Central Nervous System Brain and Spinal Cord

Holistic Synthesizing Left Brain Right Brain Logical Sequential Rational Analytical Objective Looks at parts Random Intuitive Holistic Synthesizing Subjective Looks at wholes

Lobes of Cerebral Cortex Frontal –body movement, higher level thinking - includes Primary motor cortex Parietal –sensory area, impulses traveling from body are interpreted here Ex: pain, coldness, touch (not special senses: smell, taste, sight, and hearing) -includes Primary somatosensory cortex (Frontal and Parietal seperated by Central sulcus) Occipital –visual area Temporal –auditory area Cerebellum-balance and equilibrium (not considered a lobe of the cerebral cortex)

Gray matter vs. White matter Gray outermost area of the cerebral hemisphere that is involved in functions White inner area of cerebral hemisphere carrying impulses to, from, or within cortex

So What’s Inside? Corpus callosum- connect the two halves of the cerebral hemishpere Diencephalon- “innerbrain” Thalamus -relay station for sensory impulses passing upward to the sensory cortex -recognizing if impulse is pleasant or not “Ouch, that’s hot!!!” 2. Hypothalamus –regulates body temperature, water balance, and metabolism -area for drives and emotions (thirst, appetite, sex, pain, pleasure)

Brain Stem (Midbrain, Pons, Medulla oblongata) 1. Midbrain -small section of brainstem -connects brainstem and spinal cord to hemispheres -Function: contains gray matter providing reflexes that maintain posture and move eyes and head

2. Pons –round bulge on underside of brain stem -Pons means “bridge” because it is full of nerve fibers sending impulses from medulla oblongata to cerebrum -Function: involved in controlling breathing 3. Medulla Oblongta -inferior end of brainstem -like pons contains many nerve fiber tracts sending impulses from and to spinal cord -Function: control many organ activities (heart rate, blood pressure, breathing, vomiting, swallowing, etc)

Protection of the CNS Meninges -three connective tissue membranes covering and protecting the CNS structures (brain and spinal cord) Dura mater Arachnoid mater Pia mater

Dura mater -means “tough,” double-layered membrane surrounding brain Subarachnoid space Dura mater -means “tough,” double-layered membrane surrounding brain Arachnoid mater -”spider web” looking membrane covering in the middle Pia mater -delicate thin membrane layer attached to surface of brain Subarachnoid space –empty space in between the Arachnoid mater and the pia mater that is filled with Cerebrospinal fluid (CSF)

Cerebrospinal Fluid (CSF) What is it? Fluid in and around the brain and spinal cord forming a watery cushion that protecting against blows and trauma -continuously made and re-absorbed at a constant rate by blood -circulates around and through the brain and around the spinal cord

CSF cont. -used to diagnose meningitis and other brain pathologies (such as tumors and multiple sclerosis) Spinal tap-doctor sticks a long needle in your back (spinal cord) and draws out CSF for lab testing Meningitis -inflammation of the membranes that cover the brain and spinal cord -caused by a viral or bacterial infection -viral meningitis is generally less severe and clears up without specific treatment -bacterial meningitis can be quite severe and may result in brain damage, hearing loss, or learning disabilities

Spinal Cord -approx. 17 inches long -two-way conduction pathway to and from the brain and a major reflex center -31 pairs of spinal nerves extend from the spinal cord to different areas of the body -spinal cord does not reach end of vertebral column -cauda equina-collection of nerves at inferior end of spinal cord -spinal cord protected by meniges (membrane coverings) like the brain

Gray/White Matter of the Spinal Cord Gray Matter -area that surrounds the central canal (contains CSF) -looks like a butterfly -two anterior projections (wings) are called the Anterior or Ventral Horns, the two posterior projections (wings) are called the Posterior or Dorsal Horns Function of the Gray Matter The dorsal horn is the sensory (afferent) side receiving information from the body. The ventral horn is the motor (efferent) side delivering the response to the effected area of the body. In between the two horns of the gray matter are internerons which transfer the information from sensory to motor and communicate with white matter.

White Matter Carries sensory information to the brain and returns with the motor response.

Reflex Arc: rapid involuntary response to stimuli Two types of reflexes Somatic –reflexes that stimulate body Ex: pull away from hot object Autonomic –regulate activity of smooth muscle, heart, and glands Ex: secretion of saliva, changes to eye pupils Two-neuron reflex: sensory neuron and motor neuron, simplest form of reflex Ex: Knee Jerk

Three neuron reflex: pain reflex Sensory neuron Interneuron Motor neuron The action of pulling your hand away from the hot pain is activated by the spinal cord. However, the message is sent to the brain indicating pain but the withdrawal of the hand is an involuntary reaction.