Chapter 13: Blood, Heart and Circulation
Functions of Circulatory System
 Transportation of respiratory gases, delivery of nutrients and hormones, and waste
removal
 And in temperature regulation, ________________, and immune function
Components of Circulatory System
 Include cardiovascular and lymphatic systems
 Heart pumps blood thru cardiovascular system
 From heart to arteries, arterioles, capillaries, venules, veins and back
 Lymphatic system picks up excess fluid filtered out in
___________________________ beds and returns it to veins
 Its lymph nodes are part of immune system
Components of Blood
 Consists of formed elements (cells) suspended and carried in plasma (fluid part)
 When centrifuged, blood separates into heavier formed elements on bottom and
plasma on top
 Total blood volume is about 5L
 ______________________ is straw-colored liquid - H2O and dissolved solutes:
ions, metabolites, hormones, antibodies
 Red blood cells comprise most of formed elements
 % of RBCs in centrifuged blood sample = hematocrit
 Hematocrit is 36-46% in women; 41-53% in men
Plasma Proteins
 Constitute 7-9% of plasma
 Plasma proteins:
 Albumin accounts for 60-80%
 Creates colloid osmotic pressure to maintain blood volume and
pressure
 Globulins carry lipids
 __________________ globulins are antibodies
 Fibrinogen serves as clotting factor
 Converted to fibrin
 __________________ is fluid left when blood clots
Formed Elements
 Are erythrocytes (RBCs) and leukocytes (WBCs)
 RBCs are flattened biconcave discs
 Shape provides increased _________________________ for diffusion
 Lack nuclei and mitochondria
 Each RBC contains 280 million hemoglobins
 About 300 billion RBCs are produced each day
Leukocytes
 Have a nucleus, mitochondria, and amoeboid ability
 Can squeeze through capillary walls (_____________________________)
 Granular leukocytes help detoxify foreign substances and release heparin
 Include eosinophils, basophils, and neutrophils
 Agranular leukocytes are phagocytic and produce antibodies
 _________________________ and Monocytes
Platelets (thrombocytes)
 Are smallest of formed elements, lack nucleus
 Are amoeboid ________________________ of megakaryocytes
 Constitute most of mass of blood clots
 Reduce blood flow to clot area by vasoconstriction
 Secrete growth factors for blood vessel wall
 Survive 5-9 days
Hematopoiesis
 Is formation of blood cells from stem cells in bone marrow (myeloid tissue) and
lymphoid tissue
 Marrow produces about 500 billion blood cells/day
 In ___________________ occurs in liver
 Erythropoiesis is formation of RBCs
 Stimulated by erythropoietin (EPO) from kidney
 Leukopoiesis is formation of __________________
 Stimulated by variety of cytokines
Erythropoiesis
 Lifespan of 120 days
 Old RBCs removed by phagocytic cells in liver, spleen, and bone marrow
 Iron recycled
RBC Antigens and Blood Typing
 Antigens present on RBC surface specify blood type
 Major antigen group is ___________________________
 Type A blood has only A antigens
 Type B has only B antigens
 Type AB has both A and B antigens
 Type O has neither A or B antigens
Transfusion Reactions
 Type A blood make antibodies to Type B RBCs,
 Type B blood has antibodies to Type A RBCs
 Type AB blood doesn’t have antibodies to A or B
 Type O has antibodies to both Type A and B
 Antibodies in different blood types will cause _________________________
 Type O is “universal donor”, lacks A and B antigens
 Recipient’s antibodies won’t agglutinate donor’s Type O RBCs
 Type AB is “universal recipient”, doesn’t make anti-A or anti-B antibodies
 Won’t agglutinate donor’s RBCs
Rh Factor
 Is another type of antigen found on RBCs
 Rh+ has ____________________ antigens; Rh- does not
 Can cause problems when Rh- mother has Rh+ babies
 At birth, mother may be exposed to Rh+ blood of fetus
 In later pregnancies mom may produce Rh antibodies
 In Erythroblastosis fetalis, this happens and antibodies cross
placenta causing _______________________ of fetal RBCs
Hemostasis
 Is cessation of bleeding
 Promoted by reactions initiated by vessel injury:
 Vasoconstriction restricts blood flow to area
 Platelet plug and surroundings are infiltrated by web of
______________________, forming clot
Role of Platelets
 Platelets don't stick to intact endothelium because of presence of prostacyclin
(PGI2--a prostaglandin) and NO
 Keep clots from forming and are vasodilators
 Endothelial damage lets platelets bind to exposed collagen
 ________________________________ factor increases bond by binding
to both collagen and platelets
 Platelet release reaction occurs until platelet plug is formed
Role of Fibrin
 Platelet plug becomes infiltrated by meshwork of fibrin
 Clot now contains platelets, fibrin and trapped RBCs
 Platelet plug undergoes plug contraction to form more compact plug
Conversion of Fibrinogen to Fibrin
 Can occur via 2 pathways:
 Intrinsic pathway clots damaged vessels and blood left in test tube
 Initiated by ________________________ of blood to negatively
charged surface of glass or blood vessel collagen
 Extrinsic pathway: damage outside blood vessels releases tissue
thromboplastin that triggers a clotting shortcut
Dissolution of Clots
 When damage is repaired,
 Kallikrein converts ______________________________ to plasmin
 Plasmin digests fibrin, dissolving clot
Anticoagulants
 Clotting can be prevented by Ca+2 chelators (e.g. sodium citrate or EDTA)
 or heparin which activates antithrombin III (blocks thrombin)
 Coumarin blocks clotting by _____________________ activation of Vit K
 Vit K works indirectly by reducing Ca+2 availability
Structure of Heart
 Heart has 4 chambers
 2 atria receive blood from venous system
 2 ventricles pump blood to arteries
 2 sides of heart are 2 pumps separated by muscular septum
 ______________________________ structurally and functionally separates
 Myocardial cells of atria to top of skeleton and form 1 unit (or
myocardium)
 Cells from ventricles attach to bottom and form another unit
 Fibrous skeleton also forms rings, the annuli fibrosi, to hold heart valves
Pulmonary and systemic Circulations
 Blood coming from ____________ enters superior and inferior vena cavae which
empties into right atrium, then right ventricle, pulmonary arteries and to lungs
 Oxygenated blood from lungs passes thru pulmonary veins to left atrium, then to
left ventricle which pumps it through _________________ to body
 Pulmonary circulation is path of blood from right ventricle through lungs and
back to heart
 Systemic circulation is path of blood from left ventricle to body and back to heart
 Rate of flow through systemic circulation ______ flow rate thru pulmonary circuit
 Resistance in systemic circuit > pulmonary
 Work done by left ventricle pumping to systemic is 5-7X greater
 Makes left ventricle more muscular (and 3-4X thicker)
Atrioventricular Valves
 Blood flows from atria into ventricles thru 1-way atrioventricular (AV) valves
 Between right atrium and ventricle is _____________________________
 Between left atrium and ventricle is bicuspid or mitral valve
 High pressure of ventricular contraction is prevented from everting AV valves by
contraction of papillary muscles which are connected to AVs by chorda tendinea
Semilunar Valves
 During ________________________ contraction blood is pumped through aortic
and pulmonary semilunar valves
 Closed during relaxation
Cardiac Cycle
 Is repeating pattern of contraction and relaxation of heart
 Systole refers to contraction phase
 Diastole refers to relaxation phase
 Both atria contract simultaneously; ventricles follow 0.1-0.2 sec later
 End-diastolic volume is volume of blood in ventricles at end of diastole
 ___________________ is amount of blood ejected from ventricles during systole
 End-systolic volume is amount of blood left in ventricles at end of systole
 As ventricles contract, pressure rises, closing AV valves
 Called isovolumetric contraction because all valves are closed
 When pressure in ventricles exceeds that in aorta, _____________________
valves open and ejection begins
 All valves are closed and ventricles undergo isovolumetric relaxation
 Atrial systole sends its blood into ventricles
Heart Sounds
 Closing of AV and semilunar valves produces sounds that can be heard thru
_____________________________
 Lub (1st sound) produced by closing of AV valves
 Dub (2nd sound) produced by closing of semilunars
Heart Murmurs
 Are abnormal sounds produced by abnormal patterns of blood flow in heart
 Many caused by defective heart valves
 Can be of congenital origin
 In mitral stenosis, mitral valve becomes ________________________________,
impairing blood flow from left atrium to left ventricle
 Valves are incompetent when don't close properly
 Can be from damage to papillary muscles
 Murmurs caused by __________________ defects are usually congenital
 Due to holes in septum between left and right sides of heart
 Pressure causes blood to pass from left to right
Electrical Activity of Heart
 Myocardial cells are short, branched, and interconnected by gap junctions
 Entire muscle that forms a chamber is called a myocardium or functional
___________________
 APs originating in a cell are transmitted to all others
SA Node Pacemaker
 In normal heart, SA node functions as pacemaker
 Depolarizes spontaneously to _________________________
( pacemaker potential)
 Membrane voltage begins at -60mV and gradually depolarizes to -40 threshold
 At threshold V-gated Ca2+ channels open, creating upstroke and contraction
 Repolarization is via opening of V-gated K+ channels
Ectopic Pacemakers
 Other tissues in heart are _____________________________ active
 But are slower than SA node
 Are stimulated to produce APs by SA node ______________________
they depolarize to threshold
 If APs from SA node are prevented from reaching these, they will
generate pacemaker potentials
Myocardial APs
 Myocardial cells have ______________________________________ of –90 mV
 Depolarized to threshold by APs originating in SA node
 Upstroke occurs as V-gated Na+ channels open
 MP rapidly declines to 15mV and stays there for 200-300 msec
(______________________phase)
 Plateau results from balance between slow Ca2+ influx and K+ efflux
 Repolarization due to opening of extra K+ channels
Conducting Tissues of Heart
 APs from SA node spread through atrial myocardium via ___________ junctions
 But need special pathway to ventricles because of non-conducting fibrous tissue
 AV node at base of right atrium and bundle of His conduct APs to
ventricles
 In septum of ventricles, His divides into right and left bundle branches
 Which give rise to ________________________ in walls of ventricles
 These stimulate contraction of ventricles
Conductions of APs
 Time delay occurs as APs pass through AV node
 Ventricular contraction begins 0.1–0.2 sec after contraction of atria
Excitation-Contraction Coupling
 Depolarization of myocardial cells opens V-gated Ca2+ channels in sarcolemma
 This depolarization opens V-gated and Ca2+ release channels in SR
(____________________________________________)
 Ca2+ binds to troponin and stimulates contraction (as in skeletal muscle)
 During repolarization Ca2+ pumped out of cell and into SR
Refractory Periods
 Heart AP lasts about 250 msec
 Has a refractory period almost as long as AP
 ____________________ be stimulated to contract again until has relaxed
Electrocardiogram
 Is a recording of electrical activity of heart conducted thru ions in body to surface
Types of ECG Recordings
 Bipolar leads record voltage between electrodes placed on wrists and legs (right
leg is ground)
 Lead I records between right arm and left arm
 Lead II: right arm and left leg
 Lead III: left arm and left leg
 Unipolar leads record voltage between a single electrode placed on body and
ground built into ECG machine
 Limb leads go on right arm (AVR), left arm (AVL), and left leg (AVF)
 The 6 chest leads allow certain abnormalities to be detected
ECG
 3 distinct waves are produced during cardiac cycle
 P wave caused by atrial depolarization
 _______________________________ is caused by ventricular depolarization
 T wave results from ventricular repolarization
Correlation of ECG with Heart Sounds
 1st heart sound (lub) comes immediately after QRS wave as AV valves close
 2nd heart sound (dub) comes as T wave begins and semilunar valves close
Structure of Blood Vessels
 __________________________ layer of all vessels is the endothelium
 Capillaries are made of only endothelial cells
 Arteries and veins have 3 layers called tunica externa, media, and interna
 Externa is connective tissue
 Media is mostly smooth muscle
 Interna is made of endothelium, ________________________, and elastin
 Although have same basic elements, arteries and veins are quite different
Arteries
 Large arteries are muscular and elastic
 Contain lots of elastin
 Expand during systole and recoil during diastole
 Helps ____________________ smooth blood flow during diastole
 Small arteries and arterioles are muscular
 Provide most resistance in circulatory system
 Arterioles cause greatest pressure drop
 Mostly connect to capillary beds
 Some connect directly to veins to form arteriovenous ___________
Capillaries
 Provide extensive surface area for __________________________
 Blood flow through a capillary bed is determined by state of precapillary
sphincters of arteriole supplying it
Types of Capillaries
 In continuous capillaries, endothelial cells are tightly joined together
 Have narrow intercellular channels that permit exchange of molecules
_______________________ than proteins
 Present in muscle, lungs, adipose tissue
 Fenestrated capillaries have wide intercellular pores
 Very permeable
 Present in kidneys, endocrine glands, intestines.
 ____________________________ capillaries have large gaps in endothelium
 Are large and leaky
 Present in liver, spleen, bone marrow
Veins
 Contain majority of blood in circulatory system
 Very ______________________ (expand readily)
 Contain very low pressure (about 2mm Hg)
 Insufficient to return blood to heart
 Blood is moved toward heart by contraction of surrounding skeletal muscles
(skeletal muscle pump)
 And pressure drops in chest during breathing
 _________________ venous valves ensure blood moves only toward heart
Atheosclerosis
 Is most common form of arteriosclerosis (_____________________ of arteries)
 Accounts for 50% of deaths in US
 Localized plaques (atheromas) reduce flow in an artery
 And act as sites for thrombus (blood clots)
 Plaques begin at sites of _______________________ to endothelium
 E.g. from hypertension, smoking, high cholesterol, or diabetes
Cholesterol and Plasma Lipoproteins
 High blood cholesterol is associated with risk of atherosclerosis
 Lipids, including cholesterol, are carried in blood attached to LDLs (low-density
lipoproteins) and HDLs (high-density lipoproteins)
 LDLs and HDLs are produced in liver and taken into cells by
________________________-mediated endocytosis
 In cells LDL is oxidized
 Oxidized LDL can injure endothelial cells facilitating plaque
formation
 Arteries have receptors for LDL but not HDL
 Which is why HDL ____________ atherosclerotic
Ischemic Heart Disease
 Is most commonly due to atherosclerosis in coronary arteries
 Ischemia occurs when blood supply to tissue is ______________________
 Causes increased lactic acid from anaerobic metabolism
 Often accompanied by angina pectoris (chest pain)
 Detectable by changes in ________________ segment of ECG
 Myocardial infarction (MI) is a heart attack
 Usually caused by occlusion of a coronary artery
 Causing heart muscle to die
 Dead cells are replaced by _______________________ scar tissue
Arrhythmias Detected on ECG
 Arrhythmias are abnormal heart rhythms
 Heart rate <60/min is ________________________; >100/min is tachycardia
 In flutter, contraction rates can be 200-300/min
 In fibrillation, contraction of myocardial cells is uncoordinated and pumping
ineffective
 ____________________________________ is life-threatening
 Electrical defibrillation resynchronizes heart by depolarizing all
cells at same time
 AV node block occurs when node is damaged
 First–degree AV node block is when _____________ through AV node > 0.2 sec
 Second-degree AV node block is when only 1 out of 2-4 atrial APs can
pass to ventricles
 In third-degree or complete AV node block, no atrial activity passes to ventricles
 Ventricles are driven slowly by bundle of His or Purkinjes
Lymphatic System
 Has 3 basic functions:
 Transports interstitial fluid (________________) back to blood
 Transports absorbed fat from small intestine to blood
 Helps provide immunological defenses against pathogens
 Lymphatic capillaries are ______________________ tubes that form vast
networks in intercellular spaces
 Very porous, absorb proteins, microorganisms, fat
 Lymph is carried from lymph capillaries to lymph ducts to lymph nodes
 Lymph nodes filter lymph before returning it to veins via thoracic duct or right
lymphatic duct
 Nodes make lymphocytes and contain ________________________ cells that
remove pathogens
 Lymphocytes also made in tonsils, spleen, thymus
Chapter 14: Cardiac Output, Blood Flow, and Blood Pressure
Cardiac Output
 Is volume of blood pumped/min by each ventricle
 _____________________________ (SV) = blood pumped/beat by each ventricle
 CO = SV x HR
 Total blood volume is about 5.5L
Regulation Cardiac Rate
 Without neuronal influences, SA node will drive heart at rate of its spontaneous
activity
 ____________________________ innervation of SA node modify rate of
spontaneous depolarization (chronotropic effect)
 NE and Epi open pacemaker HCN channels
 Depolarizes SA faster, increasing HR
 ACH promotes K+ outflow, slowing depolarization and decreasing HR
 Cardiac control center of medulla coordinates activity of autonomic innervation
 Sympathetic endings in atria and ventricles can _________________________
strength of contraction and __________________________ time of contraction
Stroke Volume
 Is determined by 3 variables:
 End diastolic volume (EDV) = volume of blood in ventricles at end of
diastole
 Total peripheral resistance (TPR) = ___________ to blood flow in arteries
 Contractility = strength of ventricular contraction
Regulation of Stroke Volume
 EDV is workload (preload) on heart prior to contraction
 SV is ____________________ proportional to preload and contractility
 Strength of contraction varies directly with EDV
 Total peripheral resistance = afterload which impedes ejection from ventricle
 Ejection fraction is SV/ EDV
 Normally is 60%; useful clinical _______________________ tool
Frank-Starling Law of the Heart
 States that strength of ventricular contraction varies directly with EDV
 Is an ______________________ property of myocardium
 As EDV increases, myocardium is stretched more, causing greater
contraction and SV
 (a) is state of myocardial sarcomeres just before filling
 Actins overlap, actin-myosin interactions are reduced and contraction
would be weak
 In (b, c and d) there is increasing interaction of actin and myosin allowing more
force to be developed
Extrinsic Control or Contractility
 At any given EDV, contraction depends upon level of sympathoadrenal activity
 NE and Epi produce an increase in HR and contraction (positive
___________________________ effect)
Venous Return
 Is return of blood to heart via veins
 Controls EDV and thus SV and CO
 Dependent on:
 Blood volume and venous pressure
 Vasoconstriction caused by Symp
 Skeletal muscle pumps
 Pressure drop during inhalation
 Veins hold most of blood in body (~70%) and are thus called
___________________________ vessels
 Have thin walls and stretch easily to accommodate more blood without
increased pressure (higher compliance)
 Have only 0- 10 mm Hg pressure
Blood Volume
 Constitutes small fraction of total body fluid
 2/3 of body H2O is inside cells (intracellular compartment)
 1/3 total body H2O is in extracellular compartment
 80% of this is interstitial fluid; 20% is blood __________________
Exchange of Fluid between Capillaries and Tissues
 Distribution of ECF between blood and interstitial compartments is in state of
dynamic equilibrium
 Movement out of capillaries is driven by _________________________ pressure
exerted against capillary wall
 Net filtration pressure= hydrostatic pressure in capillary (17-37 mm Hg) hydrostatic pressure of ECF (1 mm Hg)
 Movement also affected by ______________________ osmotic pressure
 = osmotic pressure exerted by proteins in fluid
 Plasma osmotic pressure = 25 mm Hg; interstitial osmotic pressure
= 0 mm Hg
Overall Fluid Movement
 Is determined by net filtration pressure and forces opposing it (Starling forces)
 Pc + Pi (fluid out) - Pi + Pp (fluid in)
 Pc = Hydrostatic pressure in capillary
 Pi = Colloid osmotic pressure of interstitial fluid
 Pi = Hydrostatic pressure in interstitial fluid
 Pp = Colloid osmotic pressure of blood plasma
Edema
 Normally filtration, osmotic reuptake, and lymphatic drainage maintain proper
ECF levels
 Edema is excessive accumulation of ECF resulting from:
 High blood pressure
 Venous ________________________
 Leakage of plasma proteins into ECF
 Myxedema (excess production of glycoproteins in extracellular matrix)
from hypothyroidism
 Low plasma protein levels resulting from liver disease
 Obstruction of lymphatic drainage
Regulation of Blood Volume by Kidney
 Urine formation begins with filtration of plasma in ______________________
 Filtrate passes through and is modified by nephron
 Volume of urine excreted can be varied by changes in reabsorption of filtrate
 Adjusted according to needs of body by action of hormones
ADH (Vasopressin)
 ADH released by Post Pit when _____________________ detect high osmolality
 From excess salt intake or dehydration
 Causes thirst
 Stimulates H2O reabsorption from urine
 ADH release inhibited by ____________ osmolality
Aldosterone
 Is steroid hormone secreted by adrenal cortex
 Helps maintain blood volume and pressure through ________________________
and retention of salt and water
 Release stimulated by salt deprivation, low blood volume, and pressure
Rennin-Angiotensin-Aldosterone
 When there is a salt deficit, low blood volume, or pressure, _________________
is produced
 Angio II causes a number of effects all aimed at increasing blood pressure:
 Vasoconstriction, aldosterone secretion, thirst
Atrial Natriuretic Peptide (ANP)
 Expanded blood volume is detected by stretch receptors in left atrium and causes
release of ANP
 ANP ___________________ aldosterone, promoting salt and water excretion to
lower blood volume
 And promotes vasodilation
 ANP, together with decreased ADH, acts in a negative feedback system to
_____________________ blood volume
Vascular resistance to blood Flow
 Determines how much blood flows through a tissue or organ
 Vasodilation decreases resistance, _______________________ blood flow
 Vasoconstriction does opposite
Physical Laws Describing Blood Flow
 Blood flows through vascular system when there is pressure difference (DP) at its
two ends
 Flow rate is directly proportional to difference (DP = P1 - P2)
 Flow rate is _______________________ proportional to resistance
 Resistance is directly proportional to length of vessel (L) and viscosity of
blood ()
 Inversely proportional to 4th power of radius
 Poiseuille's Law describes factors affecting blood flow
 Blood flow = DPr4()
L(8)
 Mean arterial pressure and vascular _________________________ are the 2
major factors regulating blood flow
Total Peripheral Resistance
 Sum of all vascular resistances within the _____________________ circulation
 Resistance in arteries supplying tissues and organs determines relative blood flow
Extrinsic Regulation of blood Flow
 ______________________________ activation causes increased CO and
resistance in periphery and viscera
 Blood flow to skeletal muscles is increased
 their arterioles dilate in response to Epi and ACh
 Thus blood is shunted away from visceral and skin to muscles
 Parasympathetic effects are ______________________________
 on digestive tract, genitalia, and salivary glands
 Angiotensin II and ADH (at high levels) cause general vasoconstriction of
vascular smooth muscle
 Which increases resistance and _________________
Paracrine Regulation of Blood Flow
 The endothelium produces several paracrine regulators that promote relaxation:
 Nitric oxide (NO), bradykinin, prostacyclin
 Vasodilator drugs such as nitroglycerin or Viagra act thru NO
 ___________________________ is vasoconstrictor produced by endothelium
Intrinsic Regulation of Blood Flow (Autoregulation)
 Maintains fairly constant blood flow despite BP variation
 Myogenic control mechanisms occur in some tissues because vascular smooth
muscle _______________ when stretched and ____________ when not stretched
 E.g. decreased arterial pressure causes cerebral vessels to dilate and vice
versa
 Metabolic control mechanism matches blood flow to local tissue needs
 Low O2 or pH or high CO2, adenosine, or K+ from high metabolism cause
vasodilation which increases blood flow (active ______________________)
Aerobic Requirements of the Heart
 Heart (and brain) must receive adequate blood supply at all times
 Heart is most aerobic tissue--each myocardial cell is within 10 m of capillary
 Contains lots of mitochondria and aerobic enzymes
 In _______________________, coronary vessels are occluded
 Myoglobin stores O2 and releases O2 to heart during systole
Regulation of Coronary Blood Flow
 Blood flow to heart is affected by Symp activity
 NE causes vasoconstriction; Epi causes vasodilation
 Dilation accompanying exercise is due mostly to _________________ regulation
Regulation of Blood Flow Through Skeletal Muscles
 At rest, flow through skeletal muscles is low because of tonic sympathetic activity
 Flow through muscles is decreased during _________________________
because vessels are constricted
Circulatory changes During Exercise
 Start of exercise, Epi and local ACh causes vasodilation
 Blood flow is shunted to active skeletal muscles
 Blood flow to __________________ stays same
 Exercise continues, Symp effects increase SV and CO
 HR and ejection fraction increases vascular resistance
Cerebral Circulation
 Gets about 15% of total ___________________________ CO
 Held constant (750ml/min) over varying conditions
 Because loss of consciousness occurs after few secs of interrupted flow
 Is not normally influenced by sympathetic activity
 Regulated almost exclusively by intrinsic mechanisms
 When BP __________________________, cerebral arterioles constrict;
and vice versa (myogenic regulation)
 Arterioles respond to changes in _______________ levels
 Areas of brain with high metabolic activity receive most blood (metabolic
regulation)
Cutaneous Blood Flow
 Skin serves as a heat exchanger for thermoregulation
 Skin blood flow is adjusted to keep deep-body at 37oC
 By arterial dilation or constriction and activity of ____________________
anastomoses which control blood flow through surface capillaries
Blood Pressure (BP)
 Blood flow to capillaries and BP is controlled by aperture of arterioles
 Capillary BP is ___________________________ because they are downstream of
high resistance arterioles
 Capillary BP is also low because of large total cross-sectional area
 Is controlled mainly by HR, SV, and peripheral resistance
 An increase in any of these _________________________ BP
 Sympathoadrenal activity raises BP via arteriole vasoconstriction and by
increased CO
 Kidney affects BP by regulating blood volume and thus stroke volume
Baroreceptor Reflex
 Baroreceptors (___________________ receptors) in aortic arch and carotid
sinuses detect increased BP
 stretched walls causes baroreceptors to send APs to vasomotor and
cardiac control centers in medulla
Measurement of Blood Pressure
 Via _____________________________ (to examine by listening)
 No sound is heard during laminar flow (normal, quiet, smooth blood flow)
 Korotkoff sounds can be heard when ___________________________ cuff
pressure is greater than diastolic but lower than systolic pressure
 Cuff constricts artery creating ___________________________ and noise
as blood passes constriction during systole and is blocked during diastole
 1st Korotkoff sound is heard at pressure that blood is 1st able to pass thru
cuff; last occurs when one can no long hear systole because cuff pressure
= diastolic pressure
 Blood pressure cuff is inflated above ______________________ pressure,
occluding artery
 As cuff pressure is lowered, blood flows only when systolic pressure is above cuff
pressure, producing Korotkoff sounds
 Sounds are heard until cuff pressure ________________________ diastolic
pressure, causing sounds to disappear
Pulse Pressure
 Pulse pressure = (systolic pressure) – (diastolic pressure)
 Mean arterial pressure (MAP) represents average arterial pressure during cardiac
cycle
 Has to be approximated because period of diastole is _________________
than period of systole
 MAP = diastolic pressure + 1/3 pulse pressure
Hypertension
 Blood pressure in excess of normal range for age and gender (> 140/90 mmHg)
 Afflicts about 20% of adults
 Most common type is primary or _________________________ hypertension
 Secondary hypertension is caused by known disease processes
Essential Hypertension
 Increase in peripheral resistance is universal
 CO and HR are elevated in many
 Secretion of renin, Angio II, and aldosterone is _____________________
 Sustained high stress and high salt intake act synergistically
 Prolonged high BP causes atherosclerosis
 ____________________ unable to properly excrete Na+ and H2O
Dangers of Hypertension
 Patients are often asymptomatic until substantial vascular damage occurs
 Increases workload of the heart leading to ventricular hypertrophy and
_________________________ heart failure
 Often damages cerebral blood vessels leading to stroke
 These are why it is called the "silent killer"
Treatment of Hypertension
 Includes lifestyle changes: cessation of ___________________, moderation in
alcohol intake, weight ___________________, exercise, reduced Na+ intake,
increased K+ intake
 Drug treatments include _____________________ to reduce fluid volume, betablockers to decrease ____________, calcium blockers, ACE inhibitors to
_________________ formation of Angio II, and Angio II-receptor blockers
Circulatory Shock
 Occurs when there is inadequate blood flow to, and/or O2 usage by, tissues
 Sometimes shock becomes irreversible and death ensues
Hypovolemic Shock
 Is circulatory shock caused by low ________________________ volume
 E.g. from hemorrhage, dehydration, or burns
 Characterized by decreased CO and BP
 Results in low BP, _____________pulse, cold clammy skin, low urine output
Septic Shock
 Refers to dangerously low blood pressure resulting from sepsis (infection)
 Mortality rate is high (50-70%)
 Bacteria release endotoxin which induces NO production causing _____________
and resultant low BP
Other Causes of Circulatory Shock
 Severe allergic reaction can cause a rapid fall in BP called __________________
 Due to generalized release of histamine causing vasodilation
 Rapid fall in BP called neurogenic shock can result from spinal cord damage or
anesthesia
 Cardiogenic shock results from cardiac failure resulting from ________________
causing significant myocardial loss
Congestive Heart Failure
 Occurs when CO is insufficient to maintain blood flow required by body
 Caused by MI (most common), ______________________ defects, hypertension,
aortic valve stenosis, disturbances in electrolyte levels
 Treated with ______________________, vasodilators, and diuretics