CHP 15 - BLOOD VESSELS

blood volume is determines by

• fluid intake

• fluid loss

cardiac output is determined by

1. heart rate

2. stroke volume

resistance of system flow is determined by

diameter of arterioles

distribution of blood between arterioles and veinous vessels are determines by

diameter of veins

what factors contribute to decrease in resistance to flow

1. cross - sectional area increases

2. radius of vessels increase

the equation for mean arterial pressure

MAP = Q X R

list blood vessels from hifghest to lowest pressure

1. aorta

2. arteries

3. arterioles

4. capillaries

5. venules

6. veins

7. vena cava

where is the velocity of blood flow slowest

where the cross-sectional area is greatest

what blood vessels holds majority of the bodys blood reservoir

veins because of their distensibility

systems in place that help blood flow from body back to the heart

1. venous valves

2. skeletal muscle pump

3. respiratory pump

4. smooth muscle in veins

5. gravity and body positioning

what is angiogenesis

development of new blood vessels from existing blood vessels

what are arteries

• act as pressure reservoirs

• carries oxygenated blood away from the heart to tissues

• thick, vascular walls

what are arterioles

• controls blood flow and pressure

• vasoconstrictors and vasodilates

• less elastic, more muscular

what are metarterioles

• connects arteries to venules

• directs blood flow to either capillaries or venous circulation

what are capillary beds

• site of exchange between blood and interstitial fluid

• tiny blood vessels that connect arteries to veins

• sit of exchange of O2 and nutrients

what are venules

• recieve blood from capillaries

what are veins

• blood vessels that carry deoxygenated blood to the heart

• have a good distensibility to hold more blood

• contain one way valves

• less elastic tissue

• thin walls

2 equations for MAP

1. diastolic pressure + 1/3 (pulse pressure)

2. Q x R

what is systolic pressure

• pressure exerted on the walls of arteries when the heart's ventricles contract and pump blood into the aorta.

• It represents the highest pressure within the arteries during each heartbeat.

what is diastolic pressure

• pressure in the arteries when the heart is at rest between beats, specifically when the heart’s ventricles relax and refill with blood.

• It represents the lowest pressure within the arteries.

what is pulse pressure

• the difference between systolic and diastolic pressure

  • systolic - diastolic

4 factors that influence mean arterial pressure

1. blood volume

2. effectiveness of the heart

3. resistance to flow

4. relative distribution of blood between arterioles and veinous vessels

the fast response to high blood volume/ high blood pressure

1. vasodilation

2. less cardiac output

the slow response to high blood volume/ high blood pressure

1. excretion of fluid through urine

effect on pressure if blood volume increases

pressure increases

effect on pressure if blood volume decreases

pressure decreases

cardiac output is determined by

• heart rate

• stroke volume

heart rate is determined by

rate of depolarization in autorhythmic cells

• sympathetic - increases heart rate

• parasympathetic - decreases heart rate

stroke volume is determined by

force of contraction in ventricular myocardium

1. contractility

2. end-diastolic volume

equation for stroke volume

end-diastolic volume - end systolic volume

equation for cardiac output

heart rate x stroke volume

equation for ejection fraction

stroke volume/ end-diastolic volume x 100

resistance to system blood flow is determined by

diameter of arterioles

1. vasocontriction

2. vasodilation

what is active hyperemia

matches blood flow to increased metabolism (exercise)

what is hyperemia

locally mediated increase in blood flow

what is reactive hyperemia

blood flow increase following a period of decreased blood flow (like a blockage)

arteriolar resistance is influenced by

both local and systemic control mechanisms

what is myogenic autoregulation

mechanism in which blood vessels automatically adjust their diameter in response to changes in blood pressure to maintain consistent blood flow.

3 factors that influence resistance in arterioles

1. myogenic autoregulation

2. paracrine signals

3. local factors

what does norepinephrone do when it binds to alpha receptors

vasoconstricts

what does norepinephrone do when it binds to beta-2 receptors

vasodilates

chemicals that cause vasodilation in arterioles

• epinephrine on B2 receptors

• nitric oxide

• adenosine

• low O2 levels

• high CO2 levels

• high H+ levels

• high K+ levels

distribution of blood between arterioles and venous vessels is determined by

diameter of the veins