cardiovascular 2 Flashcards
coronary circulation how much cardiac output, what are the 2 main arteries of heart and and what 3 smaller branches do they supply
1) left coronary artery
2) right coronary artery
1. ventricular 2. septal 3 . atrial arteries
what does the left coronary artery and right coronary artery divide into
Left coronary artery 1. Left (or paraconal) interventricular artery ○ Lies in the left I-V groove 2. Left circumflex artery (bends around the heart) Lies in the circular coronary groove right coronary artery 1. Right (or subsinuosal) I-V artery ○ Lies in the right I-V groove, and 2. Right circumflex artery ○ Lies in the circular coronary groove
what does the left and right coronary artery supply and which is larger for dogs, ruminants
Dog and ruminant ○ Left coronary artery supplies: § All I-V septum § All L. ventricle § Regions of R. ventricle adjoining the L. and R. interventricular groove ○ Right coronary artery supplies: § Remainder of R. ventricle - L. coronary a. carries 80% of coronary arterial flow
what does the left and right coronary artery supply and which is larger horses, pig
horse and pig - Left coronary a. supplies: ○ Most of the I-V septum ○ Most of the L. ventricle ○ Little of the R. ventricle - Right coronary artery supplies: ○ Part of I-V septum ○ Regions of L. ventricle adjoining the R. interventricular groove ○ Most of R. ventricle - Both coronary arteries similar in size
what does the left and right coronary artery supply and which is larger for cats
○ 50% similar to dogs and ruminants - Left over the right
○ 30% similar to horses and pigs - about even with left and right
○ 20% showing other variations
coronary blood flow how increased and effect of mechanical compression
- Increased activity produces more metabolic byproducts (e.g. adenosine) - indirect effect
○ These act as local vasodilators
○ This is called active hyperaemia - during increase in activity increase in blood flow - (Sympathetic NS increases cardiac activity and therefore acts indirectly to increase coronary blood flow)
left ventricle - systole blood vessels squashed so flow occurs in diastole
right ventricle - systole causes blood flow
hypoxic vasoconstriction where does it occur and what happens
- Hypoxia (poor oxygenation - poor circulation) causes vasoconstriction
- This helps to adjust blood flow to the level of ventilation in that part of the lung
- Increase flow in areas that are hypoxic
what are the 2 main arterial supplies to the head
- L. and R. common carotid arteries - come off brachsephalic trunk
- L. and R. vertebral arteries
skin blood flow what vascular beds are present, what is an important type and function
superfical and deep vascular beds
- Arteriovenous anastomoses
○ Very low resistance to flow so increase flow
○ Countercurrent heat exchange for heat conservation
On hot days increase blood flow through increase heat exchange - thermoregulation
what are the two main common carotid arteries and what does each supply
○ Internal carotid a. - intracranial circulation
○External carotid a. - extracranial circulation - face, head, tongue etc.
external carotid artery what are the major branches and where terminates
- Major branches: ○ Cranial laryngeal, occipital, ascending pharyngeal, lingual, facial (artery that can feel the pulse), caudal auricular and parotid aa. - Terminates in: ○ Superficial temporal a. ○ Maxillary a.
vertebral artery where branch from, what supply and what does it fuse with
- First branch of subclavian a.
- Supplies segmental arteries to the spinal cord, meninges and vertebral bodies
- fuses with cerebrospinal artery
cerebrospinal artery what type of circulation and how occurs
- L. and R. cerebrospinal aa. Fuse - ensure - collateral circulation
○ Basilar a. - cranially
○ Ventral spinal a. - caudally
basilar artery what does it form and function
- Forms Circle of Willis - where all vessels come together
○ Supplies brain
○ Internal carotid also supplies
cycle of willis what type of circulation how occur
Artery to artery anastomosis - collateral circulation
functional end arteries where preset and structure, how different to true end arteries
brain micro-circulation
arteries anastomose wit nearby arteries but too small to be functionally effective so still get local ischaemia if blockage
- true end arteries no anastomotic connections - if artery closed area of tissue dies
what are the 4 parts of the blood-brain barrier
- Endothelial cells have closed intercellular (tight) junctions - physical
- Thick basement membrane -physical
- Surrounded by ‘end feet’ from astrocytes (supporting cells) -physical
○ pseudopodia - Specific enzymes also contribute - chemical
what are the major veins draining from the head
- External jugular v.
- Internal jugular v. - runs close to carotid
- Vertebral v.
In what circumstances does active hyperaemia develop?
1) increased blood flow to gastrointestinal tract following ingestion of food - physiological
2) increased blood flow to skeletal muscles during exercise
3) increased blood flow to skin during exercise or hot weather to augment heat loss
4) inflammation - local active hyperaemia is responsible for the redness (rubor, erythema) and heat (calor) of acute inflammation - pathological
Why is active hyperaemia a localised phenomenon?
there is insufficient blood volume to permit generalised active hyperaemia whilst maintaining adequate systemic blood pressure
examples of when localised passive congestion can develop
localised
1) intestinal strangulation due to torsion or volvulus - compression of mesenteric veins - obstruction of venous outflow
2) hypostatic or dependent congestion = gravitational pooling of venous blood in dependent (down-side) areas in recumbent or inactive animals (especially large animals) or as a post mortem change
examples of when generalised passive congestion can develop
1) left-sided congestive heart failure - venous blood pulls in pulmonary veins, venules
2) right-sided congestive heart failure - blood pools in systemic veins and venules - liver
grossly distinguish between active hyperaemia and passive congestive of live animal
active - oxygenated blood so bring red, warm, pulse sometimes palpable at inflammatory sites
passive - red-purple to black-blue (cyanosis), enlargement of veins, no associated increase in temp so cooler than normal
potential consequences of passive congestion of tissues
1) hydrothorax
2) hydropericardium
3) congestion of spleen, kidneys, stomach, intestines etc
4) hepatic congestion
5) bottle jaw