Final Exam Flashcards
What are the functions of the nervous system?
Sensory input, Integration, Output
T/F Afferent nerves conduct motor signals away from CNS.
F; conduct sensory signals towards CNS
What are efferent nerves?
motor and effector neurons that conduct signals away from CNS
What are the two parts of the nervous system and what are they composed of?
CNS-> Brain and spinal cord, dorsal body cavity surrounded by meninges
PNS -> Spinal nerves, cranial nerves, and sensory receptors
what are the supporting cells of the CNS?
Astrocytes -> involved in forming blood-brain barrier
oligodendrocytes -> myelination
Ependymal cells-> line ventricles, create current for CSF
Microglia-> Macrophages
What are the supporting cells of the PNS?
Satellite cells
Schwann cells
Label the parts of an action potential, include ion movement patterns at stages of AP
Stimulus, Depolarization, Repolarization, Hyperpolarization
absolute refractory period, relative refractory period
Where are ttracts found?
CNS
What are some functions of myelin?
protection, electrical insulation, increase speed of nerve impulse transmission
How does Novocain work?
binds to VG sodium channels to inhibit AP, message of pain can’t be sent. Given as shot to induce local anesthesia
What is propagation?
The movement of electrical signals down an axon
What factors impact the speed of propagation?
Capacitance of membrane
diameter of axon
resistance to electrical flow
T/F Myelination decreases capacitance and makes propagation faster.
T
Will a larger axon or smaller axon exhibit faster propagation?
Larger
What is the difference between saltatory and continuous conduction?
Saltatory is faster, electrical impulses travel under myelin sheath, action potentials generated at nodes of ranvier. sodium channels only open in nodes of ranvier
continuous is in unmyelinated and you need more action potentials to travel across whole axon
List the types of nerve fibers
Group A -> Large and heavily myelinated -> motor neurons, 150 m/s
Group B -> intermediate diameter and lightly myelinated, 15 m/s, preganglionic autonomic fibers
Group C -> smallest diameters and unmyelinated, 1 m/s, postganglionic autonomic fibers
Describe how saxitoxin and anatoxin work.
Saxitoxin -> paralytic shellfish poisoning, toxin binds to VG sodium channels and prevents them from opening, when digested and travel through body elicits toxic effects occur
Anatoxin -> irreversibly binds to ACh receptors and muscles constantly contract, involuntary contraction leads to paralysis when we run out of ATP and calcium
Is the onset of rigor mortis sooner with saxitoxin or anatoxin?
anatoxin is sooner onset since the stored calcium is used at a higher rate. saxitoxin is same onset as natural causes since the calcium reserve isn’t used
Where is regeneration possible?
Axons of the PNS
Why is regeneration only possible in the PNS? (3 reasoons)
- No Schwann cells in the CNS, Schwann cells/neurilemma form a regeneration tube to guide the growth of new axons
- Microglia in the CNS are not as effective at debridement as immune cells in PNS
- oligodendrocytes and astrocytes release growth-inhibiting proteins
Describe the regeneration process.
- Injury to the axon, know that damage continues distally down the axon (nutrients from cell body can’t deliver thru damage)
- macrophages clean out the dead axon distal to injury
- axon sprouts grow through a regeneration tube
- axon regenerates and a new myelin sheath forms
How fast does regenereation occur?
1.5 mm a day
What are the protective structures of the spinal cord?
vertebral column, meninges, cerebrospinal fluid
Name the three layers of the meninges
dura mater (strongest, two layers of fibrous connective tissue
arachnoid mater (middle layer, weblike extensions)
pia mater( delicate, vascularized connective tissue that clings tightly to brain)
What are the functions of cerebrospinal fluid?
acts as a liquid cushion
provides nutrients from blood
removes metabolic wastes
What are the 4 protective structures of the brain?
Cranium -> 8 cranial bones
Meninges -> 3 layers (dura mater, arachnoid mater, pia mater)
Cerebrospinal fluid
Blood-brain barrier
What makes the blood-brain barrier a selective barrier?
Astrocytic feet create tight junctions, allow for fat-soluable and nutrients to enter through facilitated diffusion.
What is a concussion?
violent jarring or shaking that results in a disturbance of brain function
Why does dehydration increase risk of a serious concussion?
could reduce CSF and increase risk of shaking or jarring of brain
What is photogenic sneezing?
bright light leading to sneezing when the optic nerve is activated due to the nerves close proximity to the trigeminal nerve which triggers sneezing.
activation of trigeminal nerve via optic nerve
Describe basic brain developmennt
Neural tube -> primary brain vesicles form -> secondary brain vesicles form -> forebrain grows, at faster rate
Where is contralateral control facilitated?
medulla oblongata is where the motor cortex pyramids criss-cross
What is contralateral control?
The idea of motor neurons from the right hemisphere of the brain controlling the left side of the body due to criss-crossing of the tracks in the medulla oblongata
What are the three regions of the brrain stem?
Midbrain, pons, medulla oblongata
What are the four major regions of the brain?
Cerebrum, brain stem, cerebellum, diencephalon
What are the types of sensory receptors?
photoreceptors, mechanoreceptor, chemoreceptors
What lines the eyelids?
palpebral conjunctiva
What covers the white of the eyes?
bulbar conjunctiva
List the areas that tears move across.
Lacrimal gland -> lacrimal punctum -> canaliculus -> lacrimal sac -> nasolacrimal duct
What are the three layers of the eye?
Fibrous, Vascula, Sensory (retina)
What muscle constricts the pupil?
sphincter papillae
What muscle dilates the pupil?
Dilator papillae
What is the sympathetic contraction of the muscles that control pupil size?
dialter papillae, dilation of the pupil
How do you distinguish the pupil from the iiris?
Iris is colored region around pupil (space)
In what conditions does the pupil dilate?
Distant vision, dim light
In what conditions does the pupil constrict?
close vision, bright light
What are the two layers of the retina?
Pigmented layer and neural
T/F rods are used for color vision?
F; cones used to provide color vision, rods provide images in shades of gray
What do cones of the eye need to operate?
Bright light
Are there more rods or cones in our eye?
Rods
What is the trichromatic theory of vision?
Several colors are seen depending on which/how many of the three types of cones are activated
What are the three types of cones?
S(small) -> 420 nm, blue
M (medium) -> 520 nm, green
L (large) -> 560 nm, red
Describe signal transmission within the retina?
light hyperpolarizes photoreceptor cells
bipolar cells depolarize and release neurotransmitter on ganglion cells
ganglion cells generate APs that are transmitted in the optic nerve
How are the pathways of electrical signals and light different?
They are the opposite of each other
What is the pathway of light?
Ganglion -> bipolar cells -> photoreceptors
What is the pathway of electrical signals initiated by lightt
photoreceptor -> bipolar cells -> ganglion cells
Describe the process of light pathways triggering changes.
light enters cornea and pupil (travels thru aqueous humor)
light passes lens
light bends as it enters cornea and pupil and lens (mostly in lens)
light converges as it moves through posterior segment and vitreous humor, then make contact with retina
ganglion -> bipolar -> photoreceptors
photoreceptors respond, trigger electrical changes
photoreceptors -> bipolar cells -> ganglion -> optic nerve
What is the disc?
Location where the optic nerve leaves the eyes, no photoreceptors -> blind spot
Where is light refracted (3 places)
at cornea
entering lens
leaving lens
How does the lens refract light upon entering and leaving?
Lens is biconvex, transparent, flexible, elastic, avascular
What protein makes the lens fibers transparent?
crystallin
How does the lens change over age?
becomes denser, more convex, and less elastic
What are two problems of refraction?
Myopia (nearsightedness) and hyperopia (farsightedness)
Nearsightedness is also known as
myopia
Farsightedness is also known as
hyperopia
How is myopia corrected?
With a concave lens
How is hyperopia corrected?
with a convex lens
What is cataracts?
protein buildup at the lens (impact increases over time)
What is the impact of cataracts?
lens turns a yellow/brownish color, adds brownish tint to vision
What are risk factors of cataracts?
Age, DM, smoking, frequent exposure to intense sunlight
What is the benefit of having two eyes
brain can triangulate image, allowing for depth perception (3-D vision)
Why do we see floaters as we age?
vitreous humors turns from gel into more of a liquid and shrinks
falls away from retina
cell or debris released in vitreous humor
debris blocks light and casts shadows as photoreceptors are not activated
dark spots in vision
What happens at rest in the eye?
photoreceptors release glutamate which inhibits bipolar cells from depolarizing which inhibits ganglion cells from depolarizing, leading to no action potentials being sent down the optic nerve
What inhibits bipolar cells from depolarizing?
Glutamate -> released by photoreceptors at rest (in dark)
What happens in the ye and the presence of light?
photoreceptors hyperpolarize and stop releasing glutamate, allowing bipolar cells to depolarize, followed by ganglion cells -> APs sent down optic nerve
What characteristics of sound waves create a high pitch?
short wavelength -> high frequency -> high pitch
what contributes to loudness of a sound?
High amplitude
What are the structures of the ear
external (pinna) -> helix, auricle, lobule, external acoustic meatus
What divides the external ear and middle ear?
Ear drum (tympanic membrane)
describe the path of soundwaves that lead to hearing
Pinna -> external acoustic meatus -> tympanic membrane vibration -> meatus -> incus-> stapes -> perilymph -> endolymph -> motion between basilar membrane and tectorial membrane -> hair cell movement -> bending of stereo cilia -> potassium channels open -> electrical signals develop and transferred to cochlear nerve
Where is perilymph found?
scala vestibuli and scala tympani
Where is endolymph found?
scala media
What are the regions of the cochlea?
scala vestibuli, scala media, scala tympani
What are the two membranes of the scala media?
tectorial and basilar membrane, hair cells with stereo cilia in between membranes
What is in the endolymph?
Large [K+]
What is the benefit of having two ears?
localization of sound
What does localization of sound depend on?
relative intensity and relative timing of sound waves reaching both ears
What type of receptors help us perceive taste and smell?
Chemoreceptors
How do chemoreceptors receive signals from odorants?
inhaled air with dissolved odor molecules travel through aqueous mucous layer before entering olfactory epithelium
what type of neurons are prevalent in olfaction sensations?
bipolar
What ion channel is open as odorants bind to receptor proteins in olfactory membrane?
Na and Ca
what is the physiology of smell?
dissolved odorants bind to receptor proteins
ion channels open (Na and Ca), thru intermediary steps
depolarization of receptor -> action potential
Where are taste buds found ?
tops of fungiform papillae
side walls of foliate papillae and vallate papillae
T/F specific taste regions are found across the tongue
F
What are the taste sensations?
Sweet -> sugars, alcohol
sour -> hydrogen ions
bitter-> alkaloids
umami -> glutamate and aspartate
salt -> metal ions
T/F Mechanisms of taste sensation differ based on the specific taste sensation
T
What are the other receptors that can impact our taste?
Thermoreceptors (heat0
mechanoreceptors (texture)
nociceptors (pain)
olfaction -> via association
Why is it harder to taste things when you have a cold?
Larger mucous membrane acts as a physical barrier
How do hormones elicit reactions
Travel through blood stream and bind to target receptor
Difference between paracrine and autocrine messengers?
Paracrine -> released and travels to neighboring cell
autocrine -> released and binds to same cell
What are the types of chemical messagers?
paracrine, autocrine, neurotransmitter, neurohormone, hormone, cytokine
What are the 4 types of hormone interactions?
antagonism, additive, synergism, permissiveness
what is an example of synergism?
glucagon, cortisol, and epinephrine on blood glucose
Example of permissiveness?
estrogen needed to express oxytocin and receptors
How can the hormones be chemically classified?
amino acid base or steroid based
Which hormones are lipophilic/hydrophobic
steroid hormones
which hormones are lipophobic
protein hormones arre lipophobic and hydrophillic
what factors impact the magnitude of hormone response?
concentration of hormone, number of receptors, affinity
What factors impact hormone levels?
rate of hormone secretion
rate of hormone metabolism
hormone bound to plasma proteins -> longer half-life
agonists vs antagonists
agonists bind and mimic response, antagonists bind and have no response (block response)
How does naloxone help heroin overdose?
naloxone is a beta-endorphin antagonist so blocks heroin from binding. higher affinity for naloxone than heroin
List the primary endocrine glands (8)
hypothalamus, pituitary, thyroid, parathyroid, adrenal, pancreas, gonads, pineal
List the secondary endocrine glands
heart, kidneys, GI tract, liver, skin, adipose
What is released from the hypothalamus?
neurohormones that control release of hormones from pituitary
Which gland releases FSH?
Anterior pituitary -> targets ovaries and testes, triggered by GnRh, helps males develop sperm, females and oocyte
Which gland releases LH
anterior pituitary, triggered by GnRh, targets ovaries and testes, ovulation in females, sperm testosterone production in males
Which gland releases prolactin/
anterior pituitary, targets mammary glands, lactation
Which gland releases GH
Anterior pituitary, dwarfism in hyposecretion, gigantism in hypersecretion in children, acromegaly in hypersecretion in adults
Which gland releases ACTH
anterior pituitary
Which gland releases TSH
anterior pituitary
Which gland releases ADH
posterior pituitary
Which gland releases oxytocin
posterior pituitary
Which gland releases melatonin
pineal
Which gland releases PTH
parathyroid, triggered by low calcium levels, acts to increase calcium levels
Which gland releases epinephrine, aldosteorne, corrtisol
adrenal
Which gland releases glucagon and insulin
pancreas
Which gland releases ANP
heart
renin
kidneys
Which gland releases gastrin and secretin and cholecystokinin
GI tract
Which gland releases cholecalciferol
skin
Which gland releases leptin
adipose
How is balance and equlibirum achieved when we spin and move our head around?
semicircular canals that are filled with endolymph causes hairs to bend and activate action potentials
What does parkinson’s disease affect
substantia nigra which controls basal nuclei
What does huntington’s affect
basal nuclei
What are the parts of the diencephalon?
Thalamus, hypothalamus, epithalamus
What does the thalamus do
“sorting hat” -> sorts fits and rays inputs
what does the hypothalamus do
controls autonomic nervous system (BP, Heart rate, pupil size, digestive tract mobility_, perception of emotions, body’s thermostat, hunger/thirst
Where is the pineal gland?
Epithalamus of diencephalon
What divides the left and right hemisphere of the brain?
longitudinal fissure
What connects the left and right hemispheres of the brain?
corpus callosum
What divides the temporal lobe from parietal and frontal lobes
lateral sulcus
what divides the parietal lobe from occipital
parieto-occipital sulcus
What is an example of an association tract?
connection between Broca’s and Wernicke’s
Damage to the Broca’s area results in what
inability to produce speech, can make sense of language
Damage to Werrnicke’s area results in waht
can’t make sense of sounds into language but can produce sounds
What are the functional areas of the motor areas of the cerebrum
primary motor cortex, premotor rcortex, broca’s area, frontal eye field
Where is the primary motor cortex found?
precentral gyrus
What is blocked in Parkinson’s
Dopamine from substantia nigra to basal ganglia
