AP Exam 4 Review

What germ layer does the nervous system come from?

ectoderm

What does the neural tube eventually make?

everything within our central nervous system(cns); cerebrum, diencephalon, cerebellum, brain stem, spinal cord

What is gray matter?

neuron cell bodies, unmyelinated axons, dendrites

What is white matter?

myelinated axons

What are nuclei?

little islands of cell bodies that you find in nervous tissue

how is cerebral spinal fluid made?

produced by Choroid plexus in the ventricles

how does cerebral spinal fluid flow throughout CNS?

cerebral spinal fluid is like a little river that starts in the ventricles and flows into the subarachnoid space, spits out of the arachnoid villi and into the dural venous sinuses

what structure takes cerebral spinal fluid back to the circulatory system?

the jugular veins

hydrocephalus

accumulation of fluid in the spaces of the brain

How many cerebral hemispheres are there?

2 (left and right)

cerebral cortex is aka….

gray matter

Association tracts

goes in local regions to help share information, Axon networks that connect grey matter within regions of brain

Commissural tracts

connect hemispheres ex. corpus collosum

Projection tract

Link cerebral cortex to inferior brain regions and spinal cord

frontal lobe function

involved in motor function: problem solving, memory, judgment, impulse control

parietal lobe function

somatic sensory processing, sensation

temporal lobe function

hearing and smell

occipital lobe function

vision

insula lobe function

memory and taste

precentral gyrus….

controls voluntary movements of skeletal muscles, primary motor cortex

postcentral gyrus….

is responsible for proprioception(perception & sensation), primary somatosensory cortex

Why are some regions of the homunculus so large and others so small in both motor and sensory homunculus maps?

some are large because that's how much area is dedicated to that part of the body inside of the brain; the size of each body region in the homunculus is related to the density of sensory receptors

In general, what is cerebral nuclei's function in regard to somatic motor function?

prevent unwanted motor movement; Parkinson's disease is associated with loss of this function

What does lateralization mean?

when we have 2 hemispheres but they're not symmetrical, they're slightly different

right handed lateralization

In right handers, the left hemisphere is almost always categorical, speech-dominant

left handed affect lateralization

Left-handed individuals may have either hemisphere be categorical

What is the purpose of the prefrontal cortex?

complex thought, decision making, personality

What is the purpose of the Wernicke area?

speech, recognizing and understanding language, form language

Categorical hemisphere means…

Specialized for language abilities, functions in categorization and analysis

Representational hemisphere means…

Concerned with visuospatial relationships, imagination, comparison of senses

Pineal gland secretes what?

melatonin

What does melatonin do?

induces sleep

Thalamus is connected in the middle by____________ adhesion.

interthalamic

All somatic sensory information synapses within the thalamus except _________________.

smell

Thalamus is important for doing what?

helps filter information, filters out unnecessary information to prevent brain from being overwhelmed

somatic sensory tertiary neurons leave the____________ and go to the_____________________.

thalamus, cerebral cortex

Hypothalamus is master control center of what 6 things?

1. Autonomic nervous system: heart rate, blood pressure, digestive activities, and respiration 2. Most of the Endocrine System (hormones) 3. Body temperature 4. Food/water intake 5. Circadian rhythm: tells pineal gland to secrete melatonin 6. Emotional behavior: pleasure, aggression, fear, rage, and sex drive

Brainstem is responsible for what Nervous System?

Autonomic Nervous System (ANS): Breathing, heart rate, blood pressure, reflexes

Midbrain contains nulcei that makes what?

Dopamine called Substantia Nigra

Medulla Oblongata

Vagus nerve and its nuclei exist here, help regulate heart, respiratory rate, and digestive

Brainstem is where most cranial nerves enter/exit except for?

Olfactory and Optic

Substantia Nigra

Nucleus that houses a bunch of dopamine in the midbrain

Superior Colliculi

Visual reflex centers; turning eyes, head from visual stimulus

Inferior Colliculi

Auditory reflex centers; turning eyes, head fron loud sound

Parkinson’s Disease

Less dopamine (substantia nigra) sent to nuclei in brainstem, nuclei in motor cortex is disrupted, movement becomes choppy/shaky

General purpose of cerebellum is to?

Continuously receives convergent input from both sensory and motor pathways; perceives balance

Limbic system controls what?

Parts of the brain that controls emotions; Cingulate Gyrus, Hippocamus

Hippocampus critical for?

Transitioning short term to long term memories

When does myelination of axons happen?

First 2 years of life

Why do babies need milk so much?

Have fat necessary to support development of myelin and the brain

Non-Rem sleep (Rapid Eye movement)

75% of time sleeping; body repair

Rem Sleep

25% of time sleeping; very active, dreams, organizing memories

How does short term memory become long term memory?

Requires retrieval of info to move it from Short term memory to long term memory

Posterior Ramus

Goes to back muscles

Anterior Ramus

Somatic sensory and somatic motor neurons travel here, forms nerve plexuses; cervical, brachial, lumbar, sacral

Rami Communicantes

Connects with sympathetic trunk ganglion; entrance and exit

Does the spinal cord travel all the way down through the vertebral column?

NOPE

Lumbosacral Enlargement

Lumbar nerves exit here

Conus Medullaris

Sacral and Coccygeal nerves exit here

Cauda Equina (Horse tail)

Loose nerves in spinal cord; makes up lumbar, sacral, coccygeal nerves

How is cauda equina useful for performing a spinal tap (lumbar puncture)?

Tests for infections

Why would a spinal tap be used on somebody who has meningitis?

To identiy cause of meningitis; viral/bacteria

Posterior roots

Make up sensory neurons

Anterior roots

Make up motor neurons

Posterior Horn

Somatic sensory axon terminal connects with interneuron cell body

Anterior Horn

Interneuron axon terminal connects with dendrites and body of somatic motor neuron

Funiculi

Large tracts within spinal cord; posterior funiculus, lateral funiculus, anterior funiculus

Sensory Tracts (Ascending)

Ascending myelinated axons

Motor Tracts (Descending)

Descending myelinated axons

Conductive Pathway

Series of neurons that relay signals between brain and body

Paired Tracts

Mirror image of pathway on each side; two or more neurons

Decussate

Cross over from one side of body to the other

Primary neuron (somatosensory pathway)

Sensory neuron that receives stimulus; travels to spinal cord or brainstem

Secondary neuron (somatosensory pathway)

Interneuron; connects primary with tertiary neuron in thalamus;

secondary neuron travels to cerebellum for balance;

Secondary neuron decussate: crosses other side at spinal cord or brainstem

Tertiary Neuron (somatosensory pathway)

Interneuron; thalamus to cerebrum

Why does sensory pathway also have a secondary neuron enter cerebellum?

Subconscious postural input helps maintain posture and balance

Direct pathway

Conscious control; originate in brain and act to control effectors

Indirect pathway

Helps control the pattern of somatic motor activity

Upper motor neuron

Brain to anterior horn

Lower motor neuron

Anterior horn to effector

Dermatomes

Spinal nerves connects to regions of the skin in specific regions

How are dermatomes used to know what nerves are infected by chickenpox in individuals with shingles?

Rash and blisters along dermatome, burning or tingling pain

Cervical Plexuses

C1 to C4; neck muscles, skin of neck, portion of head and shoulder

Brachial Plexuses

C5 to T1, arm

Lumbar Plexuses

L1 to L4, anterior (front) portion of thigh, medial (middle) portion of leg

Sacral Plexuses

L4 to S4; posterior (back) part of thigh and leg

What spinal nerves dont form plexuses?

Thoracic Nerves

How are reflexes categorized?

1. Stimulus activies receptor.

2. Nerve signal propagated through sensory neuron to spinal cord.

3. Nerve signal processed in integration center by interneurons

4. Nerve signal propagated by motor neurons to effector

5. Effector responds

Stretch Reflex

Prevents over stretching of muscle

Golgi Reflex

If muscle contracts too much, it will stretch tendon by pulling on tendon it too much

Withdrawal Reflex

Contracting body away from painful stimulus; Example; moving hand from hot stove

Why would doctor tests reflexes throughout your body?

To see what spinal nerves reflexes are working and not working/damaged

Hypoactive Reflex

Diminished or absent response

Hyperactive Reflex

Abnormally strong response, not normal

Autonomic

Involuntarily controlled; internal organs

Somatic

Consciously/voluntarily controlled; skeletal muscle

Autonomic Nervous System (ANS)

Functions to maintain homeostasis; keep conditions inside body within optimal ranges; rest and digest, flight or fight

Hypothalamus, brainstem, and spinal cord are all a part of ANS. Which of those 3 is the master control center of ANS?

Hypothalamus

Motor neurons between somatic and autonomic nervous system is different. How?

Somatic motor has 1 lower neuron while Autonomic Motor has 2 lower neuron

Preganglion neuron (ANS lower neuron)

Cell body within brainstem or spinal cord