The Nervous System

1. The Nervous System And Brain Organization

2. Central Nervous System • Consists of the brain and spinal cord • The brain is the central “computer” of the nervous system • The spinal cord is the “cable” that is used to communicate to the rest of the body

3. Peripheral Nervous System • All the parts of the nervous system outside of the brain and spinal cord • Two major divisions • Somatic system – the muscles and sense organs (voluntary behavior) • Autonomic system – the internal organs and glands (involuntary behavior)

4. Autonomic Nervous System • Two divisions • Sympathetic branch – arouses the body • Prepares the body for fight or flight • Parasympathetic branch – quiets the body or brings it back to normal

5. Nervous System Central Nervous System Peripheral Nervous System Brain Spinal Cord Autonomic System Somatic System Sympathetic System Parasympathetic System

6. Brain Organization • Cerebrum – two large hemispheres that cover the upper part of the brain • Cerebral cortex – the outer layer of the cerebrum • made up of wrinkled gray matter that contains nerve cell bodies

7. Brain Organization cont’d… • Cerebral hemispheres – right and left halves of the cerebrum • Corpus callosum – bundle of fibers connecting the hemispheres • Cut in a ‘split-brain’ operation • Spatial neglect – when a person pays no attention to the left side of visual space after damage to the right hemisphere

8. Lobes of the Cerebral Cortex • Lobes – areas on the cortex defined by major fissures or functions • Occipital lobe – vision • Parietal lobe – bodily sensations (touch, temperature, pressure)

9. Lobes of the Cerebral Cortex • Temporal lobes – language (on the left only) and hearing • Frontal lobes – motor control, speech, abstract thought • Association cortex – all areas of the cerebral cortex not primarily sensory or motor in function – complex skills like language, memory, recognition, and problem solving

10. Parietal lobe Frontal lobe Occipital lobe Temporal lobe Cerebellum

11. Association Cortex • Broca’s area – language area – grammar and pronunciation – left frontal lobe • Aphasia – speech disturbance related to brain damage • Wernicke’s area – language comprehension – left temporal lobe • Agnosia – inability to identify seen objects

13. Subcortex • Subcortex - all brain structures below the cerebral hemispheres • Divided into three parts • Brainstem (or hindbrain) • Midbrain • Forebrain

14. The Brainstem • Also known as the hindbrain • Lowest portions of the brain • Contains the cerebellum, medulla and pons

15. Cerebellum – controls posture, muscle tone and coordination – stores memories related to skills and habits • Medulla – connects brain to spinal cord – controls vital life functions such as heart rate, breathing, swallowing, etc. • Pons – bridge between medulla and other structures – influences sleep and arousal

16. The Midbrain • Small region, located above spinal cord, but below the forebrain • Coordinates simple muscle movements with sensory information • Reticular formation – network of fibers and cell bodies throughout the hindbrain – associated with attention, alertness and some reflexes

17. The Forebrain • Contains the thalamus and hypothalamus • Thalamus – located on top of brain stem – relays sensory information to the cerebral cortex • Hypothalamus – controls metabolic functions including body temp, libido, hunger, thirst, and the endocrine system

19. The Limbic System • Contains hypothalamus, parts of the thalamus, amygdala, and hippocampus • Large role in producing emotion and motivated behavior • Amygdala – associated with fear responses • Hippocampus – associated with storing memories (lies in the temporal lobe)