BSN3-2

• What are the basic anatomical and functional units in the nervous system?

  Neurons
• What are the main components of a neuron?

  Cell body, axon, and dendrites
• What are the types of neurons and their functions?

  • Sensory (afferent) Neurons: transmit impulses to the brain
  • Motor Neurons (efferent): transmit impulses away from the brain or spinal cord to muscles or glands
  • Upper Motor Neurons: located in CNS, destruction leads to loss of voluntary control, muscle spasticity, and hyperactive reflexes
  • Lower Motor Neurons: located in gray matter, extends to PNS, destruction leads to loss of voluntary control, flaccidity, and loss of reflexes
• Where are upper motor neurons located?

  In the central nervous system (CNS)
• What happens when upper motor neurons are destroyed?

  There is a loss of voluntary control, muscle spasticity, and hyperactive reflexes
• What distinguishes lower motor neurons from upper motor neurons?

  Lower motor neurons are located in the gray matter and extend to the PNS
• What are the consequences of lower motor neuron destruction?

  Loss of voluntary control, flaccidity, and loss of reflexes
• What does the cell body of a neuron contain?

  A nucleus and other cytoplasmic matter
• What is the function of dendrites in a neuron?

  Dendrites carry impulses toward the cell body
• What is the role of the axon in a neuron?

  The axon carries impulses away from the cell body
• How does myelin affect nerve impulse transmission?

  Myelinated nerve fibers transmit nerve impulses more rapidly than nonmyelinated fibers
• What are the two types of nerve impulses?

  Excitatory and inhibitory
• What is a synapse?

  A point of contact between the axon of one cell and the dendrites of another
• What do synaptic terminals secrete?

  Neurotransmitters
• What are the functions of glial cells?

  • Nourish neurons
  • Support neurons
  • Protect neurons
  • Types include astrocytes, oligodendrocytes, ependymal cells, microglia (in brain), and Schwann cells (in PNS)
• What are the two main components of the central nervous system?

  Brain and spinal cord
• What are the general considerations regarding the brain?

  • Has a large blood supply and high oxygen consumption
  • Uses glucose for energy metabolism
  • Protected by the blood-brain barrier
• What can hypoglycemia alter in the brain?

  Brain function
• What are the basic tissue types in the brain?

  Neuron cell aggregations (gray matter) and tracts of myelinated fibers (white matter)
• What are the three parts of the brain?

  1. Cerebrum
  2. Cerebellum
  3. Brainstem
• What is the largest part of the brain?

  Cerebrum
• How do the hemispheres of the cerebrum function in relation to sensory input and control?

  Each hemisphere receives sensory input from and controls the opposite side of the body
• What are the functions of the cerebrum?

  • Sensory processing
  • Motor control
  • Thought and learning (intellect)
  • Personality and mood
• What are the functions of the lobes of the cerebrum?

  • Frontal: motor speech, morals, emotions, reasoning, judgment, concentration, memory retention
  • Temporal: sensation interpretation, spatial perception
  • Parietal: auditory center, speech comprehension
  • Occipital: visual processing
  • Limbic System: emotional and visceral patterns, learning, long-term memory, sexual response
• Where is the cerebellum located?

  Posterior to the pons
• What is the primary function of the cerebellum?

  Responsible for muscle movement and tone, coordination, and balance
• What are the three major parts of the brainstem?

  1. Midbrain
  2. Pons
  3. Medulla
• What is the function of the midbrain?

  Motor coordination, visual reflexes, and auditory relays
• What is the role of the pons?

  Has respiratory centers and regulates breathing
• What does the medulla contain?

  Afferent and efferent tracts
• What are the functions of the diencephalon?

  • Thalamus: sensory impulse cortex, pain gate, part of reticular activating system (wakefulness and sleep-wake transitions)
  • Hypothalamus: regulates temperature, stress response, emotions, sleep-wake cycle, hunger, water metabolism, and pituitary gland secretions
• What is the blood supply of the brain primarily used for?

  Glucose
• What happens if there is a low blood supply to the brain for more than 5 minutes?

  It leads to irreversible damage
• How much blood does the brain receive per minute?

  750 mL/min
• What percentage of cardiac output does the brain receive?

  15-20%
• What are the characteristics of cerebral arteries?

  • Thinner
  • More elastic
  • Less smooth muscle than other arteries
• What are the two sets of arteries supplying the brain?

  1. Anterior Circulation: fed by internal and external carotid arteries
  2. Posterior Circulation: fed by vertebral arteries
• What does the anterior circulation supply blood to?

  The circle of Willis at the brain's base and smaller arteries to the anterior, middle, and posterior cerebrum
• What does the posterior circulation supply blood to?

  The posterior fossa
• What are the characteristics of the venous system in the brain?

  • Vessel walls are thinner than other veins
  • Do not follow arterial paths
  • No valves; drainage depends on venous pressure and gravity