Intro To The Cardiovascular System Flashcards
How do single cell organisms obtain nutrients?
By diffusion/active transport
Why do large multicellular organisms need a transport system?
-diffusion is not efficient (only 50%)
-v metabolically active so need to deliver O2, nutrients and remove waste
-platelets and immune cells need to move around body
-chemical messages also need to be transported
what does the cardiovascular system consist of?
-blood
-heart
-arteries
-veins
-capillaries
-lymphatic vessels
What is the function of the cardiovascular system?
• Transport of nutrients, gases, hormones, water, defense cells and growth factors
• Collection of metabolic and cellular excretions and delivery to
excretory organs (eg kidneys)
• Defense against infections
• Thermo-regulation (heat - peripheral vasodilation; cold - peripheral vasoconstriction)
describe pressure of double circulatory system
-low pulmonary pressure in lungs
-high systemic pressure in arteries
describe the heart
-muscular pumping organ - v specialised
-4 chambers - 2 atria, 2 ventricles
-2 systems - one carries oxygenated blood, other carries deoxygenated blood
-pacemaker (autorhythmic) cells generate electrical signals
what does it mean to say the heart has an intrinsic conduction system?
-heart is wired to transfer signals to certain parts of the heart at certain times
-signals are transferred after short delay to allow filling of heart before it pumps
what is diastole?
relaxation of heart as blood fills
what is systole?
contraction of heart as blood is pumped
what are the valves in the heart?
-tricuspid valve - right atrium to right ventricle
-bicuspid valve - left atrium to left ventricle
-pulmonary valve - right ventricle to pulmonary artery
-aortic valve - left ventricle to aorta
describe the pressure in the heart
-left ventricle is largest muscle so massive variation in pressure
-pressure generally gets lower from artery to vein
-measured as systolic pressure over diastolic pressure
What are the 2 main components of blood
-Formed elements - blood cells and platelets
-Plasma - clear extracellular fluid
What is the function of blood
Transport
Protection
Regulation
3 main types of blood vessels
Artery
Vein
Capillary
Different types of vessel differ in:
diameter, wall thickness & constituents
what are the three layers of a blood vessel?
-intima - endothelium which provides non-adhesive surface
-media - smooth muscle, elastic tissue
-adventitia - fibrous tissue
Blood vessels table
describe the arteries
-thick wall and muscular
-large diameter so low resistance
-carries oxygenated blood away from heart
describe arterioles
-smaller diameter
-major role in blood pressure regulation by controlling their diameter
describe capillaries
-single tube of endothelial cells
-v close to cells so things can easily diffuse in and out
-can be leaky or tight - kidneys have fenestrated capillaries so larger pores
describe veins and venules
-low pressure (<15mmHg), large lumen
-some smooth muscle but less than in arteries
-veins are capacitance vessels bc they carry 60% of blood
-have unidirectional valves to prevent backflow
-returns blood to heart
describe the lymphatic system
-system of vessels and nodes
-returns interstitial fluid to circulation - into subclavian vein and is moved by muscular contraction
-involved in immunity - contain lymphocytes that are concentrated in lymph nodes
Describe the lymphatic system
-system of vessels and nodes
-returns interstitial fluid to circulation - into subclavian vein and is moved by muscular contraction
-involved in immunity - contain lymphocytes that are concentrated in lymph nodes
where are baro receptors located and what do they do?
-in carotid sinuses and aortic arch
-sense chemical or pressure changes
-they are stretch receptors so respond to pressure induced stretching of blood vessel
what is the control centre for homeostasis of the circulatory system?
medulla oblongata
what are the effectors for homeostasis of the circulatory sytstem?
heart rate, stroke volume, vascular tone (dilation/constriction)
describe intrinsic control of the heart
-frank-starling response
-stroke volume of left ventricle increases as left ventricular volume increases so more forceful contraction occurs
describe extrinsic control of the heart
-autonomic nervous system
-hormones e.g. adrenaline, thyroxin
-ions generate signals e.g. Na+, K+, Ca2+
-age , exercise
what happens during vasoconstriction?
-blood vessels contract
-lumen decrease in size so bp goes up
what happens during vasodilation?
-blood vessels dilate
-lumen increases in size so bp decreases
how do blood vessels receive signal to dilate/constrict?
via sympathetic nerve fibres which innervate smooth muscle of most blood vessels
what impact does decrease of 1/2 in lumen size have?
16 fold impact
What is the baroreflex?
an automatic, negative feedback response to changes in blood pressure
How do baroreceptors respond to hypotension?
-baroreceptors send signal to brain which sends signal to heart and blood vessels
-this increases cardiac output and increases vasoconstriction to increase bp
how are the cardiovascular and respiratory systems linked?
-both work to circulate oxygen around body
-both are homeostatic systems
-when chemoreceptors detect change in pH, pO2 or pCO2, both heart rate and ventilation rate changes
Describe cardiovascular diseases
Very common (Leading cause of death worldwide)
-Coronary heart disease (angina, heart attack, heart failure)
-Cerebrovascular disease (stroke)
-Peripheral arterial disease
-Aortic disease (aneurysm)
what is atherosclerosis?
when plaque build up in arteries cause them to narrow
what diseases can be caused by atherosclerosis and blood clots?
-stroke or transient ischaemic attack
-coronary heart disease which can cause angina or myocardial infarction
-peripheral artery disease
-aneurysm
what are the effects of hypertension?
-damage to arteries so increased deposition of fat
-increased risk of aneurysm
-heart has to work harder
-increased risk of haemorrhagic stroke
what lifestyle choices can contribute to CVD?
-smoking
-activity
-weight
-diet
what can cause diabetes?
-hypertension
-obesity
-decreased activity
-poor lipid profile
what is the Renin-Angiotensin system?
hormone system that regulates blood pressure and fluid balance
what do ACE inhibitors do?
Block conversion of angiotensin I to angiotensin II so blood vessels can widen and bp decreased
What do anticoagulants do?
prevent the extension & formation of clots by inhibiting factors in the clotting cascade & decreasing blood coagulability
What do beta adrenergic blockers do?
reduce cardiac output by decreasing sympathetic input
what do calcium ion channel blockers do?
lowers bp by blocking Ca ions from entering blood vessel bc they cause the vessels to constrict more strongly
what do statins do?
reduce cholesterol in blood
Medicine for cvd
