Nervous System

1. Nervous System

2. General Structure • Central Nervous System (CNS) • Brain & spinal cord • Peripheral Nervous System (PNS) • Cranial nerves • Carry impulses between the brain & the head & neck • Exception: Vagus Nerve • Spinal nerves • Plexuses • Plexus = large network of nerves • Peripheral nerves

3. Peripheral Nervous System • Spinal & Cranial nerves are composed of: • Sense receptors • For sight, hearing, balance, smell, touch & Sensory (afferent) nerves • Carry messages toward the spinal cord & brain • Motor (efferent) nerves • Travel from the spinal cord & brain to muscles, telling them how to respond

5. Peripheral Nervous System • Autonomic nervous system • Function involuntarily or automatically • Carries impulses away from the CNS to the glands, heart, blood vessels, & involuntary muscles (intestines, stomach, bladder) • Autonomic nerves • Sympathetic nerves • Stimulate the body in times of stress & crisis • Increase heart rate, dilate airways, increase BP, stimulate the adrenal glands, inhibit intestinal contractions • Parasympathetic nerves • Slow down heart rate, lower BP & stimulate intestinal contractions

7. Neurons, Nerves, & Glial Cells • Neuron • Individual nerve cell • Ganglia • Small collections of nerve cell bodies outside the brain & spinal cord

8. Synapse • Space where the nervous impulse jumps from one neuron to the other. • Neurotransmitter • Chemical substance that transfers the impulse • Acetylcholine, norepinephrine, epinephrine, dopamine, serotonin, endorphins

9. Nerve • Nerve • Consists of a bundle of dendrites and axons that travel together like strands of rope • Peripheral nerves • Carry impulses to the brain (afferent or sensory nerves) • Carry impulses from the CNS to organs (efferent or motor nerves)

10. Glial Cells (Neuroglial Cells) • Supportive, protective, and connective tissue of the CNS • Glial cells are stromal (framework) tissue, whereas neurons carry nervous impulses • Astrocytes • Star-like apperance (astr/o = star) • Transports water & salts between capillaries & neurons • Microglial cells • Protect neurons in response to inflammation • Oligodendrocytes • Few dendrites (olig/o = few or scanty) • Form the myelin sheath in the CNS • Ependymal cells • Line membranes where cerbrospinal fluid (CSF) circulates

12. The Brain • Cerebrum • Largest part of the brain. • Cerebral cortex • Nerve cells lie in sheets on the surface of the cerebrum • Gyri – folds in the sheets • Sulci – grooves that separate the gyri • Cerebral Hemispheres • Divides the brain in right & left sides. Each divided into lobes • Frontal • Thought processes, behavior, personality, emotion • Parietal • Body sensations, visual & spatial perception • Occipital • vision • Temporal • Hearing, understanding, speech, language

14. The Brain • Thalamus • Acts like a triage center. Decides what is important & what is not. • Hypothalamus • Contain neurons that control temperature, sleep, appetite, emotions (fear & pleasure). Regulates hormones from the pituitary gland

15. The Brainstem • Lie in the back & below the cerebrum & connect the brain to the spinal cord • Cerebellum • Functions to coordinate voluntary movements & maintain balance & posture • Pons • Literally means bridge. Connects the cerebellum & cerebrum with the rest of the brain • Medulla oblongata • Connects the spinal cord with the rest of the brain • Regulates: • Respiratory center: controls muscles of respiration • Cardiac center: slows the heart rate if beats are too rapid • Vasomotor center: constricts or dilates the blood vessels, influencing blood pressure

17. The Spinal Cord & Meninges • Column of nervous tissue from the medulla oblongata to L-2. • CaudaEquina (Latin for “horse’s tail) is a fan of nerve fibers below the end of the spinal cord.

18. Spinal Cord • Cross-Sectional View • Gray matter • Containing cell bodies & dendrites • White matter • Containing the nerve fiber tracts with myelin sheaths

19. Meninges • Three layers of connective tissue that surround the brain & spinal cord • dura mater • epidural • subdural • arachnoid • subarachnoid space • contains CSF • pia mater • blood vessels and lymph

21. Pathology • Maybe classified in the following categories • Congenital • Neoplastic (tumors) • Degenerative, movement, & seizure • Traumatic • Infectious (meningitis & encephalitis) • Vascular (stroke)

22. Congenital Disorders • Hydrocephalus • Abnormal accumulation of fluid (CSF) in the brain • Spina bifida • Congenital defects in the lumbar spinal column caused by imperfect union of vertebral parts (neural tube defect) • Spina bifida occulta • Vertebral defect is covered over & only evident on x-ray • Meningocele • Meniges protrudes to the outside • Myelomeningocele • Both spinal cord & meninges protrude

23. Degenerative, Movement, & Seizure Disorders • Alzheimer disease (AD) • Brain disorder marked by gradual & progressive mental deterioration, personality changes, & impairment of daily living • Epilepsy • Chronic brain disorder characterized by recurrent seizure activity • Huntington disease • Hereditary disorder marked by degenerative changes in the cerebrum leading to abrupt involuntary movements & mental deterioration. • Multiple Sclerosis (MS) • Destruction of the myelin sheath on neurons in the CNS & its replacement by plaques of sclerotic (hard) tissue

24. Infectious Disorders • Herpes Zoster (shingles) • Viral infection affecting peripheral nerves • Meningitis • Inflammation of the meninges; leptomeningitis • Human Immunodeficiency Virus Encephalopathy • Brain disease & dementia occurring with AIDS

25. Neoplastic Disorders • Brain Tumor • Abnormal growth of brain tissue & meninges • Most arise from glial cells or the meninges

26. Traumatic Disorders • Cerebral concussion • Temporary brain dysfunction (brief loss of consciousness) after injury, usually clearing within 24 hours • Cerebral contusion • Bruising of brain tissue as a result of direct trauma to the head; neurologic deficits persist longer than 24 hours

27. Vascular Disorders • Cerebrovascular accident (CVA) • Disruption in the normal blood supply to the brain; stroke • Thrombotic – blood clot (thrombus) in the arteries leading to the brain • Embolic – an embolus (dislodged thrombus) travels to cerebral arteries & occludes a small vessel • Hemorrhagic - blood vessel breaks

28. Audionyms

29. Auto- • Audionym • Auto • Visual Image • See the AUTOmatic car driving ITSELF • Meaning • self

30. Blephar- • Audionym • Blue fur • Visual image • See the lady wearing BLUE FUR with EYELIDS • Meaning • eyelid

31. Cau-, caus • Audionym • Cough • Visual Image • See the COUGH the BURNS • Meaning • burn

32. Dacry-, lacrim- • Audionym • Daiquiri • Visual Image • See the DAIQUIRI drink crying a tear • Meaning • tear

33. Dur- • Audionym • Door • Visual Image • See the DOOR with the HARD hat on it. • Meaning • Hard, dura mater

34. Hemi- • Audionym • Hemisphere • Visual Image • See the HEMIsphere in HALF • Meaning • Half

35. Kerat- • Audionym • Carrot • Visual Image • See the CARROT being used as HORNS • Meaning • Horny, horny tissue, cornea

36. Mening- • Audionym • Manage • Visual Image • See the MANAGER managing MEN’S BRAINS • Meaning • membrane

37. Ment- • Audionym • Mint • Visual Image • See the person picking up the MINT saying “MINE, MINE” • Meaning • mind

38. Neuro- • Audionym • Nero • Visual Image • See NERO being very NERVOUS as Rome burns • Meaning • Nerve (nervous system)

39. Ophthalm-, ocul- • Audionym • Up thumb • Visual Image • See the UP THUMB (thumbs up) with an EYE on top • Meaning • eye

40. Phren- • Audionym • Friend • Visual Image • See the people pulling on the FRIEND saying, “MINE! MINE! MINE!” • Meaning • mind

41. Radic-, radicul- • Audionym • Radish • Visual Image • See the RADISH it’s a ROOT • Meaning • Root, nerve root

42. Semi- • Audionym • Semi colon • Visual Image • See the SEMI-colon cut in HALF • Meaning • Half