Stuff I Thought Is Important Test 4 Flashcards
a whole melting pot of repro and neuro physio definitions
How is an embryo different from a fetus?
embryo - placentation has not yet taken place
- not aquired an anatomical form that is readily recognizable
fetus - placentation has taken place, within uterus
- recognizable in a species
What are the 3 primary embryonic germ layers?
endoderm
mesoderm
ectoderm
In the [endoderm/ectoderm], there is formation of the vegina/vestibule and penis/clitoris. In the [endoderm/ectoderm], there is formation of the gonads, uterus, cervix, cranial vagina, epididymis, ductus deferens, and accessory sex glands
ectoderm
endoderm
The posterior lobe is comprised of _____ and the anterior lobe comprised of ______
neural tissue
stomodeal ectoderm
In the stomodeal ectoderm, glandular epithelial cells produce _______
glycoprotein hormones
How is the posterior lobe formed? Anterior lobe?
formed from a diverticulum from floor of brain - infundibulum
formed from an evagination from the oral cavity = rathe’s pouch
The stalk of Rathke’s pouch regresses and separates from ______
stomodeal ectoderm
Rathke’s pouch become closely associated with cells of the _______
infundibulum
The anterior pituitary utilizes the _____ system
hypothalamo-hypophyseal portal system
What is the difference between sex differentiation and sex determination?
differentiation: process whereby a group of unspecified cells develops into a functional, recognizable group of cells that have a common function
determination: system that determines the sexual characteristics of an organism which generally consists of genetic (alleles or genes) or hormonal parameters
What is the difference between chimera and mosaic?
chimera: produced by fusion of 2 different zygotes in a single embryo
mosaic: an individual with 2 different cell lines that originated from the same individual (from a non-disjunction event)
List the 3 stages of sexual differentiation in order/
chromosomal sex
gonadal sex
phenotypic sex
Primordial germ cells originate in the _____ and then migrate through the ______ to the ________ (known as gonadal/genital ridge)
yolk sac
hind gut
undifferentiated gonad
What causes the development of testes?
testis determining factor (TDF)
sex-determining region Y (SRY)
List the order of sex determination
sex-determining region y and testis determining factor produce testosterone
anti-mülleran hormone cause degeneration of the paramesonephric duct
dihydrotestosterone causes development of penis, scrotum, and accessory sex glands
Testosterone + ________ = dihydrotestosterone
5-alpha reductase
What do Sertoli cells secrete?
anti-mülleran hormone
enzymes
to produce dihydrotestosterone
Define desert hedgehog gene
causes differentiation of fetal leydig cells
What do leydig cells produce?
testosterone
The presence of ______ causes regression of the female duct system
testosterone
Why are testes pulled through the inguinal region from the retroperitoneal space?
gubernaculum shrinks
What regresses in presence of AMH? What grows?
paramesonephric/mullarian ducts - regress
metanephros
gonads
Females have an absence of ____, ______, and _______
anti-mülleran hormone
testosterone
dihydrotestosterone
In female differentiation, what develops? What regresses?
paramesonephric ducts (mullarian)
follicles
mesonephric regress
What attaches to the fused paramesonephric ducts?
a small bud evaginating from the caudal urogenital sinus
become cranial and caudal vagina
The ______ is the future broad ligament
genital fold
What are the 2 things that regulate reproduction
simple neural reflex
neuroendocrine reflex
What is the neural control center for repro hormones?
hypothalamus
The hypothalamo-hypohyseal portal system allows [large/minute] quantities of releasing hormones to act on the anterior pituitary before they are diluted by the general circulation
minute
T/F: The posterior pituitary does not have a portal system and instead has neurohormones that are deposited directly into system circulation
TRUE!
What are the gonadal hormones?
prostaglandin F2 alpha - uterus
progesterone - ovary, corpus luteum
estrogen - ovary, follicle
equine chorionic gonadotropin - placenta
What is a luteolytic hormone?
prostaglandin F2 alpha
What travels freely through plasma membrane into cytoplasm and bind directly to specific nuclear receptors?
steroids
Differentiate protein hormones and steroid hormones
protein: bind to plasma membrane bound receptors
steroid: travel freely through plasma membrane into cytoplasm and bind directly to specific nuclear receptors
What does protein hormone activate>
activation of protein kinase chain
What is fast vs slow steroid hormone action?
fast: binds to membrane receptor causing protein production
slow: binds to nuclear receptor inside cell causing steroid production
Who only has a tonic center?
males
What does the hypothalamo-pituitary gonadal axis do?
regulates reproduction primarily based upon a positive and negative feedback system
What are the keys players in the HPG axis?
GnRH
LSH, FH, prolactin
Oxytocin
testosterone, estrogen
[Steroid/protein] hormones are metabolized in the liver, and [steroid/protein] hormones are metabolized in the liver and kidneys
steroid
protein
LH and FSH are
glycoproteins
Where is large amounts of GnRH released?
surge center
What defeminizes the hypothalamus during embryogenesis and eliminates the GnRH surge center in the male
testosterone but technically estradiol
_____ produced by the testes in the developing male fetus penetrates the ________ and is converted to ______
Testosterone
blood brain barrier
estradiol
In the female, estradiol is bound to ______ which prevents estradiol from crossing the blood brain barrier.
alpha-fetoprotein
T/F: Puberty is a single event
FALSE - gradual and multifactorial maturation process
_____ needs to be produced in sufficient quantities to support gametogenesis
GnRH
“It is the failure of the _______ to produce sufficient quantities of ______ to cause ______ release that is known to be the major factor limiting onset of puberty”
hypothalamus
GnRH
gonadotropin
The development of hypothalamic nuclei is dependent on ______
threshold body size
nutritional factor
environmental cues
photoperiod
genetics
In the male, the onset of puberty is brought about because of [increased/decreased] sensitivity to [positive/negative] feedback by _______
decreased
negative
testosterone/estradiol
What controls the preovulatory surge of GnRH?
surge center
About _____ months are required for the pulse frequency to become high enough for puberty to be achieved
2 months
In the prepubertal female, the surge center is quite sensitive to ____ but cannot release ovulatory qualities of GnRH because
estradiol
the ovary cannot secrete high enough levels of estradiol
What might stimulate glucose sensing neurons that stimulate GnRH neurons?
blood glucose concentrations
What are polyestrus cyclers?
cattle, swine, rodents
What are the primary ovarian structures for the follicular and luteal phases?
large follicles
corpus luteum
The luteal phase is the period from _______
ovulation to CL regression
What is characterized by major endocrine transition? What are the primary hormones responsible?
proestrus
FSH, LH
When is there peak estradiol secretion?
estrus
What are causes of anestrus? Except one in cats
pregnancy
lactation - not in cats mares, alpacas, llamas, dairy cows
presence of offspring
season (photoperiod)
stress
pathology
What inhibits GnRH when pregnant?
progesterone
When the number of suckling sessions is limited to 2 or less per day, the amplitude of ____ increases dramatically and she will begin to cycle
LH
In short day breeders, [increased/decreased] kisspeptin causes decreased GnRH which causes [increased/decreased] FSH and LH
decreased
decreased
[Estrous/estrus] is the stage of the cycle
estrus
What is the definition of folliculogenesis?
the process whereby immature follicles develop into more advanced follicles and become candidates for ovulation
What are the 4 significant events of the follicular phase?
gonadotropin (FSH, LH) released from anterior lobe of pituitary
follicular preparation (growth) for ovulation
sexual receptivity
ovulation (LH)
What is the dominant hormone in the follicular phase?
estrogen
In the follicular phase, the positive feedback of increasing levels of estrogen (in absence of progesterone) causes a release of a large quantity of ____ which then causes a release of _______ aka the ______
GnRH
LH, LH surge
Later in the follicular phase, follicles secrete ____ that causes negative feedback on _____ secretion. Estrogen can also suppress this
inhibin
FSH
What are the 2 GnRH neurons
surge center
tonic center
Why is there declining progesterone in follicular phase?
regression of previous corpus luteum
T/F: Follicles grow and regress constantly throughout the estrous cycle
TRUE
What is the term for a single follicle being selected?
monotocous
The majority of a follicle’s life is spent in the _____
prenatal stages
What are the stages of follicular dynamics
recruitment
selection
dominance
*slide 91, lecture 3
[Theca/granulosa] cell is where LH is bound
theca
[Theca/granulosa] cell is where FSH is bound
granulosa
Where is cholesterol converted to testosterone
theca cell (LH)
Where is testosterone converted to estradiol
granulosa cell (FSH)
The secondary oocyte produces the _____
first polar body
The bitch ovulates a ______
primary oocyte
Ovulation is ______ and is a 24 hour event
LH surge dependent
Which species doesn’t ovulate during estrous?
cow
Why is the preovulatory LH surge important?
it sets in motion a series of biochemical events that lead to ovulation
What does prostaglandin F2alpha accomplish?
luteolysis of the corpus luteum
causes contraction of ovarian smooth muscle which in turn increases follicular pressure
List a species other than cats that are induced ovulators
rabbits, minks, ferrtes
In induced ovulators, copulation stimulates sensory nerves in the _____ and ______
vagina
cervix
T/F: LARGE quantities of GnRH cause an LH surge
TRUE
What are the two main phases in the luteal phase?
Metestrus
Diestrus
Granulosa cells are [small/large], and theca cells are [large/small] luteal cells
large
small
When does progesterone plateau?
diestrus
The corpus luteum originates from an _____. What begins to break down as ovulation nears?
ovulatory follicle
basement membrane
What happens during the corpus hemorrhagicum?
small blood vessels rupture and theca and granulosa cells mix
What is the corpus luteum a mixture of?
small and large cells originating from theca and granulosa cells, respectively
What is luteinization?
transformation of the theca internal and granulosa cells (that produced estrogen prior to ovulation) to luteal cells producing progesterone
What produces progesterone in the corpus luteum?
small and large luteal cells
Other hormones produced by the corpus luteum include ____ and ______
oxytocin
relaxin
[Corpora hemmorrhagicum/Corpus Luteum] is first
Corpora hemmorragicum
What are the physiological affects of progesterone?
negative feedback on hypothalamus and anterior pituitary
uterus: has a positive influence to secrete “uterine milk” aka a histotroph for potential conceptus
mammary glands - causes final alveolar development
Because progesterone produced by the corpus luteum has negative feedback on the hypothalamus, what hormones are suppressed?
GnRH
LH
FSH
*remember to not abbreviate on the exam
Progesterone exerts a strong [positive/negative] influence on the endometrium of the uterus. It [increases/decreases] myometrial tone
positive
decreases (reduces contractility)
What is the luteolytic agent in domestic animals?
prostaglandin F2 alpha
What is the MAJOR source of prostaglandin F2 alpha?
endometrium (aka part of uterus)
Luteolysis causes structural regression to form a [corpus luteum/corpus albicans]
corpus albicans
What causes a new follicular phase?
removal of negative feedback by progesterone so GnRH can be secreted by the hypothalamus
What is the mechanism for luteolysis in ruminants?
vascular countercurrent exchange mechanism
high to low conc
**90% of systemic PGF2alpha is denatured in one circulatory pass through the pulmonary system
What are the mechanisms for luteolysis in the mare and sow?
mare: systemic only
sow: uses both systemic and countercurrent exchange - not responsive to PGF2a until at least day 12 post ovulation
In the first _____ days postovulation, PGF2a has a negligible effect
2-4 days
pig is different, day 12-14
The corpus luteum contains a large amount of _______
oxytocin
What aids prostaglandin f2 alpha in luteolysis via a positive feedback system?
oxytocin in the corpus luteum
[Leydig/Sertoli] are analogous to theca cells in the female, and [leydig/sertoli] cells are analogous to granulosa cells in female.
leydig
sertoli
Explain the 2-cell, 2-gonadatrope model for both male and female
theca cells: receptors for LH, convert cholesterol to testosterone
leydig cells: receptors for LH, produce testosterone, inhibin
granulosa cells: receptors for FSH, convert testosterone to estradiol
Sertoli cells: receptors for FSH, convert testosterone to estradiol, inhibin
Early sperm cells all develop in the space between two or more [sertoli/leydig] cells.
sertoli - they’re called “nurse cells” for a reason
When released as a spermatozoon, a major portion of the ______ of each spermatid remains as a residual body (______) within a pocket of Sertoli cell cytoplasm
cytoplasm
cytoplasmic droplet
[Sertoli/leydig] cells produce the enzyme necessary to convert testosterone to dihydrotestosterone. This enzyme is called ______
sertoli
5 alpha reductase
[Sertoli/leydig] cells secrete inhibin that exerts a [positive/negative] feedback on the [posterior/anterior] lobe of the pituitary to directly suppress FSH secretion
sertoli
negative
anterior
Define spermatogenesis
process of producing spermatozoa in the seminiferous tubules
What are the 3 phases of spermioogenesis
proliferation
meiotic phase
differentiation phase
What is the differentiation phase, aka spermiogenesis, marked by?
transformation from spermaTID to spermaTOZOA
from spherical-shaped to heaving a head, mid piece, and flagellum
The [first/last] mitotic divisions give rise to primary spermatocytes that enter meiosis.
last
After meiosis, [haploid/diploid] spherical spermatids differentiation into spermatozoa
haploid
Where does meiosis and differentiation take place?
adluminal compartment
What creates the blood-testes barrier?
tight junctions between sertoli cells
What are the 4 phases of differentiation?
Golgi phase
cap phase (acrostic vesicle spreading over nucleus)
acrosomic phase
maturation phase (final assembly)
“GG creates amazing masterpieces”
What happens during the Golgi phase?
newly formed, spherical spermatid has a well-developed Golgi apparatus
golgi vesicles fuse creating pro-acrosomic granules
What happens during the cap phase?
the Golgi is migrating and the acrosome is formed forming a distinct cap
What happens during the acrosomal phase?
nucleus begins to elongate and the neck between the head and tail is elongating
What happens during the maturation phase?
mitochondria form a spiral assembly around the flagellum that defines the midpiece
What makes up the majority of the tail?
principal piece
What is the geometric clutch model?
9+2 micro tubular pattern
T/F: If you travel down the seminiferous tubule, you would see spermatozoa in different stages of development.
TRUE
cycle of seminiferous epithelium
Where do “privileged pathways” take place? Capacitation?
cervix
uterus
Secretion of sulfomucins is [cranial/caudal] and is [towards/away] the lumen. It is secreted during [estrus/diestrus]
caudal
towards
estrus
During what phase has a result of muscle contraction following copulation? (sperm transport)
rapid phase
What happens during the sustained phase? (sperm transport)
sperm delivered to oviducts continually from reservoirs in (uterotubal junction and cervix)
extends time over which fertilization can occur
selected so that they are viable and morphological normal
Where is the spermatozoal reservoir?
oviductal isthmus
What is a result of capacitation? What happens?
hyper-activated sperm, unmasking of zona pellucid binding sites
- due to: stripping of sperm membrane proteins by uterine factors
Head bins to zona pellucida
Midpiece: metabolism
Tail: motility
Where must spermatozoa reside before they acquire maximum fertility?
female tract
What are some barriers to fertilization?
cumulus cells
thick zona pellucida
oocyte membrane
The sperm plasma membrane overlying the acrosome contains what 2 receptor-like regions?
zona binding region - physical attachment of sperm to zona pellucida
acrosome reaction promoting region - sperm plasma membrane to fuse to outer acrosomal membrane
What happens during the cortical reaction?
the sperm head attaches to the oocyte plasma membrane (vitelina membrane, oolemma)
- initiates the block to polyspermy!!
The spermatozoon settles into a _____ formed by the oocyte plasma membrane during the cortical reaction.
bed of microvilli
T/F: Syngamy is the fusion of the female and male pronuclei.
TRUE
Once it has taken place, the one-celled organism is a zygote
What is the difference between a zygote and embryo?
zygote: unicellular
embryo: paracellular
Where does the embryo develop and then attaches to the uterus?
zona pellucida and then hatches
Fusion of the male and female pronuclei into a single diploid nucleus constitutes _______. Then, there are cleavages which give rise to _______
syngamy
blastomeres (daughter cells)
After the morula, a blastocyst develops. What is in the blastocyst?
inner cell mass
trophoblast - single layer of cells
blastocoele - cavity
What is totipotency? What kind of embryo has it?
ability of a single BLASTOMERE to develop into a fully formed individual animal
When is there a time of incredible conceptus growth?
post-hatching blastocyst growth
Extraembryonic membrane development accounts for
rapid expansion of the blastocyst
- yolk sac
- chorion
- amnion
- allantois
essential to facilitate attachment to uterus
Along with the primitive endoderm and mesoderm, _____ gives rise to the chorion and amnion
trophoblast cells
The _______ develops from the primitive endoderm
yolk sac
What fuses with the chorion?
allantois
While the embryo is developing in the uterus, what prevents luteolysis from occurring?
maternal recognition of pregnancy which MUST occur before luteolysis
maintain high levels of progesterone
Interferon tau in ruminants is produced by ______ which does what?
trophoblastic cells
inhibits oxytocin receptor synthesis (so that prostaglandin F2 alpha cannot be released and thus lyse the corpus luteum)
In maternal recognition of pregnancy in the sow, what produces estrogen? What happens to prostaglandin F2 alpha?
blastocyst
re-routes PGF2a release into uterine lumen - then destroyed
PGF2a is changed to EXOcrine
In maternal recognition of pregnancy in the mare, what migrates? What happens to prostaglandin F2 alpha?
blastocyst throughout the uterine lumen
reduced synthesis of PGF2a
In maternal recognition of pregnancy in the dog/cat, what happens?
doesn’t require a signal from conceptus - similar lifespan in pregnant and non-pregnant
What’s another word for equine chorionic gonadotropin? What kind of activity does it have?
endometrial cups
LH and FSH-like activities
What is the purpose of equine chorionic gonadotropin?
helps to luteinize accessory and secondary corpora lutea
What is the function of the placenta?
maintain pregnancy
induce giving birth (parturition)
What is the functional unit of the placenta?
chorionic villi
- can be microscopic (micro cotyledons) and macroscopic (cotyledons)
List the types of placental classifications
diffuse
cotyledontary
discoid
zonary
microcotyledontary
What is a diffuse characteristic of a placenta? Which species?
almost the entire surface of the atlantochorion is involved in the formation of the placenta
- horses, pigs, camelids
What is a cotyledonary characteristic of a placenta? Which species?
multiple, discrete areas of attachment called placemntomes are formed by interaction of patched of allantochorion with endometrium
- ruminants
What is a placentome?
the cotyledon-caruncle complex
What is a zonary characteristic of a placenta? Which species?
area of attachment is a complete or incomplete band of tissue surrounding the fetus
- carnivores like dogs, cats, seals, bears, elephants
What is a discoid characteristic of a placenta? Which species?
area of attachment is discoid in shape
- primates and rodents
What are two physical characteristics of a cotyledonary placenta?
convex vs concave
In a cotyledonary placenta, the [caruncle/cotyledon] is associated with the mom, and the [caruncle/cotyledon] is associated with the fetus
caruncle - mom drives the CAR
cotyledonary - baby sleeps in the COT
What is the LEAST intimate and both maternal and fetal epithelium are intact?
pig, horse, cow, ewe, doe
Define endotheliochorial. Which species?
complete erosion of endometrial epithelium
- dog, cat
Define hemochorial. Which species?
chorionic epithelium is in direct apposition to maternal pools of blood
T/F: Cats are epitheliochorial and zonary.
If false, correct the statement.
FALSE
they are ENDOthelial and zonary
What is the first foray to the CNS?
spinal cord
What does a specialized sensory cell synapse with?
primary afferent neuron
What is a sensory receptor?
specialized to detect a particular stimulus modality
All ______ are able to perform [translation/transduction/transcription]
transduction
Receptors have ______ channels that open based upon a specific type of stimulus
modality-gated channels
The stimulus is then converted to ______
action potentials
What defines stimulus intensity?
rate and frequency of action potentials
If receptor has a higher rpm, it is [closer/farther] to threshold, meaning it is [more/less] sensitive
closer
more
What is encoded by receptor adaptation?
stimulus duration
Give examples of tonic receptors. Then phasic
tonic: proprioceptors, do not rapidly adapt and respond to a constant stimulus
phasic: touch receptors (Meissner & Pacinian), adapt rapidly, only respond to new stimuli
The stimulus type is encoded by ______ and responsive to specific type of stimulus based on ______
modality
labeled line code
Viscerosensory signals originate from ____ and detect changes from ______
viscera
internal stimuli
Where do special sense signals (vision, hearing, taste, olfaction) originate?
special sensory organs in head
Tactile is sensed by _______ and [most/few] are adaptable
mechanoreceptors
more
Temperature is sensed by ______
transient receptor potential channels on nerve endings
- adaptable
T/F: Nociceptors are not adaptable
TRUE
Do proprioceptors readily adapt?
NO!
What are the joint capsule mechanoreceptors? Muscle and tendon mechanoreceptors?
pacinian and ruffini
Golgi tendon organ and muscle spindle
Golgi tendon organ detects muscle [contraction/stretch], and muscle spindles detect muscle [contraction/stretch]
contraction
stretch
What are some somatosensory receptors?
thermoreceptors
nociceptors
proprioceptors
mechanoreceptors
Define exteroception vs interoception
exteroception: external stimulus
interception: visceral stimulus
After the primary afferent neuron fires, where does the signal go?
up the nerve fiber of the primary afferent neuron
cell body resides in dorsal root GANGLION
OR
nucleus of the trigeminal nerve for structures of the head
What is the receptor type for proprioception?
muscle spindle
T/F: Proprioception has a slower conduction velocity than nociception
FALSE - other way around!
What is a dermatome?
General Somatic Afferent
one spinal nerve is responsible for somatosensory innervation of a particular soma
A receptive field is the area of endings of a __________, which allows for [more/less] precise stimulus localization
primary afferent neuron
more
What are the functions of the spinal cord? Do they involve a lot of decision making?
conduction of afferent and efferent
- structural and functional link between BRAIN & BODY
neural integration - does PROCESSING, not decision making
Reflexes!
Do reflexes involve the brain?
NO - spinal cord
Lateral horns are only present in ________ because they house [axons/cell bodies] of [somatic/sensory/autonomic] motor neurons
T1-L3
cell bodies
autonomic
What do dorsal horns house? Ventral?
dorsal: house axons of sensory neurons and cell bodies of interneurons
ventral: house cell bodies of somatic motor neurons
T/F: Funiculi are in the white matter, myelinated axons. Gray matter has the neuronal cell bodies.
TRUE
The first-order neuron is also called a ______.
primary afferent neuron
The cochlear n. in the auditory reflex is a [first order/second order/third order] neuron
first
In the first-order neuron, from the body, it enters the spinal cord via the ____ or from the head, the ______
dorsal root
cranial nerve (trigeminal)
When is there decussation to the contralateral side in the somatosensory projection pathway?
second-order neuron:
- projects from CNS cranially
- decussates to contralateral side
- ends in thalamus
Where is the third-order neuron?
thalamus to primary somatosensory cortex of cerebrum
In conscious proprioception and touch, what are the two primary parts? It detects
fasciculus cuneatus
fasciculus gracilis
- detects conscious proprioception, touch, pressure, vibration
The fasciculus cuneatus is to the [cranial/caudal] trunk and the [thoracic/pelvic] limbs, and the fasciculus gracilis is to the [cranial/caudal] trunk and the [thoracic/pelvic] limbs
cranial trunk, thoracic limbs
caudal trunk, pelvic limbs
Standing on the dorsum of the foot is an example of a defect in ______
conscious proprioception
If conscious proprioception is contralateral, what is subconscious proprioception? To what structure?
ipsilateral
cerebellum
What 2 tracts are involved in subconscious proprioception? Where does it go?
spinocerebellar tract - caudal trunk and pelvic limbs
spinocuneocerebellar tract (cuneocerebellar) - cranial trunk, thoracic limbs
What runs with the fasciculus cuneatus?
spinocuneocerebellar tract (cuneocerebellar)
Fill in the blanks
- pelvic
- thoracic
- thoracic
- pelvic
- fasciculus gracilis
- fasciculus cuneatus
- cuneocerebellar tract
- spinocerebellar tract
What are the 2 tracts of the nociceptive pathways?
spinothalamic tract
spinocervicothalamic tract
T/F: Loss of nociception is a poor prognostic indicator
TRUE
Which nociceptive tract involves viscerosensory afferents? Where does it go?
spinothalamic tract
travels to the cerebrum for conscious perception
What are the fibers of viscerosensory afferents? In which 2 ways does it travel?
A and delta C fibers
1. via autonomic nervous system fibers
2. via the spinothalamic tract - goes to cerebrum for conscious perception
What cranial nerves are involved in viscerosensory afferents?
7, 9, 10 - goes to solitary tract in medulla to impact vagal reflexes
Which autonomic fibers carry nociceptive action potentials? Which for physiologic receptor action potentials?
sympathetic nervous system
parasympathetic nervous system
What is referred pain?
many somatic and visceral sensory neurons send signals via the same ascending tracts within the spinal cord
- somatosensory cortex unable to determine true source
- why people feel heart attacks in right arm
Motor control is a [1/2/3] neuron system. List the neurons
2
UMN & LMN
What initiates voluntary motor actions? Where is it located?
upper motor neuron (UMN)
brainstem, cerebral cortex
Where are LMNs located?
cell BODIES in ventral grey horn of the spinal cord or brainstem “peripheral”
- reflexes
- directly innervate skeletal muscles, spinal reflexes
Can LMNs work independently of UMNs? How so?
YES
- stepping/gaiting
- alerting and reflexes
- postural control
What does the frontal cortex do? Where is it then sent?
strategizes and provides impulse control
basal nuclei
What is the basal nuclei? It is composed of _____ and _____ areas.
deep cerebral grey matter
striatum
globus pallidus
The globus pallidus sends [excitatory/inhibitory] to the thalamus
inhibitory
List the descending motor tracts of cerebral motor control. List if they are ipsilateral or contralateral
corticonuclear - brainstem nuclei, ipsilateral
corticopontine - pontine nuclei, contralateral (to cerebellum)
corticospinal - most decussate and go contralaterally
What has direct communication between cerebral cortex UMNs and LMNs?
corticospinal tract
What is also called the pyramidal tract?
corticospinal tract
What is special about the corticospinal tract, especially in humans?
controls voluntary, fine motor control, skilled movements
List the UMNs of the brain stem. Where do they go?
red nucleus
pontine & medullary reticular nucleu
vestibular nuclei
- some go to cranial motor nuclei (LMN)
- MOST go to spinal cord ventral horn (LMNs) via long descending tracts
List the extrapyramidal aka descending tracts
ruprospinal tract
pontine reticulospinal tract
medullary reticulospinal tract
vestibulospinal tract
What is the key tract for voluntary movement in animals? What does it do?
rubrospinal tract
facilitate UMN flexor muscles
The pontine reticulospinal tract [stimulates/inhibits] extensor muscles and [stimulates/inhibits] flexor muscles
stimulates
inhibits
The medullary reticulospinal tract [stimulates/inhibits] extensor muscles and [stimulates/inhibits] flexor muscles
inhibits
stimulates
The vestibulospinal tract [stimulates/inhibits] extensor muscles and [stimulates/inhibits] flexor muscles
stimulates
inhibits
Which region are the descending tracts? Characterize them by speed, level of damage, etc
blue (go to lateral/ventral horn)
intermediate, myelinated sizes
less likely to be damaged compared to proprioceptive fibers
more likely to be damaged compared to nociceptive fibers
List the cell bodies of the LMNs.
cranial nerve cell bodies (all but 1, 2, 8)
somatic motor neuron cell bodies - ventral horn
visceral motor cell bodies - lateral horn
The autonomic motor neuron is a [1/2] neuron pathway
2
preganglionic, synapse on ganglion, postganglionic
Somatic LMNs have a _______ neuron and a motor unit, which is a ______ and the muscle fibers it innervates
peripheral efferent neuron
somatic motor neuron
alpha-motor neurons innervate and contract [extrafusal/intrafusal] muscle fibers. Gamma-motor neurons innervate contractile poles [extrafusal/intrafusal] muscle fibers of the muscle SPINDLE
extrafusal
intrafusal
T/F: UMN pathways activate both types of alpha- and gamma-motor neurons during movement
TRUE
What happens in the myotatic reflex?
stretching muscles activate Ia afferents
Ia afferents [excite/inhibit] inhibitory [flexor/extensor] motor neuron
excite inhibitory
flexor motor neuron - aka antagonist
The myotatic reflex is [mnosynaptic/polysnaptic]
monosynaptic
T/F: Reciprocal inhibition of the myotatic reflex is not monosynaptic
TRUE
What is required in polysynaptic reflex arcs? What are they in general?
interneurons
multiple synapses within CNS between sensory inout and LMN output
Do polysynaptic reflexes involve ipsilateral and contralateral activation/inhibition?
YES
What is the tendon reflex? What fiber has a higher threshold?
Golgi tendon organ stimulated by vigorous muscle contraction stretching tendon
- Ib fiber
What is stimulated in the tendon reflex?
stimulate inhibition of alpha motor neuron to AGONIST muscle
What guards against extreme muscle stress?
tendon reflex
In the withdrawal reflex, spinal cord interneurons promote activity in ipsilateral [extensor/flexor] LMNs. Conversely, it inhibits activity in ipsilateral [extensor/flexor] LMNs.
flexor
extensor
In the crossed extensor reflex, spinal cord interneurons promote activity in ipsilateral [extensor/flexor] LMNs. Conversely, it inhibits activity in contralateral [extensor/flexor] LMNs.
flexor
extensor
T/F: You can do a crossed extensor on a recumbent animal and see a reflex because it is normal.
FALSE - do standing
it is not normal to see a crossed extensor reflex in a recumbent animal
Why should there not be a crossed extensor reflex in a recumbent animal?
shows there is a loss of inhibitory UMN activity
Where is the panniculus reflex? What muscle does it affect? Ipsilaterally or contralaterally or both?
T1-L7
cutaneous trunci m.
both
In the panniculus reflex, there is bilateral transmission via [first-order/interneurons] in the ________
interneurons
fasciculus proprius
What is the term classified by repetitive, stereotypical behaviors, chewing, walking, etc? It is a neural circuit.
central pattern generator - gaiting
Gaiting is typically initiated by UMNs but maintained by LMNs and _______
fasciculus proprius
What is still possible after a transected spinal cord?
“spinal walking”
What is the RAT for LMNs?
Reflexes: decreases
Atrophy: heavily increased
Tone: decreased
What is the RAT for UMNs?
Reflexes: increased or normal
Atrophy: increased or normal
Tone: increased or normal
T/F: Muscle strength in UMN and LMN damage is both decreased
TRUE! - leads to -plegia or paresis
When [UMN/LMN] is damaged, you see +/- crossed extension in recumbency
UMN damage
Do you see UMN damage downstream of a transverse lesion in the lumbosacral plexus?
no, just LMN damage
If there is a lesion in the brachial plexus (C6-T2), where do you expect to see analgesia/hypalgesia?
only the thoracic limbs
If there is a lesion in C1-C5, where do you expect to see analgesia/hypalgesia?
all limbs
If there is a lesion in T3-L3, would the animal be paraplegic or tetraplegic? What about in the pelvic limbs? Thoracic limbs?
paraplegic
paraplegic
tetraplegic
Where do you expect to see hypalgesia/analgesia in ALL limbs? What about ataxia?
both C1-C5
If there is a lesion in T3-L3, where is there UMN damage?
pelvic limbs
What does the cerebellum do?
coordinates timing and smooth out somatic motor activity
helps maintain equilibrium - UMN
helps regulate muscle tone - UMN
T/F: The cerebellum initiates movements
FALSE - corrects them
What are the 3 parts of the cerebellar peduncles? Which one has only efferent fibers? Afferent? Both?
rostral (midbrain) - efferent
middle (pons) - afferent
caudal (medulla) - both
Cerebellar afferents are from the spinal cord from these 2 pathways:
spinocuneocerebellar
spinocerebellar
List the 3 cerebellar afferent locations
spinal cord
cerebral cortex
brainstem
From the cerebral cortex, a motor plan is sent to the cerebellum. It is called the _______ pathway
corticopontocerebellar
List the functional anatomy of the cerebellum
spinocerebellum
pontocerebellum
vestibulocerebellum
What coordinates movement and posture and goes to brainstem LMN?
spinocerebellum
What coordinates and properly times skilled movement and goes to motor cortex?
pontocerebellum
What coordinates balance and eye movement and goes to vestibular nuclei?
vestibulocerebellum also called the flocculonodular lobe
What are deep cerebellar nuclei?
cerebellar efferent
excitatory to nuclei of the pyramidal and extrapyramidal motor systems
- UMN of brainstem or cerebral cortex via thalamus
T/F: Cerebellar efferents have a descending spinal path
FALSE - no direct synapse on LMN to impact muscles
What are signs of cerebellar dysfunction? 3 main things.
spinocerebellar: hypermetria and ataxia (toy soldier)
pontocerebellar: intention tremors (cat shaking head)
vestibulocerebellar: wide-based stance
Where is the vestibular apparatus located? What is its function?
inner ear
sense position of head and neck at rest and during motion
stabilizes position of the head and trunk and coordinates eye movement
Where are receptors of the vestibular apparatus found?
3 semicircular ducts - crista ampullaris
vestibule - macula saccule & macula utricle
The crista ampullaris senses [angular acceleration/static equilibrium/lilnear acceleration], the macula saccule senses [angular acceleration/static equilibrium/lilnear acceleration], and the macula utricle senses [angular acceleration/static equilibrium/lilnear acceleration]
angular acceleration
static equilibrium
linear acceleration
What is the 1st order neuron in the vestibular apparatus? It travels to ____. What is the 2nd order neuron?
1st: vestibulocochlear n. (8)
travel to medulla or directly to cerebellum
2nd: vestibular nuclei in medulla
What is bathed in endolymph and high in _____?
crista ampullaris
K+
What tips towards kinocilium to induce an action potential in the crista ampullaris?
stereocilia
In the crista ampullaris, hair cells are bathed in [gelatinous cupula/gelatinous layer with otoliths], and in the macula saccule and macula utricle, hair cells are bathed in [gelatinous cupula/gelatinous layer with otoliths]
crista: gelatinous cupula
s&u: gelatinous layer with otoliths
The macula saccule is [horizontal/vertical] with [static equilibrium/linear] acceleration equilibrium, and the macula utricle is The macula saccule is [horizontal/vertical] with [static equilibrium/linear acceleration]
vertical and static
horizontal and linear
*crista ampullaris is angular acceleration
The vestibulospinal tract activates [extensors/flexors] and inhibits [extensors/flexors]. Is it ipsilateral or contralateral?
extensors
flexors
ipsilateral ventral funiculus
What cranial nerves do the medial longitudinal fasciculus involve? What reflex? What does it help?
3, 4, 6 - extra ocular muscles
vestibulo-ocular reflex
help fix eyes on target - “gaze stabilization”
What is the target of the vestibular system? How so?
cerebellum
direct and indirect vestibulocerebellar pathways
axons vs nuclei at cerebellar flocculonodular lobe
Differentiate peripheral vestibular subdvision and central vestibular subdivision.
peripheral: receptors (hair cells0, vestibular nerve (inner ear structures)
central: brainstem and cerebellar vestibular structures
In vestibular disease, why does the dog tilt toward the lesion?
because the pathway is ipsilateral!
A dog has a nystagmus with a slow return to the left. What side is affected?
left
A dog has a nystagmus with a fast jerk to the right. What side if affected?
left
List the 3 types of ataxia (off balance)
cerebellar
vestibular
spinal/proprioceptive
A dog is trying to walk and has exaggerated movements. Diagnose the dog and what pathway is affected.
ataxia - specifically cerebellar
subconscious proprioception is affected
A dog is crossing over to one side and has miscoordination of thoracic and pelvic limbs. He is also walking on his dorsum. Diagnose the dog and what pathway is affected.
ataxia - specifically spinal/proprioceptive
conscious proprioception is affected
A dog is falling to one side. Diagnose the dog.
ataxia - specifically vestibular (characterized by balance issues)
Where do all axons leave the eye?
optic disc - can’t see
What is comprised of the retina?
optic disc - blind spot
horizontal visual streak
The cornea refracts [more/less] light than the lens does
more
What fine-tunes the image?
lens
What are the 1st and 2nd order neurons of the retina?
1st: bipolar cell
2nd: ganglion cell
Which layer of the eye absorbs light?
pigment cell layer
Which layer of the retina houses bipolar cells, horizontal cells, and amacrine cells?
inner nuclear layer (cell bodies of retinal interneurons)
- outer plexiform layer has the dendrites of these
What are the output cells of the retina?
ganglion cells
What is the tapetum lucidum?
reflective layer in the choroid that increases light detection in dark conditions
[Rods/Cones] are used in scotopic vision.
rods
Do photopsins/lodopsins or rhodopsins have a lower threshold?
rhodopsins
What contains retinal (vitamin A derivative) in combination with an opsin (G-protein coupled receptor)?
rhodopsin
In the dark, rhodopsin contains [cis/trans]-retinal. What does light absorption cause?
cis
transformation to trans-retinal and dissociation from opsin —> bleaching reaction
In photopsins, phototransduction is [faster/slower], with [more/less] intense light needed for bleaching. Photopsins regenerate [quickly/slowly]
faster
more
quickly
What degrades cGMP during phototransduction?
PDE
What kinds of gates close during phototransduction and what happens?
cGMP gated Na+ channels close
HYPERpolarization and decrease glutamate release
_____ cells are more l likely to be activated by low levels of light due to convergence of RODS.
Bipolar cells
cones are different, only a few converge
What is the 3rd order neuron for the vision pathway? It is [cortical/subcortical]
lateral geniculate nucleus
sub-cortical
Do you see more if you have more decussation, meaning your eyes are farther apart?
YES
closer: more input each eye gets
The pupillary light response, which is 20%, bypass the lateral geniculate nucleus and go to the _______. It is a [cortical/subcortical] reflex, inducing [sympathetic/parasympathetic] pupil constriction
rostral colliculus
subcortical - does not guarantee conscious perception of vision
parasympathetic
The menace response involves which cranial nerves? It is a [cortical/subcortical] and is learned
2 and 7
cortical
The visual startle reflex is at the _______ in the midbrain and [stays ipsilateral/decussates]
rostral colliculus
decussates
What is filled with endolymph and perilymph?
membranous labyrinth
What is the organ of hearing?
cochlea
Which part(s) of the scala are filled with perilymph?
scala vestibuli - dorsal
scala tympani - ventral
Which part(s) of the scala are filled with endolymph?
scala media
What pulls open, allowing K+ to diffuse into the hair cell and depolarize it?
tip links
The [higher/lower] the pitch, the closer to the base
higher
Differentiate conductive deafness and sensorineural nerve deafness
conductive: conditions interfere with transmission of vibrations to inner ear
sensorineural: death of hair cells
What are the first and second order neurons in the auditory pathway?
1st: cochlear n
2nd: superior olivary nucleus
The auditory pathway goes to the [rostral/caudal] colliculus
caudal
Acoustic startle reflex is [contralateral/ipsilateral] to sound and involves [rostral/caudal] colliculus
ipsilateral
caudal
What is the primary afferent neuron for olfaction?
olfactory receptor cell - primary afferent neuron (bipolar cell)
What are the types of receptors for olfaction and gustation?
chemoreceptors
Where is the only location of neurogenesis of stem cells?
olfactory epithelium
Which pathway does olfactory transduction involve?
g-protein subunit with adenylyl cyclase
leads to depolarization
What is the 1st order neuron location? What is the 2nd order neuron of the olfactory path?
through cribriform plate to olfactory bulb
interneurons in bulb process, filter, and enhance transmission of specific odorants
2nd odor neuron: mitral cell, axons project to cerebrum
The olfactory pathway has a directly path to the _____ aka ____, and transmission through the ______ is not required.
olfactory cortex
piriform lobe
thalamus
What is connected to the nasal and oral cavity via the nasopalatine ducts?
vomeronasal organ
What are the sensory organs for taste? Where are they found?
taste buds
on gustatory papillae
Taste receptor cells have _____ that contain taste chemoreceptors
microvilli
For bitter, sweet, or savory, the G-protein coupled receptor has a signaling pathway that opens _______
transient receptor potential channels
For sour or salty, chemicals bind and directly open ________ to allow _____ or _____ to enter
inotropic epithelial sodium channels
H+, Na+
Where are the primary afferent axons of first order taste neurons located in the gustatory pathway?
9, 7, 10
Where are the second order neurons for the gustatory pathway?
solitary nucleus of the medulla
Where are the third order neurons for the gustatory pathway? Where do they project?
thalamus
to the taste cortex of the temporal lobe
