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  • Functions of blood vessels

    1. vessels transport blood to tissues to allow for material exchange & transport back to hear

    2. regulates blood flow

    3. control blood pressure

    4. secretes a variety of chemicals

  • Elastic Arteries

    • extensive elastic lamina w/ less smooth muscle tissue so diameter does not change signif

    • conduct blood under high pressure

    • the distensibility & elasticity dampens the pressure created by beating heart

    • when blood reaches arterioles-flow is continuous

  • Elastic arteries of the body and what they have in common

    • Aorta, pulmonary trunk, common carotids, subclavian, common iliac arteries

    • All located close to heart

  • Muscular arteries (distribution arteries)

    Tunica media mostly smooth muscle tissue and less elastic tissue; easily vasodilates and vasoconstricts to regulate blood pressure

    • external carotid, brachial arteries, mesenteric, femoral arteries

    • closer to skeletal muscles and organs

    • regulate blood flow to organs and skel muscles

  • arterioles

    smallest ARTERIES, control blood flow to tissues

  • metarterioles

    smallest ARTERIOLES which move blood directly into capillaries

  • precapillary sphincters

    smooth muscle that controls blood flow into capillary bed . If relaxed, blood moves into capillaries. If constricted, blood flows into thoroughfare channel then venule, bypassing capillary bed

  • Continuous Capillaries

    Structure: Tight junctions between cells

    Location: skin, most nervous and connective tissue, muscle tissue

    Function: least leaky

    *Most abundant

  • Fenestrated Capillaries

    Structure: cells contain pores

    Location: Kidney, endocrine glands, small intestine

    Function: Moderately leaky

  • Sinusoidal Capillaries

    Structure: cells contain large pores

    Location:Liver, lymphoid organs, bone marrow, spleen

    Function: Leakiest

  • Venules

    smallest veins; collect blood from capillaries

  • Veins (medium-sized, large veins)

    • med sized veins converge into larger veins closer to the heart

    • contain valves to prevent back flow of blood

  • Veins are a Blood reservoir

    • numerous veins & large diameter allow them to hold 70% of blood

    • venoconstriction can move blood to needed areas of body

  • Arteriovenous anastomosis (shunt)

    • artery connects to vein

    • bypass capillary bed

    • located in skin and fetal circulation (shunt bypasses liver)

  • Hemodynamics

    • physiology of blood flow

    • purpose is to maintain tissue perfusion

    • blood flow into capillary beds of body tissue

  • Blood velocity (speed of flow)

    • fastest in arteries

    • slowest in capillaries

    • increases in veins to return blood to heart

    • slow velocity is due to high cross-sectional area which is greatest in capillaries

  • BP in Arteries

    100 -35 mmHg

  • BP in Veins

    0-15 mmHg

  • BP in Capillaries

    15-35 mmHG

  • Systolic pressure

    Pressure in arteries when ventricles contract (110-120mmHG)

  • Diastolic pressure

    Pressure in arteries when ventricles are relaxed (70-80mmHG)

  • Pulse pressure

    Systolic-Diastolic pressure

  • Mean Arterial Pressure (MAP)

    • Average pressure in the arterial circuit

    • Diastolic pressure + (pulse pressure/3)

  • Mechanisms of Venous Return

    1. Luminal Diameter

    2. Valves

    3. Skeletal muscle pumps

  • Factors that determine Blood Pressure

    • Resistance

    • Cardiac Output

    • Blood volume

  • Peripheral resistance

    Factors that hinder blood flow

  • Feed Forward System

    the body's ability to anticipate change and use the autonomic nervous system to prevent it from happening

  • Myogenic mechanisms of BP maitenance

    ensures blood flow through capillaries not too fast or not too slow, increase in arteriolar pressure causes vasoconstriction to decrease velocity of blood flow through capillary and vice versa

  • Metabolic controls of BP

    ensures blood flow is directed to active tissue

  • Capillary exchange-Diffusion

    O2 & CO2 move from high to low concentration across endothelial cell membranes or pores

  • Capillary exchange-Transcytosis

    Larger molecules are move by endocytosis and exocytosis

  • Ascites

    • excess water accumulates in interstitial fluid of abdomen

    • starvation, inadequate protein in diet

    • less albumin

  • Which vessel is known as a resistance vessel?

    Arterioles

  • Which vessel allows for exchange b/n blood and tissue?

    Capillaries

  • Which blood vessel contains the largest % of blood?

    veins (70%)

  • In which vessel is there a decrease in pressure from 120/80mmHg to 35mmHg?

    Arteries

  • What causes the most immediate and rapid changes in Peripheral resistance?

    changes in blood vessel radius

    -vasoconstriction and vasodilation

  • As peripheral resistance decreases, resistance to blood flow increases

    blood flow decreases and BP increases

  • Arterioles vasodilate when tissue...

    becomes acidic

  • Which process is the movement of water and solutes from body tissue into capillaries?

    absorption or reabsorption

  • Myogenic mechanism slows blow into a capillary bed when

    arteriolar pressure rises

  • What connects vessels through vascular anastomoses?

    collaterals

  • What is the main local autoregulatory mechanism of cardiac muscle tissue?

    oxygen

  • Large, lipid-insoluble molecules cross capillary walls by?

    Transcytosis

  • Force driving reabsorption at venule end of capillary

    blood colloid osmotic pressure

  • Main chemical concentrations that dilate arterioles

    • increased CO2

    • increased H

    • decreased O2

  • small solutes can pass through small pores in some capillaries known as

    fenestrations