3Divisions of the Mammalian Nervous System Central Nervous System = the brain and the spinal cordPeripheral Nervous System = the nerves outside the brain and spinal cordTwo Divisions of the PNSSomatic Nervous System - the nerves that convey messages from the sense organs to and from the CNSAutonomic Nervous System - a set of neurons that control the heart, the intestines, and other organs
4Nervous System PNS CNS SNS ANS Brain Spinal Cord sympathetic parasympathetic
7The Nervous SystemThe Spinal Cord-part of the CNS found within the spinal columnThe spinal cord communicates with the sense organs and muscles below the level of the headBell-Magendie Law-the entering dorsal roots carry sensory information …and the exiting ventral roots carry motor information to the muscles and glandsDorsal Root Ganglia - are clusters of neurons outside the spinal cord
8Figure 4.3 Diagram of a cross section through the spinal cord The dorsal root on each side conveys sensory information to the spinal cord; the ventral root conveys motor commands to the muscles.
9Autonomic Nervous System Sympathetic - prepares thebody for activityIncreased breathing, and heart rate, decreased digestive activityForm chain of ganglia just outside spinal cordShort preganglionic axons release norepinephrineLong postganglionic axons release norepinephrineParasympathetic - facilitates vegetative, non-emergency responses by the body’s organsIncrease digestive activity, activities opposing sympathetic systemConsists of cranial nerves and nerves from sacral spinal cordLong preganglionic axons extend from the spinal cord to parasympathetic ganglia close to each internal organ; release norepinephrineShorter postganglionic fibers then extend from the parasympathetic ganglia in the organs; release acetylcholine
10The Mammalian Brain There are 4 main parts to the brain: 1. Hindbrain (cerebellum + medulla oblongata)2. Midbrain3. Diencephalon ( thalamus + hypothalamus)4. Forebrain (cerebral hemispheres)
11The Brain The Hindbrain ( Posterior part of brain ) Medulla Oblongata - controls vital reflexes likebreathing,heart beatBlood pressure(all via sympathetic and parasympathetic n.s.)Cerebellum – controls movement, shifts of attention, balance and coordination. Works by comparing intended with actual movement.
15The diencephalon Thalamus Centre of forebrain Relay Station for sensory information (‘switchboard’)HypothalamusRegulates homeostasis, sexual behavior, fighting, feedingPituitary GlandEndocrine gland attached to the base of the hypothalamus (ADH, GH, FSH, TSH)
16Cerebrum (left and right cerebral hemispheres) The BrainThe Forebrain - most anterior and most prominent part of the mammalian brain, comprising the…Cerebrum (left and right cerebral hemispheres)
17Figure 4.12 A sagittal section through the human brain
18Left and Right hemispheres are linked by the CORPUS CALLOSUM. The CerebrumThe cerebral hemispheres contain 109 nerve cells in a layer only 3mm thick.Left and Right hemispheres are linked by the CORPUS CALLOSUM.Each hemisphere has 4 LOBES:i) Frontalii) Parietaliii) Temporaliv) Occipital
19Frontal LobeThe Frontal Lobe-extends from the central sulcus (groove) to the anterior limit of the brainContains Primary Motor Cortex – responsible for fine movementsContributes to shifting attention, planning of action, delayed response tasks as examples
20Parietal LobeThe Parietal Lobe - between occipital lobe and the central sulcusContains the primary somato-sensory cortex –i.e. receiving touch sensation, muscle-stretch information and joint position informationAlso, 3-D processing (visualisations, face recognition etc)
21Temporal LobeThe Temporal Lobe - lateral portion of each hemisphere, near the templesContains targets for hearing, essential for understanding spoken language (Wernicke’s Area), complex visual processes, emotional and motivational behaviors
22Occipital Lobe The Occipital Lobe - posterior end of cortex Contains primary visual cortex
23Figure 4.20 Some major subdivisions of the human cerebral cortex The four lobes: occipital, parietal, temporal, and frontal.
24Which part of the brain contains: The cerebrum?ForebrainThe cerebellum?HindbrainThe medulla oblongata?Pituitary gland?Diencephalon.
25Which lobe of the cerebrum deals with: a) memoryb) visionc) languaged) hearinge) spatial awareness
26Essay for next week:a) Outline the functions of the cerebrum in the human brain.b) Describe the changes that occur in the cerebrum of a person with Alzheimer’s disease and discuss the possible causes of the disease.Try a web search eg or