Learning Issues Week 2 Part 2 Flashcards Preview

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Flashcards in Learning Issues Week 2 Part 2 Deck (60)
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1
Q

Dog arterial circle via vertebral artery

A

Aorta -> B. cephalic trunk -> Right subclavian -> vertebral artery -> transverse vertebral foramina -> vertebral canal (via foramen in atlas) -> join basilar artery -> arterial circle

2
Q

Dog arterial circle via int carotid

A

aorta -> B cephalic trunk -> common carotid -> int carotid -> TOF -> carotid canal (v to petrous temporal bone at junction tympanic and basioccipital bones -> foramen lacerum-> middle cr fossa ( near rostral tip petrous temporal bone) -> cavernous sinus -> penetrate meningeal dura and arachnoid and feed arterial circle in subarachnoid space on V aspect diencephalon

3
Q

cat blood supply to arterial circle via maxillary artery

A

aorta -> B cephalic trunk -> common carotid artery -> ext carotid -> maxillary artery -> round foramen -> alar canal -> rostral alar foramen -> arterial rete (maxillary rete) -> arterial circle

4
Q

cat blood supply to arterial circle via vertebral artery

A

aorta -> b. cephalic trunk -> subclavian artery - vertebral artery -> transverse vertebral foramina -> vertebral canal (via foramen in atlas) -> basilar artery -> arterial circle

5
Q

cat blood supply to arterial circle via maxillary artery

A

aorta -> B cephalic trunk -> common carotid artery -> external carotid artery -> maxillary artery -> orbital fissure -> arterial rete -> arterial circle

6
Q

vertebral artery and cats

A

blood supply from the vertebral artery doesn’t contribute significantly to cerebral hemisphere circulation in sheep and cats and blood often flows arterial circle to basilar artery

7
Q

rostral cerebral artery

A

bilateral; runs rostrally than dorsally into the longitudinal fissure to supply medial aspect of rostral telencephalon

8
Q

middle cerebral artery

A

bilateral; runs laterally then dorsally to supply lateral hemisphere. Proximal branches supply basal nuclei, internal capsule, and choroid plexus of lateral ventricle

9
Q

caudal cerebral artery

A

bilateral; runs dorsally between diencephalon and hemisphere into longitudinal fissure to supply the thalamus, and medial aspect cd telencephalon

10
Q

rostral cerebral, middle cerebral, and caudal cerebral arteries

A

branches of these arteries anastomose dorsally but these anastomoses are not adequate to supplyy brain if one of these major arteries becomes occluded

11
Q

rostral cerebellar arteries

A

bilateral; arise from arterial circle; supply midbrain and rostral cerebellum

12
Q

caudal cerebellar arteries

A

bilateral; arise from basilar artery, supply cd cerebellum

13
Q

pontine and medullary branches

A

bilateral; branches of basilar artery that supply pons and medulla

14
Q

veins draining blood from brain parenchyma

A

converge on venous sinuses

15
Q

venus sinuses

A

endothelial lined channels continuous with venous system located within bony canals and within dural reflections between periosteal and meningeal layers of dura

16
Q

venous sinuses of skull convey blood to

A

maxillary, internal jug, vertebral veins, and internal vertebral venous plexsus

17
Q

dorsal system

A

dorsal sagittal sinus, starlight sinus, transverse sinus, sigmoid sinus, temporal sinus

18
Q

dorsal sagittal sinus

A

located in dorsal aspect of falx cerebra, drains cerebral hemispheres drain to transverse sinus

19
Q

straight sinus

A

at junction of falx ceribri and tentorium cerebelli; drains deeper parts of the brain; drains to transverse sinus

20
Q

transverse sinus

A

located within the occipital bone and tentorium cerebelli adjacent to the occipital bone; it divides at the caudal aspect of the petrosal crest into 2 branches

21
Q

sigmoid sinus

A

runs medial to the PTB splits and exits skull via jugular foramen to join the internal jugular vein and vertebral vein or joins internal vertebral venous plexus

22
Q

temporal sinus

A

runs caudolateral to PTB (b/w petrous and squamous parts of temporal bone); exists skull via retroarticular foramen, joins maxillary vein

23
Q

ventral sinus systems

A

cavernous sinus

24
Q

cavernous sinus location

A

bilateral; one on either side of hypophyseal fossa

25
Q

what runs through cavernous sinus

A

internal carotid arteries; CNs III, IV, V1, V2, VI and sympathetic postganglionic fibers traveling to the face (including the eye) run through/ adjacent sinus

26
Q

where do structures running through cavernous sinus lie

A

these structures are not actually within the sinus, bathed in blood, a layer of endothelium encloses the blood in the sinus and these structures run adjacent to the venous vascular channels

27
Q

what drains to cavernous sinus

A

receives blood daring from ventral brain and skull, face, orbit, and nasal cavity

28
Q

ruminants branches of maxillary artery

A

on either side form a rete mirabile within the cavernous sinus. May protect the brain from overheating when body temp rises during flight from predator

29
Q

blood in cavernous sinus can drain by flowing caudally

A

ventral to PTB -> basilar sinus within the occipital bone -> internal vertebral venous plexsus

30
Q

blood in cavernous sinus can drain into venous branches

A

which exit skull via multiple foramina to join the maxillary vein

31
Q

venous system drainage flow follows path of

A

lowest pressure since sinuses do not have valves. The majority of blood leaving skull flows to the internal vertebral venous plexus and the maxillary veins

32
Q

which sinuses are not bilateral

A

dorsal sagital and straight sinuses (midline structures)

33
Q

blood flow direction transverse and temporal sinuses

A

medial to lateral

34
Q

blood flow direction sigmoid sinus

A

medially

35
Q

vertebral venous plexus

A

paired interconnected veins on floor of vertebral canal in epidural space;

36
Q

how does blood leave vertebral venous plexus

A

via segmental intervertebral veins at the intervertebral foramina which drains into vertebral vein, azygous vein, cd vena cava

37
Q

vertebral venous plexus anastamoses

A

inconsistent dorsal and ventral segmental anastomoses occur between veins on either side

38
Q

vertebral venous plexus reservoir

A

provides low pressure reservoir for blood if other vessels are congested

39
Q

what enlarges vertebral venous plexus

A

is often enlarged in situations of increased abdominal pressure such as pregnancy and abdominal tumors

40
Q

stagnant blood in vertebral venous plexsus

A

can facilitate the seeding of tumors or infectious agents within the vertebral column

41
Q

vertebral venous plexus in case high pressure

A

blood may move in retrograde direction into the venous sinus of cranial cavity

42
Q

vertebra venous plexus clinical significance

A

can be quite large, may be punctured during attempts at epidural or intrathecal injection

43
Q

blood CNS barrier overview

A

prevents bad things from exiting capillaries in the brain; CNS requires stable and specific chemical environment; many chemicals, proteins, drugs are excluded from CNS; barriers can be compromised under various circumstances

44
Q

what would happen if extracellular fluid of CNS had sam chemical composition of blood

A

neurons would be exposed to constantly changing chemical environment that would cause erratic activity in neuron circuits and failure of the system; fx neurons in CNS highly sensitive to alterations in pH and ionic composition of CNS interstitial fluid that neuromodulators or toxins

45
Q

systems to ensure proper conditions maintained in interstitial compartment of CNS

A

relay of fact that lipid bilayer of cell membranes and tight junctions btwn cells are relatively impermeable to diffusion of large/ and or charged molecules

46
Q

lipid membranes ineffective at

A

excluding small lipophilic molecules and gases such as CO2 and O2; barrier cells in these system scan transport specific large or charged molecules across their cell membranes into CNS and can exclude certain lipophilic molecules by active efflux pumps

47
Q

3 major components CNS barrier system

A

arachnoid cellular layer, blood- CNS barrier, Blood-CSF barrier

48
Q

arachnoid cellular layer

A

cells in this layer have tight junctions between them; barrier layer prevents substances from leaky vessels and interstitial fluid within and external to dura from contaminating CSF in the underlying subarachnoid space

49
Q

substances in subarachnoid space

A

can easily penetrate the pia matter and enter the brain or spinal cord

50
Q

Blood-CNS barrier

A

endothelium lining blood vessels within subarachnoid space and brain/ spinal cord tissue is specialized; tight junctions between non-fenestrated endothelial cells exclude many molecules from diffusing into molecuels

51
Q

astrocyte foot processes

A

play a role in barrier by modifying permeability of endothelial cells and controlling active transport mechanisms across endothelial barrier; cover most of basement membrane off capillary endothelial cells

52
Q

blood brain barrier inaccurate name

A

because same system in spinal cord; desired substances can cross capillary endothelium via facilitated diffusion or active transport

53
Q

Blood-CSF barrier

A

apical tight junctions btwn choroid epithelial cells in choroid plexus prevent free diffusion of substances from leaky choroidal capillaries into CSF; composition CSF dictated by these cells via numerous transport mechanisms; critical bc ependymal lining of ventricles is permeable and any substances in CSF will end up in brain/ spinal cord extracellular space as well

54
Q

intercerebrayl blood vessels

A

have tight junctions between non-fenestrated endothelial cells

55
Q

blood vessels in choroid plexsus

A

are leaky; choroid epithelium has tight junctions allowing CSF composition to be tightly regulated

56
Q

arachnoid cellular layers

A

has tight junctions allowing this barrier to exclude substances originating external to mingles from CSF and subarachnoid space

57
Q

fluid within SAS and ventricles

A

in free communication with interstitial compartment of brain and spinal cord tissue and plays an important tole in delivering substances and removing waste from NT

58
Q

clinical relevance CNS barrier system

A
  • CNS barrier system excludes many proteins, drugs, and other molecules from CNS; large ionized and/ or non-lipid soluble drugs may not achieve therapeutic levels in CNS; lipid soluble drugs may be excluded due to efflux pumps
  • can take advantage of this when trying to keep drug like Claritin from causing drowsiness bc keep it from crossing CNS barrier
59
Q

disruption barrier system

A

may occur during dx; fever, inflammation, elevated bilirubin can compromise brain barrier system -> CNS dysfunction because alteration in CNS chemical microenvionrment

60
Q

Circumventricular organs

A

play role in monitoring composition plasma and require access to components normally excluded by blood brain barrier; these regions of brain lack blood brain barrier to perform their fx; ex leaky capillary beds in hypothalamus and pituitary gland