Blood VesselsBlood Vessels

Arteries: vessels that carry blood away from Arteries: vessels that carry blood away from heart, surrounded by thick layer of smooth heart, surrounded by thick layer of smooth muscle, high levels of BPmuscle, high levels of BP

Capillaries: microscopic thin walled vessels Capillaries: microscopic thin walled vessels connect to the smallest veins and arteriesconnect to the smallest veins and arteries

Veins: vessels that carry blood to heart Veins: vessels that carry blood to heart surrounded by thin layer of smooth muscle and surrounded by thin layer of smooth muscle and are flaccid, low levels of BP are flaccid, low levels of BP

Vessel Wall LayersVessel Wall Layers

Tunica interna: inner of vessel, direct contact Tunica interna: inner of vessel, direct contact with blood, secretes chemicals for dilation and with blood, secretes chemicals for dilation and constriction of the vesselconstriction of the vessel

Tunica media: middle layer, made of smooth Tunica media: middle layer, made of smooth muscle and elastic fibers to prevent rupture muscle and elastic fibers to prevent rupture from BP and to aid in vasomotionfrom BP and to aid in vasomotion

Tunica externa: covers vessel and anchors it to Tunica externa: covers vessel and anchors it to tissue and other vesselstissue and other vessels

ArteriesArteries

Conducting arteries: biggest in the body i.e. Conducting arteries: biggest in the body i.e. aorta, carotid. Large amounts of elastic fibers aorta, carotid. Large amounts of elastic fibers allow expansion and contraction with each HB allow expansion and contraction with each HB normalizing BPnormalizing BP

Distributing arteries: smaller branches that Distributing arteries: smaller branches that deliver blood to specific organsdeliver blood to specific organs

Resistance arteries: very little elastic fiber, Resistance arteries: very little elastic fiber, funnel blood to capillaries, smallest called funnel blood to capillaries, smallest called arteriolesarterioles

VeinsVeins

Postcapillary venules: smallest veins, Postcapillary venules: smallest veins, more porous than capillaries allowing more porous than capillaries allowing fluid exchange fluid exchange

Muscular venules: have a thin layer of Muscular venules: have a thin layer of smooth musclesmooth muscle

Medium veins: have venous valves Medium veins: have venous valves acting in the skeletal muscle pump that acting in the skeletal muscle pump that resists retrograde flow caused by gravity resists retrograde flow caused by gravity

VeinsVeins

Venous sinuses: large thin walled Venous sinuses: large thin walled vessels found in the heart and brain not vessels found in the heart and brain not capable of vasomotioncapable of vasomotion

Large veins: thin tunica media with thick Large veins: thin tunica media with thick tunica externa made of bundles of tunica externa made of bundles of smooth muscle, (venae cavae, smooth muscle, (venae cavae, pulmonary veins)pulmonary veins)

Blood PressureBlood Pressure

Flow: amount of blood flowing in an Flow: amount of blood flowing in an organ, tissue or vessel in a given timeorgan, tissue or vessel in a given time

Perfusion: volume of blood over time per Perfusion: volume of blood over time per gram of tissuegram of tissue

Blood pressure: the pressure exerted on Blood pressure: the pressure exerted on the wall of a vessel (120/80)the wall of a vessel (120/80)

Pulse pressure: the difference between Pulse pressure: the difference between systolic and diastolic pressuressystolic and diastolic pressures

Blood PressureBlood Pressure

Hypertension: chronic high BP of 140/90 Hypertension: chronic high BP of 140/90 or higher or higher

Hypotension: chronic low BP can be Hypotension: chronic low BP can be caused by blood loss, dehydration, caused by blood loss, dehydration, anemiaanemia

ResistanceResistance

Blood viscosity: the thickness of blood can Blood viscosity: the thickness of blood can increase or decrease blood flowincrease or decrease blood flow

Vessel length: friction develops with length Vessel length: friction develops with length Vasoconstriction: narrowing vessel Vasoconstriction: narrowing vessel ↑↑ BP BP Vasodilation: widening of vessel Vasodilation: widening of vessel ↓↓ BP BP Laminar flow: blood in center of vessel Laminar flow: blood in center of vessel

travels faster than blood along vessel walltravels faster than blood along vessel wall