Cardiovascular Flashcards
what is the definition of an artery?
blood vessel that carries blood away from the heart
what is the definition of a vein?
blood vessel that carries blood to the heart
what are the exceptions to the O2 concentration trends in arteries and veins?
pulmonary arteries/veins, umbilical arteries/veins in fetus
what is the first functional system to develop in vertebrate embryos?
the vascular system
what 2 processes does development of blood vessels occur via?
vasculogenesis and angiogenesis
which is first vasculogenesis or angiogenesis?
vasculogenesis
what is vasculogenesis?
de novo making of primitive blood vessels
what is angiogenesis?
remodelling of primary capillary networks, formation of arteries and veins
what do blood and vessels develop from in intraembryonic vasculogenesis?
lateral plate mesoderm
what do blood and vessels develop from in extraembryonic vasculogenesis?
extrembryonic mesoderm associated with yolk sac (endoderm derived)
what does intraembryonic vasculogenesis form?
dorsal aorta and posterior cardinal vein, capillary networks in mesoderm of each organ
what do de novo blood vessels develop from?
blood islands
what are blood islands?
small cell clusters where the peripheral cells give rise to the endothelial cells and the central cells become blood cells
what are hemangioblasts?
central cells of blood islands which develop into blood cells
what does extraembryonic vasculogenesis form?
the capillary network draining into the veins that brings nutrients and gases to the embryo
what causes endothelial cells to migrate in angiogenesis?
secreted factors (e.g. VEGF) and hypoxia
are arteries and veins made from the same endothelial precursor cells?
yes
where do veins and arteries sort from each other?
in the capillary plexus
where do angioblasts coalesce to form the aortal and cardinal vein beneath it?
the midline of the embryo
what ensures that arteries and veins only fuse with their blood vessel type?
different cell surface receptors
what induces vein formation?
arteries
what can nerves secrete to induce artery formation?
angiogenic factors (e.g. VEGF)
why do arteries and peripheral nerves grow alongside each other?
they induce each others’ formation
when does vasculo- and angiogenesis take place in the adult body?
new blood vessels after injury, in muscle after exercise, new vessels to bypass blocked vessels
what is the tunica interna made of?
endothelial cells and basement membrane
what is it called when new vessels are formed to bypass blocked vessels?
collateral circulation
what can arteries secrete to induce nerve formation?
nerve growth factors
what are the components of the arterial wall?
tunica interna, tunica media, tunica externa
what is the tunica media made of?
smooth muscle cells and elastic net, autonomic innervation
what is the function of tunica intima?
exchange with tissues
what is the arterial wall layer that varies the most in size?
tunica media
what is tunica externa made of?
loose connective tissue, vegetative nerves, vasa nervosum, vasa vasorum
what anchors blood vessels to the surrounding tissue?
tunica externa
what is the vasa vasorum?
vessels of the vasculature, nutrient supply to larger arteries
where are the conducting arteries located?
close to the heart
where are the distributing muscular arteries located?
further from the heart
what do arterioles have to regulate flow?
sphincters
what is the average capillary diameter?
5-15micrometers
what layers make up the capillary wall?
endothelium and outer basement membrane
what layers make up vein walls?
tunica intima, media and externa
what acts as a blood reservoir in liver and spleen?
the venous system- venous sinuses
what stops backward flow in veins?
valves formed by tunica interna
what promotes venous return?
contraction of adjacent skeletal muscle and pulsation of adjacent arteries
what type of large blood vessels are found superficially?
veins
what is the name of regions where collateral arteries join with other arteries?
anastomoses
what is the Latin name of the network of blood vessels reaching a given tissue or organ?
rete arteriosum
what is the name of arteries which don’t anastomose with other arteries?
terminal or end arteries
what happens when terminal arteries are blocked?
tissue dies
where are terminal arteries found?
heart, brain, central artery of retina, kidneys
what are arteriovenous anastomoses?
connections between arterioles and venules bypassing a capillary bed
what structures are able to interrupt flow to/from a capillary bed?
barrier arteries and sphincter veins
what is a rete mirabile?
exuberant parallel branching from a blood vessels that reunites in a single vessel
where are rete mirabile found?
in brain, in renal glomeruli of kidney
what is a portal venous system?
when blood from a capillary bed pools into another capillary bed through veins before going to the heart
what is the function of portal venous systems?
to transport products directly from 1 region to another, avoiding spreading to the rest of the body
where does the hepatic portal system take blood from?
capillary beds of GI tract, spleen, pancreas
where does the hepatic portal vein take blood to?
capillary beds in sinusoids of the liver
what is the function of the hepatic portal system?
absorption and detoxification of metabolites before they reach systemic circulation
what drains venous blood from the liver into the caudal vena cava?
hepatic veins
where do hepatic veins drain blood from and to?
from liver into caudal vena cava
what are 3 examples of portal systems?
hypophyseal portal system, renal portal system, hepatic portal system
how many main chambers do fish have in their hearts?
2 - atrium and ventricle
what do fish breathe through?
their gills
where does blood pass from ventral aorta in fish?
through gills where its oxygenated, then via dorsal aorta to supply head and body
what structure in the fish developed into lungs in mammals?
swimbladder
what does the swim bladder do?
fills with air so the fish can float
what divides the heart into its 4 chambers?
septum
in what group did the 4 chambered heart evolve independently?
archosaurs
which gill arch artery became the aorta in mammals?
gill arch 4 artery
which gill arch section became the common carotid in mammals?
section between arches 3 and 4
which blood supply in fish became the external and internal carotid in mammals?
blood supply to head
what contains the ventricles of the heart, base or apex?
apex
where are atria in the heart?
craniodorsal
which ventricle is long and pointy?
left
which ventricle is crescent shaped and cranial?
right
which ventricle has a thicker muscular wall?
left
what sort of action does the cardiac muscle have?
wringing
in which species is the aorta contractile?
rabbit
which veins does the right atrium receive?
cranial and caudal vena cava, azygos vein, coronary sinus
what is the azygos vein?
a single vein which drains the dorsal thorax
what is the coronary sinus?
a venous tube that drains almost all of the heart
what is the function of the intervenous crest?
directs blood ventrally instead of blood colliding
what are auricles?
side pouches of atria
why are auricles darker tissue than rest of atria?
different embryological origin from atria
what is the function of auricles?
increase the volume of atria
where are auricles located relative to their respective atrium?
cranially and to the left
what is the foramen ovalis?
connection between left and right atrium in fetus
what is the name of the connection between the left and right atrium in the fetus?
foramen ovalis
what is the fossa ovalis?
dent in heart between left and right atrium left by foramen ovalis
what is the name of the dent in adult hearts left by the foramen ovalis?
fossa ovalis
what is the right atrioventricular valve called?
tricuspid valve
why is the right atrioventricular valve called tricuspid?
3 flaps anchored to ventricle
what anchor the RAV to the ventricle?
chorda tendinae
what is the RAV anchored to?
the papillary muscles
what are the trabeculae carneae?
fine ridges on internal surface of ventricle
what is the function of the trabeculae carnae?
create rolling cylinders of blood between them, bulk blood flow can occur above them
what path does blood take from the right ventricle?
spirals around cranial side of heart to the left side, pulmonary artery emerge on the left hand side
why does the left ventricle often look very small in dissection?
thick muscle makes it collapse post mortem
what carries the coronary vessels?
coronary groove between muscles of atrium and ventricle
where do the pulmonary veins enter the heart?
roof of left atrium
how many pulmonary veins are there?
6/7
what is the left atrioventricular valve called?
bicuspid/mitral valve
what are the moderator bands?
strands from the septum to the wall of the ventricle
what is the latin name for moderator bands?
trabecula septomarginalis
what direction does blood pump out of left ventricle?
craniodorsally through aorta
what are the ossa cordis?
bones of the heart formed in big and old cows, horses, deer
what does the great coronary vein disgorge into?
right atrium
where does the right coronary artery come out of the heart?
cranially
what path does the right coronary artery take?
rolls around right side of heart as circumflex
what path does the left coronary artery take?
rolls around left side of heart as circumflex
what is the origin of the right descending branch in dogs and ruminants?
from left coronary artery
what is the origin of the right descending branch in horses and pigs?
from right coronary artery
what is the origin of the right descending branch in cats?
either right or left coronary artery
what does the blood in coronary vein run in the same direction as?
blood in left circumflex coronary artery
what % of cardiac output is coronary?
15%
why do major vessels lie outside the myocardium?
they would be occluded by pressure inside heart
in which species does the azygos come from the left side of the heart?
pigs, some ruminants
what does the azygos drain into in species with L. azygos?
coronary sinus
what supplies parasympathetic innervation to heart?
vagus nerves with branches to SAN and AVN
what is the effect of cardiovagal stimulation?
reduces heart rate
what supplies sympathetic innervation to heart?
fibres from stellate and middle cervical ganglia to all myocardium and vessels
what is the effect of cardiosympathetic stimulation to heart?
increase rate and force of contraction
what is the audible/palpatable (and visible at ICS6 in dogs + horses) beat of the heart?
apex beat
what produces the ‘lub’ sound of the heart?
T and M valves closing
what produces the ‘dup’ sound of the heart?
A and P valves closing
what are the functions of the lymphatic system? (4)
drains + filters interstitial fluid, drains FAs + 2-monoglycerides from intestine via lacteals, transports and houses immune cells, lymph nodes and MALT
what are the 2 forces in the blood capillaries?
osmotic and hydrostatic pressure
what does osmotic pressure drive in the capillaries?
water from interstitium into capillaries
what direction does hydrostatic pressure drive water in in the capillaries?
out of the capillaries (all directions except backwards)
what is the symbol for osmotic pressure?
Π
what is the symbol for hydrostatic pressure?
P
is hydrostatic pressure or osmotic pressure greater at arterial end of capillaries?
hydrostatic pressure
is hydrostatic pressure or osmotic pressure greater at venous end of capillaries?
osmotic pressure
is the difference between hydrostatic and osmotic pressure greater at the arterial or venous end of capillaries?
arterial
what percentage of efflux drains into the lymphatic system?
about 15%
what are lymph capillaries?
blind-ending, endothelium lined, permeable collecting chambers
which are more permeable, lymph capillaries or blood capillaries?
lymph capillaries
what does lymph contain as well as water?
rbcs, wbcs, proteins (antibodies, hepatic proteins), microbes
where are lymphatic vessels not present?
CNS, bone marrow, cartilage, epidermis, alveoli, placenta
how do lymphatic vessels move lymph fluid? (3)
skeletal muscle pump, nearby arterial pulsing, intrinsic smooth muscle contractility
what causes intrinsic smooth muscle in lymphatic vessels to contract?
sympathetic nerves if BP lowers
where does most lymph drain into blood?
at venous angle, into left external jugular vein
what drains into the left external jugular vein?
most lymph vessels
what drains via the right lymphatic duct to the right jugular vein?
right head, neck, forelimb and thorax
what is the only lymph chamber in domestic mammals?
the cisterna
where is the cisterna?
between CdVC, aorta and spine
what are lymphaticovenous anastomoses?
dormant connections between lymphatic system and venous system
how many sacs does the lymphatic system develop from?
6
what do the chambers of the early lymphatic system grow out of?
veins
what grows out of the chambers of the early lymphatic system?
ducts
how many of the sacs regress in lymphatic development?
5
which sac doesn’t regress in lymphatic development?
the cisterna chyli
what might inadequate lymph drainage lead to in tissues?
oedema
what might inadequate lymph drainage lead to in cavities?
effusions
do large animals tend to get more oedema or effusions?
oedema
do small animals tend to get more oedema or effusions?
effusions
what might rupture of the thoracic duct lead to?
chylothorax
what is chylothorax?
chyle filling up the thoracic cavity
what is a lymphocentre?
a lymph node/cluster of lymph nodes
in which species are lymphocentres a single lymph node?
carnivores
in which species are lymphocentres a cluster of lymph nodes?
ungulates
what does lymph drain into lymph nodes via?
afferent lymphatics at the periphery
what forms the internal network of lymph nodes?
capsules (elastic and smooth muscle)
what are the capsules in lymph nodes made of?
elastic and smooth muscle
what divides the lymph fluid into compartments in lymph nodes?
trabeculae given off by capsules
what is the first thing lymph encounters in the lymph nodes?
the germinal centres
what are the germinal centres?
B-lymphocytes surrounded by T cells
what is the final part of the lymph nodes lymph drains through before leaving?
medullary sinuses- series of inflated tubes lined by antibody secreting mature B-cells
where does lymph exit the lymph node?
efferent lymphatics at the stalk
in which species is the lymph node reversed?
pigs
what is inflammation of the lymph node called?
lymphadenitis
what does MALT stand for?
mucosa-associated lymphoid tissue
which ducts does MALT not have?
afferent ducts
where is MALT found (8)?
pharynx (tonsils), nose, intestine, prepuce, vagina, mammary glands, larynx, 3rd eyelid
where are ungulate tonsils usually situated?
under mucosa
how does the spleen develop?
as mesodermal swelling in greater omentum
what is the shape of the dog spleen described as?
England-shaped
how many splenic arteries does the visceral surface of the spleen receive?
around 25
what is the red pulp of the spleen?
complex reticuloendothelial mesh and blood-filled sinusoids, many monocytes
what is the function of the red pulp of the spleen?
breaks down rbcs, stores rbs, makes rbcs in fetus
what percentage of the blood in the resting horse is stored in the spleen?
30%
what is the white pulp of the spleen made of?
lymphoid B-cell nodules or cylinders, surrounded by T-cells
what innervation does the spleen receive?
sympathetic, a few vagal fibres, some myelinated sensory fibres
what is the spleen a common site of in dogs?
tumours
what is the thymus?
a primary lymphoid organ
where is the thymus?
ventral to trachea, dorsal to sternum, cranial to heart
what is the function of the thymus?
formation and maturation of T lymphocytes
where do immature T-lymphocytes infiltrate the thymus from?
the internal thoracic artery
what happens to thymocytes in the thymus cortex?
weakly binding thymocytes are eliminated
what are Hassall’s corpuscles?
epithelial whorls of endo-, meso- and potentially ectoderm
what is the first functional organ in the embryo?
the heart
what does the circulatory system develop from?
mesoderm, primarily lateral plate
where is the mesoderm that the heart develops from located?
lateral to the cranial part of the neural plate
what is the endocardial tube?
tube of fused cardiac precursors that will form the inner layer of the heart
what does the myocardium secrete?
cardiac jelly
what does the cardiac jelly separate?
the myocardium and endocardium
what lie between the primitive atrium and ventricle?
sulci (atrioventricular and bulboventricular)
what acts as the pacemaker in the heart tube?
sinus venosus
what help in preventing back flow in the heart tube?
the cardiac jelly and sulci
what is the first change in looping of the heart tube?
a leftward and ventral movement of the ventricle
what is dextrocardia?
folding of the heart tube in the wrong direction
what is dextrocardia often accompanied by?
situs invertus
what does the inversus viscerum mutation lead to?
randomised left-right orientation of the heart
what gene is normally only transcribed in cells on the left side of the primitive streak?
nodal
where is the nodal gene found to be transcribed in inv/inv mutants?
on the right side of the primitive streak
where is the nodal gene found to be transcribed in iv/iv mutants?
randomly on right or left side
what will the caudal part of the bulbus cordis give rise to?
the right ventricle
what does the primitive atrium remain as in the heart?
the auricles
what do the atria arise from?
sinus horn and pulmonary veins
what fuse to form the septum intermedium?
the cranial and caudal cushions
what is the first septum to form in the atria?
septum primum
what is the ostium primum?
the gradually diminishing hole between the atria in cardiac development
what creates the ostium secundum?
apoptosis in some of the cells near the cranial edge between the atria
what is the second septum to form?
septum secundum
where does septum secundum grow from?
the roof of the atria to the right of the septum primum
what is the name for the remaining gap between the septum secundum and septum intermedium?
the foramen ovale
what causes the foramen ovale to close at birth?
the change in pressure in the atria
where does the muscular ventricular septum grow from?
the caudal edge of the original bulboventricular sulcus
what is the final step in septation?
formation of the spiral septum
what do the ridges that form the spiral septum develop from?
neural crest cells
where does fusion of the paired ridges in spiral septum formation begin?
at the caudal edge of the truncus arteriosus
why does fusion of the paired ridges in spiral septum formation spread rostrally and caudally?
ensures that the ventricles don’t become separated before outflow is partitioned
what does the spiral septum link with caudally?
the muscular ventricular septum and septum intermedium
what are the two shunts that allows the lung to be bypassed in foetal circulation?
foramen ovale, ductus arteriosus
what causes the foramen ovale to close after first breath?
reduced pressure in right atrium means septum primum is flattened against septum secundum
what can be used to keep the ductus arteriosus patent?
injection of prostaglandins
what can induce the ductus arteriosus to constrict if it remains patent?
prostaglandin inhibitors
what is the most commonly diagnosed congenital heart defect in dogs?
patent ductus arteriosus
what may be seen as part of the tetralogy of fallot?
ventricular septal defects
what is the lymphoid role of bone marrow?
formation and maturation of B lymphocytes
