Chapter 47

Question 0

What does the spinal cord do?

Answer 0

Mediate simple reflexes, coordinates movement involving more than one muscle, receives information from descending tracts (pyramidal tract) from higher centers (cortex), sends information (touch/pain) to higher centers in ascending tracts (medial lemniscus) to brain stem, cerebellum, and cortex

Question 1

What are the different sections of the brain?

Answer 1

Thalamus, Hypothalamus, Pituitary, Brainstem- midbrain, pons, medulla, Spinal Cord, Cerebullum

Question 2

What is the medial lemniscus?

Answer 2

Large bundle of heavily my myelinated axons that desiccate in the brainstem specifically the medulla

Question 3

What is a syrinx?

Answer 3

A huge cavity in the spinal cord extending all the way up to the brain.

Question 4

What is the autonomic nervous system?

Answer 4

Comprises the output pathways of the CNS the control involuntary functions such as heart rate sweating and digestive activities. control of diverse organs and tissues is crucial to homeostasis. Has two divisions- sympathetic and parasympathetic

Question 5

What is the sympathetic division of the ANS?

Answer 5

Produce the fight-flight response increasing heart rate blood pressure and cardiac output and preparing the body for emergencies.
Preganalinoic fibers are cholinergic and terminate on sympathetic ganglia adjacent to the spinal cord and other nearby ganglia
Postganglionic fibers terminate on organs and are mostly noradenergic (use norepinephrine)

Question 6

What is a cholinergic?

Answer 6

A neuron that uses acetylcholine neurotransmitter

Question 7

What is the difference between preganalinoic and postganglionic?

Answer 7

Preganglionic- The second neuron in the pathway with which they synapse resides in a collection of neurons outside the CNS called ganglion, not first
Postganglionic- The second one is called the postganglionic neuron because it’s axon extends out from the ganglion

Question 8

What is the Parasympathetic division of the ANS?

Answer 8

Slows the heart and lowers blood pressure it’s actions have been characterized as rest and digest
Ganglia tend to be located closer to the target organs, preganalinoic again cholinergic
Fibers terminating on organs are mostly cholinergic (use acetylcholine) or peptidergic (use neurpeptides)

Question 9

What are the parts of the brain stem?

Answer 9

1) Medulla
2) Pons
3) Midbrain

Question 10

What are the parts of the Medulla?

Answer 10

Inferior olivary nucleus: receiver inputs from the brain and spinal cord, send outputs to cerebellum (climbing fibers)
Pyramid: Fibers of the pyramidal tract from cortex to spinal cord
Medial lemniscus: Principal ascending pathway from spinal cord for touch and pain

Question 11

What is the Pons and what does it do?

Answer 11

Located directly below the cerebellum
Contains many descending and ascending tracts to cerebellum from spinal cord and to the spinal cord from the cerebellum
Contains pontine nuclei and pontine tracts that assist in and coordinate massive flow of information from cortex to mossy fibers of cerebellum (control movement)

Question 12

What are the parts of the midbrain?

Answer 12

Superior colliculus: processes visual and auditory information for control of Eye movements
Periaqueductal gray: Control of pain, stimulation causes inhibition of pain so great that major surgery can be performed without an anesthetic, stimulation can also reduce intractable pain in patients
Substantia nigra: Control of movement, many neurons of this nucleus contain dopamine which they use as a synaptic transmitter, malfunction causes Parkinson’s disease
Cerebral peduncle: contains major descending tracts from cerebellum to spinal cord, control of movement

Question 13

What does the reticular formation do?

Answer 13

Major role is to control levels of arousal and attention
Ascending projections are very widespread and reach many areas of the brain including cortex
Sustained output from the reticular formation is essential for the maintenance of consciousness, damage to these fibers can produce a prolonged coma

Question 14

Which parts of the brain do the pathways of reticular formation go?

Answer 14

Cerebral hemisphere, Thalamus, Hypothalamus, Pons, Medualla, Spinal Cord, Midbrain, Cerebellum

Question 15

What are the inputs of the cerebellum?

Answer 15

Inputs for mossy fibers come directly from spinal cord, the vestibular system, and cortex through pontine nuclei in pons
Mossy fibers synapse onto Granule cells that form from parallel fibers
Parallel fibers synapse onto Purkinje cell dendrites
Inputs from climbing fibers from inferior olivary nucleus in Medulla, these synapse directly onto Purkinje dendrites

Question 16

What are the outputs of the cerebellum?

Answer 16

Entire output of cerebellum provided by axons of Purkinje cells
Some axons go to the vestibular nuclei and from there directly to spinal cord
Most axons and in three clusters of cells called deep Cerebellular nuclei, axons of the cells form the cerebral peduncle in the midbrain and project too many parts of the brain that are involved in the control of movement

Question 17

What does the cerebellum do?

Answer 17

Plans movements together with cortex, particularly those that improve with practice
Adjust movements as they are made
Control of posture
Control of eye movements
Motor learning, particularly skilled movements and agility
Cognitive functions (still poorly understood)

Question 18

What is the basal ganglia?

Answer 18

The principal are the caudate nucleus, putamen, and globus pallidus.
Closely linked in function to the substantia nigra in the midbrain
All function by modulating the flow of information to and from the cortex
Particularly important for the control of movement

Question 19

What are some diseases associated with basal ganglia?

Answer 19

Degeneration occurs during aging
Huntington disease: hereditary degeneration producing involuntary movements and loss of cognition
Parkinson’s disease: caused by degeneration in basal ganglia, causes tremor and lack of motor control

Question 20

What is the thalamus?

Answer 20

Sensory input from every major sensory system comes into thalamus
Output from thalamus is to sensory areas of cortex
These areas of the cortex also send strong inputs back into thalamus
This cortical input together with input from the reticular formation act as a gate to regulate the sensory input, so that some sensory input is allowed to enter cortex but other input is kept out

Question 21

What is the amygdala in the limbic system?

Answer 21

Receives sensory input from all the major senses, especially smell
Outputs project to many parts of brain including basal ganglia and cortex
Stimulation of amygdala produces immediate increase in attentiveness, followed by strong emotion, especially fear.
Destruction of amygdala in animal produces decrease in aggression: animal becomes tame

Question 22

What is the hippocampus in the limbic system?

Answer 22

Hippocampus and nearby cortical areas are critically important in short term memory, especially the learning of facts (as opposed to the acquiring of skills)
Destruction/removal of hippocampus leaves patients unable to form new memories of facts or events, early memory are largely intact- so are learned skills (piano, tennis)

Question 23

What is the limbic system?

Answer 23

Structures deep within the cerebral hemispheres and surrounding the hypothalamus control aspects of motivation, drives, emotions, and memory.
Includes the Olfactory bulbs, Hypothalamus, Pituitary, Amygdala, Hippocampus

Question 24

What are the mechanisms of long term potentiation (LTP)?

Answer 24

A persistent strengthening of synapses, patterns of synaptic activity that produce a long lasting increase in signal transmission between 2 neurons
Strong and repeated depolarization of presynaptic membrane releases glutamate, opens AMPA- type receptors and produces strong depolarization of membrane of spine
Depolarization of spine membrane potential relieves Mg2+ inhibition of NMDA-type glutamate receptors
Binding of glutamate to NMDA receptors causes opening and Ca2+ enters spine
Ca2+ acts as second messenger to alter spine and produce long term increase in efficacy of synaptic transmission

Question 25

What experiment process was done to understand the effect of synapse simulation on long lasting changing?

Answer 25

A cell is simulated through either of two input pathways and responses are recorded
High frequency stimulation of synapses can cause a long lasting change in sensitivity of these synapses (LTP or synaptic memory)

Question 26

What are the 4 cortex lobes in the brain?

Answer 26

Frontal Lobe- speech, primary motor cortex, smell
Parietal Lobe- primary somatosensory cortex, body awareness
Occipital Lobe-primary visual cortex
Temporal Lobe- hearing, face recognition, language, reading

Question 27

What does the primary motor cortex do?

Answer 27

Located in the frontal lobe

Receives information from various lobes of the brain and utilizes this info to carry out body movement

Question 28

What does the primary somatosensory cortex do?

Answer 28

Located in parietal lobe

Essential for the processing of the body’s senses

Question 29

What are the principal language areas in the brain?

Answer 29

Broca’s area: essential for speech, a stroke in Broca’s area results in difficulty speaking or even complete loss of speech but does not affect understanding of speech of others or reading
Wernicke’s area: essential form comprehension, a patient with a stroke in Wernicke’s area can speak but words are out of sequence and often meaningless, has difficulty understanding spoken or written language
Both aras on the left side of brain only

Question 30

How does speaking a heard word affect different parts of the brain?

Answer 30

1) Heard
2) Wernicke’s area
3) Speech
4) Motor

Question 31

How do different parts of the brain work when speaking a written word?

Answer 31

1) vision
2) angular gyrus (reading)
3) Wernicke’s area
4) speech
5) motor

Question 32

How does positron emission topography (PET) scan work?

Answer 32

Radioactive glucose emits a positron (beta decay) which collides with electrons in the tissue to produce light (photons). Light intensity indicates amount of glucose taken up and is an indicator of the activity in the tissue.

Question 33

How do excitatory and inhibitory synapses affect action potential?

Answer 33

Excitatory and inhibitory synapses are on dendrites or cell body, inhibition decreases the size of the excitatory synaptic response which is reducing the probability of generation of an action potential

Question 34

What is partial decussation?

Answer 34

The crossing of of optic nerves to form the X of the optic chiasm, the relay areas of the left and right neurons take visuals from both individuals sides which then cross to provide a combined visual

Question 35

What is the corpus callosum?

Answer 35

Major bundle of 300 million axons connecting right and left hemispheres of cortex
Bundle has been split in some patients to prevent epileptic seizures from spreading
“Split brain” patients can be given tasks for only one side of the brain by presenting visual stimuli (including words) only to right or left visual field

Question 36

How do split brain patients suffer?

Answer 36

Words flashed in left visual field cannot be read, those in right can
If picture of object is flashed in left visual field, the patient may use left hand to pick up object but denies ever having seen it
In many patients some sorts of cognitive operations are more readily done in one hemisphere than in the other