Medical Terminology

1. Medical Terminology The Nervous System

2. Nervous system • Complex, highly organized system • Coordinates all of the many activities of the body • Allows body to respond and adapt to changes that occur both inside and outside the body

3. Neuron • Known as the nerve cell and is the basic structural unit of the nervous system • Parts of Neuron • Cell body • Nucleus • Nerve Fibers • Dendrites – carry impulses toward cell body • Axon – carries impulses away from cell body • Covered with myelin sheath composed of lipid • Increases rate of transmission of an impulse • Insulates and maintains the axon

4. Neuron,cont • Axon of a neuron lies close to the dendrite of other neurons • Space between them is a synapse • Impulses coming from axon “jump” synapse to get to dendrite of another neuron • Special chemicals called neurotransmitters located at end of each axon allow nerve impulses to pass from one neuron to another; examples of neurotransmitters: adrenaline, dopamine, and serotonin

5. Structures of a Neuron

6. Impulses • Occurs when external stimuli and/or internal chemicals activate cell membranes of nerve cells • Causes release of stored electrical energy within cells • This energy is passed through length of nerve cell and is called the nervous impulse • Impulses (video link)

7. Impulses • Two types of impulses: • Afferent or Sensory – carry impulses from sensory receptors to brain and spinal cord • Efferent or Motor – carry impulses from brain and spinal cord to organs that produce response such as glands and muscles

8. Divisions of nervous system • Central Nervous System (CNS): consists of brain and spinal cord • Peripheral Nervous System (PNS): consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves

9. Peripheral Nervous system • cranial nerves carry impulses between the brain and the head and neck; one exception is vagus nerve which carries messages to and from the chest and abdomen as well as the head and neck • spinal nerves carry messages between the spinal cord and the chest, abdomen, and extremities

10. Central Nervous System: BRAIN • Largest section of the brain is the cerebrum • Outer tissue of the cerebrum is known as the cerebral cortex • Cerebral cortex is arranged in folds to from elevated portions known as convolutions • Fissures are the depressions or grooves of the cerebral cortex

11. Ventricles of the brain • Four spaces or canals in the brain which contain cerebral spinal fluid (CSF) • CSF contains lymphocytes, sugar, chlorides, and protein • CSF carries nutrients and removes wastes • CSF provides a cushion and acts as a shock absorber • http://www.bing.com/videos/search?q=ventricles+of+the+brain&view=detail&mid=A1197512942CE0C28738A1197512942CE0C28738&first=0&FORM=LKVR7&adlt=strict

12. Ventricles of the brain

13. Functions of the brain • Cerebrum – thinking, reasoning, sensations, movements, memory • Thalamus – Relay station for impulses that travel from receptors such as the eye, ear, and skin; controls perception of pain • Hypothalamus – body temperature, sleep, appetite, emotions, control of pituitary gland • http://www.bing.com/videos/search?q=brain+function&view=detail&mid=CBF26161EB8A620FD8C2CBF26161EB8A620FD8C2&first=0&FORM=LKVR12&adlt=strict

14. Functions of the brain • Cerebellum – Coordination of voluntary movements such as posture, maintaining balance, and muscle tone • Pons – Nerve fiber tracts that connect the cerebellum and cerebrum with the rest of the brain • Medulla Oblongata – Regulates heart, blood vessels, and respiratory system

15. Spinal cord • Nervous tissue that extends from medulla oblongata to second lumbar vertebra • Ends at caudaequina (horse’s tail) which is a fan of nerve fibers below second lumbar vertebra • Carries nerve that affect limbs and lower part of body • Pathway for impulses going to and from brain

17. Meninges • Three layers of connective tissue membranes that surround brain and spinal cord

18. Meninges • Divided into three separate membranes • dura mater – outermost membrane containing channels through which blood can enter brain tissue • subdural space – space below dura membrane that contains many blood vessels • arachnoid membrane – middle membrane which is spider-like and is loosely attached to other meninges • subarachnoid space – Space formed by web-like fibers of arachnoid membrane; between 2nd and 3rd meninges; Contains CSF • pia mater – inner most meninges closest to brain and spinal cord; made of delicate connective tissue with rich supply of blood vessels

19. Autonomic nervous system • Part of peripheral nervous system • Nerve fibers which carry impulses from CNS to glands, heart, blood vessels, and involuntary muscles found in walls of intestines and hollow organs such as stomach and bladder

20. Autonomic nervous system • Divided into two systems • Sympathetic Nervous System • Stimulate body in times of stress and crisis • Increase blood pressure, adrenaline is released and decreases digestion • Parasympathetic Nervous System • Acts as balance for sympathetic nervous system • Decreases heart rate and blood pressure, increases digestion