A&p.2.exam.2.cardio

Front 1

what is the coronary blood supply?

Back 1

supplies the heart with oxygenated blood and then goes back to heart to get oxygenated again

Front 2

what are the two walls of the pericardium?

Back 2

1. fibrous pericardium (pericardial sac)
2. serious pericardium

Front 3

where is the fibrous pericardium located?

Back 3

it goes up around the vessels and attaches to diaphragm

Front 4

what are the three main functions of the fibrous pericardium?

Back 4

1. protects
2. anchors
3. prevents overfilling because of dense CT=prevents overstretching

Front 5

what are the two layers of the serous pericardium?

Back 5

1. parietal layer (parietal pericardium)- fused to fibrous pericardium; very thin and smooth which allows mvmt of the heart
2. visceral layer (epicardium)- adheres to heart surface

Front 6

what are the three layers of the heart wall?

Back 6

1. epicardium
2. myocardium
3. endocardium

Front 7

what is the myocardium?

Back 7

-muscular wall that forms both atria and ventricles
-75% of heart wall

Front 8

how are muscle cells tethered together in the myocardium?

Back 8

by crisscrossing CT fibers

Front 9

what is the arrangement of the myocardium?

Back 9

arranged in spiral or circular bundles

Front 10

what is the endocardium?

Back 10

-inner surface- lines heart chambers
-covers fibrous skeleton of valves

Front 11

what is the endocardium continuous with?

Back 11

endothelial linings of blood vessels leaving and entering the heart

Front 12

what is the epicardium?

Back 12

-visceral pericardium
-covers the outer surface of heart
-consists of an exposed mesothelium and loose areolar CT

Front 13

what four characteristics differentiate cardiac muscle tissue from skeletal?

Back 13

1. small cell size
2. single, central nucleus
3. branching interconnections between cells
4. specialized intercellular connections

Front 14

what do cardiac muscle cells obtain the energy they need to continue contracting from?

Back 14

aerobic metabolism because the sarcoplasm contains many mitochondria and myoglobin

Front 15

where and how are cardiac muscle cells bound together?

Back 15

at intercalated discs by desmosomes and gap junctions

Front 16

what do gap junctions allow?

Back 16

direct electrical connection

Front 17

why has cardiac muscle been called a functional syncytium?

Back 17

because the cells are mechanically, chemically, and electrically connected to one another, the entire tissue represents a single, enormous muscle cell

Front 18

where is the heart located?

Back 18

in the mediastium, suspended within the pericardial cavity

Front 19

what does the paricardial cavity contain?

Back 19

pericardial fluid that reduces friction between the opposing surfaces as the heart beats

Front 20

what is cardiac tamponade?

Back 20

occurs when traumatic injuries damage the pericardium or chest wall and can result in fluid accumulation in the cavity which can restrict the mvmt of the heart

Front 21

what are sulci?

Back 21

shallow grooves that mark the boundaries between the atria and ventricles and between the right and left ventricles

Front 22

what does the CT of the epicardium generally contain?

Back 22

a lot of fat

Front 23

explain the walls of the two atria

Back 23

thin musclular walls that are highly expandable

Front 24

what is an auricle?

Back 24

in the atrium and is an expandable extension

Front 25

what is the coronary sulcus?

Back 25

deep groove border between the atria and ventricles

Front 26

what is the ligamentum anteriosum?

Back 26

-attaches the pulmonary trunk to the aortic arch

Front 27

what is the anterior interventricular sulcus?

Back 27

boundary between the left and right ventricles

Front 28

what veins is the left atrium connected to?

Back 28

pulmonary veins

Front 29

what veins is the right atrium connected to?

Back 29

coronary veins and vena cavae

Front 30

what is the coronary sinus?

Back 30

-carries blood collected from the myocardium
-conveys blood to right atrium

Front 31

what is the posterior interventricular sulcus?

Back 31

boundary between left and right ventricles

Front 32

what does the coronary circulation supply?

Back 32

blood to the myocardium because it needs its own separate blood supply

Front 33

where are coronary arteries?

Back 33

originate in the base of the aorta, where BP is highest

Front 34

myocardial flow is not steady. explain

Back 34

it peaks while the heart muscle is relaxed and almost ceases when it contracts

Front 35

what do marginal arteries from the right coronary artery supply blood to?

Back 35

the surface of the right ventricle

Front 36

where does the left coronary artery supply blood to?

Back 36

the left ventricle, left atrium, and interventricular septum

Front 37

what supplies the posterior interventricular artery?

Back 37

the right coronary artery

Front 38

what does the posterior interventricular artery suuply blood to??

Back 38

the interventricular septum and adjacent portions of the ventricles

Front 39

what do the anterior cardiac veins drain and empty into?

Back 39

drain the anterior surface of the right ventricle and empty into the right atrium

Front 40

what does the great cardiac vein drain blood from?

Back 40

the region supplied by the anterior interventricular artery

Front 41

where does the coronary sinus open into?

Back 41

the right atrium

Front 42

where does the small cardiac vein recieve blood from? where does it empty into?

Back 42

recieved from the right atrium and ventricle
-empties into the coronary sinus

Front 43

what is elastic rebound?

Back 43

everytime the left ventricle contracts, it forces blood into the aorta which stretches the elastic walls of the aorta

Front 44

where does elastic rebound push blood?

Back 44

forward into the systemic circuit and backward into the coronary arteries

Front 45

what separates the atria?

Back 45

interatrial septum

Front 46

what separates the ventricles

Back 46

the thicker interventricular septum

Front 47

what do atrioventricular (AV) valves permit?

Back 47

blood flow in one direction only, atria->ventricle

Front 48

what three veins does the right atrium recieve blood from?

Back 48

the superior vena cava
the inferior vena cava
the coronary sinus

Front 49

what what is the fossa ovalis?

Back 49

-right atrium
-remnant of the foramen ovale in the embry
-depression in the wall of the interatrial septum

Front 50

where are the pectinate muscles?

Back 50

-right atrium
-the anterior wall of the right atria and continues up to the auricle of right atrium

Front 51

from the right atrium, what does the blood pass through to the right ventricle?

Back 51

the tricuspid valve

Front 52

from the right ventricle, where does blood pass through to get to the pulmonary trunk?

Back 52

the pulmonary valve

Front 53

what is the chordae tendineae?

Back 53

-ventricle (right in this case)
tendinous chords that connect the AV valve (tricuspid) to papillary muscles

Front 54

what is trabeculae carnea?

Back 54

raised bundles of cardiac muscle fibers on the inner surface of ventricles

Front 55

what are the walls of the left atrium like?

Back 55

-inside of walls are smooth
-same thickness as right atrium

Front 56

where does the left atrium recieve blood from?

Back 56

the lungs through 4 pulmonary veins

Front 57

where are the pectinate muscles in the left atrium?

Back 57

confined to the auricle

Front 58

from the left atrium, where does the blood pass through to get to the left ventricle?

Back 58

the bicuspid valve

Front 59

why does the left ventricle have the thickest wall?

Back 59

because it is pumping to the entire body

Front 60

what type of arteries does the left ventricle consist of?

Back 60

coronary arteries

Front 61

from the left ventricle, where does the blood pass through to the aorta?

Back 61

the aortic valve

Front 62

what part of the left ventricle carry blood throughout the body?

Back 62

branches of aortic arch and descending aorta

Front 63

why does the right ventricle have a thin wall?

Back 63

because it doesnt need to work hard to push blood since lungs are close and pulmonary vessels are short and wide

Front 64

when the right ventricle contracts, where does it squeeze the blood?

Back 64

against the thick wall of the left ventricle; develops low pressures

Front 65

what three things happen when the left ventricle contracts?

Back 65

1. the diameter of the ventricular chamber decreases
2. the distance between the base and apex decrease
(toothpaste)
3. reduces the volume of the right ventricle (why some people can live if right ventricle is damaged)

Front 66

what are aortic sinuses?

Back 66

-saclike dilations adjacent to each cusp
-where the coronary arteries originate

Front 67

what happens when ventricles relax?

Back 67

when ventricles relax, so do papillary muscles. chordae tendinae are loose, valves open, and cusps project into the ventricles

Front 68

when ventricles contract what happens to the valves and why?

Back 68

-they close because the papillary muscles contract to prevent valves from backflow in response to high pressure

Front 69

as the ventricular pressures rise above those in the pulmonary and systemic circuits, what happens?

Back 69

the aortic and pulmonary valves open and blood flows out of the ventricles

Front 70

what is the cardiac skeleton?

Back 70

dense bands of tough elastic tissue that encircle the heart valves

Front 71

what are the two functions of the cardiac skeleton?

Back 71

1. stabilize the positions of the heart valves and ventricular muscle cells
2. isolate the ventricular myocardium from the atrial myocardium

Front 72

where are the semilunar valves?

Back 72

in the pulmonary and aortic valve, each contain three semilunar valves

Front 73

what do semilunar valves do?

Back 73

-allow ejection and prevent backflow

Front 74

explain the blood flow of the semilunar valves?

Back 74

pressure builds up as ventricles contract, pushing blood out. as ventricles relax, cusps fill up causing closure

Front 75

what are the 4 steps of contraction?

Back 75

1. begins at SA node (spontaneous depolarization) across both atria and reaches AV node
2. AV node enter atrial septum and passes bundle of HIS (AV bundle)
3. travels left and right bundle branches to apex
4. signal passes upwards to base via perkinje fibers

Front 76

what happens if SA node is damaged during a contraction?

Back 76

AV node takes over

Front 77

what happens if both the SA node and AV node are damaged?

Back 77

the bundlee of HIS takes over (20-30 beats)

Front 78

what is systole and what does the chamber do?

Back 78

contraction

Front 79

what is diastole and what does the chamber do?

Back 79

relaxation

Front 80

what is cardiac cycle determined by?

Back 80

atria

Front 81

what happens to the phases of the cardiac cycle when HR increases?

Back 81

are shortened

Front 82

when heart rate increases, what phase has the greatest reduction?

Back 82

diastole by almost 75%

Front 83

what are the eight stages of a cardiac cycle?

Back 83

1. chambers relaxed and ventricles partially filled
2. atrial systole
3. atrial diastole
4. ventricular systole- first phase; isovolumentric contration
5. ventricular systole- second phase
6. ventricular diastole- early
7. isovolumetric relaxation
8. ventricular diastole- late

Front 84

what happens during atrial systole?

Back 84

atria contract filling ventricles

Front 85

what is atrial diastole?

Back 85

atrial systole ends and this continues until start of next cycle

Front 86

when does ventricular systole begin?

Back 86

when atrial systole ends

Front 87

what happens during the first phase of ventricular systole?

Back 87

contraction closes AV vales but not enough pressure to open semilunar valves

Front 88

what is isovolumetric contraction?

Back 88

when AV valves close but not enough pressure is created to open semilunar valves

Front 89

what happens during the second phase of ventricular systole?

Back 89

pressure rises and exceeds pressure in arteries, semilunar valves open and blood is forced out

Front 90

what is ventricular ejection?

Back 90

when blood is forced out during ventricular systole

Front 91

what happens during early ventricular diastole?

Back 91

ventricles relax, pressure drops, blood flows back and forced semilunar valves closed

Front 92

what is isovolumetric relaxation?

Back 92

when blood flows into the relaxed atria but AV valves are closed

Front 93

what happens during late ventricular diastole?

Back 93

all chambers relaxed, ventricle begins passively filling

Front 94

what is a dicrotic notch and when does it occur?

Back 94

double beating; occurs when semilunar valves close, pressure rises again and the elastic arterial walls recoil

Front 95

what does S1 ("lubb") mark the start of?

Back 95

ventricular contraction

Front 96

when does S2 occur?

Back 96

when the semilunar valves close

Front 97

what causes S3?

Back 97

blood flowing into the ventricles

Front 98

what causes S4?

Back 98

atrial contraction

Front 99

what is the best overall indicator of peripheral blood flow?

Back 99

cardiac output CO

Front 100

what two factors does cardiac output depend on?

Back 100

stroke volume (SV) and heart rate

Front 101

what is stroke volume

Back 101

the amount of blood pumped out of the ventricle during a single heartbeat

Front 102

what is the conducting system?

Back 102

responsible for initiating and distributing the stimulus to contract

Front 103

how does the heartbeat begin?

Back 103

with an AP by an SA node in the right atrium

Front 104

where are conducting cells in the atria found?

Back 104

internodal pathways

Front 105

what do internodal pathways do?

Back 105

distribute the contractile stimulus to atrial muscle cells toward ventricles

Front 106

where is the AV node located?

Back 106

bwteen the atria and ventricles
-dont effect heart rate

Front 107

if SA node is damaged, at what rate ill the AV node begin generates impules?

Back 107

40-60 beats/min

Front 108

what are purkinje fibers?

Back 108

-large-diameter conducting cells that propagate action potentials rapidly
-final link in distribution network

Front 109

what are purkinje fibers responsible for?

Back 109

the depolarization of the ventricular myocardial cells that triggers ventricle systole

Front 110

where do the AV nodes deliver the stimulus to/

Back 110

AV bundles

Front 111

what is the AV bundle?

Back 111

only electrical connection between the atria and the ventricles

Front 112

what does the AV bundle lead to?

Back 112

the bundle branches
-left bundle branch is much bigger than right

Front 113

what are the five steps of distribution of the contractile stimulus?

Back 113

1. AP generate by SA node-atrial activation
2. stimulus speads by cell-to-cell contact to AV node
3. 100-msec delay at AV node- atrial contraction
4. atrial contraction completed, impulse within AV bundle which branches to Purkinje fibers- ventricular contraction
5. purkinje cells distribute impulse and is relayed through ventricular myocardium

Front 114

after atrial contraction, how and where does the impulse travel?

Back 114

travels within the AV bundle which branches to the purkinje cells through the moderator band to the papillary muscles

Front 115

what is the maximum rate an AV node can conduct?

Back 115

230 beats/min- maximum normal HR

Front 116

what is the prepotential or pacemaker potential?

Back 116

gradual depolarization due to an instable resting potential produced by the nodes

Front 117

why does the SA node establish the HR?

Back 117

because spontaneous depolarization is fastest at the SA node so it reaches threshold first

Front 118

what is the effect of parasympathetic stimulation on the heart rate?

Back 118

-K+ channels open which slows the rate of depolarization and extends the duration of repolarization
-decline in HR

Front 119

what is the effect of sympathetic stimulation on the heart rate?

Back 119

-opening of ion chaneels that increase depolarization and shorten repolarization
-HR increases

Front 120

what is the normal range of a resting heart rate?

Back 120

60-100 bpm

Front 121

where are the autonomic headquarters for cardiac control contained?

Back 121

within the medulla oblagata

Front 122

what does the cardoinhibitory center control?

Back 122

parasympathetic neurons that slow the HR

Front 123

what does cardiacceleratory center control?

Back 123

sympatheric neurons that increase HR

Front 124

where does sympathetic innervation arrive and what do they innervate?

Back 124

arrives in postganglionic fibers and these fiber innervate conduction system, nodes, and the atrial and ventricular myocardium

Front 125

where does the parasympathetic innervation arrive and what do they synapse with?

Back 125

arrives in the vagus nerve and synapses with the ganglion cells

Front 126

what is innervated in parasympathetic innervation?

Back 126

nodes and atrial musculature; ventricular musculature is very limited

Front 127

what is the end-diastolic volume (EDV)?

Back 127

amount of blood in a ventricle at the end of diastole (pump is just filled)

Front 128

what is end-systolic volume (ESV)?

Back 128

blood that remains in the ventricle at the end of ventricular systole

Front 129

what is the stroke volume in correlation with ESV and EDV?

Back 129

it is the difference between the two

Front 130

what are the normal values at rest for:
1. EDV
2. ESV
3. SV
4. HR
5. CO

Back 130

1. 125 ml
2. 50 ml
3. 75 ml
4. 60-80 bpm
5. 5L/min; ~1.3 gallons

Front 131

what is EDV influenced by?

Back 131

venous return and filling time

Front 132

what is venous return?

Back 132

amount of venous blood delivered ti heart by the venae cavae (pulmonary veins) each minute

Front 133

what factors determine venous flow?

Back 133

-blood volume-decreased amounts decreases return
-muscular activity- contraction increases return
-the rate of blood flow- accelerated blood flow increases return

Front 134

what is filling time?

Back 134

the duration of ventricular diastole

Front 135

what does slowing the HR do to the EDV?

Back 135

increases the EDV

Front 136

what is the preload?

Back 136

-amount of myocardiac stretching
-larger the EDV, larger the preload

Front 137

what is the Frank-Starling law of the heart?

Back 137

the greater the EDV the greater the SV because it produces more powerful contractions and ejects more blood

Front 138

what is contractility?

Back 138

-the amount of force produced during a contraction at a given amount of preload

Front 139

what type of activation increases contractility/

Back 139

sympathetic

Front 140

what increases contractility? decreases it?

Back 140

increase- many hormones (E, NE)
decrease- many clinical drugs

Front 141

what is the afterload?

Back 141

the amount of tension the contracting ventricle must produce to force open the semilunar valve and eject blood

Front 142

explain the correlation between afterload and ESV and why?

Back 142

the greater the afterload, the longer the period of isovolumetric contraction, the short the duration of ventricular ejection, and the larger the ESV

Front 143

what is the afterload increased by?

Back 143

any factor that restricts blood flow

Front 144

what is ESV influenced by?

Back 144

contractility and afterload

Front 145

what is the P wave?

Back 145

depolarization of the atria

Front 146

what is the QRS complex?

Back 146

appears as ventricles depolarize; strong electrical signal; complex signal

Front 147

what doe sthe peak of R wave mark?

Back 147

the beginning of ventricular contraction

Front 148

what is the T wave?

Back 148

ventricular repolarization

Front 149

what is the Q-T interval?

Back 149

the time required for the ventricles to undergo a single cycle

Front 150

what are cardiac arrhythmias?

Back 150

abnormal patterns of cardiac electrical activity

Front 151

what is cardiac reserve?

Back 151

in abdomen and skin (in capillary beds)
-the difference between resting and maximal CO

Front 152

what are the normals of cardiac reserve for rest, light exercise, heavy exercise, and trained athlete?

Back 152

rest: 5-6 L/min (1.5 gal)
light: 9.5 L/min (2.5 gal)
heavy: 17.5 L/min (4.5 gal)
trained: 30 L/min (7.5 gal)

Front 153

what is myocardial contractility?

Back 153

contractile strength achieved at any given muscle length (independent of muscle stretch and EDV)

Front 154

what happens to calcium influx during AP?

Back 154

greater influx to get more to sarcolemma from cytoplasm

Front 155

what effect does enhanced contractility have on SV? ESV?

Back 155

SV- increase
ESV- decrease

Front 156

what two factors play a role in the extrinsic regulation of SV?

Back 156

1. increased sympathetic stimulation
2. glucagon, thyroxine, and high levels of Ca+

Front 157

what happens with sympathetic stimulation such as NE/E in regulating SV

Back 157

increase in Ca+ entry which promoted cross bridge binding

Front 158

when does sympathetic system release NE?

Back 158

when activated by emotional or physical stressors

Front 159

in general what happens when symp. nervous system is activated?

Back 159

-pacemaker fires more rapidly, heart beats faster
-enhances contractility speeds relaxation

Front 160

how does the sympatheric system enhance contractility which speeds relaxation?

Back 160

-enhances Ca+ movements in cells
-ESV falls as a result so SV doesnt decline

Front 161

what effect does parasympathetic division have on contractility?

Back 161

no effect

Front 162

what are the three layers of blood vessels?

Back 162

1. tunica intima
2. tunica media
3. tunica externa

Front 163

what is the tunica intima?

Back 163

-innermost, interna
-includes endothelial lining
-elastic fibers

Front 164

what is the internal elastic membrane?

Back 164

-in arteries of the tunica intima
-contain thick layer of elastic fiber

Front 165

what is the tunica media?

Back 165

-middle layer
-contains smooth muscle tissue

Front 166

what is vasodilation?

Back 166

when smooth muscles relax and diameter increases

Front 167

what is vasoconstriction?

Back 167

smooth muscles contract, vessel diameter decreases

Front 168

what is the tunica externa?

Back 168

-outermost layer; tunica adventida
-connective tissue sheath

Front 169

what does the tunica externa contain in arteries?

Back 169

collagen fibers with scattered bands of elastic fibers

Front 170

what does the tunica externa contain in veins?

Back 170

-thicker than tunica media
-network of elastic fibers and smooth muscle cells

Front 171

what is a large vein?

Back 171

-includes the superior and inferior vena cavae
-tunica externa consists of elastic and collagen fibers

Front 172

how big are medium-sized veins?

Back 172

-2-9mm

Front 173

what does the tunica externa contain of medium sized veins?

Back 173

smooth muscle cells, elastic and collagen fibers

Front 174

what are venules?

Back 174

-they collect blood from capillary beds
-smallest venous vessels
-lack a tunica media and resemble expanded capillaries

Front 175

what are elastic arteries?

Back 175

-transport blood away from heart
-pulmonary trunk and aorta

Front 176

what are muscular arteries?

Back 176

medium sized arteries that distribute blood to the bodys skeletal muscles and internal organs

Front 177

what are arterioles?

Back 177

-have poorly defines tunica externa
-tunica media consists of only one or two layers of smooth muscle cells

Front 178

what are capillaries?

Back 178

only blood vessel whos walls permit exchange between the blood and surrounding interstsitial fluids

Front 179

why can exchange in capillaries occur quickly?

Back 179

because the walls are thin and diffusion distances are short

Front 180

what are the five general classes of blood vessels?

Back 180

1. arteries
2. arterioles
3. capillaries
4. venules
5. veins

Front 181

what are arteries?

Back 181

they carry blood away from the heart and branch repeatedly forming arterioles

Front 182

what are arterioles?

Back 182

smallest arterial branches that pushes blood into capillaries

Front 183

fromthe capillaries, where does the blood flow?

Back 183

enters small venules that form veins

Front 184

what are veins?

Back 184

return blood to the heart

Front 185

what does a typical capillary consist of?

Back 185

-a tube of endothelial cells within a delicate basal lamina
-lacks a tunica media and a tunica externa

Front 186

what two types of capillaries are there?

Back 186

continuous and fenestrated

Front 187

what are continuous capillaries?

Back 187

-endothelium is the complete lining
-in all tissues except epithelia and cartilage

Front 188

what do continuous capillaries permit?

Back 188

the diffusion of water, small solutes, and lipid soluble materials

Front 189

what do continuous capillaries prevent?

Back 189

the loss of blood cells and plasma proteins

Front 190

in specialized continuous capillaries, how are endothelial cells bound together?

Back 190

by tight junctions causing permeability to be restricted and regulated

Front 191

what do fenestrated capillaries contain?

Back 191

"windows" or pores that penetrate the endothelial lining

Front 192

what do fenestrated capillaries permit?

Back 192

the rapid exchange of water and solutes between the plasma and interstitial fluid

Front 193

what are sinusoids?

Back 193

-resemble fenestrated capillaries flat and irrgeularly shaped
-have gaps between adjacent cells
-basal lamina is thin or absent

Front 194

what do sinusoids permit?

Back 194

free exchange of water and solute between slow-moving blood and interstitial fluid

Front 195

where domany sinusoids occur?

Back 195

liver, bone marrow, spleen, and many endocrine organs

Front 196

what are collateral arteries?

Back 196

when capillary bed recieves blood from more than one artery
-fuse before giving rise to arterioles

Front 197

what is arterial anastomosis?

Back 197

like an insurance policy; if one artery is compressed or blocked, capillary circulation will continue

Front 198

what is a precapillary sphincter?

Back 198

the band of smooth muscle that guards the entrance to each capillary

Front 199

what is arteriovenous anastomosis?

Back 199

-a direct connection between arteriole and a venule
-when dilated, will flow directly into venous circulation

Front 200

what are these anastomoses regulated by?

Back 200

sympatheric innervation

Front 201

what do capillary beds contain?

Back 201

-direct connections between arterioles and venules

Front 202

what is a metarteriole?

Back 202

the wall in the initial part of the direct passageway (provided by the capillary beds)

Front 203

what is the thoroughfare?

Back 203

the rest of the passageway

Front 204

what is vasomotion?

Back 204

the cycling of contraction and relaxation of the smooth muscles that control the blood flow through the capillary beds

Front 205

what are valves?

Back 205

-fold of the tunica intima that project from vessel valls and point in the direction of blood flow

Front 206

what happens if the walls of the veins near the valves weaken, stretch, or become distorted?

Back 206

valves may no longer work properly

Front 207

what are varicose veins?

Back 207

superficial in the thighs and legs that causes mild discomfort and cosmetic problems

Front 208

what are hemorrhoids?

Back 208

painful distortion of tissues in the anal canal

Front 209

how do valves ddivide the weight of the blood?

Back 209

through compartmentalizing

Front 210

what do valves above the contracting muscles do?

Back 210

open and allow blood to move toward the heart

Front 211

what do valves below the contracting muscles do?

Back 211

close and prevent backflow

Front 212

how does the body maintain blood volume with the arterial system at near-normal levels?

Back 212

by reducing the volume of the blood in the venous system through venoconstriction

Front 213

what is venoconstriction?

Back 213

reducing the blood diameter of the veins and the amount of blood contained in the venous system

Front 214

where does blood enter the general circulation from?

Back 214

liver, bone marrow, and skin

Front 215

(endocrine2) what three factors regulate the heart rate?

Back 215

1. ANS
2. parasympathetic division
3. chemicals

Front 216

what chemicals regulate the heart rate?

Back 216

hormones such as epinephrine (adrenal medulla), thyroxine (thyroid), and ions

Front 217

what does thyroxine do?

Back 217

-causes a slower but more sustained increase in HR
-enhances effects of NE/E

Front 218

how do ions regulate heart rate?

Back 218

plasma electrolyte balance must be maintained

Front 219

what does hypocalcemia do?

Back 219

supresses the heart; too little calcium

Front 220

what does hypercalcemia do?

Back 220

prolongs the plateau phase of AP

Front 221

what does hyperkalemia do?

Back 221

interferes with depolarixation (lowers resting potential)- cardiac arrest

Front 222

when does blood pressure fall progressively?

Back 222

as the distance from the left ventricle increases

Front 223

what is capillary exchange?

Back 223

primary focus of the cardiovascular system; pressures are very low so blood flows slowly allowing plenty of time for diffusion

Front 224

what is total peripheral resistance?

Back 224

resistance of the entire cardiovascular system

Front 225

what three factors does total peripheral resistance depend on?

Back 225

1. resistance
2. viscosity
3. turbulence

Front 226

what is peripheral resistance?

Back 226

resistance of the arterial system as a whole

Front 227

what is vascular resistance?

Back 227

resistance of the blood vessels
-largest component of total peripheral resistance
-results from friction between blood and the vessel walls

Front 228

what two factors does the amount of friction depend on?

Back 228

1. vessel length
2. vessel diameter

Front 229

what is the relationship between friction and vessel length?

Back 229

-friction occurs between moving blood and the walls of the vessel
-longer the vessel, greater the surface area in contact with the blood, and the greater the resistance

Front 230

when do you see the most dramatic changes in blood vessel length?

Back 230

birth and maturity
-considered constant in adults

Front 231

what is the relationship between friction and vessel diameter?

Back 231

-friction occurs between layers of fluid moving at different speeds
-in small diameter vessel, blood is slowed and resistance is high vise versa with large diameter

Front 232

what does R=1/r4 mean?

Back 232

vessel radius (r), resistance (R)
-means that a small change in vessel diameter produces a large chain in reistance

Front 233

so how do vasomotor centers primarily control peripheral resistance and blood flow?

Back 233

by altering the diameters of the arterioles

Front 234

what is viscosity?

Back 234

resistance to flow caused by interactions among molecules in a liquid (molasses); low viscosity=low pressure

Front 235

what is turbulence?

Back 235

-when the flow of the blood is disturbed by high flow rates, irregular surfaces, and sudden changes in vessel diameter
-increases resistance and slows blood flow

Front 236

when in normal individuals, where does turbulence occur?

Back 236

1. when blood flows between the atria and the ventricles
2. between the ventricles and the aortic and pulmonary trunks

Front 237

what is turbulent flow responsible for?

Back 237

the production of the third and fourth heart sounds

Front 238

what is a pressure gradient?

Back 238

the difference in pressure from one end of the vessel to the other

Front 239

where is the largest pressure gradient found?

Back 239

between the base of the aorta and the ends of peripheral capillary beds

Front 240

what happens to the diameter of arteries as blood proceeds towards the capillaries? toward the heart?

Back 240

decreases; increases

Front 241

why does blood flow accelerate in the venous system even though pressures are falling?

Back 241

because vessels are merging into large diameter passages with very low resistance

Front 242

what is systolic pressure?

Back 242

highest pressure attainted in arteries during systole (110 mmHg)

Front 243

what is diastolic pressure?

Back 243

the lowest arterial pressure during diastole (70 mmHg)

Front 244

what is the pulse pressure?

Back 244

difference between systolic and diastolic pressures

Front 245

what is the mean arterial pressure (MAP)

Back 245

used to measure how much blood is being pumped out of the heart

Front 246

what thee things does capillary exchange involve?

Back 246

1. diffusion
2. filtration
3. reabsorption

Front 247

what is capillary hydrostatic pressure (CHP)

Back 247

-the blood pressure within the capillary beds
-provides driving force for filtration
-pushes water and small soluble molecules out of the bloodstream and into the interstitial fluid

Front 248

when is diffusion most rapid?

Back 248

1. when distances are short
2. small ions or molecules are involved

Front 249

what is diffusion important for?

Back 249

solute exchange

Front 250

why do rates of filtration and reabsorption gradually change as blood passes along the capillary?

Back 250

because in a capillary, blood pressure declines as blood flows from arterial end to venous end

Front 251

where does filtration predominate?

Back 251

-at the arterial end where CHP is highest

Front 252

what is blood colloid osmotic pressure (BCOP)?

Back 252

plasma osmolarity

Front 253

as filtration occurs, what happens to the BCOP?

Back 253

it increases because water is depearting leaving the larger solutes behind

Front 254

what is filtration important for?

Back 254

the regulation of relative volumes of blood and interstitial fluid

Front 255

what is the net filtration pressure (NFP)?

Back 255

difference between the CHP and the BCOP; large at start of capillary then CHP decreases as water moves out and BCOP increase

Front 256

when CHP falls below BCOP in the final segment, what happens?

Back 256

water flows into the capillary
-more water leaves the blood during filtration than gets retrieves through reabsorption

Front 257

what is interstitial fluid colloid osmotic pressure (ICOP) involved in?

Back 257

filtration; 0 mmHg

Front 258

what is reabsorption?

Back 258

-pressure driven from interstitial fluid into blood capillaries

Front 259

what two mechanisms are involved in reabsorption?

Back 259

1. BCOP 25 mmHg
2. interstitial fluid hyrostatic pressure (IHP) 0 mmHg

Front 260

what does net filtration pressure (NFP) indicate?

Back 260

the direction of fluid movement

Front 261

what is starling law of capillaries?

Back 261

overall the volume of fluid and solutes reabsorbed is almost as large as the volume filtered