The Nervous System Part II 

Cerebrum  Largest part of the brain  CEREBRAL CORTEX – layer of gray matter that covers the upper and lower surfaces of the cerebrum – most highly evolved portion of the brain  Divided into R and L hemispheres by a deep grove called the longitudinal fissure

Cerebral Cortex  The most recently evolved animals have a larger proportion of the brain taken up by the cerebral cortex  In the “higher” animals (especially the higher mammals), the surface of the cerebral cortex becomes folded

Cerebrum (continued)   If the right or left side of your cerebral cortex was rolled out flat, it would be the size of an extra large pizza  CONVOLUTIONS – elevated folds on the surface of the cerebrum, they increase the surface area of the brain.  Sulci – fissures or grooves separating cerebral convolutions

Lobes of the Cerebrum 

Frontal Lobe  Located in front of the central sulcus  Motor cortex of frontal lobe controls skeletal muscles  Concerned with: reasoning planning parts of speech emotions problem solving 

Frontal Lobe (continued)  Responsible for personality  Damage to frontal lobe can cause changes in personality  Broca’s Speech Area – allows a person to forms words  Damage to Broca’s Area – person can still understand language but cannot produce speech. If can talk at all – speech will be slow and slurred

Temporal Lobe   Located below the lateral fissure  Auditory area – interprets the sounds we hear  Olfactory area is located here – interprets the odor we smell from our nose

Temporal Lobe (continued)  Houses Wernicke’s Area – ability to understand language.  Damage to this area can result in the ability to understand language – person can speak clearly, but the words that are put together make no sense  In 97% of people, both Broca’s area and Wernicke’s area are found only in the left hemisphere of the brain

Parietal Lobe  Located behind the central sulcus between frontal and occipital lobes  Sensory center where impulses from skin such as pain, pressure, and temperature are interpreted  Area for estimation of distances, sizes, and shapes

Occipital Lobe   Located at the back of the brain behind the parietal lobe and the temporal lobe  Primary visual area  Trauma can result in blindness  Lesions can cause visual hallucinations

Diencephalon  Located between cerebrum and midbrain  Composed of THALAMUS AND HYPOTHALAMUS

Thalamus  Thalamus acts as a relay station for incoming and outgoing nerve impulses  All sensory imput expect olfactory (smell) is routed to the thalamus for processing and then transmitted to the cerebral cortex for interpretation  Damage to the thalamus may result in increased sensitivity to pain, or total loss of consciousness 

Nine Vital Functions of the Hypothalamus  1. Autonomic nervous control  2. Cardiovascular control  3. Temperature control  4.Appetite control  5. Water balance  6. Manufacture of oxytocin  7. Gastrointestinal control  8. Emotional state  9. Sleep control

Cerebellum  Located behind the pons and below the cerebrum  Composed of two hemispheres  Controls all body functions related to skeletal muscles, including: 1. Balance 2. Muscle Tone 3. Coordination of muscle movements  

Brain Stem  Made up of PONS, MEDULLA, and MIDBRAIN  Pathway for ascending and descending tracts  Sensory fibers conduct impulses up from the cord to other parts of the brain  Motor fibers conduct impulses down from the brain to the spinal cord

Pons  Located above the medulla. Located below the midbrain in the brain stem  “Pons” means bridge and the pons is the bridge between the cerebrum and the cerebellum  Consists of white matter with scattered bits of gray matter

Pons  Responsible for conduction messages to other parts of the brain and for certain reflex actions including: chewing tasting production of saliva

Midbrain  Superior to the pons and the smallest region of the brainstem  Two-way conduction pathway ; relay for visual and auditory impulses

Medulla Oblongata  Bulb-shaped structure between pons and spinal cord, inside the cranium above foramen magnum  Responsible for 1. Heart rate 2. Rate and depth of respiration 3. Blood pressure 4. Swallowing and vomiting

Spinal Cord  Begins at foramen magnum and continues down to 2 nd lumbar vertebrae  White and soft in spinal canal  Surrounded by cerebrospinal fluid

Spinal Cord  Functions as: 1. Refelex center Conduction pathway to and from the brain

The End