Nervous System

1. Nervous System Chapter 14

2. Objectives: • Describe the nervous system • List the functions of the nervous system • Identify some clinical disorders • Review lab test and procedures • Identify some medical terms

3. Study of the Nervous System is: • Neurology • One who studies Neurology is a: • Neurologist

4. Nervous System: • Usually described as having two interconnected divisions • The Central Nervous system (CNS) • The Peripheral nervous system (PNS)

5. Nervous system: • One of the most complex systems in the human body • Sort of like your bodies built in computer system but far more complex • There are over 10 billion nerve cells that operate constantly all over the body

6. Contd: • Nerve cells are called neurons • Nerves are made of bunched together neurons and their supporting tissue. • Collectively they are called neuroglia • Nerves either carry impulses to the brain and spinal cord (sensory or afferent) or carry messages from the brain and spinal cord (motor or efferent).

7. Nervous system: • Control all involuntary (eyes dilating) and voluntary movements (raising your eyebrows) • Center for all mental activity such as Thought process, learning and memory

8. Central Nervous system: • Includes the brain and spinal cord • Located in the skull and vertebral canal • It is the main control center of your body, and the center of thought. Your Central Nervous System controls most of the actions within your body.

9. Contd: • 2: Peripheral nervous system (PNS) • Which involve 12 pairs of cranial nerves and 31 pairs of spinal nerves. • works in conjunction with the central nervous system • Transmits sensory and motor information between the CNS and rest of the body

10. PNS: • The peripheral nervous system (PNS) runs from your spinal cord to your appendages (arms, legs, hands and feet) and you DO HAVE TO consciously and voluntarily make this nervous system move or work.

11. Brain: • Weighs about 2.5 to 4 lbs • Consumes 25 % of its oxygen • Receives 15% of its cardiac output • Central control center for regulating and controlling body functions • Lies in the cranial cavity • Size of skull does not dictate size of brain

12. Brain: • The brain and spinal cord are covered by 3 connective tissue layers • Dura mater, arachmoid and pia mater • collectively called the meninges • singular meninx

13. Contd: • The major structures of the brain are: • Cerebrum • Cerebellum • Diencephalon • brainstem

14. Brain contd: Cerebrum • Cerebrum is the main and largest portion of the brain. Represents 7/8ths of total weight • It occupies the upper part of the cranial cavity. • It is the most superior portion of the brain's anatomy. • It is the part of the brain that controls thought, memory and the senses.

15. Contd: • The cerebrum is divided into two parts - the right hemisphere, which controls the left side of the body; and the left hemisphere, which controls the right side of the body. • The outer part of the cerebrum is called gray matter and contains nerve cells. The inner part is called white matter and contains connections of nerves.

16. Contd: • Certain areas of the cerebrum perform special activities: • Occipital Lobe Interprets what you see • Frontal Lobe The primary area for thought, reason and speech • Temporal Lobe The hearing area • Parietal Lobe The awareness of sensation

17. Brain contd: Cerebellum: • Located behind the cerebrum at the back of the head is the cerebellum. • contains more nerve cells than both hemispheres combined. • When cut in half looks like a tree so referred to as arbor vitae (tree of life)

18. Cerebellum contd: • The cerebellum is primarily a movement control center, responsible for: • Voluntary muscle movements, Fine motor skills, Maintaining balance, posture, and equilibrium

19. Brain contd: Diencephalon • Means second portion of the brain • Thalamus and hypothalamus

20. Thalamus: • The largest of the two • The part of the brain that receives and processes all sensory modalities, except smell. • Sensations include vision, touch (including pain, temperature, pressure), taste, and hearing.

21. Hypothalamus: • Regulates body temperature, blood pressure, heartbeat, metabolism of fats and carbohydrates, and sugar levels in the blood. • It also plays a role in awareness of pleasure and pain • It is involved in the expression of emotions, such as fear and rage, and in sexual behaviors. • It is located below thalamus about the size of an almond

22. Brain stem: • Is the lower part of the brain located in front of the cerebellum and continuous with the spinal cord • It is the main control panel for the body that passes messages back and forth between the brain and other parts of the body

23. Brain stem contd: • The cerebrum, the cerebellum, and the spinal cord are all connected to the brainstem. • It controls vital functions of the body: • Breathing ,Consciousness, Cardiac function, Involuntary muscle movements, Swallowing, Movement of the eyes and mouth, Relaying sensory messages (pain, heat, noise, etc.) and Hunger

24. Contd: • Brain stem contd: The brainstem has three main parts: • The midbrain = joins the lower parts of the brain stem and spinal cord with the higher parts of the brain. (mesencephalon) • The pons= is a rounded bulge on the inferior side of the brain stem where it separates the midbrain from the medulla oblongata.

25. Brain stem contd: • medulla oblongata • is an enlarged continuation of the spinal cord at its superior end. • It extends from the foramen magnum to the pons.

26. Spinal Cord: • Encircled by white matter that consists of nerve tracts and fibers • Adult spine is about 44 cm long • Extends down the vertebral canal

27. Cerebrospinal Fluid: • The subarachnoid space, located between the arachnoid membrane and the pia mater, contains the cerebrospinal fluid (CSF) • Normal adult has 120 – 150 mL in circulation

28. Brain contd: • The CSF fluid cushions and supports the brain • It acts as a shock absorber for the brain, to prevent injury from the brain hitting against the bony inside of the skull. • The fluid also carries nutrients and waste products.

29. Peripheral nervous system (PNS) • is that portion of the nervous system that is outside the brain and spinal cord. • It connects with the CNS, serving as a conduit for neural signals to be transmitted to and from the CNS to the body.

30. PNS: • Has 12 pairs of cranial nerves • Has 31 pairs of spinal nerves

31. Cranial Nerves: • Provide :sensory input and motor control • 12 pairs • Named for the function they serve

32. PNS contd: • the PNS is not protected by bone or the blood-brain barrier, leaving it exposed to toxins and mechanical injuries. • Without the peripheral nervous system, one could not sense the external environment (smell, sight, touch, taste, hear), and would neither recognize threats or pleasurable experiences.

33. Spinal Nerves: • 31 pairs • Named for the region of the vertebral column they exit • 8 pairs of cervical spine nerves • 12 pairs of thoracic spinal nerves • 5 pairs of lumbar spinal nerves • 5 pairs of sacral spinal nerves • 1 pair of coccygeal spinal nerve

34. The PNS is divided into two subsystems: • The somatic nervous system, or voluntary nervous system, that regulates body movement through control of skeletal (voluntary) muscles also is the reception of external stimuli, such as vision, hearing, taste, and smell. • It also controls such voluntary actions as walking and smiling.

35. Contd: • autonomic nervous system (ANS) • acts involuntarily and consists of nerves in cardiac muscle, smooth muscle, and exocrine and endocrine glands. • responsible for metabolism, cardiovascular activity, temperature regulation, digestion.

36. Root words: • Algesi/o excessive sensitivity to pain • Cerebell/o Cerebellum • Cerebr/o Brain, cerebrum • Dur/o Dura mater • Ech/o Sound • Encepha/o Brain • Esthesi/o Feeling, nervous, sensation

37. Root words contd: • Kinesi/o Movement • Mening/o Membrane • Ment/o Mind • Myel/o Spinal cord • My/o Muscle • Neur/o Nerve

38. Root words contd: • Phas/o Speech • Psych/o Mind • Thalam/o Thalamus • Ventricul/o Ventricle

39. Prefixes: • Hemi- Half • Para- Beyond, around, beside • Polio- Gray • Quadri- Four • Sub- Below, under

40. Suffixes: • -algia pain • -itis inflammation • -malacia softening • -paresis slight paralysis • -plegia paralysis • -schisis cleft or splitting • -thenia lack of strength • -us condition

41. Terms: • Affect: refers to an emotion or symptom. • Aggression: refers to behavior that is intended to cause pain or harm • Amnesia: is a condition in which memory is disturbed. In simple terms it is the loss of memory. • Delusion: is a fixed belief that is either false, fanciful, or derived from deception.

42. Contd: • Echolalia: The immediate and involuntary repetition of words or phrases just spoken by others. • Hallucinations: involve sensing things that aren't there while a person is awake and conscious. • Megalomania: is a historical term for behavior characterized by an obsession or preoccupation with wealth, power, and genius,

43. Contd: • Phobia: is an irrational, intense, persistent fear of certain situations, activities, things, or people. • Comatose: is a profound state of unconsciousness. A comatose person cannot be awakened, fails to respond normally to pain or light, does not have sleep-wake cycles, and does not take voluntary actions.