A&PI Chapter 14

• Blood flow TO the brain

  Vertebral & Carotid Arteries
• Blood flow FROM brain to heart


  Jugular Veins
• Brain utilizes 20% of body's oxygen supply
• Glucose deficiency

  Mental confusion, dizziness, convulsions & unconsciousness
• Blood Brain Barrier (BBB)


  Protects brain cells from harmful substances/pathogens by serving as selective barrier
• CSF (Cerebrospinal Fluid)

  Liquid that protects brain and spinal cord
• Extracellular Fluid

  Carries oxygen, glucose, etc. from blood to nervous tissue cells
• Ventricles

  Contain CSF
• Choroid Plexuses

  Make CSF
• The Brainstem

  • 3 components (PMM)
  • Pons
  • Midbrain
  • Medulla Oblongata
• Pons

  • Located superior to the Medulla Oblongata
  • Cranial Nerves origin here: Trigeminal (V), Abducens (VI), Facial (VII)
  • Relays voluntary skeletal muscle nerve impulses from cerebrum to cerebellum
  • Control of respiration
• Midbrain

  • Located superior to Medulla Oblongata
  • Cranial nerves origin here: Oculomotor (III) and Trochlear (IV)
  • Conveys motor impulses from cerebrum to the cerebellum and spinal cord
  • Sends sensory impulses from spinal cord to the thalamus
  • Regulates auditory and visual reflexes
• Medulla Oblongata

  • Continuous with superior aspect of spinal cord
  • Cranial Nerves origin here: Vestibulocochlear (VIII) and Hypoglossal (XII)
  • Heart rate, respiratory rate, vasoconstriction, swallowing, coughing, vomiting, sneezing and hiccupping
• Cerebellum

  • 2 hemispheres with a central vermis
  • Coordination of skeletal muscle contractions
  • Maintenance of normal muscle tone, posture and balance
• The Diencephalon

  • Thalamus
  • Hypothalamus
  • Epithalamus
• Thalamus

  • Located superior to the midbrain
  • Serves as relay stations for all sensory impulses (EXCEPT smell) to the cerebral cortex
• Hypothalamus


  • Located inferior to the thalamus
  • Major regulator of homeostasis
• Epithalamus

  • Lies superior and posterior to the thalamus
  • Contains pineal gland
  • Secretes melatonin
• CVOs (Circumventricular Organs)

  • Monitor chemical changes in the blood (b/c diencephalon lacks BBB)
  • Coordinate homeostatic activities of the endocrine and nervous systems
• The Cerebrum

  • Gray and white matter
  • Corpus Callosum
  • Lobes: Frontal, Parietal, Temporal Occipital
  • Insula
  • Cerebral Cortex
• Corpus Callosum


  Connects the right and left hemispheres of the cerebrum
• Cerebral Cortex

  • Perception of sensory info
  • Motor areas: control execution of voluntary movements
  • Association areas: memory, personality traits, intelligence
• Hemispheric Lateralization

  Right vs. Left brain
• CN III, IV and VI


  All innervate movement of the eyeballs
• Trigeminal N. (CN V)


  Has 3 branches: Opthalamic, Maxillary, Mandibular
• Vagus N. (CN X)


  • The longest cranial nerve
  • Innervates a larger number of major organs: Heart, Lungs, Digestive System (Liver, Stomach, Intestines)
• Accessory N. (CN XI)


  Innervates the Trapezius and SCM (Motor)
• Development of the Nervous System

  Begins during the 3rd week of gestation- ectoderm thickens
• Aging and the Nervous System

  • Loss of neurons
  • Diminished capacity to send nerve impulses and process info
  • Decreased conduction velocity
  • Slowing of Voluntary movements
  • Increased reflex time
  • Degenerative changes in vision, hearing, sight, taste, smell, touch and balance
• CVA (Stroke)

  • Leads to death of brain cells- lack of oxygen
  • MC cause is ischemic- due to blood clot (85%)
  • The other 15% are hemorrhagic (leaky/ruptured vessel)
• TIA (Transient Ischemic Attack)

  • Temporary cerebral dysfunction caused by impaired blood flow
  • "Mini-stroke"
  • Roughly 5-10 mins
  • Dizziness, weakness, numbness, etc
• Alzheimer's

  • Progressive dementia- loss of reasoning and loss of ability to care for self
  • Neuronal degeneration, beta-amyloid plaques, neurofibrillary tangles
• Brain Tumor

  Abnormal growth of brain tissue; malignant (cancerous) or benign (non-cancerous)
• ADHD

  • Short attention span, hyperactivity, impulsiveness
  • Cause not fully understood
• Right Hemisphere Functions

  • musical and artistic awareness
  • space and pattern perception
  • recognition of faces and emotional content of facial expression
  • generating emotional content of language, mental images
  • identifying and discriminating among odors
  • Damage: Broca's and Wernicke"sthe
• Left Hemisphere Functions

  • receive somatic sensory signals from right side of body
  • reasoning
  • numerical and scientific skills
  • ability to use and understand sign language
  • spoken and written language
  • Damage: Aphasia