Chapter 12: The Brain Continued

Front 1

What structure is deep to the cerebral peduncle that makes the neurotransmitter Dopamine?

Back 1

Substantia Nigra

Front 2

What are the white fiber tracts that connect the midbrain to the cerebellum?

Back 2

Superior cerebellar peduncles

Front 3

Describe the Pons structure and its location

Back 3

Situated between the midbrain and medulla oblongata, 4th ventricle lies behind it (the pons forms the anterior wall of the 4th ventricle), composed of conduction tracts and fibers that run in 2 directions to and from brain, fibers that relay info between motor cortex & cerebrellum make the middle cerebellar peduncles connecting pons to cerebellum.

Front 4

Describe the medulla oblongata

Back 4

Most the indferior part of the brain stem, blends into the spinal cord @ level of foramen magnum of the skull, along w/pons helps form the ventral wall of the 4th ventricle, decussation of the pyramids just above the medulla spinal cord junction, where pyramidal fiber tracts (from pyramidal cells) descending from motor cortex cross over to opposite side before going into the spinal cord (concept of contralateralization-rt hemisphere controls leftside of body and visa-versa,controling vol. muscle movements on the opposite side of the body. Inferior cerebellar peduncles-connects m.oblongata to cerebellum.

Front 5

What are the 3 paired fiber tracts that connect the brain stem to the cerebellum?

Back 5

The superior, middle and inferior cerebellar peduncles.

Front 6

What are the functions of the medulla oblongata?

Back 6

It controls the autonomic vital centers-a reflex center to maintain body homeostasis. The vital autonomic centers that are controlled are: cardiovascular center, vasomotor center (diamter/dilation of blood vessels-controls blood pressure) respiratory cneter-controls the rate and depth of breathing ;average is 12 breaths per minute. Also controls: sneezing, coughing, swallowing, vomiting, hiccuping (these overlap w/ hypothalamus)-reflexive parts are respon. of m.oblongata

Front 7

Describe the cerebellum

Back 7

Located dorsally under occipital lobes of cerebral hemispheres and is separated from the cerebrum by transverse cerebral fissure processes input received from cerebral motor cortex & allows for smooth coordinated movements (driving, typing, etc.). Cerebellar activity is subconscious. Has 2 lobes; cerebellar hemispheres conncected by vermis. Has convoluted surface w/pleatlike gyri called folia. Like the cerebrum, the cerelbellum has an outer gray matter. (Cortex=cerebellar cortex-unmylenated cell bodies, has inner white matter (mylenated fibers=arbor vitae-tree of life, deep cerebellar/dentate nuclei-nuclei that are islands of gray matter similar to basal nuclei, purkinje cells are axon sthat make the tree of life, have many dendrites; axons extend thru white matter to synapse w/the central nuclei of the cerebellum-association neurons, ipsilateral inneravation all fibers entering & leaving the cerebellum go from and to the ame side of the body. The right lobe of the cerebellum innervates the right side of the body & the body & visa versa; cerebellum innervates ipsilaterally which is opposite of the contralateral innervation.

Front 8

Describe one of the 2 functional brain systems that is known as the emotional brain.

Back 8

The limbic system located in the medial aspect of each cerebral hemisphere and diencephalon. Synapses/interacts w/both the frontal lobes& hypothalamus; this is why any cognitive things processed gives us an emotional feeling that links the things we do with feelings. Our limbic system and frontal lobes connect to make us human. Smell is located here and odors trigger emotional reactions and memories. Psychosomatic illnesses emotion-induced illnesses indicating our brains is reponding to outside environmental stimuli relaying it to hypothalamus=stomachache, anxiety...

Front 9

Name and describe a functional brain system that is considered the brain's wakefulness center.

Back 9

The RETICULAR FORMATION that runs the length of the brain stem and governs brain arousal and alertness. The RAS =Reticular Activating System is part of the reticular formation. Reticular neurons that send impulses to the cerebral cortex keeping it alert conscious, and excitable. RAS is an atinuating (lessening) filter for all sensory stimulating input coming in-preventing overstimulation. LSD suppresses the RAS=sensory overload.

Front 10

What things can inhibit the RAS.

Back 10

Pineal body(sleep center) makes melatonin, alcohol, tranquilizers, valium LSD?

Front 11

What are the 4 main structures (not sub structures), that protect the brain.

Back 11

Skull, Meninges, Cerebrospinal fluid, & Blood Brain Barrier

Front 12

Explain the meninges, one of the structures that protects the brain.

Back 12

Aka Meninx, is 3 connective tissue membranes:( Dura Mater, Arachnoid mater, Pia mater) that are external to the CNS organs that cover & protect the CNs, protect blood vessels & enclose venous sinuses, contain CSF (cerebrospinal fluid) forms partitions in the skull. 1) The Dura mater means tough membrane, thick and leathery, outermost layer(superficial layer touching skull periosteum), meningeal layer, deeper layer, forms true external covering of the brain touches periosteal lyr just until it reaches sinus area, goes into fissure, dropping in forming dural septa. 2) Arachnoid mater lies beneath meningeal layer of dura mater,(w/a subdural space w/film of fluid inbetween), drops into sinus but keeps contact w/menigeal dura mater, called arachnoid because of spidery projections in the subarachnoid space secure arachnoid mater to the underlying pia mater. 3) Pia mater-deepest of the meninges; clings tightly to the brain like saran wrap.

Front 13

What is the dura septa?

Back 13

3 indented cavital divisions or partitions involving the meningeal layer of the dural mater. 1)Falx Cerebri: dural septa (meningeal) that is found in longitudinal fissure between cerebral hemispheres 2) Falx Cerebelli: dural septa between the vermis of the cerebellum, 3) Tentorium Cerebelli: dural septa that runs into transverse cerebral fissure that separates the cerebrum & the cerebellum.

Front 14

Describe the subdural space and the subarachnoid space

Back 14

Subdural space is a serous cavity with film of fluid between meningeal dura mater & arachnoid mater. Subarachnoid space is beneath arachnoid membrane filled with spidery projections and CSF and lgst. non-leaky blood vessels.

Front 15

What are arachnoid villi's location and function?

Back 15

They are knob-like projections in teh arachnoid mater that bud up into the triangular dural sinus area like a portal that filters out blood, hormones, helps with ionic balance.

Front 16

Explain the 3rd protection of the brain: Cerebrospinal Fluid

Back 16

Found in and around brain, functions as a liquid cushion. Buoyant, floating brain, CSF is produced in the Choroid Plexus that is located on the roof of each ventricle, makes CSF daily, cleanses CSF by removing waste. CSF is a blood filtrate-filters out blood to let blood plasma come through. CSF contains sodium Cl, Mg ions, O2, vitamins, & glucose (brain needs exact ionic balance to maintain blood/brain barrier. After CSF is made it fills up the ventricles & ependymal cells push it down into central canal of the spinal cord. Most enters subar. space through lateral or median apertures of the 4th ventricle, circulates thru arach. space around brain, returns to blood in dural sinuses via arachnoid villi. If it doesn't circulate is accumlates causing pressure.

Front 17

Explain the 4th protection of the brain: Blood-brain barrier.

Back 17

It is a protections that ensures a stable environment. Has 2 structures: choroid plexus: prevents blood from getting into CSF, and arachnoid mater: responsible for cleaning up spillage from blood vessels found in subarachnoid space. The blood brain barrier keeps hormones and bacteria out of brain (except hypothalamus). Barrier maintains crucial ionic balance needed for proper function. In spite of barrier certain things get across: alcohol, nicotine, anesthesia.

Front 18

Describe the Spinal cord.

Back 18

Goes from Foramen magnum to conus mudullaris L1 /L2 Part of CNS is a 2 way conduction path bring motor (efferent) down and out to muscles or back or sensory (afferent) up to the brain. A reflex center (gray matter) is where decisions are made. Surrounded by a spinal dural sheath (mater) that is a single layer, not attached directly to flexible vertebral column, but indirectly by denticulate ligaments that run around spinal nerves, and secure spinal dura to vertebral column, spinal nerves come out of intervertebral foramen=31 pairs, cord ends at conus m. and starts roots called cauda equina (rootlets), epidural space with fat & blood vessels where you get epidural for a baby, deep to that is spinal meninges, subarachnoid spaced filled w/ SF.

Front 19

Where is CSF taken from in the spinal column?

Back 19

Perfect place is in the Cauda Equina in lumbar puncture. It is not good to take CsF above L1, good at cauda equina because there's only rootlets, need can go into fluid w/out worry of damage.

Front 20

Describe gray mater inside spinal cord.

Back 20

Dorsal horns, lateral, and ventral connected by gray commissure (center of gray commissure is the central canal) , rt side of cord talks to Lateral horns only found in thoracic area because they have visceral motor nerves for those organs, won't be found in cervical or lumbar areas. Looks like a butterfly

Front 21

Where do sensory nerves enter the cord?

Back 21

Sensory nerves enter dorsal roots, they are unipolar, (long axon), sensory roots reside in dorsal root ganglion. 2types of sensory neurons: somatic sensory (limbs) interneuron (inside),synapses w/cell bodies in the dorsal horn) and visceral sensory (thoracic area), axons synapse with interneuons synapse w/motor neuron in the ventral horn (motor neurons) which take info out or exit out the ventral roots.

Front 22

Where do Visceral sensory neurons enter cord?

Back 22

Come in and synapse w/visceral sensory nerves, then synapse w/visceral motor or somatic motor and go out.

Front 23

Describe the white fiber tracts in the spinal column.

Back 23

mylenated sheaths that run up and down highways running up and down lenght of body. Ascending or descending. Descending are motor going from brain to body, ascending are blue carrying sensory to brain, specifically located (no mumbojumbo), On right are ascending sensory, where 3 neurons (1st,2nd,3rd order) going up. 1st order: have cell bodies in dorsal root ganglion, then their sensory endings are in the foot. 2nd order: cell body in thalamus, 3rd order is in post central gyrus?, decussation in sensory happens at the limb. Descending motor only has 2: Upper motor and lower motor: Upper has cell bodies in pre central gyrus of mortor cortex and cross at decussation of pyramids, synapse w/ another cell body is in ventral horn-goes out ventral root to effector organ.

Front 24

How are dorsal, lateral, and ventral horns connected.

Back 24

They are connected by a gray commissure (nonmylenated looks like a butterfly) where rt. side of cord talks to the left side. Note: lateral horns are only found in thoracic area because they specifically contain visceral motor nerves that are needed for the viscera.

Front 25

Which horns do sensory and motor nerve impulses enter and exit?

Back 25

Messages (sensory afferent nerves) enter from periphery into dorsal root, and Motor impulses exit via ventral root.

Front 26

Describe sensory nerves in the spinal cord.

Back 26

Sensory nerves: unipolar, dorsal root ganglion is where ganglion ofall sensory converge (where cell bodies are). 2 types of sensory: somatic sensory: come from skin/muscles;synapses w/cell bodies on dorsal horn. Visceral sensory-come from viscera. These axons synapse on cell bodies of interneurons.

Front 27

Where do somatic sensory neurons synapse?

Back 27

They synapse with cellbodies (interneurons) on the dorsal horn>>>then synapse w/somatic motor neuron on ventral horn >>exit through ventral root.

Front 28

Where do Visceral sensory neurons synapse?

Back 28

Visceral sensory neurons enter dorsal root>>>synapse w/cell bodies of visceromotor neurons that are in the lateral horn

Front 29

T/F Interneurons and motor neurons are multipolar

Back 29

True. and sensory neurons are unipolar (think dorsal root ganglion), and special senses are bipolar.

Front 30

Describe the white matter of the spinal cord.

Back 30

Mostly mylenated fibers that run up and down carrying info from brain through cord to body or back; allows communication between different part os spinal cord and between cord and brain. Descending tracts go to motor, Ascending tracts go to sensory.

Front 31

Ascending pathways have 3 neruons with functions:

Back 31

1st order neurons: have cell bodies in dorsal root ganglion; receptor endings on extremities; unipolar neuron, synapses on gray matter (on dorsal horn); synpases w/2nd order neurons. 2nd order neurons: cell bodies on the dorsal horn synapses w/1st order neuron after which will cross over in gray commissure between lateral horns to other side of column, axons continue up column thru brain stem and synapse with cell bodies of 3rd order neurons in thalamus, this signal continues to cerebral cortex.

Front 32

T/F Sensory nerves cross at decussation of pyramids.

Back 32

F Sensory nerves cross at the gray commissure found between the lateral horns.

Front 33

Explain the descending pathways in the spinal cord tract.

Back 33

Descending pathways are motor: they have 2 pathways (upper & lower motor neurons) 1)upper motor neuron cell bodies in pyramidal neurons of motor cortex (pre-central gyrus) ; g down and cross @ decussation of pyramids; synapse w/ motor neuron w/ cell body in the ventral horn; exits ventral root to the muscles. 2) lower motor neuron accepts the impulse and synapses with upper motor neuron and goes through ventral root to muscles.