exam 3 new

Systemic Circuit

Carries blood between heart and rest of body; Allows blood to release O₂ to tissues, pick up CO₂ as waste; Delivers oxygen to heart and lung tissue as well (Chapter 19, page 3)

Pulmonary Circuit

Carries blood between heart and lungs for gas exchange; Picks up O₂ and releases CO₂ (Chapter 19, page 4)

Blood Vessels

Arteries, veins and capillaries (Chapter 19, page 5)

Pericardium

double-walled sac; Isolates heart from other organs and stabilizes it; Prevents excessive expansion (Chapter 19, page 6)

Parietal pericardium

Outer parietal pericardium (Chapter 19, page 7)

Visceral pericardium

Inner visceral pericardium (epicardium) (Chapter 19, page 7)

Pericarditis

Inflammation of the pericardium; causes friction rub (Chapter 19, page 8)

Cardiac tamponade

Excess fluid accumulates in pericardial sac; Inhibits normal heart contraction (Chapter 19, page 8)

Epicardium (Visceral Pericardium)

Outermost layer; Serous membrane: simple squamous epithelium over areolar tissue (Chapter 19, page 9)

Myocardium

Middle layer formed of cardiac muscle; Thickness proportional to workload on respective heart chamber (Chapter 19, page 10)

Endocardium

Innermost layer continuous with endothelium of blood vessels; Simple squamous epithelium (Chapter 19, page 11)

Atria

Thin-walled upper chambers receiving blood returning to heart (Chapter 19, page 15)

Ventricles

Two lower chambers with thicker walls receiving blood from atria (Chapter 19, page 16)

Atrioventricular Valves

Ensure one-way blood flow from atria to ventricles (Chapter 19, page 17)

Tricuspid valve

right AV valve (Chapter 19, page 17)

Bicuspid valve

left AV valve/mitral valve (Chapter 19, page 17)

Chordae tendineae

connect valves to papillary muscles on ventricle floor (Chapter 19, page 17)

Semilunar Valves

Prevent backflow of blood into ventricles after it leaves heart; Open when ventricles contract to let blood out • Close when pressure in ventricles is less than that of great arteries (Chapter 19, page 19)

Coronary Circulation

Heart has very high O2 and nutrient demand • ~5% of blood is pumped to itself via coronary arteries • Diffusion from heart chambers through myocardium insufficient

Coronary Arteries

Left and right coronary arteries are first arteries to branch off aorta; Provide oxygenated blood to cardiac muscle (Chapter 19, page 24)

Coronary (Cardiac) Veins

Cardiac veins and coronary sinus drain deoxygenated blood from heart muscle (Chapter 19, page 25)

Coronary sinus

drains into right atrium (Chapter 19, page 25)

Thebesian Veins

Network of very small veins that return blood directly to the heart chambers; Most returned to right ventricle (Chapter 19, page 27)

Coronary Artery Disease

Blockage (ischemia) of coronary arteries resulting in reduced blood flow to heart; Typically caused by lipid deposits on arterial walls (Chapter 19, page 28)

Heart Attack

Death of patch of myocardial tissue caused by coronary ischemia (Chapter 19, page 30)

Myogenic

signal originates in the heart itself (Chapter 19, page 32)

Autorhythmic

built-in pacemaker and electrical system (Chapter 19, page 32)

Cardiocytes

Short striated cells linked to adjacent cells by intercalated discs

Intercalated Discs

Plasma membranes of adjacent cells lock by interdigitating folds

cardiac muscle

•Cardiocytes responsible for heart contraction

Metabolism of Cardiac Muscle

Depends exclusively on aerobic respiration to make ATP

•Fatigue resistant

makes little use of anaerobic fermentation or O2 debt mechanisms

Cardiac Conduction System

Coordinates heartbeat by way of pacemaker and conduction pathways through myocardium (Chapter 19, page 41)

Sinoatrial Node (Pacemaker)

Cluster of modified cardiocytes in right atrium; Initiates heartbeat and so determines heart rate (Chapter 19, page 42)

Pacemaker potential

Gradual depolarization (Chapter 19, page 43)

Depolarization Wave

Wave spreads to atrial muscle cells and AV node (Chapter 19, page 44)

Atrioventricular (AV) Node

Excited by SA node firing; sends signal to both ventricles in response (Chapter 19, page 45)

Atrioventricular bundle

passes signal from AV node into atrioventricular septum (Chapter 19, page 46)

Bundle of His

Atrioventricular bundle (Chapter 19, page 46)

Purkinje Fibers

Nerve-like processes off the bundle branches; Transfer signals to cardiocytes in ventricles (Chapter 19, page 47)

Heartbeat

cycle of contraction and relaxation (Chapter 19, page 48)

Systole

atrial or ventricular contraction (Chapter 19, page 48)

Diastole

atrial or ventricular relaxation (Chapter 19, page 48)

Electrocardiogram (EKG)

Electrical basis assessed visually with an electrocardiogram (EKG) (Chapter 19, page 48)

Major EKG Events

P wave, QRS spike, T wave (Chapter 19, page 49)

Ventricular fibrillation

random electrical signals results in no pumping action (Chapter 19, page 52)

Atrial fibrillation (AF; Afib)

weak rippling contraction in atria due to chaotic signals (Chapter 19, page 53)

Premature ventricular contraction (PVC)

ventricular ectopic focus fires and sets off extra beat (Chapter 19, page 54)

Proprioceptors

in muscles and joints inform cardiac centers about changes in activity (Chapter 19, page 58)

Baroreceptors

pressure sensors in aorta and internal carotid arteries (Chapter 19, page 59)

Chemoreceptors

detect chemical stimuli (pH, CO₂, O₂) in aortic arch, carotid arteries, medulla (Chapter 19, page 60)

Chemoreflex

occurs to maintain stable respiratory and cardiovascular function (Chapter 19, page 60)

•Hypercapnia

lowers pH

•Hypoxemia

results in decrease HR

Arteries

carry blood away from heart; Most carry oxygenated blood (Chapter 20, page 2)

Veins

carry blood back to heart; Most carry deoxygenated blood (Chapter 20, page 2)

Capillaries

connect smallest arteries to veins (Chapter 20, page 2)

Tunica Interna

Thin, innermost lining of blood vessel; Simple squamous epithelial cells (endothelium); Continuous with endocardium (Chapter 20, page 4)

Tunica Media

Thick middle layer; Smooth muscle, collagen, and elastic tissue; Strengthens vessel to prevent BP from rupturing it (Chapter 20, page 6)

Tunica Externa

Outermost layer; Loose connective tissue anchoring vessel to surrounding tissues (Chapter 20, page 7)

Conducting Arteries

Largest arteries; Expand during ventricular systole, recoil in diastole, decreasing fluctuations in BP (Chapter 20, page 9)

Distributing Arteries

Medium-sized arteries that carry blood to individual organs (Chapter 20, page 10)

Arterioles

Smallest major class of arteries; control amount of blood delivered to each organ (Chapter 20, page 11)

Aneurysm

Bulging sac in arterial wall, often arising when arterial tissue layers separate (Chapter 20, page 12)

Continuous Capillaries

Endothelium forms continuous tube with tight junctions (Chapter 20, page 15)

Intercellular clefts

allow only small solutes (like glucose) to cross (Chapter 20, page 15)

Pericytes

lie external to epithelial cells (Chapter 20, page 16)

Fenestrated Capillaries

Found in organs with rapid absorption or filtration (Chapter 20, page 17)

Filtration pores

fenestrations (Chapter 20, page 18)

Discontinuous Capillaries (Sinusoids)

Allow large proteins or whole blood cells move to bloodstream (Chapter 20, page 19)

Capillary Beds

Network of capillaries delivering blood to tissues (Chapter 20, page 20)

Proximal metarteriole in Capillary Beds

Enters by way of proximal metarteriole (Chapter 20, page 20)

Thoroughfare channel in Capillary Beds

Departs by distal thoroughfare channel (Chapter 20, page 20)

Precapillary sphincter

Metarteriole muscle cells form precapillary sphincter that regulates blood flow through tissues (Chapter 20, page 21)

Venules

Smallest veins; Site where most WBCs leave bloodstream(Chapter 20, page 24)

Medium Veins

Thin tunica media (Chapter 20, page 25)

Venous Valves

Help ensure steady return of blood to heart (Chapter 20, page 26)

Varicose Veins

Distensions of leg veins due to pooling of blood (Chapter 20, page 28)

Large Veins

Largest class of veins (Chapter 20, page 29)

Venous Sinuses

Veins with very thin walls, large lumens, and no smooth muscle (Chapter 20, page 30)

Pathway of Circulation

Heart, arteries, capillaries, veins, heart

Pathway of Blood

Heart ➔ Conducting artery ➔ Distributing artery ➔ Arteriole ➔ Metarteriole ➔ Capillary ➔ Thoroughfare channel ➔ Venule ➔ Medium vein ➔ Venous sinus ➔ Large vein ➔ Heart

Portal System

Blood flows through two capillary networks before return to heart (Chapter 20, page 34)

Shunt

Artery flows directly into vein, bypassing capillary bed (Chapter 20, page 35)

Arterial anastomoses

when two arteries merge (collateral circulation) (Chapter 20, page 36)

Venous anastomoses

drain blood from an area via multiple routes (Chapter 20, page 36)

Pulmonary Circulation

Pulmonary arteries enter each lung; Pulmonary veins depart lungs (Chapter 20, page 37)

Pulmonary Capillaries

Site of gas exchange with air in lungs (Chapter 20, page 38)

Common Carotids

Each common carotid divides into internal and external carotids (Chapter 20, page 41)

Circle of Willis

Basilar and internal carotid arteries help form Circle of Willis (arterial circle); Arterial anastomosis (Chapter 20, page 42)

Thoracic Aorta

Portion of descending aorta from aortic arch to diaphragm (Chapter 20, page 44)

Celiac trunk

supplies liver, stomach, pancreas, spleen (Chapter 20, page 45)

Mesenteric arteries

supply small and large intestine, pancreas (Chapter 20, page 45)

Renal arteries

supply kidneys (Chapter 20, page 45)

Common iliac arteries

supply legs (Chapter 20, page 45)

Hepatic Portal System

Blood from intestines, stomach, pancreas, and spleen joins together in hepatic portal vein (Chapter 20, page 47)

External jugular vein

receives blood from external parts of head (Chapter 20, page 50)

Brachiocephalic vein

forms from merger of external and internal jugular veins (Chapter 20, page 50)

Superior Vena Cava

Receives blood from upper thorax, head, neck, arms; Deposits blood into right atrium of heart (with inferior vena cava) (Chapter 20, page 51)

Lymphatic System

Organs and vessels that carry fluid (lymph) rich in immune cells; Lymph screened for presence of foreign cells; Closely linked to circulatory system (Chapter 21, page 2)