Ch. 8: The Central Nervous System

What does the CNS consist of

brain & spinal cord

What do the sensory neurons receive

input (afferent)

What do the motor neurons receive

output (efferent)

What do Association (interneurons) do

integrate sensory input and help direct response to maintain homeostasis

What is Grey matter (cities)

cell bodies: brain found in cortex and deep nuclei, spinal cord found deep (horns, central commissure)

What is White matter (highways)

tracts of axons (myelinated): brain found deep, spinal cord superficial (outside)

The neural tube is a part of the

CNS

The neural crest is part of the

PNS

The R & L cerebral hemispheres connected by the

corpus callosum

What is the Gyrus(Gyri) of the cerebrum

bumps

What is the Sulcus(Sulci of the cerebrum

invaginations

What's the purpose of the Gyri and Sulci

they provide more surface area of cortex

What are the 5 lobes of the brain

Frontal, Parietal, Occipital, Temporal, and Insular

What are the characteristics of the Frontal lobe

Contents: -primary motor cortex, premotor cortex, prefrontal cortex; Functions: motor planning, executive functioning, logic, emotion, judgement

What are the characteristics of the Parietal lobe

Contents: postcentral gyrus/primary (1o ) somatosensory cortex; Functions: somesthetic info (cutaneous, muscle, tendon, jt capsule)

What does somesthetic mean

the senses related to touch, temperature, pain, and the body's position and movement

What is the frontal and parietal lobe divided by the

central sulcus

What's Homunculus

spatial mapping of body in 1o motor & somatosensory cortex

What are the characteristics of the occipital lobe

vision & coordination of eye mvmt

What are the characteristics of the temporal lobe

auditory sensation & interpretation of auditory & visual info

What are the characteristics of the insular lobe

memory & integration of sensory with visceral response (olfactory, gustatory, auditory, pain), controls autoimmune response

What are mirror neurons

motor & sensory neurons in frontal & parietal lobes, connected through the insula & cingulate gyrus to emotional centers of the brain. Activation by watching others: visual imagery, learning behaviors, imitation, understanding intention, empathizing with emotions of others (social skills - may be impaired with autism).

What are the basal nuclei

6 nuclei focused on motor control and behavior reward (influenced by substantia nigra)

What is the Corpus Striatum

a central component of the basal ganglia, a group of deep-brain nuclei involved in motor control, reward, habit formation, and decision-making

What does the reduction of dopamine from substantia nigra to corpus striatum cause

Parkinson's disease

What does the motor circuit do

it stimulates & inhibits appropriate movements

The premotor region sends Glutamate (excitatory) to

putamen

Putamen sends GABA (inhibitory) to

other basal nuclei

Globus pallidus sends GABA to

thalamus (normally sends excitatory signals to cerebrum)

Motor and sensory information in the pre/post-central gyrus is controlled/received from the

contralateral (opposite) side of the body

Communication between the two sides via the corpus callosum can be severed in severe forms of

epilepsy

What are the functions of the right hemisphere

visuospatial tasks, recognizing faces, composing music, arranging blocks, reading maps (Creativity)

What are the functions of the left hemisphere

Language, speech, writing, calculations, understand music (Logic)

What is aphasia

speech & language disorders from injury/stroke

What is Wernicke's area

left superior temporal gyrus, allows for understanding language

if damage is done to Wernicke's area (Wernicke's aphasia) it is characterized by

• Difficulty understanding spoken and written language

• Fluent but nonsensical speech (word salad)

• Inability to produce grammatically correct sentences

• May use made-up words or real words in the wrong context

• Often unaware of their language errors

What is Broca's area

left inferior motor cortex, allows for speaking language correctly

if damage is done to Broca's area (Broca's aphasia) it is characterized by

• Difficulty speaking fluently

• Use of short, grammatically incorrect sentences

• Trouble finding words

• Good comprehension of language 

What is the limbic system composed of

Cingulate gyrus, amygdala, hippocampus, fornix, septal nuclei, anterior insula; parts of hypothalamus & thalamus

What is the limbic system responsible for

emotional drives such as Aggression & fear (amygdala & hypothalamus), hunger (hypothalamus), sex drive, goal-directed behaviors

The fornix connects hippocampus (memory) to

mammillary bodies (smell)

What's the function of the Hippocampus

formation and retrieval of memories, assists in consolidating STM > LTM, works with several other structures. stress can impair consolidation in hippocampus

What's the function of the Amygdala

learning fear response. Emotions influence/enhance memory encoding in amygdaloid

What's the ventricular system composed of

2 lateral ventricles, interventricular foramen, 3rd ventricle, cerebral aqueduct, 4 th ventricle to SC (central canal) & subarachnoid space.

What's the choroid plexus & CSF do

Secretes cerebrospinal fluid (made from blood, returned to blood) Bathes cerebrum, 4th ventricle continues into spinal cord as central canal

a condition where there is an excessive buildup of cerebrospinal fluid (CSF) in the brain's ventricles is called

hydrocephalus

What are special functions involving the cerebrum

sleep and memory.

What is the Diencephalon (interbrain) composed of

The thalamus, Epithalamus, Hypothalamus, and Pituitary Gland

What is the thalamus, and what does it do

paired masses of grey matter (each thalamus has multiple nuclei) ii) relay center to cerebrum for sensory information iii) important for arousal from sleep &alertness

What is the Epithalamus

Contains pineal gland > secretes melatonin to regulate circadian rhythms (24 hr cycles)

What is the Hypothalamus (master gland) do

Hunger/satiety and thirst ii) Thermoregulation iii) Regulates sleep and wakefulness iv) Sexual arousal and performance v) Emotions of fear, anger, pain &pleasure vi) Controls endocrine system

What are the three nuclei of the hypothalamus

The Suprachiasmatic nuclei (SCN), The Supraoptic nuclei, and The Paraventricular nuclei

What does the suprachiasmatic nuclei do

maintains control of circadian rhythms, controls secretion of melatonin in pineal gland

What does the Supraoptic nuclei do

produced antidiuretic hormone

What does the Paraventricular nuclei do

produces oxytocin (childbirth, milk letdown, cuddling) and a little antidiuretic hormone. It directly controls hormone secretion from the pituitary gland

The Pituitary Gland is broken into a

anterior and posterior gland

What does the anterior pituitary gland do

produces many other hormones on it's own (growth, reproduction)

What does the posterior pituitary gland do

secretes antidiuretic hormone & oxytocin produced in the hypothalamus

What's the mesencephalon

the midbrain

What's the superior colliculi's reflex

the visual reflex

What's the inferior colliculi's reflex

the auditory reflex

What do the cerebral peduncles have

ascending & descending tracts

What does the red nucleus do

connects cerebrum & cerebellum (motor coordination)

What's the Nigrostriatal system involved in

movement initiation and coordination, projects to basal nuclei

What does Levodopa (L-dopa) do

mimics dopamine, difficult to pass through blood-brain barrier

What do MAO inhibitors do

keeps dopamine in synapse longer

What does the mesolimbic system do

limbic system & forebrain for behavioral reward system (addiction & psychiatric disturbances) Affected by nicotine, opioids, cannabinoids, benzodiazepines (valium & ambien), cocaine,amphetamines

What is the metecephalon composed of

The pons and the cerebellum

What is the pons

functions as a "bridge" for crucial communication between the forebrain and the cerebellum, while also housing important cranial nerves and centers that regulate unconscious, vital functions such as breathing and sleep.

What does the Apneustic center of the pons do

promotes inspiration (gas)

What does the Pneumotaxic center of the pons do

limits inspiration (brake)

What are some characteristics of the cerebellum

2nd largest brain structure: grey matter superficial, white matter deep (arborvitae) ii) Receives input from proprioceptors in joints, tendons & ms. iii) Coordinates mvmt with basal nuclei & motor cortex (via Red nucleus & thalamus)

disorder of mvmt, often associated with gait, balance, eye movement & swallowing is called

Ataxia

What does the Myelencephalon contain

the Medulla Oblongota

What does the medulla oblongota do

controls the involuntary, life-sustaining functions of the autonomic nervous system, including breathing, heart rate, and blood pressure.

What are the three vital centers of the medulla

The Vasomotor Center (VMC), Cardiac Control Center (CCC), and the Respiratory Rhythmicity Center (RRC)

What does the Vasomotor Center aid with

autonomic innervation of blood vessels

What does the Cardiac Control Center aid with

autonomic nerve control of the heart

What does the Respiratory Rhythmicty Center do

controls breathing with apneustic & pneumotaxic centers

What's the reticular activating system

a network of neurons in the brainstem responsible for regulating wakefulness and consciousness by filtering sensory information and modulating attention, arousal, and sleep-wake cycles

What is the order of the Dorsal Column - Medial lemniscus pathway

1 st order sensory neuron enters SC via DRG to fasciculus gracilis (LE) orfasciculus cuneatus (UE) to nucleus gracilis & cuneatus(M.O.) 2 nd order sensor neuron crosses (decussates) in pyramids of M.O., proceedsto thalamus 3 rd order sensory neuron extends to cerebral cortex (contralateral to original stimulus)

What's the order of the Anterolateral spinothalamic pathway

1 st order sensory neuron enters SC via DRG and immediately synapse in dorsal horn 2 nd order sensor neuron crosses (decussates) immediately and ascends on contralateral side from stimulus, synapsing on thalamus 3 rd order sensory neuron extends to cerebral cortex (contralateral to original stimulus)

what's the order of the Corticospinal (Pyramidal) tracts

1 st order motor neuron (UMN) - precentral gyrus > 80-90% decussate in pyramids (lateral CST), 10+% in SC (ant CST) > ventral horn of SC 2 nd order motor neuron (LMN) - ventral horn > muscle

What's extrapyramidal

many tracts from nuclei in brain stem directly to muscle, mostly controlled by basal ganglia Associated with substantia nigra, thalamus, red nucleus, reticular formation, cerebellum Can be motor or sensory

What does the Peripheral Nervous system contain

Cranial & Spinal Nerves

Characteristics of Cranial nerves

12 pairs with nuclei (cell bodies) in CNS ii) Most are mixed (optic, olfactory, & vestibulocochlear sensory only)

Characteristics of Spinal Nerves

Arise directly from spinal cord ii) Mixed motor and sensory iii) Cell bodies: sensory in DRG, motor in lateral & ventral grey horn

What does damage to spinal nerves cause

i) Sensory loss: dermatomal distribution ii) Motor loss: myotome distribution

The Quadriceps is innervated by the

Femoral nerve.

Semitendinosus is innervated by the

Sciatic nerve.

Tibialis anterior is innervated by the

Anterior fibular nerve (also known as the Deep fibular nerve).

Gastrocnemius is innervated by the

Tibial nerve.

What's the reflex arc

Unconscious motor response to a sensory stimulus

What are parts of the reflex arc

i) Sensory receptor ii) Sensory neuron iii) (Association neuron in CNS - not always) iv) Motor neuron v) Effector - muscle or gland that respond

What's the monosynaptic reflex

the most rapid and simplest reflex involving a two-neuron pathway: a single sensory neuron and a single motor neuron, with no interneurons Stretch reflex of ms. Spindles

What's the Disynaptic or polysynaptic reflex

a neural pathway involving two synapses and one interneuron between a sensory input and a motor output that prolongs stretch of GTO, or pain/temp, and may be inhibitory or excitatory

GTO is a

prolonged stretch, resulting in inhibition of the same muscle and excitation of its antagonist.

What does the dorsal column lemniscus pathway do

transmit sensory information related to light touch, vibration, and conscious proprioception (awareness of body position) from the body to the brain for conscious perception

What if the dorsal column lemniscus pathway was damaged

loss of light touch, vibration, proprioception (joint position sense), and pressure

What does the anterolateral spinothalamic pathway do

transmit sensory information, including pain, temperature, and deep touch, from the body to the brain for processing