Nervous System Notes Part 2

What are the two parts of the central nervous system? The two parts of the central nervous system are the brain and spinal cord. What part of the brainstem regulates breathing, heart rate, swallowing, etc.? (involuntary actions) The medulla oblongata regulates breathing, heart rate, swallowing, etc. What does the pons do? The pons acts as a bridge between cerebrum and cerebellum. What does the midbrain do? The midbrain functions in hearing and visual reflexes.

What functions in arousing and maintaining consciousness? The reticular activating system functions in arousing and maintaining consciousness. Which part of the brain process info from sensory receptors? The cerebellum processes info from sensory receptors. Which part of the brain enables smooth movements of skeletal muscles? The cerebellum enable smooth movements of skeletal muscles.

What does the hypothalamus control? Autonomic control: heart rate, blood pressure, involuntary responses Emotional responses: pain, pleasure, etc Hunger, sleep Endocrine system hormones What is the gray matter on the surface of the brain? The gray matter on the surface of the brain is the Cerebral cortex. What does the cerebral cortex do? The cerebral cortex enables us to perceive, communicate, remember, understand, move voluntarily.

What are the functional areas of the cerebral cortex? Motor areas: movement Sensory areas: awareness of sensations Association areas: connects parts of the cortex (smells, tastes, etc) What does white matter in the brain do? White matter provides communication inside the brain. List some brain disorders Some brain disorders include Parkinson’s disease, epilepsy, stroke, Alzheimer’s disease.

EVEN MORE INTERESTING BRAIN FACTS The brain itself cannot feel pain. While the brain might be the pain center when you cut your finger or burn yourself, the brain itself does not have pain receptors and cannot feel pain. That doesn’t mean your head can’t hurt. The brain is surrounded by loads of tissues, nerves and blood vessels that are plenty receptive to pain and can give you a pounding headache. 80% of the brain is water. Living brain tissue is a squishy, pink and jelly-like organ thanks to the loads of blood and high water content of the tissue.

The Spinal Cord Cranial & Spinal Meninges 3 membranes that cover and protect the brain & spinal cord 1. Dura Matter tough connective tissue

2. Arachnoid thin, transparent

3. Pia Matter delicate, contains many blood vessels – nourishment for cells of the cord Cerebrospinal Fluid (CSF) important in protection and nutrition

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc  Reflex—rapid, predictable, and involuntary response to a stimulus  Occurs over pathways called reflex arcs  Reflex arc—direct route from a sensory neuron, to an interneuron, to an effector

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc Figure 7.11a Stimulus at distal end of neuron Skin Spinal cord (in cross section) Interneuron Receptor Effector Sensory neuron Motor neuron Integration center (a)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc Figure 7.11a, step 1 Stimulus at distal end of neuron Skin Receptor (a)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc Figure 7.11a, step 2 Stimulus at distal end of neuron Skin Receptor Sensory neuron (a)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc Figure 7.11a, step 3 Stimulus at distal end of neuron Skin Spinal cord (in cross section) Interneuron Receptor Sensory neuron Integration center (a)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc Figure 7.11a, step 4 Stimulus at distal end of neuron Skin Spinal cord (in cross section) Interneuron Receptor Sensory neuron Motor neuron Integration center (a)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings The Reflex Arc Figure 7.11a, step 5 Stimulus at distal end of neuron Skin Spinal cord (in cross section) Interneuron Receptor Effector Sensory neuron Motor neuron Integration center (a)

all of this happens BEFORE signal is sent to the brain (“no brainer”)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Types of Reflexes and Regulation  Patellar, or knee-jerk, reflex is an example of a two-neuron reflex arc Figure 7.11d

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord  Extends from the foramen magnum of the skull to the first or second lumbar vertebra  31 pairs of spinal nerves arise from the spinal cord  Cauda equina is a collection of spinal nerves at the inferior end

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy Figure 7.20 (1 of 2)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy Figure 7.20 (2 of 2)

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Internal gray matter is mostly cell bodies  Dorsal (posterior) horns  Anterior (ventral) horns  Gray matter surrounds the central canal  Central canal is filled with cerebrospinal fluid  Exterior white mater—conduction tracts  Dorsal, lateral, ventral columns

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy Figure 7.21

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Spinal Cord Anatomy  Meninges cover the spinal cord  Spinal nerves leave at the level of each vertebrae  Dorsal root  Associated with the dorsal root ganglia— collections of cell bodies outside the central nervous system  Ventral root  Contains axons

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Pathways Between Brain and Spinal Cord Figure 7.22

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings Peripheral Nervous System (PNS)  Nerves and ganglia outside the central nervous system  Nerve = bundle of neuron fibers  Neuron fibers are bundled by connective tissue

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Structure of a Nerve  Endoneurium surrounds each fiber  Groups of fibers are bound into fascicles by perineurium  Fascicles are bound together by epineurium

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Structure of a Nerve Figure 7.23

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Classification of Nerves  Mixed nerves  Both sensory and motor fibers  Sensory (afferent) nerves  Carry impulses toward the CNS  Motor (efferent) nerves  Carry impulses away from the CNS

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Cranial Nerves  12 pairs of nerves that mostly serve the head and neck  Only the pair of vagus nerves extend to thoracic and abdominal cavities  Most are mixed nerves, but three are sensory only

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Cranial Nerves  I Olfactory nerve—sensory for smell  II Optic nerve—sensory for vision  III Oculomotor nerve—motor fibers to eye muscles  IV Trochlear—motor fiber to eye muscles

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Cranial Nerves  V Trigeminal nerve—sensory for the face; motor fibers to chewing muscles  VI Abducens nerve—motor fibers to eye muscles  VII Facial nerve—sensory for taste; motor fibers to the face  VIII Vestibulocochlear nerve—sensory for balance and hearing

Copyright © 2009 Pearson Education, Inc., publishing as Benjamin Cummings PNS: Cranial Nerves  IX Glossopharyngeal nerve—sensory for taste; motor fibers to the pharynx  X Vagus nerves—sensory and motor fibers for pharynx, larynx, and viscera  XI Accessory nerve—motor fibers to neck and upper back  XII Hypoglossal nerve—motor fibers to tongue