain is responsible for processing information and controlling body functions. The spinal cord acts as a communication pathway between the brain and the rest of the body.

Peripheral Nervous System (PNS)

• The PNS consists of cranial nerves and spinal nerves. These nerves connect the CNS with the rest of the body.
• The PNS is divided into two systems: the somatic nervous system and autonomic nervous system.

Somatic Nervous System

• The somatic nervous system controls voluntary muscle movements.
• It transmits sensory information from the body to the brain and motor information from the brain to muscles for movement

Autonomic Nervous System (ANS)

• The autonomic nervous system controls involuntary functions, such as heart rate, breathing, digestion, and urination.
• It is further divided into sympathetic and parasympathetic divisions.

Sympathetic Nervous System

• The sympathetic nervous system is activated during times of stress or danger, triggering the "fight-or-flight" response.
• It accelerates the heart rate, increases blood pressure, and dilates pupils to prepare the body for action.

Parasympathetic Nervous System

• The parasympathetic nervous system counteracts the effects of the sympathetic nervous system, promoting relaxation and rest.
• It slows the heart rate, lowers blood pressure, and constricts pupils.

Nervous System Structures and Functions

• Neuron (Nerve Cell): The basic unit of the nervous system. It has four key parts: dendrites, axons, myelin sheath, and synapse.
  • Dendrites: Branch-like structures that receive messages.
  • Axon: Long, slender fiber that transmits messages away from the cell body
  • Myelin Sheath: Insulating layer around the axon, that speeds up message transmission.
  • Synapse: Junction between neurons where information passes from one neuron to another.
• Neurotransmitters: Chemical messengers that transmit signals across the synapse.
• Types of Neurons:
  • Sensory neurons: Receive sensory information from the body and transmit it to the CNS.
  • Motor neurons: Transmit signals from the CNS to muscles and glands.
  • Interneurons (also known as association neurons): Connect sensory and motor neurons within the CNS.

Brain Structures

• Cerebrum: The largest part of the brain, divided into four lobes—frontal, parietal, occipital, and temporal. Each lobe has specific functions.
• Cerebellum: Controls balance, posture, and coordination.
• Brainstem: Connects the brain to the spinal cord, controlling basic life functions such as breathing and heart rate.
• Diencephalon: Contains the thalamus and hypothalamus; involved with autonomic functions & endocrine regulation.
• Limbic System: Associated with emotions, memory, and motivation.

Divisions of the Nervous System

• Central Nervous System (CNS): Brain and spinal cord.
• Peripheral Nervous System (PNS): Nerves outside the CNS, divided into somatic and autonomic nervous system.

Nervous System Disorders

• Alzheimer's Disease: A progressive degenerative disease of the brain.
• Cerebral Palsy: Permanent motor problems diagnosed in infants and children.
• Epilepsy: Seizures believed to result from spontaneous uncontrolled electrical activity in neurons.
• Meningitis: Infection or inflammation of the meninges, the membranes protecting the brain and spinal cord.
• Multiple Sclerosis: A disorder where myelin is destroyed, potentially by autoimmune attack
• Parkinson's Disease: Brain disorder by the loss of dopamine-producing neurons.
• Poliomyelitis: Contagious viral illness causing nerve damage, often resulting in paralysis.

Spinal Cord Injury

• Damage to the spinal cord, resulting in loss of function.
• Frequent causes include trauma, disease (polio), or spina bifida

Encephalitis

• Inflammation of the brain, may be caused by a virus.

Cerebrovascular Accident (CVA)

• Interruption of blood and oxygen to the brain
• Primarily caused by blood clots blocking blood flow

Hemiplegia

• Paralysis on one half of the body due to brain injury, often resulting from a stroke.

Traumatic Brain Injury (TBI)

• Sudden damage to the brain caused by impact or jolt to the head.

Concussion

• Mild traumatic brain injury from impact. Symptoms include headaches and problems with concentration, memory, balance, and coordination.