Central Nervous System :BRAIN

Central Nervous System :BRAIN

1. 12 Billion Neurons

2. With the spinal cord, the brain regulates body process and co-ordinates voluntary movements.

3. Parts of the Brain

   • Cerebral Hemispheres or Cerebrum
   • Diencephalon (the term used to describe collectively the hypothalamus, thalamus and sometimes pituitary)
   • Brain Stem (collectively the medulla, pons and midbrain)
   • Cerebellum: controls balance and posture

4. Protection

   • Scalp and Skin
   • Skull and vertebral column
   • Meninges
   • Cerebrospinal fluid
   • Blood brain barrier

5. Cerebral Hemispheres (Cerebrum)

   • Paired (left and right) anterior parts of the brain
   • Include more than half of the brain mass
   • The surface is made of ridges and grooves

6. Lobes of the Cerebrum

   • Fissures (deep grooves) divide the cerebrum into lobes
   • Frontal Lobe
   • Parietal Lobe
   • Occipital Lobe
   • Temporal Lobe

7. Specialized Areas of the Cerebrum

   • Somatic sensory area – receives impulses from the body’s sensory receptors
     • Sensory association area
   • Primary motor area – sends impulses to skeletal muscles
     • Motor association area

8. Layers of the Cerebrum

   • Grey Matter
     • Outer Layer
     • Mostly neuron cell bodies
     • Processes info
   • White Matter
     • Inner Layer
     • Mainly of axons of the neurons
     • Communication 'lines'

9. Thalamus

   • Surrounds the third ventricle
   • relay stations for all sensory impulses except smell to the cerebral cortex.
   • relays motor impulses from the cerebral cortex to the spinal cord.
   • interprets pain, temperature, light touch and pressure sensations.
   • anterior nucleus functions in memory.

10. Hypothalamus

    • Under the thalamus
    • An important part of the limbic system (emotions)
    • Important autonomic nervous system center e.g regulation of internal processes.
      • Helps regulate body temperature
      • Controls water balance
      • Regulates metabolism

11. Pituitary Gland

    • controls release of hypothalamic hormones
    • secretes hormones regulating endocrine activity

12. The Brain Stem

    • Attaches to the spinal cord
    • PONS
      • Bulb center part of brain stem
      • Composed of fibers
      • helps control breathing
    • MEDULLA
      • Lowest part of brain stem
      • Merges into spinal cord
      • relays sensory impulses to thalamus.
    • Control centers
      • Heart rate
      • Blood preasure
      • Breathing
      • Swallowing
      • Vomiting

13. Midbrain

    • processes visual and auditory data.
    • moderates involuntary somatic motor reflexes
    • concerned with maintenance of consciousness.