Blood Vessels
All blood vessels have 3 layers except
arteries. *capillaries* veins. venules and arterioles.
Which of the following vessels have valves?
arteries. *lymphatic vessels* *veins* capillaries
After blood leaves the capillaries, it enters the
arteries. arterioles. *venules* veins. capillaries
In what vessel is blood pressure the highest?
arteriole venule vein *artery* capillary
Each of the following will cause an increase in blood pressure, except
increased levels of ADH (antidiuretic hormone). increased levels of aldosterone. increased blood volume. *increased levels of ANP (atrial natriuretic peptide)* increased levels of angiotensin II.
Which of the following conditions is least likely to lead to renin release?
increased sympathetic activity renal artery thrombus vasospasm of the renal arteries circulatory shock *hypertension*
Some of the fluid that is forced out of capillaries is returned to the blood by the:
liver muscular arteries hepatic portal vein venules *lymphatic system*
Vasoconstriction
the contraction of arterial smooth muscle causing the lumen to constrict w/a corresponding elevation in B/P
During exercise
venous return increases. vasodilation occurs at the active skeletal muscles. both cardiac output and stroke volume increase. venous return increases and vasodilation occurs at the active skeletal muscles. *All of the answers are correct*
What vessels hold the largest percentage of the blood supply?
venule artery *vein* arteriole capillary
Things move in and out of the circulatory via which blood vessels?
venules. arteries. arterioles *capillaries. *
Exchange between a blood vessel and the cells that surround it can occur only in
venules. arteries. *capillaries* arterioles. veins
Capillary Filtration Pressure (CFP)
water & small solutes are forced across the capillary leaving large solutes & plasma proteins in the bloodstream
2 Circuits
*Pulmonary Circuit*: leads away from the heart to the lungs & back to the heart right ventricle --> pulmonary trunk --> pulmonary arteries --> alveolar capillaries --> pulmonary veins --> back to the left atrium *Systemic Circuit*:leads from the heart to all parts of the body & back to the right atrium left ventricle --> continues out of the aorta to all parts of the body via branches of the aorta --> back to the right atrium via IVC,SVC, & coronary sinus
Vascular Resistance
*caused by friction btwn blood & blood vessel* -resistance in blood vessel to blood flow -depends on length of vessel: increased length results in increased friction due to a larger surface area over which blood comes into contact w/the vessel -vessels w/large diameters have relatively low friction -decrease in lumen size--> increases resistance -differences in diameter significantly affect resistance (ex: if 2 vessels are the same length, the one w/the narrower diameter has a resistance that is 16x that of one of the larger vessels) -anything that increases friction or vascular resistance decrease blood flow -changes in vessel length CANNOT be controlled -changes in diameter of a vessel can occur physiologically or may be to due pathology -changes in vessel resistance occur most frequently in arterioles- remember they are the resistance vessels -exercise & low fat diet can decrease resistance
Resistance is a force that
*decreases blood flow* acts with pressure to move blood along a vessel. is always higher than blood pressure. increases blood flow. never changes in a blood vessel
Net Filtration Pressure (NFP)
*difference btwn Net Hydrostatic Pressure (NHP) & Net Oncotic Pressure (NOP)* (NFP = NHP - NOP) -net hydrostatic pressure : NHP = CHP - IHP -net osmotic pressure = BCOP - ICOP -net filtration pressure: the difference btwn net hydrostatic pressure (NHP) & net oncotic pressure (NOP) -NFP = NHP - NOP
Capillaries
*exchange vessels* 3 types: continues capillaries, fenestrated capillaries, sinusoids -made of a tube of endothelial cells (simple squamous ET) inside a thin basement membrane -only blood vessels that will permit exchange of btwn blood & interstitial fluids -exchange can take place quickly bc capillary walls are thin & diffusion distances are short -blood flows relatively slowly through the capillaries allowing time for diffusion or active transport
Blood Vessels
*have 3 layers (except capillaries)* -dilate to bring B/P down -contract to bring B/P up 1) Tunica Interna (inner) 2) Tunica Media (middle) 3) Tunica Externa (outside)
Blood flow through a capillary is controlled by the
*precapillary sphincter.* vasa vasorum. venule. plexus. thoroughfare channel.
This blood vessel is most commonly used to take a pulse.
*radial artery* median cubital vein carotid artery femoral artery
Which of the following are branches of the abdominal aorta?
*renal artery* subclavian artery. *iliac artery.* *splenic artery.*
Veins
*return blood to/toward the heart* -have valves that prevent backward blood flow - holds most of blood volume (60-65% of BV)
Blood Pressure
*rise & fall of pressure in the arteries when the ventricles contract & relax* -systolic pressure: maximum pressure in artery when ventricles contract -diastolic pressure: minimum pressure in arteries before next contraction -pulse pressure (PP): the difference btwn systolic & diastolic pressures -Mean Arterial Pressure (MAP) = 1/3 PP + diastolic pressure -MAP tells us if tissues are being perfused
Turbulence
*swirling action that disturbs blood flow* -caused by high flow rates, irregular surfaces & sudden changes in vessel diameter -increases resistance & slows blood flow -occurs when blood flows from atria to ventricles, when blood flows from the aorta & pulmonary trunk -occurs in large arteries when CO & arterial flow rates are very high -increase EPO to make RBCs to increase ability to carry oxygen -bruit: abnormal sloshing sound of blood in carotid artery or abdomen
Osmotic Pressure [capillary pressure]
*the force needed to prevent osmosis across a membrane* -determined by the solute concentration of a solution -the greater the solute concentration the greater the osmotic pressure -Osmotic Pressure forces water INTO a solution -Hydrostatic Pressure pushes water OUT of a solution -Blood Colloid Osmotic Pressure (BCOP) (Oncotic Pressure): osmotic pressure caused by the presence of suspended proteins that cannot cross the capillary walls- exerted by plasma proteins -BCOP is the pressure exerted by proteins to hold onto fluid IN vessels -if no plasma proteins, the fluid will leak into tissues and cause swelling (ex: little boy who swelled up due to lack of ability to make plasma proteins)
The 3 layers that make up a blood vessel include
*the tunica adventitia (external).* the tunica albicans. *the tunica intima (interna)* *the tunica media*
Veins and lymphatic vessels share the following characteristics:
*valves to prevent backflow of blood and lymph.* *the need for muscle contractions to move blood and lymph within them* high pressure due to ventricular contractions. *low pressure within them*
Pulses
-are felt in superficial arteries as their walls expand & recoil -commonly take B/P from brachial artery -commonly take pulse from radial artery
Differences btwn Arteries & Veins
-arteries & veins runs side by side -arteries: have thicker walls & higher B/P, blood moves due to ventricular contractions, lumen is usually smaller due to elastic fibers that recoil during relaxation in artery, has folds during relaxation, do NOT have valves -veins: have lower B/P, blood moves due to skeletal muscle contractions, lumen is usually bigger, does not have folds during relaxation, HAVE VALVES
Pre capillary Arterioles (metarterioles)
-capillaries contain several direct connections (branches) btwn arterioles -walls in the first part of these vessels have the ability to change diameters bc they contain smooth muscle -rest of the passageways leading through the capillary resemble a typical capillary & are called *thoroughfare channels* -more than an artery that can supply blood to the same capillary are referred to as *collaterals*
Capillary Pressures
-capillary pressures & capillary exchange are vital to homeostasis bc it moves materials across capillary walls by: o Diffusion-move from high conc.-->low conc. (doesn't require energy) o Filtration-things move OUT of circulatory system (only need energy to go from low conc.--> high conc.) o Reabsorption-things move INTO circulatory system -reabsorption occurs as a result of osmosis (movement of water across selectively permeable membrane)
Blood Viscosity & Blood Pressure
-caused by interactions of molecules & suspended particles of blood -viscosity of blood remains fairly constant -viscosity increases peripheral resistance -consuming large amounts of fat increases your blood viscosity, meaning your heart has to work harder to pump blood (this increases B/P) -anything affecting hematocrit affects viscosity & peripheral resistance such as: -Anemia: any decrease in your body's ability to carry oxygen -Polycythemia: over production of RBCs; treated by bleeding to release RBCs -Dehydration causes increase in hematocrit, EPO, TPO, # of platelets
Fenestrated Capillaries
-contain windows/pores that penetrate the endothelial lining -pores allow rapid exchange of water & small solutes btwn plasma & interstitial fluid -found in the choroid plexus of the brain, in endocrine organs & glands (hypothalamus, pituitary, pineal, & thyroid) -found in absorptive areas like the intestinal tract & kidneys
Vasomotion
-cycling btwn contraction & relaxation of smooth muscles that changes blood flow through the capillaries -controlled by changes in concentrations of chemicals & dissolved gases in interstitial fluid -capillary auto regulation: when oxygen concentration in a tissue decreases, capillary sphincters will relax so blood flow to that area increases -increases in gases will affect vasomotion
Arteriovenous Anastomoses (AV Shunts)
-direct connection btwn arterioles that can become dilated so blood bypasses the capillary bed & flow directly into the venous circulation -regulated by sympathetic NS under the control of cardiovascular centers in the medulla oblongata -responsive to changes in B/P -*pre-capillary sphincters*: control the flow of blood into the capillary bed-contraction of sphincters slows the flow of blood into the capillary bed & relaxation of sphincter hastens the entry of blood into the bed
Tunica Interna/Tunica intima
-innermost layer -composed of simple squamous ET known as *endothelium* -thin layer of elastic tissue lines the lumen of the vessels
Continuos Capillaries
-mean to keep blood in circulatory system -endothelium is a complete lining -located in all tissues except epithelia & cartilage -prevent loss of blood & plasma proteins -permit water, small solutes, & lipid soluble materials to diffuse into the interstitial fluid -found in brain (the blood brain barrier) & the thymus -very restricted permeability
Carotid Message
-messes w/oxygen supply to brain & could lead to a stroke due to plague build up in blood vessel -decreases HR
Tunica Externa/Tunica adventitia
-outermost layer -thin layer of connective tissue w/irregular elastic & collagenous fibers -attaches to the artery to the surrounding structures -anchors arteries in place -function: to protect & support the artery
Where Pulses Are Felt
-radial pulse: radial side (thumb side) of the anterior wrist -temporal pulse: in front of & toward the top of the ear -facial pulse: just under the mandible -carotid pulse: in the neck -brachial pulse: in the arm; at the bend of the elbow, where we take B/P -femoral pulse: in the groin -politeal pulse: behind the knee -posterior tibial: back of the ankle -dorsalis pedis- top of the foot
Capacitance
-relationship btwn the blood volume a vessel contains & the B/P in the vessel -a vessel that expands easily under low B/P has high capacitance -veins are high capacitance vessels -blood volume in veins is large due to low pressure
Venules & Veins
-small vessels that continue from capillaries & merge to form veins -cary blood back to heart -have same layers as arteries -bood in veins move due to contractions in surrounding vessels -veins serve as reservoirs for blood
Arterioles (resistance vessels)
-smaller arterial structures -have smaller lumen which creates resistance to flow
Tunica Media (middle)
-thickest layer; made of smooth muscle & elastic connective tissue -allows vessel to tolerate the increased force of B/P & sudden increases in blood volume -the elasticity of the layer, allows the vessel to "recoil" & allows blood to keep moving -smooth muscle of this layer responds to nervous stimulation & can relax allowing the diameter of the lumen to increase (*vasodilation*); stimulated by sympathetic NS -muscle fibers can also contract to decrease the size of the lumen (*vasoconstriction*); stimulated by parasympathetic NS -affected by after load, peripheral B/P, & capillary blood flow
Pulse Pressure
-usually btwn 30-50 -lower than normal may indicate bleeding, CHF, & shock -higher than normal may indicate hardening of the arteries, aortic regurgitation or AV malformation (extra connection btwn artery & vein)
If a person has a blood pressure of 120/90, his mean arterial pressure would be ________ mm Hg.
210 93 *100* 90 105
Cardiovascular Regulation
Tissue Perfusion: delivery of oxygen to tissues - blood flow through the tissues -carries oxygen & nutrients to tissues & organs -carries CO2 & waste away -is affected by cardiac output, peripheral resistance, & B/P -cardiac output (CO): decrease in CO decreases tissue perfusion -peripheral resistance: increase in resistance decreases blood flow, B/P, & tissue perfusion -blood pressure: decrease in B/P decreases tissue perfusion
In which of the following would the blood flow be highest?
a vessel 0.5 cm in diameter and 4 meters long a vessel 1.0 cm in diameter and 10 meters long *a vessel 1.0 cm in diameter and 2 meters long* a vessel 0.5 cm in diameter and 2 meters long
The large vessels that return blood to the heart are called
arterioles. capillaries. venules. *veins* arteries.
Blood pressure is reported
as diastolic over systolic. as mm of Hgb. *in mm of Hg* *as systolic over diastolic*
Turbulent blood flow occurs
at high flow rates. when there are irregularities in the vessel wall. when blood pressure is excessively high. when there are sudden changes in vessel diameter. *All of the answers are correct*
Which of the following affects blood flow through the body?
blood viscosity vessel diameter vascular resistance turbulence *All of the answers are correct*
Pulmonary arteries
carry blood to the left atrium from the lungs. contain oxygenated blood. *contain deoxygenated blood.* *carry blood away from the heart to the lungs.*
Friction/Inflammation of Blood Vessel
causes blood to slow
The blood colloid osmotic pressure mostly depends on the
concentration of plasma waste products. *concentration of plasma proteins.* number of red blood cells. concentration of plasma sodium ions. concentration of plasma glucose.
The difference between the systolic and diastolic pressures is called the ________ pressure.
critical closing blood mean arterial circulatory *pulse*
Fear can result in
decreased heart rate. * increased stimulation of the cardioaccelerator center by higher brain centers*. increased stimulation of the cardioinhibitory center by higher brain centers. parasympathetic stimulation. decreased blood pressure.
Each of the following factors would increase peripheral resistance, except
elevated levels of epinephrine. increased sympathetic stimulation. *vasodilation* irregularities in the vessel walls caused by plaques. elevated hematocrit.
Capillary Hydrostatic Pressure (CHP)
for exerted by the weight of a liquid forcing water & small solutes out of the capillary
Hypertension
high B/P
Pulses are felt
in deep veins when the ventricles contract. *in superficial arteries when the ventricles contract* in superficial veins when the ventricles contract. *on the thumb side of the wrist, on the back of the knee and in the groin*
To defend blood volume against dehydration, the body
increases water intake. experiences a recall of interstitial fluids. accelerates reabsorption of water at the kidneys. experiences an increase in the blood colloidal osmotic pressure. *All of the answers are correct*
Factors that increase the risk of atherosclerosis include which of the following?
lack of exercise obesity high cholesterol smoking *All of the answers are correct*
This blood vessel is most commonly used for venipuncture.
radial vein femoral vein basilic vein *median cubital vein*
Sinusoids
really big gaps in capillaries -regulate fenestrated capillaries but are flattened & irregularly shaped -have large gaps btwn adjacent endothelial cells -allow for free exchange of water & solutes btwn the blood & interstitial fluid -allow plasma proteins to move freely btwn the blood & interstitial fluid -found in liver, spleen, & bone marrow -blood moves slowly through these capillaries -phagocytic cells line these capillaries in liver, spleen, & bone marrow & remove debris, pathogens & dead RBCs
Uncirculated blood
sits there & coagulates (blot clots form)
Venules
small venous structures -lead away from the capillaries
Arteries
take blood away from heart
Blood pressure measures
the maximum pressure in the arteries when the ventricles relax. *the minimum pressure in the arteries when the ventricles relax. the maximum pressure in the arteries when the ventricles contract.* the minimum pressure in the arteries when the ventricles contract.
The blood vessel that supplies the upper arm is called
the radial artery. the digital artery. the palmar arch. *the brachial artery*
Vasodilation
the relaxation of arterial smooth muscle causing the lumen to dilate w/a corresponding decrease in B/P
The muscular layer in the wall of a blood vessel is the
tunica adventitia. tunica externa. tunica interna. tunica intima. *tunica media*
The layer of the arteriole wall that can produce vasoconstriction is the
tunica adventitia. tunica mater. tunica externa. *tunica media* tunica intima.
Homeostatic mechanisms in response to blood loss include all of the following, except
uptake of interstitial fluid due to reduced capillary pressure. *inhibition of EPO secretion* increased thirst and water intake. activation of aldosterone secretion. activation of ADH secretion
Blood flow to a tissue will increase if the
veins constrict. arterioles constrict. level of carbon dioxide at the tissue decreases. level of oxygen at the tissue increases. *arterioles dilate*
