cardiovascular 1 Flashcards
what are the two parts of the extracellular fluid and function
1) Blood plasma
2) Interstitial fluid - (site of metabolic exchange) - middle man - take fluid from capillaries to the cells as some cells don’t have direct access to the circulation (unlike liver (hepatocytes and heart cells)
- Exchange takes place between intracellular fluid and interstitial fluid
list 4 factors effecting diffusion rate
- Concentration difference
- Surface area
- Diffusion distance - very rapid over 5-7um not 1cm - need thing cell wall
- Permeability to that substance
interstitial fluid where released, where reabsorbed
- Released from the arterial ends of capillaries
- 90% reabsorbed at venous end of capillaries
- 10% returned to CVS via the lymphatics
what is needed for flow to occur and what can flow be altered by
- pressure difference
Therefore blood flow can be altered by:
1) changing the pressure difference across its vascular bed
2) or by changing its vascular resistance.
vessels in series and parallel how does resistance occur
largest pressure drop will occur in the part having the greatest resistance to flow: arterioles
parallel - resistance to flow in a parallel network of vessels is given by Ohm’s law - overall resistance for any parallel network will always be less than the resistance of any of the elements of the network
heart and circulation in a fish what is the greatest advantage and greatest disadvantage
advantage is that the blood passing through the gills is fully oxygenated when it moves into the tissues.
limitation is that in passing through the gills, blood loses much of its pressure developed by contraction of the heart
- This limits rate of oxygen delivery to the rest of the body as limits flow
what occurs with systole and diastole
Systole:•Muscle contraction → increased pressure→ blood flow from heart into blood vessels
Diastole:•Muscle relaxes → pressure falls below atrial pressure → ventricle fills through AV valve
what are the 3 things needed for effective functioning of the heart
1) conductivity
2) contractility
3) autorhythmicity
position of the heart, size of heart and shape of the heart
- Between 3rd and 6th rib
- 3rd, 4th or 5th intercostal space
- Slightly towards the left side
size - 0.6% of total body weight
shape - cone shape in horses and ruminants, more globular in small animals
pericardium how many walls and function
Inner wall - - Single layer of flattened mesothelium - Visceral pericardium (inner pericardial sac layer) •Outer wall - two layers 1. Inner parietal pericardium 2. Outer fibrous pericardium - hard to tear •Pericardial cavity - Occupied by thin film of serous fluid - lubricant Functions of the pericardium •Protective •Help maintain position •Minimise friction during cardiac cycle •Prevent over-distension of the heart
where is the site for performing pericardiocentesis
Typical site - 4th or 5th intercostal spaces
what is the auricle, where is it found and what is the most cranial part of the heart
auricle - blind diverticulum
right and left auricles curve around the origin of the pulmonary trunk
right auricle most cranial part of the heart
what is the left surface and right surface of the heart called and what parts of the heart are in those areas
•Left lateral surface of the heart (auricular surface)
- Left atrium and left ventricle
- Right ventricle and right auricle extend around the cranial border
•Right lateral surface of the heart (atrial surface)
- Right atrium and right ventricle
- Left ventricle and left atrium extend around the caudal border
what are the grooves within the ventricle and what do they mark
○ Left interventricular groove (or paraconal)
○ Right interventricular groove (or subsinuosal)
- mark the interventicular septum
what are the four main openings in the right atrium and where do they come from
1) cranial vena cava - drains neck, head, forelimb
2) caudal vena cava - abdominal viscera, hindlimbs, abdominal wall
3) coronary sinus - from heart itself - ventral to caudal vena cava
4) right atrio-ventricular opening - guided by A-V valve
small coronary veins and azygous vein where drain and when present
coronary - heart supply azygous - part of lumbar region, bronchial circulation and oesophagus right in carnivores left usually in pigs both in ruminants
what are the 3 vestigaes of the fetal circulation in right atirum
1) fossa ovalis - depression on interatrial septum
2) intervenous ridge (tubercle) - directs blood from cranial vena cava into ventricle
3) cista terminalis - muscular ridge on internal surface of right atrium
entry into the right ventricle what guarded by and what made from
- guarded by the tricuspid valve - prevent backflow of blood back into atrium
○ Three thin flap-like cusps - Cusps are composed of a layer of collagen fibres between two layers of endothelium
○ Free edge of cusp - restrained by chordae tendineae
○ Chordae tendineae arise from papillary muscles - Fan out to attach to the cusps of the A-V valve
where is the right septomarginal trabeculae found and what parts
right ventricle
2 functional components
1) inflow channel - 3 papillary muscles
2) outflow channel - (conus arteriosus) - directs blood into pulmonary trunk
pulmonary valve structure
3 semi-lunar valves
3 buldges in the wall of hte pulmonary trunk
left ventricle what valve guarding entry and structure
aortic valve what enter into and structure
atrioventricular (mitral) valve
2 cusps and 2 papillary muscles arise from outer wall
3 semi-lunar valves
left coronary artery from left aortic sinus
right coronary artery from right aortic sinus
list the openings into the left atrium
1) 6 pulmonary veins
2) small coronary veins
3) left A-V orifice into left ventricle
what is the cardiac skeleton made up of and function
fibrous rings to which valves are tethered
1) ensure heart doesn’t tear with force of pressure
2) blocks electrical impulses so only one way for impulses to move through to ventricle via AV node - stops random contraction of ventricle when not filled
where are the valves of the heart positioned in terms of ribs
Left hand side - 3rd intercostal space- pulmonic - 4th intercostal space - Aortic - 5th intercostal space - Mitral - most caudal - hear heart sound the loudest Right hand side - Tricuspid valve