Exam 2 Flashcards
(398 cards)
1
Q
Dura mater
A
outer layer; thick; collagen & elastin; blood vessels; nerves; lymph vessels; fibroblasts
2
Q
Arachnoid
A
middle layer; collagen & fibroblasts
3
Q
Pia mater
A
inner layer; collagen & fibroblasts
4
Q
Leptomeninges
A
arachnoid & pia mater
5
Q
Subarachnoid space
A
b/w arachnoid & pia mater; CSF circulates here
6
Q
Function of CSF
A
protection; maintains chemical stability of CNS (removes waste, provides macronutrients, & maintains electrical properties)
7
Q
Function of spinal nerve
A
carries motor, sensory, & autonomic signals b/w spinal cord & body
8
Q
Characteristics of gray matter
A
found in middle of spinal cord; neurons & neuroglia; lighter staining
9
Q
Characteristics of white matter
A
found surrounding grey matter in spinal cord; neuroglia; darker staining
10
Q
Parts of a neuron
A
cell body w/ nucleus; dendrite (input); axon (to target)
11
Q
Cytoplasm of neurons
A
nissl substance: RER & ribosomes
12
Q
Function of multipolar neurons
A
sensory/ motor (most common neurons)
13
Q
Function of bipolar neurons
A
sensory (eye & ear)
14
Q
Function of unipolar neurons
A
sensory (more common than bipolar)
15
Q
When do neurons stop dividing
A
3-4 months after birth
16
Q
Ependymal cell location
A
central canal & ventricles
17
Q
Ependymal cell morphology
A
cuboidal to columnar
18
Q
Ependymal cell function
A
assist w/ CSF circulation; have cilia on apical surface
19
Q
Components of choroid plexus
A
choroid epithelium (modified ependymal cells w/ microvilli form tight junctions b/w blood & CSF), connective tissue, & fenestrated capillaries
20
Q
Function of choroid plexus
A
CSF production
21
Q
Fenestrated capillaries of choroid plexus allow what to pass through
A
electolytes & sm molecules
22
Q
Astrocytes morphology
A
numerous cell processes
23
Q
Function of astrocytes
A
form scar tissue in response to injury; maintain optimal CNS environment (induct & maintain capillary endothelium as the blood brain barrier; help transport glucose to neurons; store glycogen; promote neuronal survival; prevent glutamate neurotoxicity)
24
Q
Function of blood brain barrier
A
regulates the exchange of solutes b/w blood & CNS tissue via a capillary endothelium
25
How do astrocytes impact the blood brain barrier
release glial cell line derived neurotrophic factor (GDNF) to promote formation & maintenance of capillary tight junctions
26
What can diffuse across the blood brain barrier
water, gasses, & lipophilic substances (alcohol, heroine, nicotine, & cyanide)
27
What is actively transported across the blood brain barrier
glucose
28
What moves across the blood brain barrier via carrier-mediated transport
AAs not synthesized in brain move in (Leu, Tyr, Val, Trp); AAs synthesized in brain move out (glycine & GABA)
29
How does glutamate neurotoxicity occur
glutamate is a neurotransmitter that is released at the terminal end of axons & is toxic at high conc; astrocytes convert glutamate -> glutamine via glutamine synthase
30
Function of microglia
respond to tissue damage & remove debris by phagocytosis
31
Function of oligodendrocytes
increase conduction velocity by myelinating axons; do not support small non-myelinated axons
32
Function of schwann cells
increase conduction velocity by myelinating axons; support small axons but does not myelinate them
33
Describe the organization of peripheral nerves
axon + schwann cell = nerve fiber = endoneurium
nerve fibers = fascicle = perineurium
fascicles = nerve = epineurium
34
Describe structure & location of PNS sensory nerve
unipolar; cell body found in dorsal root ganglion
35
Function of sensory receptors
detect changes in thermal, mechanical, or chemical stimuli applied to the surface or interior of the body & generate nerve impulses to be transmitted to the CNS for processing
36
Types of terminal ends for primary sensory neurons
free nerve ending, innervates special cells, or encapsulated by cells/ CT
37
Function & terminal end of free nerve endings
pain, temp, or touch
| free nerve ending
38
Function & terminal end of hair follicle terminal
touch
| free nerve ending
39
Function & terminal end of merkel's corpuscle
touch or pressure
| innervates Merkel cells
40
Function & terminal end of meissner's corpuscle
touch or vibration
encapsulated by cells
only in thick skin
41
Function & terminal end of pacinian corpuscle
vibration or pressure
| encapsulated by many layers of cells
42
Function & terminal end of golgi-tendon organ
muscle tension or proprioception
| encapsulated by collagen fibers, sensory fibers, & CT capsule
43
Function & terminal end of muscle spindle
proprioception
| encapsulated by intrufusal muscle fibers, sensory fibers, & CT capsule
44
Somatic sensory receptors in the epidermis
free nerve endings
45
Somatic sensory receptors b/w dermis & epidermis
meissner's & merkel's corpuscle
46
Somatic sensory receptors in dermis
pacinian & hair follicles
47
Examples of somatic sensory receptors
skin, muscles, tendons, bones, retina, organ of corti, carotid body, & carotid sinus
48
Examples of visceral sensory receptors
viscera, taste buds, & olfactory cells
49
How is neuronal resting membrane potential generated
due to uneven distirbution of ions across the plasma membrane by the electrochemical gradient
50
What affects the electrochemical gradient in relation to cell membranes
Na+/K+ pump (2 K+ in/ 3 Na+ out); intracellular negative ions to large to exit cell; selective membrane permeability to ions (K+ & Cl- non-gated/ leak channels; few Na+ non-gated/ leak channels)
51
Describe signal transduction of sensory receptors
conversion of sensory stimuli to electrical signals; open stimlus specific Na+ channels; generate receptor potential
52
Receptor potential is proportional to what
stimulus intensity; more stimulus corresponds to more Na+ released
53
What is action potential
brief reversal in electrical potential across a membrane
54
When is an action potential generated
when receptor potential > threshold potential (-55 mV)
55
Action potential requires voltage-gated channels of axons that are activated by
membrane depolarization
56
Describe resting state of voltage-gated Na+ channel
channel closed (activation gate shut)
57
Describe activated state of voltage-gated Na+ channel
channel open (both gates open)
58
Describe inactivated state of voltage-gated Na+ channel
channel closed (inactivation gate shut)
59
When does Na+ cross the voltage-gated Na+ channel
when channel is at an activated state
60
What has to happen before depolarization can occur again
voltage-gated Na+ channel must be de-inactivated
61
What are the state of the Na+ & K+ voltage gated channels at RMP
```
Na+ = resting state; channels closed
K+ = channels closed
```
62
What are the state of the Na+ & K+ voltage gated channels at receptor potential > RMP
```
Na+ = some activated; some channels open
K+ = some channels slowly open
```
63
What are the state of the Na+ & K+ voltage gated channels at receptor potential > threshold
```
Na+ = activated w/ all channels open; at peak, inactivated w/ all channels shut
K+ = all channels slowly open & close
```
64
Ionic mechanisms of Na+
higher conc on outside of cell; both neg charge interior & conc gradient result in Na+ rushing in
65
Ionic mechanisms of K+
higher conc on inside of cell; when Na+ depolarizes membrane, then K+ rushes out to re-polarize membrane
66
Describe absolute refractory period
Na+ voltage- gated channels are in inactivated state & an action potential cannot be generated
67
Describe relative refractory period
stronger than normal stimulus needed to elicit an action potential
68
Describe hyperkalemia
too much extracellular K+ leading to depolarization & a greater likelihood of an action potential being generated
69
Describe hypokalemia
too little extracellular K+ leading to hyperpolarization & a lesser likelihood of an action potential being generated
70
Explain the properties of voltage-gated Na+ & K+ pumps as it relates to action potential (think toilet example)
majority of channels open only when membrane potential > threshold potential so AP = all or none
channels undergo 3 states that determine AP amplitude, duration of each cycle, & propagation speed
channels have refractory periods so AP = no overlaps
71
Where are voltage gated channels located on non-myelinated axons
all along the axon
72
Where are voltage gated channels located on myelinated axons
nodes of ranvier
73
Describe spread of AP on non-myelinated axons
AP triggers local depolarizing electrical current that spreads along an axon, activating adjacent voltage-gated Na+ & K+ channels that generate new APs that end up at the terminal end of axons
74
What type of axon is more efficient & faster
myelinated
75
What effect does myelin have on an axon
insulates axons, which increases its signal transduction efficiency & enables local current to reach a longer distance
76
What is signal transduction efficiency
Rm (membrane resistance) / Rin (longitudinal resistance)
77
Current travels faster w/ what values for Rm & Rin
high Rm & low Rin
78
Describe spread of AP on myelinated axons
AP generates local currents that are strong enough to generate a new AP that is re-generated at each node of Ranvier
79
What is saltatory conduciton
describes how APs jump from node to node in myelinated axons
80
Why are APs called non-decremental
once an AP is conducted, the signal is constantly regenerated as it moves down the axon
81
What factors influence conduction speed
larger axon diameter results in less Rin (longitudinal resistance) & a faster conduction speed
myelination results in more Rm (membrane resistance) & a faster conduction speed
82
What is the result of demyelination
decrease in signal membrane efficiency; APs unable to reach node of Ranvier; sometimes voltage-gated Na+ & K+ channels will reappear alog the demyelinated areas of axons, but this occurs less w/ repeated demyelination events
83
Describe Multiple Sclerosis
demyelination disease; degenerative myelopathy-> progressive muscle weakness & incoordination; complete paraylsis & muscle atrophy
84
Locations for synapses
axosomatic; axodendritic; axoaxonic
85
Excitatory neurotransmitters & receptors
Acetylcholine w/ AChR (CNS & PNS)
| Glutamate w/ GluR (CNS)
86
Function of excitatory neuron & synapses
makes excitatory synapses; release excitatory neurotransmitters that depolarize the postsynaptic membrane
87
Steps of excitatory synapses
1) excitatory NTs are released & bind to receptors
2) receptors open ligand-gated ion channels for Na+
3) Na+ influx occurs (depolarization)
4) generation of graded potential EPSP
5) amplitude of EPSP is proportional to the amount of NTs released, the frequency of APs, & stimulus intensity
88
Inhibitory neurotransmitters & receptors
Glycine w/ GlyR (CNS)
| GABA w/ GABA receptor (CNS)
89
Function of inhibitory neuron & synapses
makes inhibitory synapses; releases inhibitory NTs that hyperpolarize postsynaptic membrane
90
Steps of inhibitory synapses
1) inhibitory NTs are released & bind to receptors
2) receptors open ligand-gated ion channels for Cl-
3) Cl- influx occurs (hyperpolarization)
4) generatation of graded potential IPSP
5) amplitude of IPSP is proportional to the NTs released, the frequency of APs, & the stimulus intensity
91
Properties of graded potentials
voltage change that depends on multiple factors (amount of NT, AP frequency, & stimulus intensity)
92
Graded potentials are summated where
axon hillock
93
How do graded potentials generate an AP
sum of graded potentials > threshold potential
94
Temporal summation involves
addition of multiple signals arriving at a single synaptic site (AA, BBB, CCC)
95
Spatial summation involves
addition of multiple separate signals arriving at different sites simultaneously (A+B, A+B+C, A+B+C+D)
96
Describe the axon hillock
located where the nucleus body meets the axon; contains voltage-gated Na+ & K+ channels (in contrast to the body that does not have voltage-gated channels & cannot generate an AP)
97
What is strychnine
pre-synaptic deficit of inhibitory synapses by toxins; muscle spasms 10-20 min after exposure; no GABA/ glycine so muscle contracts; death by asphyxiation
98
What is tetanus
pre-synaptic deficit of inhibitory synapses by toxins; toxin bound to inhibitory neurons for 3 weeks; prevents release of GABA/ glycine; results in over activity of skeletal muscle
99
Soma of multipolar motor neuron is found where
in ventral horn of spinal cord
100
Axon of motor neuron passes through where on the way to the muscle spindle
ventral root
101
Neuromuscular junction forms where
motor end plate (numerous nerve endings) & junctional fold of sarcolemma
102
Neurotransmitters & post-synaptic receptor at neuromuscular junction
Acetylcholine & AChR
103
Steps of neuromuscular junction
1) membrane depolarization by AP opens voltage-gated Ca2+ channels
2) synaptic vesicles release ACh by exocytosis
3) ACh & AChR open ligand-gated ion channels for Na+
4) Na+ influx & depolarization
5) voltage-gated Na+ & K+ channels open when membrane voltage > threshold voltage
6) APs of sarcolemma -> muscle contraction
104
Describe tic paralysis
pre-synaptic defect; neurotoxin secreted by feeding female wood tick that interferes w/ release of Ach; clinical sings = generalized muscle weakness/ paralysis days after attachment of ticks; recovery = 1-3 days after tick removal
105
Describe myasthenia gravis
post-synaptic defect; autoimmune disease; antibody blocks, alters, & destroys AChR which results in progressive loss of AChR & muscle strength; exercise-induced motor weakness that improves after rest
106
Define congenital defect
birth defect caused by genetics or environement (drugs, plants, infection, pesticide, radiation, etc)
107
Describe critical periods
point in time where an organ or organ system is developing
108
Why is susceptibility to birth defects increased during the middle section of the critical periods
lots of cell division which increases susceptibility to adverse environmental effects
109
When do critical periods occur
in utero & some after birth
110
How would you compare different species critical periods
same order, spread over different times
111
Order of critical periods
fertilization -> gene activation -> placentation -> brain & spinal cord -> vertebrae & tail -> head & face -> heart -> sense organs -> limbs -> palate -> reproductive organs -> cerebellum & cerebrum -> vision
112
What does cell restriction mean
as further cell division occurs, the cells become more restricted as to what cells they can become
113
What impacts cell restriction
factors released by other cells in the surrounding environment that signal for certain genes to be turned off
114
How can all cells in the body have the same DNA but different functions
some genes turned on & off
115
Cell restriciton progression
totipotent non-self renewing -> pluripotent self-renewing -> broad potential self-renewing -> limited potential & limited self-renewal -> limited division non-functional -> non-mitotic functional
116
Function of zona pellucida
causes dividing cells to increase in number but decrease in size; allows a large zygote to become a normal sized cell
117
First 8 cells during cell celavage are undifferentiated & have identical potential until they differentiate into
inner & outer cells
118
Outer blastomeres in morula phase become what
trophoblasts in blastula phase
119
Trophoblasts become what
placenta
120
Inner blastomeres in morula phase become what
inner cell mass in blastula phase
121
Inner cell mass becomes what
embryo & 2 fetal membranes
122
In blastula phase, what happens to the inner cell mass
localizes to one pole inside a cavity (blastcoele) that is formed by the surrounding trophoblast cells
123
When does the embryo first start growing in size
during morula divisions
124
Cavity that forms in blastula phase is important for
diffusion of nutrients/ waste
125
Separation of early blastomere (up to 8 cell stage) leads to what
each blastomere develops into an independent embryo & placental membrane
126
Separation of inner blastomeres w/in a single morula leads to what
each separate blastomere develops into an independent embryo but the placenta is shared
127
Separation at later stages of development (near gastrulation) leads to what
shared amniotic cavity; umbilical cord may twist around neck or conjoined twins result when there are two primitive streaks but the inner cells masses do not separate enough
128
Gastrulation marks what
beginning of organ & body development
129
End result of gastrulation is
formation of 3 germ layers (endoderm, mesoderm, & ectoderm)
130
Beginning of gastrulation has a bilaminar disk with what parts
yolk sac (RBC production) & amniotic cavity
131
Cells surrounding biconcave disk (gastrulation)
tall cells = epiblast; short cells under other cells = hypoblast
132
Differential growth of epiblast cells generate what
primitive node & primitive streak
133
W/ a primitive streak, what is established
polarity (head vs tail; left vs right)
134
Describe what the epiblast cells become that flow through (or stay at) the primitive groove
1) some flow deep w/in the embryo -> endoderm
2) flow above deep layer & below epiblast cells that do not migrate -> mesoderm
3) epiblast cells that stay -> ectoderm
135
Epiblast cells that move cranially through the primitive groove form
notochord
136
Endoderm
lining of digestive & respiratory tracts; organs of digestion
137
Mesoderm
muscle, skeletal tissue, urogenital, & cardiovascular
138
Ectoderm
epidermis, neural tissue, & some skeletal/ CT of head
139
Divisions of mesoderm & what they become
somatic -> body wall; splanchnic -> organs
140
Location of other germ layers in relation to division of mesoderm
ectoderm adj to somatic mesoderm & endoderm adj to splanchnic mesoderm (both good arrangements)
141
How is the coelom of the embryo closed during body wall closure
both sides of somatic mesoderm grow ventrally & medially until they meet
142
How is the primitive gut tube closed during body wall closure
both sides of splanchnic mesoderm grow ventrally (just not as much as somatic mesoderm) & medially until they meet up
143
End result of body wall closure
folded embryo w/ body wall & primitive gut in center
144
What is amorphus globosus
free, asymmetrical twins; outside = hairy ball & integument; inside = bundles of muscle, cartilage, bones, & teeth; unknown cause
145
CNS critical periods
1st organ system to start differentiation & last organ (besides eyes) to finish differentiation
146
Neural tube is derived from
ectoderm
147
When does neural tube formation occur
shortly after gastrulation
148
Notochord releases factors that induce the surface epithelium to become
neural plate
149
Underlying ectoderm & mesoderm that become raised on each side of a midline depression are called what and form what
neural fold & neural groove
150
Neural folds separate from the surface ectoderm & contact each other, forming what
cavity
151
What allows the cavity in the neural tube to communicate w/ the amniotic cavity
neuropores
152
If neuropores do not close properly, what happens
developmental issues occur
153
Where does neural tube closure start in
cervical area
154
Is neural tube closure a dynamic process
yes
155
What direction does the neural tube close
rostro-cranial & caudal
156
What cells separate from the ectoderm during neural tube closure
neural crest cells
157
Neural crest cells become
sensory ganglia of cranial nerves V, VII, IX, & X, schwann cells, enteric ganglia, parasympathetic ganglia, dorsal root ganglia, sympathetic ganglia, adrenal medulla
158
What completely surrounds the neural tube & is b/w the surface ectoderm & neural crest cells
mesoderm
159
What are the layers of the neural tube
mantel & marginal layer
160
What does the mantel layer contain
developing neurons
161
What does the marginal layer contain
axons projecting from the mantel layer
162
Divisions of mantel layer
alar & basal plate
163
Alar plate cells become
dorsal horn -> sensory
164
Basal plate cells become
ventral horn -> motor & autonomic
165
In spinal cord formation, what happens to the alar & basal plates compared to the roof & floor
alar & basal plates expand while roof & floor do not
166
What results from the minimal development of the roof & floor plates
median fissure & dorsal sulcus
167
How does the ventral root form
neuronal cell body in ventral horn projects axon into periphery (target is skeletal muscle)
168
How does the dorsal root ganglion form
neural crest cells migrate in dorsal root; project one axonal projection to the spinal cord & one axonal projection to a target (sensory receptor)
169
What is a ganglion
collection of neuronal cell bodies outside the CNS
170
What is a nucleus
collection of neuronal cell bodies inside the CNS
171
What leaves the vertebral column when the spinal cord completely fills it
spinal nerves that innervate muscle bundles (somite)
172
As differential growth occurs in the spinal cord, what happens
embryo & vertebral column grow faster than the spinal cord -> results in a positional shift
173
As the spinal nerve moves in a cranial direction, what happens
roots of spinal nerves become elongated
174
As the spinal cord moves, what is a critically important aspect of the spinal nerves
must maintain contact w/ muscle bundles (somites)
175
Further elongation of spinal nerve roots as spinal cord continues to move cranially gives rise to what
cauda equina
176
What is spina bifida
malfunction in formation of neural tube that results in the malformation of a vertebral arch
177
Describe spina occulta
most benign spina bifida; 1-2 vertebrae lack vertebral arch
178
Describe myeloschisis
form of spina bifida; neural tube does not form; no meninges on top to protect spinal cord
179
Describe meningomyelocele
form of spina bidfida; small abnormal segments; meninges & spinal cord herniated through where the vertebral arch should be
180
Neural tube gives rise to
spinal cord & brain
181
Wall of brain has what
mantle & marginal layers
182
Primary vesicles of brain are what
forebrain, midbrain, & hindbrain
183
The primary vesicles of brain become what
five secondary vesicles
184
Neural tube cavity forms what
2 lateral ventricles, third ventricle, fourth ventricle, & aquaduct
185
Forebrain becomes
cerebral hemispheres
186
Midbrain becomes
midbrain
187
Hindbrain becomes
cerebellum
188
In midbrain/ hindbrain development, what do the alar & basal plate become before they pick up sensory vs motor functions
Alar - visceral/ somatic afferant
| Basal - visceral/ somatic efferant
189
In cerebellar development, alar plate cells stream dorsal to what until they make contact w/ each toher
4th ventricle
190
What early structure provides the bulk of the cerebellum
external germinal layer
191
As axons project from the external germinal layer & move past dendritic processes of Purkinje cells, what happens
functional synaptic connections are made
192
Viral causes of cerebellar hypoplasia target the external germinal layer, leading to
Purkinje cells dying; small cerebellum
193
In cerebrum development, what cells receive a signal & what signal do they receive
mantel layer cells keep dividing & receive a signal to migrate through the marginal layer
194
Mantel layer cells continue continue dividing and receive a second signal to do what
migrate through the marginal layer & past the previously migrated layer
195
As mantel layer cells keep migrating, what happens
functional connections are made
196
Movement of mantel layer cells explains what
why grey matter is on the outside (instead of inside like in the spinal cord)
197
Migration of mantel layer cells allows the brain to have what feature
convulated surface (sulcus = depression & gyrus = elevation)
198
Describe ancephaly
either lack of or diminished brain
199
Describe lissencephaly
smooth cortex
200
Describe cranium bifidum
brain outside of head; result of a disruption in neural tube formation
201
Describe hydrocephalus
choroid plexus makes CSF but it does not get absorbed
202
Which pituitary gland has a direct neuron connection
posterior
203
Which pituitary gland has a indirect neuron connection via the cardiovascular system
anterior
204
Posterior pituitary comes from what
direct downgrowth from the floor of the forebrain
205
Anterior pituitary comes from what
ectoderm from embryos mouth
206
Describe formatioon of neuron connection of posterior pituitary
neuronal cell bodies in brain project axons to posterior pituitary where it synapses on the target cell
207
Describe formation of neuron connection of anterior pituitary
neuronal cell bodies in brain synapse on a portal vein that then carries the released product to the anterior pituitary target cell
208
Adult heart blood flow
cranial & caudal vena cava -> RA -> RV -> pulmonary trunk -> pulmonary arteries -> lungs -> pulmonary veins -> LA -> LV -> aorta -> body
209
Function of RA
systemic return
210
Function of RV
pulmonary outflow
211
Function of LA
pulmonary return
212
Function of LV
systemic outflow
213
Organization of adult heart
atria dorsal to ventricles
atria adj to each other
ventricle adj to each other
pulmonary trunk & aorta (outflow) spiral around each other
214
CVS critical periods
1st organ to functionally differentiate
215
When does the heart 1st beat
around neural tube closure
216
Where does the cardiogenic plate start
in an extra-embryonic location
217
During body folding, where does the cardiogenic plate go
moves 180 degrees into embryo where the adult mandible is
218
W/in the endocardial plate, what spontaneously contracts
two endocardial tubes
219
Endocardial tubes become folded into each other until they fuse and what happens
1st heart beat
220
The embyologic heart first beats how
peristaltic from caudal to cranial
221
What are the primitive heart regions from inflow (caudal) to outflow (cranial)
sinus venosus -> atrium -> ventricle -> bulbus cordus -> truncus arteriosus
222
Sinus venosus becomes
left -> coronary sinus
| right -> part of atrium wall
223
Atrium becomes
right & left atria
224
Ventricle becomes
right & left ventricle
225
Bulbus cordis becomes
part of right (conus arteriosus) & part of left ventricle
226
Truncus & bulbus cordis become
ascending aorta & pulmonary trunk
227
Differential growth of cardiac loop results in
rotation of the developing heart to the right side
228
By the end of the cardiac loop formation, what happens
atrium is dorsal to the ventricle & bulubs cortis & ventricle are both next to each other
229
Inside the cardiac loop, there is a constriction b/w the atrium & ventricle called the
atrioventricular canal
230
Endocardial cushions on each side of the atrioventricular canal starts growing towards each other until they
make contact, thus dividing the atrioventricular canal
231
Goal of atria patitioning
blood to flow from RA -> LA & for there to be a way to block it later
232
As septum 1 starts growing down towards endocardial cushions what forms
foramen 1
233
Septum 1 eventually reaches the endocardial cushions and does what
closes out foramen 1
234
Apoptosis in septum 1 leads to what
foramen 2
235
Septum 2 forms & moves across atria; space w/in incomplete septum is
foramen ovale
236
Blood flow after atrial partitioning
RA -> oval foramen -> in b/w septum 1 & 2 -> foramen 2 -> LA
237
Outflow separation occurs w/ the partitioning of
truncus arteriosus & bulbus cordis
238
What invades the lumen of truncus arteriosus and grow together until they meet
cushions
239
What eventually results in the formation of a spiral septum dividing the outflow
cushions close at dif orientations/ levels
240
What is the name of the elevation that first forms b/w the ventricles
interventricular septum
241
What forms w/in the IV septum
IV foramen
242
Is a right to left shunt necessary in the ventricles
no so IV foramen closes
243
What has to happen to close the IV foramen
1) IV septum grows upwards
2) projection from endocardial cushions move downwards
* 3) formation of spiral septum; one part of developing septum fuses w/ IV septum & the other part fuses w/ the partitioning of atriventricular canal
244
Describe ectopic cordis
heart in abnormal location; occurs when thoracic cavity or sternebrae fuse before heart moves to the proper location
245
Describe dextocardia
basic folding of heart is swapped & cardiac loop goes to the right instead of the left
246
Describe valvular defects
stenosis (narrow valve); insufficiency (leaky valves); dysplasia (abnormal development)
247
Describe partitioning errors
at any step
248
Describe tetralogy of fallot that results from an uneven division of the spiral septum
1) IV septal defect
2) pulmonary stenosis (narrow)
3) dextroposition (overriding) of aorta
4) right ventricular hypertrophy (occurs b/c RV pumps blood into a smaller pulmonary trunk & is exposed to higher pressure of LV)
249
Explain fetal circulation
blood from placenta -> umbilical vein -> liver -> caudal vena cava (shunt through ductus venosus can skip over liver) -> caudal vena cava -> RA -> oval foramen -> in b/w septum 1 & 2 -> foramen 2 -> LA -> LV -> aorta -> head or umbilical arteries
also from caudal vena cava plus cranial vena cava -> RA -> RV -> pulmonary trunk -> ductus arteriosus -> aorta -> head & umbilical arteries
250
What is unique about fetal circulation compared to adult circulation
RV & LV both cotnribute to systmic output b/c blood flow must support the fetus & placenta
251
What happens to umbilical arteries in the trainsition to post natal life
crushed by mother; springs back & muscular wall closes
252
What signals the umbilical vein & ductus venosus to close
decreased bp & PGE2
253
What signals the oval foramen to close
bp RA decreases- removal of placenta
bp LA increases- addition of lungs
septum 1 & 2 fuse
254
What signals the ductus arteriosus to close (this one takes the longest)
decreased bp & PGE2
| increased O2
255
Embryo starts w/ 2 dorsal aortae that fuse; what is the arrangement of these
cranial to heart is 2 dorsal aortae & ventral to heart is a common dorsal aorta
256
What connects the dorsal aortae to the ventral aorta
aortic arches
257
Where is the developing GI system located
in b/w aortic arches
258
What are the numbers for aortic arches
1, 2, 3, 4, & 6
| 5 only develops in lower vertebraes
259
What aortic arches degenerate first
1 & 2
260
Degeneration at dorsal aorta b/w 3rd & 4th aortic arches allows for what
3rd - responsible for head
| 4th - responsible for body
261
Symmetry is lost with aortic arches when what happens
6th right aortic arch degenerates
| right dorsal aorta separates from the common aorta
262
3rd right & left aortic arches become
internal carotid artery (supply head)
263
4th left aortic arch becomes
aortic arch
264
4th right aortic arch becomes
subclavian artery
265
6th left aortic arch becomes
ductus arteriosus
266
Why does the 6th right aortic arch degenerate
cuts right side free so that there is no ring around the developing GI system
267
Describe patent ductus arteriosus
ductus arteriosus fails to close
268
Describe aortic coarctation
constriction that occurs if differential growth is abnormal
269
Describe what a vascular ring anomaly consists of (in general)
right side fails to become free
270
Result of right 4th aortic arch becoming adult arch & right 6th aortic arch becoming the ductus arteriosus
sitrus inversus
| right -> right connection
271
Result of right 4th aortic arch becoming the adult arch & left 6th aortic arch becoming the ductus arteriosus
vascular ring
pulmonary artery, arch of aorta, & ligamentum arteriosum surround esophagus
prevents solid food from traveling further through the esophagus
right -> left connection
272
Describe pronephros kidney
7-8 tubules
non-functional
degenerates
273
What parts of pronephros kidney remain
pronephric duct persists as the mesonephric duct
274
Describe mesonephros kidney
70-80 tubules
functional
degenerates
275
What parts of mesonephros kidney remain
caudal tubules & mesonephric duct remain to form testicular channels, epididymis, ductus deferens, & contribute to gonad development
276
Describe metonephros kidney
last attempt at making a kidney
| functional kidney
277
Mesonephric duct forms a bud called what
metanephric diverticulum
278
As the metanephric duct invades the surrounding mesoderm, what forms
metanephrogenic mass
279
As the kidneys develop, where do they move to
from pelvic cavity to abdomen
280
Metanephric diverticulum gives rise to
all urinary conducting tubes up to the bladder
| ureter, renal pelvis, calyxes, & collecting ducts
281
Metanephrogenic mass gives rise to
nephron
282
When does nephron formation end
around the time of birth
283
Can new nephrons be made after birth
no
284
Urinary bladder develops from an expansion of
urachus & cranial part of urogenital sinus
285
Urogenital sinus in males gives rise to
pelvic & penile urethra
286
Urogenital sinus in females gives rise to
pelvic urethra, vestibule of vagina, & caudal vagina
287
At the beginning of urinary bladder development, where does the mesonephric duct open
at site of future urinary bladder
288
As the bladder moves dorsally, what happens
metanephric diverticulum (future ureter) opens near bladder at site of future urethra
289
Differential growth of the urogenital sinus moves what around
metanephric diverticulum (future ureter) shifts to open in the future bladder & mesonephric duct (future ductus deferens) moves to open into future urethra
290
Evidence of differential growth & swapping of ducts in adult animal
trigone region
291
Varied development of the metanephric diverticulum & metanephrogenic mass leads to
dif kidney shapes among animals
292
Describe renal agenesis
kidney fails to develops
293
Describe renal dysplasia
abnormal growth (horseshoe kidney)
294
Describe renal hypoplasia
small kidney
295
Describe patent urachus
urachus does not close at birth
| wet umbilical stalk -> infection
296
What is the urachus
channel extending from cranial part of urinary bladder that goes down the allentoic stalk & into the allentoic cavity
297
Function of urachus
moves urine out of embryonic bladder
298
Urachus membrane does what
prevents urine from going the alternate route to the amniotic cavity until later in development
299
Describe ectopic ureter
transposition in dorsal part of urogenital sinus does not occur so the ureter opens to the urethra or vagina vestibule
300
Describe ectopic kidney
kidneys stay in pelvic area; issue during pregnancy
301
Testis influence what hormone(s)
ovarian-inhibiting substance & testosterone
302
Ovarian inhibiting substance does what
suppresses paramesonephric duct
303
Testosterone does what
stimulates mesonephric duct (ductus deferens & epididymis)
metabolites stimulate male external genitalia (penis/ scrotum) & accessory sex glands
304
Ovaries influence what hormone(s)
estrogen
305
Estrogen does what
stimulates paramesonephric duct (uterine tube, uterus, & cranial part of vagina)
stimulates formation of female external genitalia (labia, clitoris, & caudal part of vagina)
306
What is the effect of the fact that genetic sex is determined at fertilization, but it takes a while for the signal to reach the entire embryo
indifferent stage
307
Early reproductive system has what duct(s)
both paramesonephric & mesonephric
308
What develops in the caudal part of the yolk sac & migrates to the developing embryo through the hindgut, mesentery, & into mesoderm (urogenital development)
primordial germ cells
309
Primordial germ cells form what ventral to the mesonephros
genital/ gonadal ridge
310
Cells from degenerating mesonephric tubules join w/ primordial germ cells to form
gonadal cords
311
Genital tubercle in males give rise to
glans of penis
312
Genital tubercle in females give rise to
clitoris
313
Urogenital folds in males give rise to
ventral penis
314
Urogenital folds in females give rise to
labia of vulva
315
Labioscrotal swelling in males give rise to
scrotum
316
Labioscrotal swelling in females give rise to
poorly develops in domestic animals
317
Explain testicular descent
gubernaculum tethers testicle to scrotum as embro continues growing
swelling of gubernaculum dilates inguinal canal & scrotum
shrinking of gubernacuum pulls testicles into scrotum
318
What causes gubernaculum to swell
mesenchymal cells influence ECM to produce hyaloronic acid, which attracts water & causes swelling
319
What causes gubernaculum to shrink
mesenchymal cells influence ECM to produce less hyaloronic acid, which causes shrinkage as water leaves
320
Remnants of gubernaculum
tail of the epididymis & proper ligament of the testis
321
In ovarian development, what breaks down
gonadal cords
322
Oocytes are surrounded by epithelial cells (called follicular cells) that are derived from
mesonephric duct
323
Varied paramesonphric duct formation amongst species leads to
varied fusion of vagina & uterus
324
Vagina & uterus duplex means
no fusion; 2 uteri, 2 cervixes, & 2 vaginas
325
Vagina simplex/ uterus duplex means
some fusion; 2 uteri, 2 adj cervical canals, & 1 vagina
326
Uterus bicornis means
most fusion; 2 uterine horns, 1 uterine body, 1 cervix, & 1 vagina
327
Describe genital hypoplasia
few or no germ cells
328
Describe cryptorchism
retained testicle(s)
329
Describe stenosis of duct
abnormal fusion -> narrowed ducts
330
Describe genital hypospadia
occurs in males; urogenital sinus & urogenital folds do not close properly
331
Describe intersex conditions
improper hormonal signaling
332
Describe free martin
dizygotic twins of opposite genders influence hormone signals -> infertility issues
more pronounced in females since male differentiation starts earlier than female differentiation
333
Foregut gives rise to
esophagus, stomach, descending duodenum, liver, & pancreas
334
Blood supply of foregut
celiac artery (also supports spleen)
335
Foregut fermenters are
ruminants
336
Midgut gives rise to
ascending duodenum, jejunum, ileum, cecum, ascending & transverse colon
337
Blood supply of midgut
cranial mesenteric artery
338
Hindgut gives rise to
descending colon
339
Blood supply of hindgut
caudal mesenteric artery
340
Hindgut fermenters are
equine
341
At the start of gastric rotation, what occurs
differential growth of the dorsal stomach wall
342
90 degree rotation around what axis moves the dorsal portion of the stomach in what direction
longitudinal axis
| left
343
Rotation around what axis shifts what end of the stomach to the right & cranially
dorsoventral axis
| caudal end
344
End result of gastric rotation
descending duodenum on right & fundus on left
345
What organs are still supported by a vetnral mesentery
stomach & caudal part of bladder
346
For the stomach to be able to rotate, what has to happen
one mesentery has to grow
347
Dorsal mesogastrium does what
grows into greater omentum
348
Greater curvature of stomach is equivalent to the embryologic
dorsal
349
Ventral mesogastrium does what
no growth but becomes lesser omentum
350
Lesser curvature of stomach is equivalent to the embryologic
ventral
351
At the start of intestinal development, the intestines are supported by
elongated dorsal mesentery & cranial mesenteric artery
352
Cecum forms from what
evagination of the caudal limb of the intestinal loop
353
Intestines first loop towards the umbilicus & yolk sac to produce what
physiological herniation
354
What fixes the duodenum to the right during intestinal development
short dorsal mesentery
355
What part of intestinal loop has explosive growth
cranial limb
356
Cranial limb passes to the right side of what during its first phase of explosive growth & results in what
cranial mesenteric artery
| cranial & caudal limb switch places
357
Cranial limb grows in a cranial direcion and does what
sweeps caudal limb to the right
358
As the embryo continues growing, what happens to the developing intestines
become drawn back into the body cavity
359
270 degree rotation of developing intestines forms what
mesenteric root
360
Caudal to the mesenteric loop, what part of the intestines in involved & how does ingesta flow
caudal duodenal flexure
| right -> left
361
Cranial to the mesenteric loop, what part of the intestines in involved & how does ingesta flow
transverse colon
| right -> left
362
Cloaca is closed by what
cloacal membrane
363
Urorectal septum at the junction b/w the hindgut & urogenital sinus does what (cloaca separation)
grow caudally dividing anal canal & rectum from urogenital sinus
divides cloacal membrane into anal & urogenital membrane
364
Describe intestinal stenosis
narrowing due to rapid growth of epithelial cells
| no recanalization
365
Describe intestinal atresia
blood supply lost
| results in some missing intestines
366
Describe atresia ani
anal membrane doesn't break down
| no anus
367
Describe urorectal fistula
urorectal septum fails to divide correctly
368
Basic elements of pharyngeal arches
aortic arch, cartilage rod, nerve, & muscle
369
Pharyngeal arch 1 gives rise to
CN V (Trigeminal nerve)
mandible, maxilla, incus, & malleus
muscles of mastication & rostral digastricus
370
Pharyngeal arch 2 gives rise to
CN VII (Facial nerve)
hyoid & stapes
muscles of facial expression & caudal digastricus
371
Pharyngeal arch 4 & 6 give rise to
CN X (Vagus nerve)
laryngeal cartilage
4 -> cricothyroideus muscle
6 -> remaining intrinsic laryngeal muscle
372
Recurrent layngeal nerve is a branch from what
CN X (Vagus nerve) -> caudal laryngeal nerve -> recurrent laryngeal nerve
373
Explain path of left recurrent laryngeal nerve
left 6th aortic arch is maintained
| recurrent laryngeal nerve wraps around ligamentum arteriosus
374
Explain path of right recurrent laryngeal nerve
right 6th aortic arch degenerates & right 5th never develops
recurrent laryngeal nerve wraps around the right subclavian artery
375
To prevent cheiloschisis, what has to happen
cleft lip
| medial nasal process & maxillary process must grow together
376
Can a cleft lip occur on just one side
yes, left right or both
377
Start of closing off a cleft palate
combined oronasal cavity where nasal pits excavate into the developing animals head
378
What leads to the separation of the oronasal cavities
maxillary process -> primary palate
| lateral palatine process -> secondry palate
379
As the tongue b/w the secondary palates shrinks, wht happens
secondary palate becomes more horizontal
| right & left secondary palates connect
380
To prevent palatoschisis, what has to happen
cleft palate
| right & left secondary palates must connect before the head of the developing animal grows
381
What divides the nasal cavity in two
nasal septum that grows down to make contact w/ the palate
382
Secondary palates fuse w/ primary palate, what do the rostral 2/3rd & caudal 1/3rd become
2/3rd - ossify into hard palate
| 1/3rd - no ossification, soft palate
383
Trachea begin to develop as a laryngotracheal groove where
ventral part of pharynx in b/w the 4th & 6th pharygeal arches
384
As laryngotracheal groove stretches caudally, what happens
trachea is pinched off the ventral part of the esophagus
385
Trachea moves to what area where the lung will develop
mesodermal area
386
Airway conducting part of the lung divides, developing into
primary & secondary bronchi
387
When do alveoli develop & why is this important
late, most post-natally
| pneumonia is severe in young animals
388
Why do the ribs move in utero
to prevent joints from fusing
strengthens muscles that will be used for breathing
takes in amniotic fluid
389
What is the first thing that happens during the postnatal transition for the respiratory system
calf presents normally
| cow bears down on calf -> squeezes thoracic cavity
390
Once the umbilical cord connection is lost, what must the lungs do
increase surface area
| get rid of fluid & start gas exchange
391
Importance of lymphatic vessels in alveolar compartments in the lungs of a newborn
large in diameter
| help capillaries to remove amniotic fluid
392
Describe pulmonary hypoplasia
abnormal structure in pleural cavity prevents lungs from growing normally
393
Describe tracheal hypoplasia
occurs in brachiocephalic breeds
394
Describe tracheoesophageal fistula
connection b/w esophagus & trachea persists post-natally
395
Name for pain receptors
nociceptor
396
Name for temp receptors
thermoreceptor
397
Name for touch receptors
mechanoreceptors
398
Name for proprioception receptors
proprioceptors
