valves and vessels Flashcards
function of valves
ensure blood flows in the correct direction by opening to allow blood through and closing to prevent backflow.
structure of mitral or bicuspid left AV valve
has 2 cusps
structure of tricuspid right AV valve and the difference in dogs
3 cusps but 2 in dogs with several small commissural cusps at the free edge.
what are valve cusps joined together by and to
by strands of fibrous tissue called chordae tendinae to muscular projections of the ventricular walls called the papillary muscles.
how many cusps are attached to each muscle?
2
how many muscles to each cusp by the chordae
2
what do the chordae prevent the cusps from doing
prevent cusps from everting into the atrium during ventricular systole.
function of semilunar valves
prevent arterial blood flowing back into the ventricles in diastole.
structure of semilunar valves
made up of 3 semilunar shaped cusps which meet tightly in the middle due to thickening contact areas,
annulus fibrosis
supports the valves
fibrous skeleton which also serves as electrical insulation between atria and ventricles
function of arteries
takes blood away from heart
function of capillaries
exchange gas, nutrients, heat and waste products
function of veins
returns blood to heart.
where are large elastic arteries found and what is good about them
found near heart eg aorta
able to withstand the high pressure output from the heart due to the proportion of elastic tissue in their walls.
structure and location of muscular arteries
contain some elastic tissue and have large amount of smooth muscle.
found further from the heart than elastic arteries
what are arterioles and what are they made from
arteries that branch into smaller arteries
contain a thinner layer of smooth muscle.
what are precapillary arterioles and what are they made from
arterioles that divide further.
intermittent smooth muscle cells and no elastic layer.
where do precapillary arterioles terminate
in beds of thin walled capillaries
what do the smooth muscle contained within the walls of the capillaries act as and what is their function
precapillary sphincter zone
regulates blood flow into the capillary
what is collateral circulation
when arteries give off side branches as a safety net in case of blockage in the main trunk. they accommodate increased blood flow when the main route is compromised.
retia
networks formed by inter-arterial anastomoses.
end arteries
arteries that do not have collateral circulation
ischaemia
blood supply to an area being cut off due to blockage if an end artery
persistent ischaemia leads to …
infarction and necrosis of the tissue
what is the modified capillary called
sinusoid
function of sinusoid
connect the arterial wall to the venous side of the circulation
anatomy of sinusoids and where they are located
very thin walled, large diameter tubular channels
bone marrow and liver tissues
what do gaps between sinusoids allow
free communication between the blood plasma in the sinusoid and the surrounding tissues and movement of cells
speed of blood movement through sinusoids
slowly
what do the post-capillary venules allow and what is this process called
allow diffusion to occur which allows the movement of cells out of the vessel lumen = diapedesis
diapedesis
the means by which blood cells move out of the circulation and into tissues to fight infections
what are the 3 direct capillaries called
thoroughfare channels, metarterioles or arteriovenous capillaries.
function of arteriovenous anastomosis
vessels that enable a capillary bed to be shut off entirely (or opened up) depending on the needs of the body.
function of venules
acts as a blood reservoir
what reservoir are arteries
pressure
what reservoir is veins
volume
why do arteries have a high proportion of elastic tissue
withstand and transfer the high pressure from the ventricles
why do arteries have smooth muscle
enables contraction
what are the three basic layers that make up veins and arteries and describe their anatomy
tunica intima = internal layer with an endothelial lining
tunica media= middle layer containing smooth muscle and elastic tissue
tunic adventitia= external layer of connective tissue
what are the major vessels of the heart
aorta
pulmonary trunk
cranial and caudal venae cavae, pulmonary veins and coronary arteries and veins
where does the pulmonary trunk arise from
right ventricle on the craniosinistral aspect of the heart
where is the pulmonary trunk slightly dilated
just after the origin at the pulmonic valve
what does the pulmonary trunk divide into after penetrating the pericardium?
left and right pulmonary arteries
where does the left and right pulmonary arteries go
to the hilus of corresponding lungs
what do the pulmonary arteries run in company with
principle bronchus and the pulmonary veins
where does the pulmonary vein drain into
left atrium
what receives the full output of the left ventricle
the aorta
which valve is blood pumped through in the aorta
semilunar aortic valve
what is the aortic valve
area between atria and forms the sinuses and where the vessels first branch off
what does the cranial sinus give rise to
right coronary artery
what does the caudosinistral sinus give rise to
left coronary artery
what does the aorta give rise to after the aortic bulb
brachiocephalic trunk and paired subclavian arteries
what does the brachiocephalic trunk give off and what part of the body do they supply
common cartoid arteries
supplies most structures of the head
what are the 4 vessels that the subclavian arteries give off
vertebral artery
costocervical trunk
internal thoracic artery
superficial cervical artery
what do the subclavian arteries supply
the forelimb
neck
cervicothoracic junction
portion of the brain via the vertebral artery
what is the smaller vessel called that is left after the 4 subclavian vessels and what does it supply
axillary artery
supplies forelimb and chest wall
what does the internal thoracic artery supply after branching off the subclavian
pleura
pericardium
thymus
pectoral muscles
cranial mammary glands
what does the internal thoracic artery become in the abdomen
cranial epigastric artery
what supplies the vertebrae and the ribcage
thoracic aorta via costoabdominal artery
what supplies the the tissues of the lungs and oesophagus
thoracic artery via the bronchoesophageal arteries
what does the aorta enter the abdomen via
aortic hiatus of the diaphragm
what supplies blood to the diaphragm and the cranial abdomen
paired phrenicoabdominal arteries
what supplies blood to the lumbar tissues
paired lumbar arteries
what supplies blood to the small intestine and part of the large intestine
cranial mesenteric artery
what supplies blood to the kidneys
renal arteries
what supplies the gonads
testicular/ovarian arteries
what does the deep circumflex iliac arteries supply
the flank
what branches off caudally to testicular/ovarian arteries and what does it supply
caudal mesenteric artery
colon and rectum
what do the external iliac arteries supply?
adductors of thigh
groin
caudal mammary glands
what does the internal iliac artery supply
pelvic viscera and walls
gluteal muscles
proximocaudal thigh
what does the aorta become when it diminishes in diameter
medial sacral artery
becomes median caudal artery to the tail.
what are the 3 major veins that returns blood to the right atrium
cranial vena cava
caudal vena cava
coronary sinus
what vein receives all venous return from the body cranial to the heart
cranial vena cava
what veins does the caudal vena cava receive blood from the thorocolumbar area and ribcage via
azygous and internal thoracic
which vein does the coronary sinus receive venous blood from the heart wall via and what is the vein in ruminants and pigs called
great cardiac vein
azygous
where does the azygous vein pass through
aortic hiatus
which veins is the head drained by
internal and external jugular
which vein is the cranial chest and forelimb drained by
cephalic
what 2 veins join to drain the intercostal area and forelimb
axillary and subclavian
what drains into the vertebral vein which enters cranial vena cava just cranial to the azygous vein
vertebral venous plexus
what vein drains most of the gastrointestinal tract
portal
what does the hepatic vein drain into
caudal vena cava
where do the rectal and anal region drain towards
internal iliac veins which joins external iliac veins which forms left and right common iliac veins
what are the left and right common iliac veins joined together by
deep circumflex iliac veins
