Nervous System

1. Nervous System By: Joe Matten Casey Crocamo Kevin Li Allie Erickson Wenyi Lau

2. Nervous System • Neurons can help to take in stimuli from both outside and inside the body. • They can process these stimuli to control other bodily functions.(motor output) • The three types of neurons are sensory(afferent), interneurons, and motor(efferent) • A good way to remember the difference is efferent=effect

3. Nervous System(CNS+PNS) • The nervous system is separated into two parts, peripheral and central. • The central includes the brain and the spinal cord. • The peripheral includes all of the nerves outside of the brain and spinal cord

4. PNS • PNS is separated into the somatic (voluntary) and autonomic (involuntary) systems.

5. Types of nervous system cells • Astrocytes, microglia, ependymal, oligodendrocytes, satellite, schwann. • Astrocytes are starshaped, they form the barrier between the capillaries and neurons in the brain. • Microglia are spider-like phagocytes that collect trash. • Ependymal cells line the brain+spinal cord spaces. They help move CSF.

6. Nervous system cells • Oligodendrocytes produce myelin sheath around nerve fibers in the CNS • Satellite cells protect neurons • Schwann cells produce myelin sheath around the nerve fibers in the PNS

7. Cell Body • Nissl substance is the specialized rough ER • Neurofibrils provide a cytoskeleton that helps cells maintain their shape

8. Neurons • Dendrites conduct impulses towards the body, while Axons take them away from the body. • There are axon terminals with vesicles and neurotransmitters. They are separated with a synaptic cleft. • Schwann cells produce myelin sheaths. The gaps between these schwann cells are called the Nodes of Ranvier.

9. Cell bodies • Gray matter consists of cell bodies and unmylenated fibers. • Nuclei are clusters of cell bodies within the white matter.

10. Cell bodies • Multipolar neurons have multiple extensions from the body • Bipolar neurons have one axon and one dendrite • Unipolar neurons have a short single process leaving the cell body.

11. Neurons • The plasma membrane is polarized at -70mv • There are more sodium ions outside of the membrane, with more potassium ions inside the membrane. • Threshold is at -55mv. • It depolarizes, Na+ channels open to let sodium ions flow in. • It then repolarizes, the potassium channels opens and the potassium ions are sent in.

12. Neurons • It then hyperpolarizes for a few milliseconds and enters the refractory period where it cannot transmit any signals

13. Reflex Arc • The reflex arc is the route from a sensory neuron to an interneuron then to an effector. • There are two types of reflex arcs, autonomic and somatic. • Autonomic reflexes include smooth muscle regulation, heart+blood pressure regulations, glandular regulation and digestive system regulations. • The somatic reflexes include activation of skeletal muscles

14. CNS • The CNS develops from the embryonic neural tube, includes the brain and the spinal cord. There are four chambers in the brain filled with CSF. • There are 4 main regions of the brain, the cerebral hemispheres, diencephalon, brain stem and cerebellum. • There cerebrum has a frontal, parietal, occipital and temporal lobe.

15. Lobes of The Brain • Frontal Lobe • Parietal Lobe • Occipital Lobe • Temporal Lobe

17. Cerebrum • The cerebrum consists of an outer layer made up of gray matter. • The cerebral cortex is involved in speech, memory, logical and emotional responses, consciousness, interpretation of sensation, and voluntary movement

18. White Matter • Corpus Callosum connects the hemispheres of the brain.

19. Diencephalon • Made of three parts: • Thalamus • Hypothalamus • Epithalamus

20. Diencephalon • Thalamus: relays sensory impulses • Hypothalamus: helps to regulate body temperature, controls water balance and regulates metabolism • Part of limbic system • Epithalamus: includes pineal gland and the choroid plexus (forms CSF)

21. Brain Stem • Midbrain: reflex centers for vision and hearing • Pons: control of breathing • Medulla oblongata: heart rate control, blood pressure regulation, breathing, swallowing and vomiting

22. Reticular Formation • Involved in sleep/wake cycles and consciousness • Also involved in motor control of visceral organs

23. Cerebellum • coordination of body movements • The central nervous system is protected by the scalp, skin, skull, cerebrospinal fluid, blood brain barrier and vertebral column and the meninges

24. Meninges • Dura mater: exterior cover and contains periosoteum and meningeal layer • Arachnoid layer: middle layer and is web-like • Pia mater: the internal layer and clings to the surface of the brain

25. Cerebrospinal Fluid • Formed by the choroid plexus and protects and cushions the brain • Found inside the arachnoid space

26. Blood Brain Barrier • Protects the brain from harmful substances • The things that can pass through: • Fats and fat soluble molecules • Respiratory gases • Alcohol • Nicotine • Anesthesia

27. Traumatic Brain Injuries • Concussion: slight brain injury and leads to no permanent brain damage • Contusion • Nervous tissue destruction occurs • Nervous tissue does not regenerate • Cerebral edema • Swelling from the inflammatory response • May compress and kill brain tissue ; 3 ;

28. Stroke • Cerebrovascular Accident (CVA) • Caused by a ruptured blood vessel and results in oxygen deprivation

29. Alzheimer’s disease • This is when victims experience memory loss, irritability, confusion, and hallucinations and eventually death

30. Spinal Cord • Carries nerve impulses from the brain to the limb • Protected and cushioned by the meninges

31. Peripheral Nervous System

32. Structure of a Nerve • Outer: endoneurium • Middle: perineurium • Inner: epineurium