The Cardiovascular System Flashcards
What are the 3 circulatory systems that form once tissue layers form?
- circulatory system within the embryo
- circulatory system between embryo/yolk sac
- circulatory system between embryo/placenta
When does the first heartbeat occur?
When does blood flow begin?
- 1st heartbeat: day 22-23 of development
- blood flow: around 4th week of dev.
What are the 2 parts of the adult circulatory system?
- pulmonary circuit (lungs)
- systemic circuit (rest of body)
What is the principal artery of the systemic circuit?
in adult
the aorta
What are the 2 veins that enter the right side of the heart?
-superior vena cava
(body above diaphragm - deoxygenated blood from head/thorax/arms)
-inferior vena cava
(body below diaphragm - deoxygenated blood from legs/abdomen/pelvis)
both veins enter the right atrium (top right chamber)
What are arteries? (describe characteristics)
- carry blood away from heart
- high pressure blood
- thick walled (look pink in living person - muscular for contraction)
- elastic walls (=stretch)
- usually carry oxygenated blood (except pulmonary artery)
What are veins? (describe characteristics)
- carry blood to heart (except portal vein from gut to liver)
- low pressure blood
- think walled (look blue/purple - thinner muscle wall)
- less elastic
- valves to aid venous return against gravity
- usually carry deoxygenated blood (except pulmonary vein)
Why is venous return more difficult in the legs?
- low pressure blood from very bottom of body has to be returned to heart, working against gravity
- contraction of muscles important (squeezes veins, blood flows upwards - problem when sitting down for too long)
What is the exceptional artery which carries deoxygenated blood?
pulmonary artery
What is the exceptional vein which carries oxygenated blood?
pulmonary vein
What vein does not directly supply the heart? i.e. begins and ends in capillaries
hepatic portal vein
directly from gut to liver (storage of nutrients)
What are varicose veins?
-valves fail
=venous return is poor, valves leak, blood pools in vessels
(most obvious in superficial veins)
What is Deep Vein Thrombosis (DVT)?
- DVT = blood clot
- occurs when blood pools in veins (ex: due to inactivity)
- if small part of clot (= an embolus) breaks off it may pass to lungs and block pulmonary artery
What is the lymphatic system?
-network of vessels and nodes
-return of tissue fluid to blood
(plasma squeezed out of arterial capillaries into tissues, then returned to veins)
-lymph nodes = immune response
How can the lymphatic system result in spread of cancer?
-danger: cancer can break off and be spread through lymphatic system
-radiation therapy: short-term damage of lymphatics
=pooling of fluid, no drainage = swelling
What blood vessels connect head and heart?
- 2 carotid arteries (oxygenated blood from heart to head)
- 1 jugular vein (deoxygenated blood from head to heart)
What are the 4 heart chambers? describe adult heart
Right side blood flow:
- right atrium (deoxygenated blood from 2 vena cava)
- tricuspid valve
- right ventricle
- pulmonary artery
Left side blood flow:
- left atrium (oxygenated blood from pulmonary arteries)
- bicuspid/mitral valve
- left ventricle
- aorta
What prevents backflow of blood into atrium?
- bicuspid and tricuspid/mitral valves
- inversion of valves prevented by contraction of papillary muscles = tenses the chordae tendinae (heartstrings)
What are the coronary arteries?
-right + left coronary arteries branch from first part of aorta and supply muscle of heart
=heart gets high quality oxygenated blood
What is coronary thrombosis?
-coronary thrombosis = heart attack
-due to blockage of coronary arteries = death of heart muscle
= “myocardial infarct” (heart attack)
(-branches of right and left coronary arteries to connect but connections cannot open quickly)
What is the conducting system?
-coordination = everything beating at same rate
-heart contraction coordinated by pacemaker (sinoatrial node) = wave of stimulation across heart (to AV node, then interventricular bundle)
(-heart muscle has its own intrinsic rhythm)
-heart rate can be changed by sympathetic + parasympathetic (autonomic) nerves to the pacemaker
What is the heart’s pacemaker? (name + location)
sinoatrial node in top of right atrium
Where does gas exchange occur during development?
placenta
Describe heart in embryo
simple tube with 1 atrium and 1 ventricle
will later divide
Describe the foetal heart at 12 weeks of dev.
by 12 weeks, atrium and ventricle partly subdivided, but gap remains in interatrial wall = foramen ovale
Describe blood flow in foetal heart
- Oxygenated blood:
- from placenta; umbilical vein
- ductus venosus; inferior vena cava
- right atrium; foramen ovale; left atrium
- left ventricle; aorta; carotids to head + body
- Deoxygenated blood:
- from head/arms/thorax
- super vena cava
- right atrium; right ventricle
- pulmonary artery; ductus anteriosus; aorta
- umbilical cord; placenta
What helps deoxygenated blood bypass the lungs during foetal dev?
the ductus arteriosis from pulmonary artery to aorta (but after carotids so no deoxygenated blood goes to head)
What is the fossa ovalis?
remnant of the foramen ovalis
Describe changes at birth
-lungs open; pulmonary circuit opens
-blood pressure in left atrium rises due to venous return from lungs for 1st time
-rise in left atrial pressure = closure of foramen ovale
-changes in blood flow + blood 02 levels
=closes ductus venosus + ductus arteriosis
-umbilical vessels cut and placenta ejected
What is the ductus venosus?
shunts oxygenated blood from placenta past the liver and directly to the inferior vena cava
