Chapter 21: The Cardiovascular System: Blood Vessels

Heart arteries arterioles capillaries venules veins heart

Blood Vessel Anatomy Arterial Blood System ______________

vessels- “air,” “to carry” Types:

Elastic = conducting muscular = distributing

Venous Blood System - _________________ vessels

Capillaries - ______________ vessels

Arteries- 3 tunics figure 21.1 ____________________- lining of simple

squamous epithelium = 1. ____________, closest to the lumen 2. Basement membrane 3. Internal elastic lamina

________________- middle coat, usually thickest, elastic & circular smooth muscle __________________- stretch without tearing Innervated by sym NS for constriction/dilation

_____________________- outer, elastic & collagen

Vaso vasorum

“_______________________” Larger blood vessels require oxygen

and nutrients, to do so they are served by these types of blood vessels

Types of arteries

________________–largest diameter __________________ in tunica media Walls ___________ compared to diameter Help ______ blood while ventricles relax

Walls stretch to store ______________ Conduct blood to more muscular arteries Aorta, brachoiocephalic, common

coratid, subclavian, vertebral, pulmonary, common iliac

Types of arteries (2)

_____________________- distribute to various parts of the body Media- more smooth muscle, less elastic Capable of > vasoconstriction/dilation Examples: brachial artery, radial artery

Arterioles Small artery 10-100 μm in diameter ________________________ Similar to arteries but usually just a ring of

endothelial cells surrounded by scattered smooth muscle fibers

______________ – opposition to blood flow Mainly friction between blood an inner walls

Arterioles can be dilated or constricted called resistance vessels

_________________ can affect bp

Capillaries = microcirculation Microscopic vessels, 4-10μm connect arterioles to venules Near almost every cell in the body

# vary w/metabolic activity of the tissue _______________ – exchange of nutrients and

waste between blood and tissue cells thru interstitial fluid

Walls= single cell layer thick & b.m. ________________– emerges from arteriole &

supplies 10-100 capillaries (capillary bed)

Capillaries (2)

__________________ – ring of smooth muscle at the junction of the arteriole with metarteriole Control flow to capillary bed

__________________- bypasses the capillary bed

Types of capillaries, fig. 21.4 _______________ – endothelial cells form

continuous tube only interrupted by intercellular clefts (gaps) Skeletal & smooth muscle, CT, lungs

__________ – “window,” have small pores Kidneys, villi, choroid plexuses, endocrine glands

____________ – wider than other cap, may have unusually large fenestrations Incomplete or absent basement membrane Liver, red bone marrow, spleen, some endocrine

Venule

______________________ forming these small veins

Walls very porous Many phagocytic WBC migrate from here

Few scattered smooth muscle cells Larger venules more ____________ _______________________

Veins 3 layers, interna & media much thinner

than artery (less smooth muscle & elastic) thickest layer - tunica externa = collagen &

elastic fibers, lack external & internal elastic lamina

__________ to handle volume & pressure Δ yet not capable to withstand pressure

have abundant __________ (esp. in limbs) thin folds in the tunica interna form flaplike

cusps projecting into the lumen towards the _________________________

Capillary exchange, fig 21.7 7% blood in systemic cap at any one time Diffusion _______________- plasma in vesicles are

endocytosed by endothelial cells & exocytosed out other side Insulin, Ab from mother to fetus

________________- passive process, large # of ions, molecules particles move in same direction at rates > than w/diffusion Filtration & resorption

Pressure driven movements ________– fluid & solutes interstitial fluid ___________– FROM interstitial fluid blood

capillaries 2 pressures accountable for filtration:

Blood hydrostatic pressure (BHP)- generated by pump action of heart

Interstitial fluid osmotic pressure Main pressure accountable for reabsorption:

Blood colloid osmotic pressure (BCOP) _____________________ (NFP) = balance of all

of these pressures

Pressure driven movements (2) __________________ – pressure due to water

in plasma exerted against bv Interstitial fluid hydrostatic pressure pushes

fluid back into capillaries Is close to zero

Difference in ________________ across due to plasma proteins too large to pass pores or fenestrations BCOP force of these large proteins to pull IF into

capillaries (remember- diffusion from to )

Edema __________________________________ Interstitial fluid 30% > than normal Causes of excess filtration:

capillary blood pressure permeability of capillaries

Chemicals, bacterial, thermal, mechanical Cause of inadequate reabsorption:

concentration of plasma proteins Liver disease, burns, malnutrition, kidney

disease

Blood pressure Hydrostatic pressure exerted by blood on

walls of blood vessel __________________________________ __________________________________ @ 110mmHg during systole drops

to70mmHg during diastole Systolic- highest pressure in arteries during

systole Diastolic- lowest arterial pressure during diastole Pressure falls progressively as distant from L.V.

Mean arterial pressure MAP = average bp in arteries @1/3 between systolic & diastolic MAP = diastolic bp +1/3(systolic-dia) CO MAP blood volume MAP

*Don’t forget, just as in the ventricles, blood flows from areas of high to low pressure

Resistance = opposition to flow BF = P/R BP = CO x TPR (TPR=total peripheral

resistance= all the vascular R offered by systemic bv) Viscosity- thickness, viscosity resistance, flow vessel length- longer vessel, resistance vessel diameter (1/ r4)- lumen resistance

Blood volume- volume pressure CO = SV x HR

If CO, P as long as R is same

Systemic Vascular Resistance (SVR) and venous return

Arterioles control SVR bp & blood flow to particular areas by Δ diameter Controlled by brainstem

____________________: Besides heart 2 mechanisms to pump blood:

_________________: valves open, muscle contraction pushes blood thru proximal valve and closes distal, muscle relax & close proximal

_________________: pressure in thoracic pressure in abdominal volume from abdomen to Rt Atrium

Regulation of Blood pressure CV center – input from higher brain regions

& sensory receptors Figure 21.12

Neural Baroreceptors – Δ pressure

Carotid sinus- for pressure in the brain Aortic- regulate systemic pressure

Chemoreceptors – Δ O2, CO2, H +

acidosis symp hormones, vasoconstriction Hormonal control

Renal regulation, symp hormones, ANP, Angiotensin II

Hormonal regulation of bp _______________________ (RAA)- blood volume

falls or kidney blood flow, renin angiontensin II bp Vasoconstriction Stimulates release of aldosterone

______________- CO by HR and force, also cause vasoconstriction

_______- released due to blood volume urine output, vasoconstriction

__________________________- released by , bp by vasodilation

Circulatory shock Failure to deliver O2 and nutrients to meet

metabolic need Hypovolemic – low blood volume Cardiogenic – poor heart function Vascular – inappropriate vasodilation Obstructive- obstruction to blood flow

See figure 21.16 – responses Activation of RAA ADH Sympathetic hormones Local vasodilators: K+, H+, lactic acid, NO

Shock: signs and symptoms Systolic bp 90 Resting HR due to symp Pulse weak and rapid, CO & HR Skin is cool, pale, clammy Mental state altered urine production thirst pH due to acidosis Nausea - impaired blood flow to GI tract

Disorders _________________- a group of diseases

characterized by thickening of artery walls and loss of elasticity

_____________- thin weakened section of the wall of artery or vein, bulges out Graft or replace

_______- inflammation of vein, often in leg CVA= cerebrovascular accident- destruction

of brain tissue (infarction) resulting of obstruction or rupture of bv supplying brain

Atherosclerosis, LDL, and HDL Atherosclerosis - a stage of arteriosclerosis

involving fatty deposits or plaques (atheromas) inside the arterial walls, thus narrowing the arteries 

Plaques develop from due to excessive LDL (containing much cholesterol) accumulate in the inner layer of the artery wall

HDLs decrease amount of excessive cholesterol, transport it to liver for elimination

Hypertension Silent killer- damage to bv, heart, brain, kidney before

any noticable pain or symptoms Major risk factor for both#1 cause of death = heart

disease, & #3 = stroke Lifestyle changes: lose weight, exercise, reduce salt

intake, maintain proper electrolyte intake, don’t smoke, manage stress

Drug treatment- ACE (angiotensin converting enzyme) inhibitors beta blockers- inhibit renin Vasodilators Ca 2+ channel blockers- decrease heart rate

Fetal circulation O2 & nutrients- diffusion from maternal

blood (& eliminates its CO2 & wastes) exchange occurs ______________-inside uterus

Normally, no direct mixing of maternal & fetal blood; all exchanges by diffusion thru capillaries

Deoxy blood from fetus to placenta via 2 umbilical arteries -____________________

___________________________________

Fetal circulation (2) Umbilical vein ascends to liver, forms 2

branches: some thru the branch that joins the

hepatic portal vein most flows into ____________ IVC

Deoxygenated blood IVC mingles w/blood from ductus venosus

Deoxy blood from upper body SVC, this blood mixes in the right atrium

Fetal circulation (3) Most blood does not pass to rt

ventricle & lungs but thru _________- opening between right & left atria, bypassing pulmonary circuit

Blood reaches rt ventricle, but little reaches nonfunctioning lungs

Instead, most blood sent thru another bypass _____________-vessel connecting pulmonary trunk & aorta (becomes ____________________)