Cardiovascular System Flashcards
Heart position
Mediastinum - behind the sternum and angled slightly left
Heart - pericardium
Fibrous pericardium
Serous pericardium - parietal (outer layer and visceral (inner) layer
Function of the pericardium
Protect the heart
Anchor the heart into position
Prevent over filling
Friction free environment
Epicardium
Outer layer - visceral pericardium
Supports blood vessels and nerves
Myocardium
Middle layer
Made of cardiac muscle
Endocardium
Inner layer
Made of squamous epithelium - smooth, friction free environment for blood flow
Structure of the heart
Four chambers - 2 atria and 2 ventricles
Two sets of valves - atrioventricular (tricuspid and bicuspid) and semilunar
Septum
Right to lungs
Left to bods
Valves of the heart
Prevent backflow of blood
Chordae tendineae attaches to the papillary muscle and anchor the valves into position - stop inverting
Open and close due to pressure changes
Blood vessels - Tunica externa layer
Outer layer
Loose, thick layer of connective tissue
Elastic and collagen fibres
Anchor the vessels to surrounding structures
Protection
Blood vessels - tunica media layer
Middle layer
Muscular and connective tissue
Smooth muscle cels
Vasoconstriction and vasodilation
Elastic fibres - recoil after stretch
Blood vessels - tunica intima layer
Innermost layer
Epithelial lining forming perimeter of lumen
Internal elastic lamina - elastic fibres, recoil after stretch
Lamina propria - outer layer of elastic connective tissue
Basement membrane - collagen fibres, firm supportive base, regulates molecular movement, tissue repair
Endothelium - squamous, permeate, regulate diffusion
Elastic/conducting arteries
Thick walled
Close to the heart
Elastic tissues - expansion and contraction causing blood to flow smoothly
Muscular arteries
Smaller
Branch from, elastic arteries
Distribute blood top body
More muscular tunica media - control blood flow
Arterioles
Smooth muscle (media) around endothelium
Collagen fibres
Regulate blood flow to capillaries
Vasodilation and vasoconstriction
Capillaries
Smallest
Thin walled
Tunica intima
Access to all the cells
Slower blood flow for to allow exchange
Larger SA
Continuous capillaries
Least permeable
Most common
E.g. skin, muscle
Fenestrated capillaries
Large fenestrations (pores) - increase permeability
Special locations
E.g. kidney, small intestine
Sinusoidal capillaries
Most permeable
Special locations
E.g. liver, bone marrow, spleen
Precapillary sphincters
Redirect blood flow depending on body needs
Open - through true capillaries
Closed - through metarteriole
Veins and venules
Venules - capillaries joining together
Veins - venules joining together, lower BP, walls (tunicas) much thinner
Return of blood to the heart
Pressure
Valves
Skeletal muscle pump
Respiratory pump
Coronary arteries - left
Two branches
Anterior interventricular artery - left anterior descending artery
Circumflex artery
Coronary arteries - right
Two branches
Right marginal artery
Posterior interventricular artery
Coronary veins
Venus blood collected by cardiac veins
Join together to form coronary sinus - empties into the right atrium, three large tributaries; great cardiac vein, middle cardiac vein, small cardiac vein
Anterior cardiac veins empty into right atrium
Pulse
Pressure waves felt in an artery that lies close to the surface of the body
Result from the left ventricle contracting
Blood pressure
Pressure exerted by the blood on the walls of a blood vessel
mmHg
Sphygmomanometer
Systolic blood pressure (SBP)
True highest pressure
Measured when the left ventricle is contracting and expelling blood into the aorta
Diastolic blood pressure (DBP)
Lowest pressure
Measured when the left ventricle is relaxing and blood is flowing into the peripheral blood vessels
Pulse pressure (PP)
The difference between systolic and diastolic blood pressure
Felt in arteries
Indication of health of blood vessels
Over 60mmHg = not healthy
Mean arterial pressure (MAP)
The pressure that propels the blood through the tissue
Equivalent to the DBP + one third of PP
What determines blood pressure
Cardiac output
Peripheral resistance - diameter and length
Blood volume
Blood viscosity
Vasodilation
Vasoconstriction
Vascular tone
Control of blood pressure - low
Stimulus - low BP
Baroreceptors inhibited
Stilmulates cardioaccelerator centre and vasomotor centre
Vasoconstriction - increase restriction
Increase sympathetic impulse to heart - increase HR, contractility and CO
Control of blood pressure - high
Stimulus - high BP
Baroreceptors stimulated
Stimulate cardioinhibitory centre and inhibit vasomotor centre
Vasodilation - decrease restriction
Decrease sympathetic impulses to heart - decrease HR, contractility, CO