Nervous

• Functions of the Nervous System

  Sensory Input - Through its receptors, it keeps us in touch with both the external and internal environment
• Functions of the Nervous System

  Integration - It is the major controlling, regulatory, and communicating system of the body
• Functions of the Nervous System

  Homeostasis - It is the ability to maintain a stable internal state that persists despite changes in the outside world.
• Functions of the Nervous System

  Mental Activity - It is the center for all mental activity including thought, learning and memory
• Functions of the Nervous System

  Control of Muscle and Glands - It participates in controlling skeletal, cardiac, and smooth muscles, and many glands.
• 2 Cells of the Nervous System

  1. Neuron - like messengers in the body's communication system.
  2. Neuroglia - glial cells, are like the support staff for neurons.
• Neuron and its Parts

  1. Cell Body - the control center of the neuron. It contains the nucleus, which controls the cell's activities.
  2. Dendrites -like antennas that receive signals from other neurons.
  3. Axon - like a long wire that carries signals away from the cell body.
• Structures Seen with the Axon

  • Axon hillock - junction between the cell body and the axon.
• Structures Seen with the Axon

  • Collateral Axon - branches that extend from the main axon
  • Schwann Cell - glial cell that produces the myelin sheath in the peripheral nervous system
• Structures Seen with the Axon

  • Myelin - fatty substance that surrounds and insulates the axon.

  Myelinated Axon - covered with myelin are called myelinated axons
• Structures Seen with the Axon

  • Nodes of Ranvier - gaps in the myelin sheath along the axon.
  • Presynaptic Terminals - axon terminals or synaptic boutons, these are the ends of the axon branches that form synapses with other neurons or target cells
• Types of Neurons

  • Multipolar - Several dendrites and one axon

  Function: Most neurons and most CNS neurons
• Types of Neurons

  • Bipolar - One dendrite and one axon

  Function - Found in special organs such as the eye and the nose
• Types of Neurons

  • Unipolar - A neuron with a single axon

  Function: Most sensory neurons
• Neuroglia

  • Astrocyte - Star-shaped

  Function: Structural support of the CNS; Bloodbrain barrier
• Neuroglia

  • Ependymal - Squamous epithelia-like

  Function: line walls of ventricles & canals of CNS; produce and circulate CSF
• Neuroglia

  • Microglia - Small mobile cells

  Function: Phagocytic that protect the CNS from infection
• Neuroglia

  • Oligodendrocytes - With processes

  Function: Surround axons in the CNS
• Neuroglia

  • Schwann cells - Single cell

  Function: Surround axons in the PNS
• Central NS - body's master control unit
• Peripheral NS - body's link to the outside world
• Central NS

  • Brain - control center
• Central NS

  • Spinal Cord - Serves as the reflex centre for all spinal reflexes

  -Provides the 2-way conduction routes to (afferent) and from (efferent) the brain
• Spinal Cord

  Afferent Neurons - carry sensory information from sensory receptors (such as those in the skin, eyes, ears, and internal organs) to the central nervous system (brain and spinal cord).

  Efferent Neurons - carry signals from the central nervous system to muscles, glands, and other effector cells.
• Peripheral NS

  • Somatic NS - Transmits sensory and motor signals to and from the central nervous system
• Peripheral NS

  • Autonomic NS - Controls the functions of the organs and glands
• Autonomic NS (Peripheral NS)

  • Sympathetic NS - “Fight-or-flight” system

  -Prepares the body for physical activity to either stand and face the threat or leave as quickly as possible

  • Parasympathetic NS - Inhibits the body from overworking and restores the body to a calm and composed state