Rosario (Final exam 4) Bio 259

How do spinal nerves branch (for example, which ramus of the spinal nerves eventually connects with the limbs?)

dorsal rami branch to the posterior trunk

ventral rami branch to the anterior trunk and limbs

What is the neuromuscular junction? What is end plate potential?

the connection between a motor nerve and a muscle; end plate potential for skeletal muscles

How do efferent nerves synapse with smooth muscle/glands?

synapses form in passing (don't have to wait); varicosities release neurotransmitters into a synaptic cleft

Why are nerve plexuses important to control the limb muscles?

they are a mixed network of nerves that creates different pathways to allow for continued communication

phrenic nerve

innervates the diaphragm (cervical)

What is the action of muscles innervated by the radial nerve? By the ulnar nerve?

radial nerve- extensions

ulnar nerve- flexion

What is the action of muscles innervated by the femoral nerve? The obturator nerve? The Sciatic nerve?

femoral nerve- hip flexion and leg extension

obturator nerve- most adductors (stays on same side)

sciatic nerve- hip extension, leg flexion (thickest/longest nerve in body)

What structures make up the CNS? What parts make up the PNS?

CNS- brain and spinal cord

PNS- everything else

What kind of information is found in the dorsal roots of spinal nerves? Ventral roots?

dorsal roots- sensory (afferent); cell body is sticking out

ventral- motor (efferent); cell body in spinal cord

When do sensory and motor axons mix in the spinal nerve?

at the ramus

What is the difference between an intrinsic and learned reflex?

intrinsic- unlearned reactions to stimuli (hard-wired in neurons, survival instincts)

learned- acquired from practice ("muscle memory"; simplify and coordinate complex movements)

Can intrinsic reflexes be modified?

yes- get modified based on experiences (driving stick shift, writing)

What is the difference between a polysynaptic and monosynaptic reflex arc?

polysynaptic- two synapses are formed (one at a inter neuron and the other at a motor neuron)

monosynaptic- only one synapse

What is the difference between an extrafusal and intrafusal muscle fiber?

extrafusal- skeletal muscle fibers

intrafusal fibers- can't contract

How do muscle spindles use action potentials to provide information to the CNS? What kinds of information do muscle spindles send?

when a muscle is stretched, the AP frequency is increased by sensory fibers

How does the muscle stretch reflex work? What role does reciprocal inhibition play in the knee-jerk reflex?

stretch reflex maintains muscle length by activating a (monosynaptic) sensory neuron that processes at the motor neuron and activates it to contract the muscle

What role does reciprocal inhibition play in the knee-jerk reflex?

shortens muscle to prevent over stretch- as one muscle contracts, the antagonists relaxes

What are the 3 primary vesicles of the brain?

forebrain (prosencephalon), midbrain (mesencephalon), hindbrain (rhombencephalon)

From which primary vesicles do the 5 secondary vesicles develop?

forebrain: telencephalon and diencephalon

midbrain: stays mesencephalon

hindbrain: metencephalon and myelencephalon

From which secondary vesicles do cerebral hemispheres develop?

telencephalon

From which secondary vesicles does the thalamus/hypothalamus/epithalamus develop?

diencephalon

From which secondary vesicles does the midbrain develop?

mesencephalon

From which secondary vesicles does the cerebellum and pons develop?

metencephalon

From which secondary vesicles does the medulla oblongata develop?

myelencephalon

Know the structure of the diencephalon. What makes up the walls, floor, and roof? What is found in the center of the diencephalon?

thalamus: thick walls

hypothalamus: floor

epithalamus: thin roof

the third ventricle is inside

What parts of the midbrain are important in vision? What about hearing?

the superior colliculus (vision)

the inferior colliculus (hearing)

What is a brain ventricle? How are they connected?

a network of cavities in the brain filled with and connected by cerebrospinal fluid- interventricular foramen connects the lateral to third, cerebral aqueduct connects third to fourth

What are the meninges of the brain? What are their relationships with cerebrospinal fluid?

dura mater (protection), arachnoid (spider webbing where CSF travels), pia mater (thin layer on top of brain)- choroid plexus and blood vessels work to create CSF

What are the major functions of the medulla oblongata?

the "thermostat" of the brain,

autonomic: respiration, circulation (changes blood vessel size)

What are the major functions of the cerebellum

processes muscle info and sends it back; used for coordination and fine motor activity (balance)

What are the major functions of the hypothalamus

hormone function. controls body temp, hunger, thirst

What are the major functions of precentral gyrus

primary motor functions

What are the major functions of post central gyrus

primary sensory functions

What is the function of the reticular formation? Where is it found?

keeps the brain alert and filters out weak, repetitive, and familiar senses- found in medulla, pons, and midbrain

What is the limbic system? What does it do? What parts of the brain are part of the limbic system?

the part that links emotional and visceral function- runs through diencephalon to cerebrum

What is the function of the amygdala?

responds to threats, strong emotions, and smell

What is the function of the hypothalamus?

secretes hormones and is the link between emotion and reaction (ie: heart beating faster due to stress)

How does the limbic system contribute to psychosomatic illnesses?

chronic stress can trigger amygdala due to "threat" of stress. then triggering hypothalamus, causing an illness of the body due to stress of the mind

What is the function of the hippocampus?

spatial memory and learning

What are the two kinds of memory and where are they physically located in the brain?

long term memory(cerebral cortex) and short term(prefrontal cortex)

Why does sensory data first connect with the cerebral cortex instead of directly forming short term memories?

because the hippocampus coverts short term memory to long term memory

What are the two different kinds of sleep? What state of sleep is most like being awake?

REM sleep or NREM

What is a REM cycle?

alternating between REM and NREM sleep

What happens to our bodies during REM sleep? What happens during deep sleep?

rapid eye movement- most skeletal muscles are inhibited. during deep sleep, slow-wave brain pattern and decrease in BP and heart rate

What divides the spinal cord into left and right halves?

ventral median fissure and dorsal median sulcus

How are the brain and spinal cord different? How are they the same?

similar: fissure/sulcus, central canal and meninges

different: white and gray matter are flipped

What functions are the different horns of the spinal cord responsible for?

dorsal- sensory

ventral- motor

lateral- motor

What are funiculi and why are they important in the nervous system?

region of spinal cord containing white matter that serves as tracts for signals to travel in spinal cord

What is decussation and where do we find it?

the crossing from one side of the body to the other, occurs in spinal cord

What are the functions and patterns of decussation of the spinocerebellar pathway?

muscle/tendon stretch info to cerebellum, only reaches pons, no decussation

What are the functions and patterns of decussation of the dorsal column pathway?

focuses on fine, precise localized sensation (itches), reaches the postcentral gyrus (completely conscious), decussation at the medulla

What are the functions and patterns of decussation of the spinothalamic pathway?

pain, temperature, coarse touch (difficult to localize), reaches postcentral gyrus, immediate decussation before ascending

What is a cranial nerve? What part of the nervous system do they belong to?

nerves branching off from the brain/brain stem innervating the head/neck- belongs to PNS

How do cranial nerves and spinal nerves differ?

SN branch off from the spinal cord and are mixed nerves while CN branch off the brain and can be solely sensory or motor

Which cranial nerves are mostly sensory?

Olfactory (smell, cribriform plate)

optic (vision, optic chiasma)

vestibulocochlear (hearing and balance)

Which cranial nerves are mostly motor?

trochlear (trochlea, superior oblique of eyeball)

abducens (eye "abduction", lateral rectus

oculomotor (other extrinsic eye muscles)

accessory (move head and neck, moves trapezius and sternocleidomastoid)

hypoglossal ("below the tongue", food manipulation and speech)

Which cranial nerves are mixed?

trigeminal: (ophthalmic-s, maxillary- s, mandibular- s&m)

facial: (facial expression; glands- m, anterior taste buds, proprioception- s)

glossopharyngeal: (parotid glands- m, taste; touch; pressure; pain- s)

vagus: heart rate; breathing; digestion- m, visceral sensory; proprioception- s)

What is a hair cell? What is the relationship between hair cells, mechanically-gated ion channels, and action potentials?

a hair cell is similar to a mechanically-gated ion channel in that it responds to force or stretch (touch, hearing balance) and releases neurotransmitters to nerves through the neuromuscular junction

What are the three parts of the ear, and what function do they serve?

external ear- cartilage, eardrum (sound funnel)

middle ear- transmits sound through ossicles

internal ear- sensory organs

What are the ossicles? What structures do they connect to? Why are they important in our sense of hearing?

malleus, incus, stapes- connect to oval window (sound in), round window (sound output), and eustachian tube (connects to throat to equalize pressure)

What are the structures of the inner ear? What functions do they serve?

cochlea, vestibule (balance), semicircular canals (balance, gravity)

What are the two most important structures located in the scala media? What function does each of the structures serve?

basilar membrane- registers vibrations to determine pitch

sensory organs- hair cells, organ of Corti

How do these two structures interact to indicate the pitch of a sound? How do they work together to indicate volume?

the base is stiff, apex is floppy- the place of vibration determines which frequency we hear based on what hair cells it moves. (base moves: high frequency, apex moves: low frequency)

Which inputs are integrated in the brain to form our sense of balance?

visual cues (eyes), joints and muscles, inner ear

What is the general anatomy of the inner ear?

vestibule- big empty room. holds saccule (cochlea), utricle (semicircular canals)

semicircular canals- each contain an ampullae (ballooning duct), filled with endolymph fluid

What structures in the vestibule are important for balance?

semicircular canals sense angular acceleration,

vestibule senses linear acceleration

What structures in the semicircular canals are important for balance?

the canals are oriented in three directions to account for all areas around us

What is the difference between speed and acceleration? Why is that important for understanding our sense of balance?

speed- how fast you move

acceleration- how quickly you change speed/direction

What are maculae? Where do you find them? How are they oriented? What are they good for?

tiny structures in the saccule and utricle- the macula monitors the position of the head relative to the vertical. in the utricle the macula projects from the anterior wall of that tubular sac and lies primarily in the horizontal plane

What is the anatomical relationship between hair cells, the otoliths, and the otolith membrane? Why is that important for the physiology of the maculae?

otoliths (ear rocks) add mass to the otolith. as they move, they cause the membrane to shift and sag, which bends the hair cells

How does our inner ear detect spinning acceleration?

fluid in semicircular canals moves as our heads move, pushes on cupula within canal based on the movement- after we stop spinning, the fluid continues to move, which causes dizziness

What are the three layers of the eyeball?

fibrous layer- connective tissue

vascular layer- muscles, blood vessels

inner layer- photoreceptors

What kinds of tissues make up the fibrous layer of the eyeball? What does that tell you about the function of the fibrous layer?

connective tissue- it is closest to the outside and is used for protection (continuous with dura mater)

What are the different parts of the vascular layer? What is the function of each part of the vascular layer?

choroid- blood vessels (nourish eyeball), melanocytes (prevents light from bouncing around inside)

ciliary body- muscles that control lens shape

iris- controls the size of the pupil (how much light is let in)

What are the different parts of the inner layer? What is the function of each part of the inner layer?

lens- flexible, stretched by ciliary body to focus images, continuously grows in thickness

retina- retinal pigment (absorbs light), rods and cones (distinguishes color), ganglion cells form the optic nerve,

bipolar cells connect retina and ganglion

What structures does light pass through in the eyeball? Which structures are capable of changing the light that enters the eye?

light passes through the cornea, the pupil determines how much light enters the eye

What are the anatomical and physiological differences between rods and cones?

rods- senses are grouped together, longer in shape

cones- sensor information is separate, shaped like cone on end

What is the macula lutea? The fovea? The optic disk? How do these structures relate to our ability to see?

the yellow spot in the retina (mostly cones) that surrounds the fovea (all cones) (center of the field of vision). most clear area of eye. the optic disc is the blind spot of the eye where the optic nerves exits

Where do you find rhodopsin? What is rhodopsins' role in our sense of vision?

rhodopsin is embedded in the photoreceptive discs- it starts a protein cascade when light hits retina

Understand how potential changes in the photoreceptors, bipolar cells, and ganglion cells when light activates photoreceptors.

photoreceptors- hyperpolarize

bipolar cells- inhibitory neurotransmitters not sent to bipolar cells

ganglion cell- neurotransmitters sent to ganglion