A&P2 Ch19 (17 questions)

Discuss pressure differences in systemic circulation starting at the aorta and ending at the right atrium

(aorta) pulsating rise/fall, smoothing out pulsations, steady flow (capillaries), (venous) steady/changing little, venae cavae only needs 1mmHg to return to rt atrium

Correctly order vessel tunic layers (9 deep->superficial)

(intima) endothelial layer, subendothelial layer, (internal elastic membrane), (media) smooth muscle layer, elastin sheets, (externa) loose collagen fibers, nerves, elastic fibers, lymphatic vessels, vasa vasorum

Order the sequence of blood flow entering a capillary bed (parasympathetic/normal and sympathetic/altered)

(parasympathetic) Normal: Terminal arteriole > metarteriole + true capillaries + thoroughfare channel > postcapillary venule (sympathetic) Altered: Terminal arteriole > metarteriole > thoroughfare channel > postcapillary venule

Vasa vasorum

(vessel-of-vessels) tiny system of external blood vessels found in larger veins/arteries that "feeds" external layers while lumen "feeds" internal layers

Sources of peripheral resistance (3) and how each affects blood flow

1. blood viscosity: internal resistance to blood flow that is related to its "thickness" or "stickiness" 2. total blood vessel length: longer vessels demonstrate greater resistance 3. blood vessel diameter: changes in blood vessel diameter significantly alter peripheral resistance (R)

Vasodilation _1_ blood vessel lumen ID, _2_ R Vasoconstriction _3_ blood vessel lumen ID, _4_ R

1. decreases, 2. increases; 3. increases, 4.decreases

True capillaries

10 to100 capillary branches off a metarteriole (short proximal vessel linking arterioles/venules) delivering blood to local tissues, merge at thoroughfare channel (short distal vessel linking arterioles/venules)

Factors (3) influencing systemic blood pressure

CO, R, blood volume; F(CO)=P/R or P=CO x R

Cardiac output (CO)

HRxSV; F is equal to it in entire vascular system

Hypertension and Hypotension

Hyper: repeatedly elevated BP readings exceeding 140 mm Hg systolic or 90 mm Hg diastolic Hypo: chronically low BP readings below 90 mm Hg systolic or 60 mm Hg diastolic

Describe both short-term and long-term blood pressure regulations mechanisms

Short-term control involves changes in R + CO Long-term control involves changes in blood volume (kidney-mediated)

Describe origins/destinations a) plasma fluid b) interstitial fluid c) lymphatic vessels

a) "forced out" of distal capillaries, becomes interstitial b) enters lymphatic capillaries, becomes lymph c) returns lymph fluid to blood circulation

Differentiate on a functional basis a) arteries b) veins c) capillaries

a) carry blood away from heart, diverge/branch to smaller vessels b) carry blood to heart, converge/join to larger vessels c) smallest vessels for gas, nutrients, & waste exchange

Describe blood pressure differences in a) aorta b) arteries c) arterioles d) capillaries e) venules f) veins g) venae cavae

a) highest BP b) BP not constant, rise(systole)/fall(diastole) c) steepest BP change, small ID = most R to F d) 20-40mmHg (avg 35mmHg) e) BP decreasing f) steady, low BP (avg 15mmHg) g) only 1mmHg needed to move blood to rt atrium

Body locations of capillaries a) continuous b) fenestrated c) sinusoidal

a) skin, muscles, lung, CNS b) sm. intestine, endocrine glands, kidneys c) liver, bone marrow, lymphoid tissue, some endocrine organs

Define: a) pulsatile b) systolic pressure c) diastolic pressure d) pulse pressure e) mean arterial pressure

a) throbbing, rise/fall in P b) peak pressure (120mm Hg) during ventricular contraction c) lowest pressure (80mm Hg) during ventricular relaxation d) difference b/w systolic and diastolic pressures e) avg arterial pressure propelling blood to tissues/organs

Explain why a blood pressure gradient is necessary for blood circulation

adequate BP must be maintained to provide a "driving force" (pressure gradient, high to low); blood always moves from an area of high pressure to low pressure

Compare/contrast venous blood pressure to arterial blood pressure

arterial: BP reflects elasticity and blood volume of arteries close to heart, avg 120->35mmHg venous: BP is steady and changes little, P is demonstrated during blood loss, avg 35->1mmHg

Recall the type of blood vessel where the steepest blood pressure change occurs

arterioles

Microcirculation

blood flow through capillary beds, composed of terminal arterioles, capillaries, venules draining capillary blood

Blood flow (F)

blood volume flowing through a vessel, an organ, or entire circulation in a given time (mL/min)

Intercellular cleft

capillary general feature, incomplete (unjoined) tight junctions, allow outward passage of fluids/small solutes

Sinusoid

capillary structural type meaning large pores, most permeable, involved in large molecule (protein) passage

Fenestration

capillary structural type meaning small pores, more permeable than continuous, primarily active nutrient absorption or filtrate production

Lumen

central opening in all blood vessels, determines a vessel's internal diameter (ID) + perfusion rate

Capillary bed

concentration of capillaries supplying blood to body tissues (inside organs)

Describe how muscular arteries reduce pulsations

distal elastic arteries help eliminate pulsing before blood enters capillaries (less elastin = less pulsing)

Muscular (distributing) arteries

distal to elastic arteries, proximal to arterioles, more smooth muscle & active in vasoconstriction, primary function: deliver blood to body organs

Explain how blood is propelled through arteries while the heart is in diastole

elastic arteries serve as auxiliary pumps (pressure reservoirs), the recoil after expansion provides pressure needed

Describe arterial elasticity and its relationship to blood volume

elasticity is a conducting arteries ability to stretch (compliance), blood volume is the amount forced into elastic arteries at one time

Blood pressure (BP)

force per unit area that is exerted on a blood vessel wall by its contained blood

Venules

formed where several capillaries unite/merge, postcapillary are smallest

Veins

formed where several venules converge/merge, termed capacitance vessels (blood reservoirs) b/c can contain 60-65% of blood supply during vascular shunting

Route of blood vessels starting at the heart and returning blood to the heart

heart -> elastic arteries (largest) -> muscular arteries (large) -> arterioles (small) -> capillaries (smallest) -> venules (small) -> veins (larger) -> vena cavae (largest) -> heart

Explain the relationship between blood flow, difference in blood pressure (P), and peripheral resistance. Recall which factor is more important in controlling local blood flow.

heart pumping generates F, P results when blood flow is opposed by R; R is a more important factor than P in influencing local blood pressures

Which 4 organs cooperate to ensure adequate BP

heart, blood vessels, kidneys, & brain (CNS) control

Differentiate between true capillaries and a vascular shunt

in vascular shunt, precapillary sphincters shut and blood moves from metaarteriole to thotoughfare channel bypassing the true capillaries

Discuss the effects of dec BP on heart activity (ESV, EDV)

inc preload (inc EDV) + inc contractility (dec ESV)=inc SV

Describe structural/functional features of all 3 vessel tunics

intima: smooth uninterrupted inner surface, dec friction inc blood flow, support lumen endothelium media: cause changes in lumen ID affecting BP and flow, allows expansion/recoil externa: protect vessels, control smooth muscle, expand/recoil, lymph return, vasa vasorum

Explain why the aorta is called a pressure reservoir

it is the largest elastic (conducting) artery, which serve as serve as auxiliary pumps in between ventricular contractions, providing P to move blood while ventricles are refilling

Explain why low capillary pressure is desirable

it won't rupture fragile thin-walled continuous capillaries

Elastic (conducting) arteries

large ID w/ thick-walls, includes aorta/major aortic branches, most elastin of any vessel, primary function: conduct blood from heart to medium-size arteries

Describe special adaptations that help veins return blood to the heart

large-diameter lumens - offer little resistance to blood flow and valves - prevent blood backflow especially in lower limbs, composition resemble heart semilunar valves

Tunic (layer)

lumens may be defined by a single layer of endothelium or several tissue layers extending outward from endothelium; arteries/veins express three different layers

Pericyte

mesenchymal-like cells located on outer endothelium surface to help stabilize capillary walls

Capillaries

microscopic blood vessels present in most body tissues Primary: timely exchange of materials b/w blood plasma and interstitial fluid

Continuous capillaries of the blood-brain barrier

modified continuous capillary, tight junctions are seen between all endothelium = no intercellular clefts

Resistance (R)

opposition to blood flow (F) through one or more vessels

Perfusion & Closed circulation

pumping of a fluid through an organ or tissue through a closed system of vessels

Laminar flowing of blood (streamlining) and how turbulence affects it

relative speed/position of blood in different areas of a blood vessel cross section remains constant; turbulence from vessel lesions interrupt laminar flow dramatically increasing resistance

List three factors aiding venous blood return

respiratory pump, muscular pump, smooth muscle

Arterioles

smallest arteries interfacing with tissue capillary beds, deliver blood to tissues located inside body organs

Explain the effects of smooth muscle contraction and relaxation on blood vessel diameter

smooth muscle relaxation increases lumen ID, contraction decreases lumen ID

Venous sinuses

specialized, wide/flattened veins w/ extremely thin walls (ex. heart coronary sinus & brain venous sinuses)

Vessel Tunics from deep to superficial

tunica: intima, media, externa

Vascular Anastomoses

union/joining of blood vessels in certain body areas; 3 types: venous (most common, back of hands/feet, rarely blocked), arterial (collateral channels in joints, heart, brain, abdominal organs), arteriovenous (vascular shunts seen in digestive/urinary tissues)