Heart

Question 1

heart location within thorax

Answer 1

apex lies to the left of the midline

base is broad posterior surface

Question 2

healthy heart weighs ____ grams

Answer 2

250-350 grams

Question 3

4 “corners” of the heart

Answer 3

superior right corner: at costal cartilage of third rib and sternum
inferior right corner: at costal cartilage of sixth rib lateral to the sternum
superior left corner: costal cartilage of second rib lateral to the sternum
inferior left: lies in the fifth intercostal space at the midclavicular line

Question 4

coronary sulcus

Answer 4

contains left and right coronary arteries and coronary sinus

Question 5

anterior interventricular sulcus

Answer 5

contains anterior interventricular artery and great cardiac vein

Question 6

posterior interventricular sulcus

Answer 6

contains posterior interventricular artery and middle cardiac vein

Question 7

coronary artery branches

Answer 7

left: circumflex artery and anterior interventricular artery
right: marginal artery and posterior interventricular artery

Question 8

pericardium: 2 layers

Answer 8

fibrous pericardium - strong layer of dense connective tissue
serous pericardium - parietal and visceral (epicardium)

Question 9

3 layers of the heart

Answer 9

epicardium - visceral pericardium
myocardium - cardiac muscle cells surrounded by conective tissue “fibrous skeleton”
endocardium - simple squamous epithelium and a layer of connective tissue

Question 10

right atrium features

Answer 10

pectinate muscles
fossa ovalis
crista terminalis - C-shaped ridge used to locate veins entering right atrium

Question 11

right ventricle features

Answer 11

trabeculae carneae
papillary muscles
chordae tendineae

Question 12

fibrous skeleton

Answer 12

lies in the plane between the atria and ventricles
surrounds and reinforces all four valves
composed of dense connective tissue
anchors cusps of valves
prevents overdilation of valve openings
main point of insertion for bundles of cardiac muscle in the atria and ventricles
supports proper coordination of atrial and ventricular contractions by blocking direct spread of electrical impulses from atria to ventricles

Question 13

AV valves open when

Answer 13

blood returns to the heart and fills atria
atrial pressure > ventricular pressure forcing atrioventricular valves to open
atria contract, forcing additional blood into ventricles

Question 14

AV valves close when

Answer 14

atrial pressure < ventricular pressure
ventricles contract, forcing blood against AV valve cusps
papillary muscles contract and chordae tighten -> prevents valve flaps from entering into atria

Question 15

semilunar valves

Answer 15

pulmonary and aortic valve
as ventricles contract, intraventricular pressure rises and semilunar valves are forced open
as ventricles relax, blood flows from aorta and pulmonary trunk arteries and semilunar valves are forced shut as cusps fill

Question 16

heart murmur

Answer 16

function/physiologic or pathological
pathological causes - structural problems such as narrowing or leaking of valves, or the presence of abnormal passages through which blood flows in or near the heart

Question 17

where to hear each murmur

Answer 17

pulmonary valve: superior left corner
aortic valve: superior right corner
mitral valve: at the apex
tricuspid valve: inferior right corner

Question 18

heart valve abnormalities

Answer 18

valve insufficiency or incompetence
mitral valve prolapse
valve stenosis

Question 19

mitral valve prolapse

Answer 19

weak collagen or chordae allow one or both cusps to flop back into atrium during ventricular systole
causes blood to flow back into left atrium from left ventricle
most common heart valve disorder

Question 20

myocardium contracts by _____ mechanism

Answer 20

sliding filament mechanism

Question 21

cardiac muscle cells

Answer 21

short compared to skeletal muscle fibers
branching
have one or two nuclei
less apparent striations than in skeletal muscle

Question 22

endomysium

Answer 22

loose fibrous connective tissue
contains blood vessels and nerves that supply muscle cells
binds adjacent cardiac fibers
merges with fibrous skeleton of the heart and thus functions to anchor muscle cells and facilitate transmission of contractile forces

Question 23

fasciae adherens

Answer 23

contained in transverse regions

long desmosome-like junctions that bind adjacent cells together, transmitting contractile forces to adjacent cells

Question 24

gap junctions

Answer 24

contained in longitudinal regions

allow ions to pass between cells, transmitting contractile signal to adjacent cells

Question 25

cardiac muscle contraction

Answer 25

triggered by Ca2+ entering the sarcoplasm

• > small amount of Ca2+ ions from extracellular fluid enter sarcoplasm through the sarcolemma
• > signals T tubules and sarcoplasmic reticulum to release stored Ca2+ ions
• > ions diffuse into the sarcomeres
• > triggers sliding filament mechanism

Question 26

cardiac control centers in the medulla and heart innervation

Answer 26

visceral sensory fibers - can perceive cardiac muscle stress in a person with ischemic heart disease
parasympathetic motor branches of the vagus nerve decrease heart rate
sympathetic motor fibers from cervical/thoracic chain ganglia increase heart rat

Question 27

autonomic nervous system input into heart rate

Answer 27

controlled by cardiac centers in reticular formation of medulla oblongata
cardioinhibitory centers - influence parasympathetic
cardioacceleratory centers influence sympathetic