ch 13. reminder: consists of…. the brain and spinal cord

CH 13

Reminder: Consists of….

the brain and spinal cord

The outer covering of the brain consists of bone and the outer covering of the spinal cord consists of vertebrae bones.

The inner coverings consist of THREE Layers called meninges.…we are going to talk about the three layers from outward in…

Dura Mater

• Outer most covering

Arachnoid membrane

• The second layer of meninges in between the dura mater and pia mater.

• Only meninge which contains Cerebro spinal fluid (CSF)

Pia mater

• Innermost meninge

• Adheres to outermost surface of the brain

Cerebrospinal fluid (CSF)

• Another form of protection for the CNS

• Acts as a liquid cushion

• 140 mL of cerebro spinal fluid in the average human adult

• Made from blood plasma

• CSF can be found in…– Subarachnoid space– Central canal of the spinal cord– Ventricles within the brain

Lumbar Puncture

• Withdrawal of cerebrospinal fluid from subarachnoid space (under arachnid and outside pia matter)

• Physician inserts a needle just above fourth vertebrate

• Cerebrospinal fluid can be tested for presence of blood or bacteria

Structure

• Dorsal nerve root- brings sensory information to spinal cord

• Ventral Nerve root- brings motor information to the spinal cord

FUNCTIONInclude colliculi which control visual and auditory centers of the brain

Hydrocephalus• Interference with circulation of

cerbrospinal fluid.

• Example: brain tumor might press against brain, now allowing cerbraspinal fluid to drain.

• For an infant, a tube can be inserted to drain fluid since infant skull has not ossified. In adult, this is more problematic since skull will not yield.

• The brain is made up of …– Brainstem– Cerebellum– Cerebrum

Brainstem• Consists of

– Medulla oblongata- connects the brain to the spinal cord and is in control of vital and control centers within the brain.

– Pons- charge of normal breathing rhythms– Midbrain- Include colliculi which control visual

and auditory centers of the brain

Cerebellum • coordinates skilled movements, helps

control posture, and controls skeletal muscles for balance

Cerebrum

• 60% of brain weight

• Left and right halves

• Wenicke’s area- comprehension of written

• Broca’s area- motor speech and articulation of words

• Consciousness

• memory

Diseases of the CNS• Alzheimers- Demntia- lesions develop in brain in middle to late

adulthood. Cause unknown.• Huntingtons- dominant gene that causes body to make a protein

incorrectly which prevents normal function. Symptoms do not occur until late adulthood.

• Cerebral palsy- permanent, nonprogressive damange to motor control areas of brain at birth or shortly after

• Epilepsy- Chronic seizures caused by tumors or chemical imbalances

• MS- Myelin loss and destruction of oligodendrocytes (what are those again??) causing lack of coordination, visual impairment, and speech disturbance.

Chapter 14

Peripheral Nervous System

Now we talk about all the spinal nerves, cranial nerves, and the many smaller nerves that branch from these main nerves!

• Sensory (afferent) division– Sensory afferent fibers – carry impulses from skin,

skeletal muscles, and joints to the brain– Visceral afferent fibers – transmit impulses from

organs to the brain

• Motor (efferent) division – Transmits impulses from the CNS to effector organs

What are the divisions of the peripheral nervous system?

Spinal Nerve

Spinal nerves (31 pairs of them!) have no special names but are numbered according to level of vertebral column.

Roots lay within spinal cavity.

Ventral(Anterior)root(includes motor fibers)

Dorsal(Posterior)root(includes sensory fibers)

Cranial Nerves

There are 12 pairs of cranial nerves. The twelve pairs of nerves are assigned names

and numbers. They can be of three types:

-Sensory Cranial nerves- consist of sensory axons only.

-Motor Cranial nerves- consist of motor axons only.

-Mixed cranial nerves- Contain axons of sensory and motor neurons.

Nerve TypesNerve Types*you do not need this for test but this shows the 12 *you do not need this for test but this shows the 12 pairs and how they can be classified as a type of pairs and how they can be classified as a type of

nerve*nerve* Olfactory: SensoryOlfactory: Sensory Optic: SensoryOptic: Sensory Oculomotor: MotorOculomotor: Motor Trochlear: MotorTrochlear: Motor Trigeminal: Sensory and MotorTrigeminal: Sensory and Motor Abducens: MotorAbducens: Motor Facial: Sensory and MotorFacial: Sensory and Motor Vestibularcochlear: SensoryVestibularcochlear: Sensory Glossopharyngeal: Sensory and MotorGlossopharyngeal: Sensory and Motor Vagus: Sensory and MotorVagus: Sensory and Motor Accessory: MotorAccessory: Motor Hypoglossal: MotorHypoglossal: Motor

ReflexesReflexesA reflex is a predictable, involuntary response to a stimulus.

They produce the simplest behaviors. Ex. Removing hand from a hot object.

Occur over neural pathways called reflex arcs. 5 basic components: receptor, sensory neuron,

integration center, motor neuron, and effector

Somatic Reflexes- Somatic Reflexes- contractions of skeletal musclescontractions of skeletal muscles Knee Jerk: extension of lower leg from tap on Knee Jerk: extension of lower leg from tap on

patellar tendonpatellar tendon

Ankle Jerk: extension of foot from tap on Ankle Jerk: extension of foot from tap on Achilles tendonAchilles tendon

Babinski: extension of great toe from stimulation Babinski: extension of great toe from stimulation of sole of foot in normal infantsof sole of foot in normal infants

Corneal: blinking from touching corneaCorneal: blinking from touching cornea

Abdominal: drawing in abdominal wall from Abdominal: drawing in abdominal wall from stroking side of abdomenstroking side of abdomen

How a Reflex WorksHow a Reflex Works

http://health.howstuffworks.com/adam-200012.htm

http://bcs.whfreeman.com/thelifewire/content/chp46/46020.html

Autonomic ReflexesAutonomic Reflexes

Autonomic (visceral) Reflex: Autonomic (visceral) Reflex: contractions of smooth/cardiac contractions of smooth/cardiac muscles or gland secretionsmuscles or gland secretions

Discussing this Flow Chart Again…